# Baryon Acoustic Oscillations from Integrated Neutral Gas Observations: an instrument to observe the 21cm hydrogen line in the redshift range 0.13 < z < 0.45 – status update

Carlos A. Wuensche, Elcio Abdalla, Filipe Batoni Abdalla, Luciano Barosi, Bin Wang, Rui An, João Alberto de Moraes Barreto, Richard Battye, Francisco A. Brito, Ian Browne, et al.

► To cite this version:

Carlos A. Wuensche, Elcio Abdalla, Filipe Batoni Abdalla, Luciano Barosi, Bin Wang, et al.. Baryon Acoustic Oscillations from Integrated Neutral Gas Observations: an instrument to observe the 21cm hydrogen line in the redshift range 0.13 < z < 0.45 – status update. Anais da Academia Brasileira de Ciências, 2021, 93 (suppl 1), 10.1590/0001-3765202120201096 . hal-03578696

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# Baryon Acoustic Oscillations from Integrated Neutral Gas Observations: an instrument to observe the 21cm hydrogen line in the redshift range 0.13 < z < 0.45 – status update

Carlos A. Wuensche, Elcio Abdalla, Filipe Batoni Abdalla, Luciano Barosi, Bin Wang, Rui An, João Alberto de Moraes Barreto, Richard Battye, Francisco A. Brito, Ian Browne, et al.

► To cite this version:

Carlos A. Wuensche, Elcio Abdalla, Filipe Batoni Abdalla, Luciano Barosi, Bin Wang, et al. Baryon Acoustic Oscillations from Integrated Neutral Gas Observations: an instrument to observe the 21cm hydrogen line in the redshift range 0.13 < z < 0.45 – status update. Anais da Academia Brasileira de Ciências, 2021, 93 (suppl 1), pp.1-13. 10.1590/0001-3765202120201096. hal-03578696

HAL Id: hal-03578696

https://hal.science/hal-03578696v1

Submitted on 11 Mar 2024

HAL is a multi-disciplinary open access
archive for the deposit and dissemination of sci-
entific research documents, whether they are pub-
lished or not. The documents may come from
teaching and research institutions in France or
abroad, or from public or private research centers.

L'archive ouverte pluridisciplinaire HAL, est
destinée au dépôt et à la diffusion de documents
scientifiques de niveau recherche, publiés ou non,
émanant des établissements d'enseignement et de
recherche français ou étrangers, des laboratoires
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<figure><img src="image_1.png" /></figure>

Distributed under a Creative Commons Attribution 4.0 International License
<figure><img src="image_2.png" /></figure>

## PHYSICAL SCIENCES

# Baryon Acoustic Oscillations from Integrated Neutral Gas Observations: an instrument to observe the 21cm hydrogen line in the redshift range 0.13 < z < 0.45 – status update

CARLOS A. WUENSCHE, ELCIO ABDALLA, FILIPE ABDALLA, LUCIANO BAROSI, BIN WANG, RUI AN, JOÃO A.M. BARRETOS, RICHARD BATTYE, FRANCISCO A. BRITO, IAN BROWNE, DANIEL CORREIA, ANDRÉ A. COSTA, JACQUES DELABROUILLE, CLIVE DICKINSON, CHANG FENG, ELISA G. M. FERREIRA, KARIN FORNAZIER, GIANCARLO DE GASPERIS, PRISCILA GUTIERREZ, STUART HARPER, RICARDO G. LANDIM, VINCENZO LICCARDO, YIN-ZHE MA, TELMO MACHADO, BRUNO MAFFEI, ALESSANDRO MARINS, MILENA M. M. MENDES, EDUARDO MERICIA, CHRISTIAN MONSTEIN, PABLO MOTTA, CAMILA NOVAES, CARLOS H. OTOBONE, MICHAEL PEEL, AMILCAR R. QUEIROZ, CHRISTOPHER RADCLIFFE, MATHIEU REMAZEILLES, RAFAEL M. G. RIBEIRO, YU SANG, JULIANA F.R. SANTOS, LARISSA. SANTOS, MARCELO. V. SANTOS, CHENXI SHAN, GUSTAVO B. SILVA, FREDERICO VIEIRA, JORDANY VIEIRA, THYRSO VILLELA, LINFENG XIAO, WEIQIANG YANG, JIAJUN ZHANG, XUE ZHANG & ZENGHAO ZHU

**Abstract:** BINGO (BAO from Integrated Neutral Gas Observations) is a unique radio telescope designed to map the intensity of neutral hydrogen distribution at cosmological distances, making the first detection of Baryon Acoustic Oscillations (BAO) in the frequency band 980 MHz - 1260 MHz, corresponding to a redshift range 0.127 < z < 0.449. BAO is one of the most powerful probes of cosmological parameters and BINGO was designed to detect the BAO signal to a level that makes it possible to put new constraints on the equation of state of dark energy. The telescope will be built in Paraíba, Brazil and consists of two ~ 40m mirrors, a feedhorn array of 50 horns, and no moving parts, working as a drift-scan instrument. It will cover a 15° declination strip centered at ~ δ = -15°, mapping ~ 5400 square degrees in the sky. The BINGO consortium is led by University of São Paulo with co-leadership at National Institute for Space Research and Campina Grande Federal University (Brazil). Telescope subsystems have already been fabricated and tested, and the dish and structure fabrication are expected to start in late 2020, as well as the road and terrain preparation.

**Key words:** 21cm cosmology, radio astronomy, baryon acoustic oscillations, BAO.
<figure><img src="image_2.png" /></figure>

## PHYSICAL SCIENCES

# Baryon Acoustic Oscillations from Integrated Neutral Gas Observations: an instrument to observe the 21cm hydrogen line in the redshift range 0.13 < z < 0.45 – status update

CARLOS A. WUENSCHE, ELCIO ABDALLA, FILIPE ABDALLA, LUCIANO BAROSI, BIN WANG, RUI AN, JOÃO A.M. BARRETOS, RICHARD BATTYE, FRANCISCO A. BRITO, IAN BROWNE, DANIEL CORREIA, ANDRÉ A. COSTA, JACQUES DELABROUILLE, CLIVE DICKINSON, CHANG FENG, ELISA G. M. FERREIRA, KARIN FORNAZIER, GIANCARLO DE GASPERIS, PRISCILA GUTIERREZ, STUART HARPER, RICARDO G. LANDIM, VINCENZO LICCARDO, YIN-ZHE MA, TELMO MACHADO, BRUNO MAFFEI, ALESSANDRO MARINS, MILENA M. M. MENDES, EDUARDO MERICIA, CHRISTIAN MONSTEIN, PABLO MOTTA, CAMILA NOVAES, CARLOS H. OTOBONE, MICHAEL PEEL, AMILCAR R. QUEIROZ, CHRISTOPHER RADCLIFFE, MATHIEU REMAZEILLES, RAFAEL M. G. RIBEIRO, YU SANG, JULIANA F.R. SANTOS, LARISSA. SANTOS, MARCELO. V. SANTOS, CHENXI SHAN, GUSTAVO B. SILVA, FREDERICO VIEIRA, JORDANY VIEIRA, THYRSO VILLELA, LINFENG XIAO, WEIQIANG YANG, JIAJUN ZHANG, XUE ZHANG & ZENGHAO ZHU

**Abstract:** BINGO (BAO from Integrated Neutral Gas Observations) is a unique radio telescope designed to map the intensity of neutral hydrogen distribution at cosmological distances, making the first detection of Baryon Acoustic Oscillations (BAO) in the frequency band 980 MHz - 1260 MHz, corresponding to a redshift range 0.127 < z < 0.449. BAO is one of the most powerful probes of cosmological parameters and BINGO was designed to detect the BAO signal to a level that makes it possible to put new constraints on the equation of state of dark energy. The telescope will be built in Paraíba, Brazil and consists of two ~ 40m mirrors, a feedhorn array of 50 horns, and no moving parts, working as a drift-scan instrument. It will cover a 15° declination strip centered at ~ δ = -15°, mapping ~ 5400 square degrees in the sky. The BINGO consortium is led by University of São Paulo with co-leadership at National Institute for Space Research and Campina Grande Federal University (Brazil). Telescope subsystems have already been fabricated and tested, and the dish and structure fabrication are expected to start in late 2020, as well as the road and terrain preparation.

**Key words:** 21cm cosmology, radio astronomy, baryon acoustic oscillations, BAO.
# INTRODUCTION

One of the main cosmological challenges in the 21st century is to explain the present acceleration in the expansion of the universe, first unequivocally inferred in 1998 by two independent groups measuring supernovae of type Ia, one led by S. Perlmutter (Perlmutter et al. 1998) and the other by A. Riess (Riess et al. 1998). This led to the 2011 Nobel Prize in Physics and can be explained by postulating a negative pressure from a new component, the so-called Dark Energy (hereafter, DE). In combination with other observations, such as the Cosmic Microwave Background (CMB), there is little doubt about the existence of such an accelerated phase and the main focus of observational cosmology is now to try to determine its detailed properties.

Among the various programs to measure those properties, Baryonic Acoustic Oscillations (BAO) are recognised as one of the most powerful probes of the properties of DE (e.g. Albrecht et al. 2006, Weinberg et al. 2013). BAO are a signature in the matter distribution from the recombination epoch and are imprinted in the distribution of galaxies at redshifts less than that of the epoch of reionization ($z \lesssim 0.5$). In the context of the standard cosmological model (ΛCDM model), BAO can be identified as a small but detectable excess of galaxies with separations of order of 150 Mpc.h$^{-1}$ (Eisenstein et al. 2005, Anderson et al. 2014, Planck Collaboration et al. 2018). This excess is the imprint of the acoustic oscillations generated during CMB times and its linear scale is known from basic physics. Consequently, a measure of its angular scale can be used to determine the distance up to a given redshift. The same oscillations produce the familiar peaks observed in the CMB anisotropy power spectrum.

To date, BAOs have only been detected by performing large galaxy redshift surveys in the optical waveband, where they are used as tracers of the underlying total matter distribution. It is important they are confirmed in other wavebands and measured over a wide range of redshifts. Since optical surveys demand more time to detect individual galaxies and cover a relatively small fraction of the sky, just a few percent of the local volume has been mapped with such a type of technique. The radio band provides a complementary observational window for studying BAO, and the natural radio tracer is the redshifted 21cm emission line. However, the volume emissivity associated with this line is low, meaning that detecting individual galaxies up to $z \sim 0.5$ requires a very substantial collecting area. It has been proposed that mapping the Universe measuring the collective 21cm emission of the underlying matter distribution, using a technique known as intensity mapping, hereafter IM (Loeb & Wyithe 2008, Masui et al. 2013, Switzer et al. 2013, Peterson et al. 2006), can be many times more efficient than optical surveys (e.g., Chang et al. 2008, Loeb & Wyithe 2008).

The BINGO (BAO from Integrated Neutral Gas Observations) telescope is a new instrument designed specifically for observing BAO in frequency band around 1 GHz and to provide a new insight into the Universe at $0.13 \lesssim z \lesssim 0.45$ with a dedicated instrument. The optical configuration consists of a compact, two 40m diameter, static dishes with an exceptionally wide field-of-view ($\sim 12^\circ \times 10^\circ$) and 50 feed horns in the focal plane. BAO observations will be carried through IM HI surveys (see, e.g., Peterson et al. (2006)). BINGO's main scientific goal is to claim the first BAO detection in radio in this redshift range, mapping the three dimensional distribution of HI, yielding a fundamental contribution to the study of DE,
# INTRODUCTION

One of the main cosmological challenges in the 21st century is to explain the present acceleration in the expansion of the universe, first unequivocally inferred in 1998 by two independent groups measuring supernovae of type Ia, one led by S. Perlmutter (Perlmutter et al. 1998) and the other by A. Riess (Riess et al. 1998). This led to the 2011 Nobel Prize in Physics and can be explained by postulating a negative pressure from a new component, the so-called Dark Energy (hereafter, DE). In combination with other observations, such as the Cosmic Microwave Background (CMB), there is little doubt about the existence of such an accelerated phase and the main focus of observational cosmology is now to try to determine its detailed properties.

Among the various programs to measure those properties, Baryonic Acoustic Oscillations (BAO) are recognised as one of the most powerful probes of the properties of DE (e.g. Albrecht et al. 2006, Weinberg et al. 2013). BAO are a signature in the matter distribution from the recombination epoch and are imprinted in the distribution of galaxies at redshifts less than that of the epoch of reionization ($z \lesssim 0.5$). In the context of the standard cosmological model (ΛCDM model), BAO can be identified as a small but detectable excess of galaxies with separations of order of 150 Mpc.h$^{-1}$ (Eisenstein et al. 2005, Anderson et al. 2014, Planck Collaboration et al. 2018). This excess is the imprint of the acoustic oscillations generated during CMB times and its linear scale is known from basic physics. Consequently, a measure of its angular scale can be used to determine the distance up to a given redshift. The same oscillations produce the familiar peaks observed in the CMB anisotropy power spectrum.

To date, BAOs have only been detected by performing large galaxy redshift surveys in the optical waveband, where they are used as tracers of the underlying total matter distribution. It is important they are confirmed in other wavebands and measured over a wide range of redshifts. Since optical surveys demand more time to detect individual galaxies and cover a relatively small fraction of the sky, just a few percent of the local volume has been mapped with such a type of technique. The radio band provides a complementary observational window for studying BAO, and the natural radio tracer is the redshifted 21cm emission line. However, the volume emissivity associated with this line is low, meaning that detecting individual galaxies up to $z \sim 0.5$ requires a very substantial collecting area. It has been proposed that mapping the Universe measuring the collective 21cm emission of the underlying matter distribution, using a technique known as intensity mapping, hereafter IM (Loeb & Wyithe 2008, Masui et al. 2013, Switzer et al. 2013, Peterson et al. 2006), can be many times more efficient than optical surveys (e.g., Chang et al. 2008, Loeb & Wyithe 2008).

The BINGO (BAO from Integrated Neutral Gas Observations) telescope is a new instrument designed specifically for observing BAO in frequency band around 1 GHz and to provide a new insight into the Universe at $0.13 \lesssim z \lesssim 0.45$ with a dedicated instrument. The optical configuration consists of a compact, two 40m diameter, static dishes with an exceptionally wide field-of-view ($\sim 12^\circ \times 10^\circ$) and 50 feed horns in the focal plane. BAO observations will be carried through IM HI surveys (see, e.g., Peterson et al. (2006)). BINGO's main scientific goal is to claim the first BAO detection in radio in this redshift range, mapping the three dimensional distribution of HI, yielding a fundamental contribution to the study of DE,
with observations spanning several years. No
detection of BAOs in radio has been claimed so
far, making BINGO an interesting and appealing
instrument in the years to come. Moreover, in
view of the observation strategy and with some
adjustment in its digital backend, BINGO will also
be capable to detect transient phenomena at
very short time scales (≤ 1 ms), such as pulsars
and Fast Radio Bursts (FRB, Lorimer et al. 2007,
Cordes & Chatterjee 2019.

Earlier versions of the BINGO telescope
concept are described in Battye et al. 2013 and
Wuensche & the BINGO Collaboration 2019 and
a comprehensive analysis of foregrounds and
1/f noise that can limit the BINGO performance
was published by Bigot-Sazy et al. (2015). The
Project Design Review that ocurred in July 2019
fixed the telescope location in the hills of “Serra
do Urubu” in the municipality of Aguiar, Paraíba,
Brazil (Lon: 38° 16′ 4.8″ W, Lat: 7° 2′ 27,6″S).
It presents a very clean radio environment,
as reported by Peel and collaborators (Peel
et al. 2019), which is one of the most critical
requirements for high-quality measurements.

The main institutions in the BINGO
consortium are: University of São Paulo (USP),
National Institute for Space Research (INPE) and
Campina Grande Federal University (UFCG), in
Brazil, University of Manchester and University
College London (United Kingdom), and Yang
Zhou University (China). This paper reports the
current status of the BINGO project as of June
2020 as presented in the BRICS Astronomy
Working Group in October, 2019.

SCIENCE GOALS

Recent observational results have been useful in
shedding new light onto aspects of dark matter
and DE, which comprise about 95% of the mass
of the Universe, and it is expected that maybe a
new physical picture emerges once we find more

about the structure of the Dark Sector (Abdalla
et al. 2010). BAO studies are one of the most
powerful probes of the properties of DE (see, e.g.,
Albrecht et al. 2006, Weinberg et al. 2013) and
have only been probed by optical galaxy redshift
surveys (see, e.g., Eisenstein et al. 2005, Percival
et al. 2010, Tojeiro et al. 2014, Anderson et al. 2014,
Reid et al. 2015).

Constraints on various existing DE models
(see, e.g., Wang et al. 2005, 2007, Feng et al.
2008, Micheletti et al. 2009, He et al. 2009, He
et al. 2011, Ferreira et al. 2017) coming from BAO
measurements break the degeneracies between
cosmological parameters that are present when
inferring them from the CMB observations. This
potentially allows to constrain extensions of the
standard cosmological model which are usually
degenerate with the Hubble constant.

Following the first detection of BAOs using
SDSS surveys (Eisenstein et al. 2005), BAOs have
been measured with several new generation
galaxy and quasar redshift surveys. In particular,
the recent measurements with the BOSS survey
achieve a precision in the BAO scale of a few
percent in the redshift range z = [0, 2](Anderson
et al. 2014, Tojeiro et al. 2014, Reid et al. 2015).
New large experiments are being designed or
are already under construction to refine BAO
measurements in the optical band, such as DESI
(Aghamousa et al. 2016a,b), Euclid (Refregier
et al. 2010) and WFIRST (Levi et al. 2011, Green
et al. 2011), as well as LSST for imaging (Tyson
et al. 2002). Their goal is to achieve a precision
below the percent level at higher redshifts.
Nevertheless, all of them are large endeavours
and the first light of any of them is not expected
before the mid-2020's decade.

This is why it is so important that
the current results are confirmed in other
wavebands and measured over a wide range
of redshifts. The radio band provides a unique
and complementary observational window for
with observations spanning several years. No
detection of BAOs in radio has been claimed so
far, making BINGO an interesting and appealing
instrument in the years to come. Moreover, in
view of the observation strategy and with some
adjustment in its digital backend, BINGO will also
be capable to detect transient phenomena at
very short time scales (≈ 1 ms), such as pulsars
and Fast Radio Bursts (FRB, Lorimer et al. 2007,
Cordes & Chatterjee 2019.

Earlier versions of the BINGO telescope
concept are described in Battye et al. 2013 and
Wuensche & the BINGO Collaboration 2019 and
a comprehensive analysis of foregrounds and
1/f noise that can limit the BINGO performance
was published by Bigot-Sazy et al. (2015). The
Project Design Review that ocurred in July 2019
fixed the telescope location in the hills of “Serra
do Urubu” in the municipality of Aguiar, Paraíba,
Brazil (Lon: 38° 16′ 4.8″ W, Lat: 7° 2′ 27,6″S).
It presents a very clean radio environment,
as reported by Peel and collaborators (Peel
et al. 2019), which is one of the most critical
requirements for high-quality measurements.

The main institutions in the BINGO
consortium are: University of São Paulo (USP),
National Institute for Space Research (INPE) and
Campina Grande Federal University (UFCG), in
Brazil, University of Manchester and University
College London (United Kingdom), and Yang
Zhou University (China). This paper reports the
current status of the BINGO project as of June
2020 as presented in the BRICS Astronomy
Working Group in October, 2019.

SCIENCE GOALS

Recent observational results have been useful in
shedding new light onto aspects of dark matter
and DE, which comprise about 95% of the mass
of the Universe, and it is expected that maybe a
new physical picture emerges once we find more

about the structure of the Dark Sector (Abdalla
et al. 2010). BAO studies are one of the most
powerful probes of the properties of DE (see, e.g.,
Albrecht et al. 2006, Weinberg et al. 2013) and
have only been probed by optical galaxy redshift
surveys (see, e.g., Eisenstein et al. 2005, Percival
et al. 2010, Tojeiro et al. 2014, Anderson et al. 2014,
Reid et al. 2015).

Constraints on various existing DE models
(see, e.g., Wang et al. 2005, 2007, Feng et al.
2008, Micheletti et al. 2009, He et al. 2009, He
et al. 2011, Ferreira et al. 2017) coming from BAO
measurements break the degeneracies between
cosmological parameters that are present when
inferring them from the CMB observations. This
potentially allows to constrain extensions of the
standard cosmological model which are usually
degenerate with the Hubble constant.

Following the first detection of BAOs using
SDSS surveys (Eisenstein et al. 2005), BAOs have
been measured with several new generation
galaxy and quasar redshift surveys. In particular,
the recent measurements with the BOSS survey
achieve a precision in the BAO scale of a few
percent in the redshift range z = [0, 2](Anderson
et al. 2014, Tojeiro et al. 2014, Reid et al. 2015).
New large experiments are being designed or
are already under construction to refine BAO
measurements in the optical band, such as DESI
(Aghamousa et al. 2016a,b), Euclid (Refregier
et al. 2010) and WFIRST (Levi et al. 2011, Green
et al. 2011), as well as LSST for imaging (Tyson
et al. 2002). Their goal is to achieve a precision
below the percent level at higher redshifts.
Nevertheless, all of them are large endeavours
and the first light of any of them is not expected
before the mid-2020's decade.

This is why it is so important that
the current results are confirmed in other
wavebands and measured over a wide range
of redshifts. The radio band provides a unique
and complementary observational window for
<figure><img src="image_3.png" /><figcaption>**Figure 1.** Constraints on DE equation of state, including forecasts from CHIME and BINGO. Note the tight error ellipse obtained with combined radio data (BAO from CHIME and BINGO + Planck).</figcaption></figure>

the understanding of DE via measurements of integrated redshifted 21cm hydrogen emission line (Abdalla et al. 2010). HI redshift data allow us to construct a unique three dimensional map of the mass distribution, with a different perspective compared to the data obtained with optical telescopes. Indeed, HI is expected to be one of the best tracers of the total matter (see, e.g., Padmanabhan et al. 2015).

The combination of BAO radio measurements with other data sets (for instance, CMB and optical BAO) can be a powerful strategy to put more stringent constraints in the cosmological parameters analysis. Fig. 1 shows the forecast of the constraints from BINGO, combined with other data sets, for the time dependent parametrisation of the equation of state of the DE with $w_0$ and $w_a$ (1st time derivative of $w_0$) for various data sets. The constraints were computed using the Fisher matrix approach as described by Bull et al. (2015).

The plot shows the improvement in the constraints obtained with the combination

of simulated results from BINGO and CHIME (Newburgh et al. 2014), compared to the current constraints given by the combination of the results of the Planck and WMAP satellites (Planck Collaboration et al. 2014, 2016, 2018, Bennett et al. 2013), with the optical galaxy surveys (BOSS (Anderson et al. 2014, Tojeiro et al. 2014), WiggleZ (Kazin et al. 2014) and 6dF (Beutler et al. 2011)). For constant $w$, the measurement would lead to an accuracy on $w$ of ≲ 8% when including BINGO together with CHIME and Planck.

Tight constraints can be obtained with radio data alone (BAO from CHIME and BINGO plus Planck), providing a completely independent measurement from optical surveys. The improvement from the red to the yellow contour is due to having two independent measurements at different redshifts, showing the importance of BINGO. We have made estimates of the projected errors of the DE parameters assuming that all the other cosmological parameters are fixed. BINGO will be competitive and complementary
<figure><img src="image_3.png" /><figcaption>**Figure 1.** Constraints on DE equation of state, including forecasts from CHIME and BINGO. Note the tight error ellipse obtained with combined radio data (BAO from CHIME and BINGO + Planck).</figcaption></figure>

the understanding of DE via measurements of integrated redshifted 21cm hydrogen emission line (Abdalla et al. 2010). HI redshift data allow us to construct a unique three dimensional map of the mass distribution, with a different perspective compared to the data obtained with optical telescopes. Indeed, HI is expected to be one of the best tracers of the total matter (see, e.g., Padmanabhan et al. 2015).

The combination of BAO radio measurements with other data sets (for instance, CMB and optical BAO) can be a powerful strategy to put more stringent constraints in the cosmological parameters analysis. Fig. 1 shows the forecast of the constraints from BINGO, combined with other data sets, for the time dependent parametrisation of the equation of state of the DE with $w_0$ and $w_a$ (1st time derivative of $w_0$) for various data sets. The constraints were computed using the Fisher matrix approach as described by Bull et al. (2015).

The plot shows the improvement in the constraints obtained with the combination

of simulated results from BINGO and CHIME (Newburgh et al. 2014), compared to the current constraints given by the combination of the results of the Planck and WMAP satellites (Planck Collaboration et al. 2014, 2016, 2018, Bennett et al. 2013), with the optical galaxy surveys (BOSS (Anderson et al. 2014, Tojeiro et al. 2014), WiggleZ (Kazin et al. 2014) and 6dF (Beutler et al. 2011)). For constant $w$, the measurement would lead to an accuracy on $w$ of $\lesssim 8\%$ when including BINGO together with CHIME and Planck.

Tight constraints can be obtained with radio data alone (BAO from CHIME and BINGO plus Planck), providing a completely independent measurement from optical surveys. The improvement from the red to the yellow contour is due to having two independent measurements at different redshifts, showing the importance of BINGO. We have made estimates of the projected errors of the DE parameters assuming that all the other cosmological parameters are fixed. BINGO will be competitive and complementary
to optical surveys, which are limited by different systematic errors.

The combination of BINGO and Planck only also place good constraints in the values of the equation of state of DE. In figure 2 we compare the 68% and 95% confidence levels constraints on the parameters of the DE equation of state using BINGO alone and BINGO plus Planck. The constraints improve with increasing number of redshift bins. Those figures can be compared with the optimal case results from Olivari et al. (2018). Our marginalised 68% c.l. constraints on the DE equation of state parameters are 2.4% for $w_0$ and $\zeta_{w_0} = 0.11$. Olivari et al. obtained 4% for a constant equation of state model.

A more detailed work discussing the forecast methods under development for the BINGO data analysis is being developed by Costa et al. (2021).

## HI intensity mapping

Together with other experiments, IM radio surveys can become a very promising complementary route to study BAOs. Indeed, optical experiments are required to gather data with very high angular resolution (of the order of an arcsecond) to detect individual galaxies, while the BAO scale is typically of the order of a degree. On the other hand, radio BAO experiments have angular resolutions which are well matched to the BAO scale and thus offer a very low cost-effective approach. IM experiments are a more direct tracer of dark matter being less sensitive to “peak statistics” bias. Moreover, radio experiments can use other elements/molecules (CO, H-α) besides neutral hydrogen (Kovetz et al. 2017), and are subject to different astrophysical effects and systematics when compared to optical surveys. The combination of their results with those obtained from optical surveys can significantly reduce systematic effects during cosmological parameter analysis.

BINGO will also use IM to map the three-dimensional distribution of HI, with observations spanning a few years. Also, an experiment such as BINGO will pave the way to the extension of the use of 21cm IM to high redshifts, opening a new window on cosmological epochs, which cannot be probed in the optical or near-infrared bands. Extensive simulations of the expected BAO signal and how it can be extracted are currently in progress, with results to be published in the near future.

At frequencies below a few GHz the future of radio astronomy will be dominated by SKA (Square Kilometre Array) project (Maartens et al. 2015), that should operating by mid-2020's. Its design has been strongly driven to probe the HI 21cm line from its rest frequency (1420 MHz) down to 50 MHz. The great importance of the IM technique is highlighted by the decision to change the baseline design of the SKA Phase 1 to enable a IM approach (Square Kilometre Array Cosmology Science Working Group et al. 2020). Albeit SKA is designed to work mainly in interferometric mode, the proposed IM observations are to work in autocorrelation mode; i.e. using each dish separately, so that SKA and BINGO operation modes will be somewhat similar. Each BINGO beam will be equivalent to a single SKA dish, so that the hardware and software know-how acquired during BINGO development will be readily available to take advantage of the much larger signal to noise ratio achieved by SKA (Bull et al. 2015, Abdalla et al. 2015).

## THE INSTRUMENT

Interferometers are the most suitable instruments to perform IM in the angular resolution of ~ 0.5°, covering very large areas of the sky. However, they also require expensive hardware and sophisticated electronics and
to optical surveys, which are limited by different systematic errors.

The combination of BINGO and Planck only also place good constraints in the values of the equation of state of DE. In figure 2 we compare the 68% and 95% confidence levels constraints on the parameters of the DE equation of state using BINGO alone and BINGO plus Planck. The constraints improve with increasing number of redshift bins. Those figures can be compared with the optimal case results from Olivari et al. (2018). Our marginalised 68% c.l. constraints on the DE equation of state parameters are 2.4% for $w_0$ and $\zeta_{w_0} = 0.11$. Olivari et al. obtained 4% for a constant equation of state model.

A more detailed work discussing the forecast methods under development for the BINGO data analysis is being developed by Costa et al. (2021).

## HI intensity mapping

Together with other experiments, IM radio surveys can become a very promising complementary route to study BAOs. Indeed, optical experiments are required to gather data with very high angular resolution (of the order of an arcsecond) to detect individual galaxies, while the BAO scale is typically of the order of a degree. On the other hand, radio BAO experiments have angular resolutions which are well matched to the BAO scale and thus offer a very low cost-effective approach. IM experiments are a more direct tracer of dark matter being less sensitive to “peak statistics” bias. Moreover, radio experiments can use other elements/molecules (CO, H-α) besides neutral hydrogen (Kovetz et al. 2017), and are subject to different astrophysical effects and systematics when compared to optical surveys. The combination of their results with those obtained from optical surveys can significantly reduce systematic effects during cosmological parameter analysis.

BINGO will also use IM to map the three-dimensional distribution of HI, with observations spanning a few years. Also, an experiment such as BINGO will pave the way to the extension of the use of 21cm IM to high redshifts, opening a new window on cosmological epochs, which cannot be probed in the optical or near-infrared bands. Extensive simulations of the expected BAO signal and how it can be extracted are currently in progress, with results to be published in the near future.

At frequencies below a few GHz the future of radio astronomy will be dominated by SKA (Square Kilometre Array) project (Maartens et al. 2015), that should operating by mid-2020's. Its design has been strongly driven to probe the HI 21cm line from its rest frequency (1420 MHz) down to 50 MHz. The great importance of the IM technique is highlighted by the decision to change the baseline design of the SKA Phase 1 to enable a IM approach (Square Kilometre Array Cosmology Science Working Group et al. 2020). Albeit SKA is designed to work mainly in interferometric mode, the proposed IM observations are to work in autocorrelation mode; i.e. using each dish separately, so that SKA and BINGO operation modes will be somewhat similar. Each BINGO beam will be equivalent to a single SKA dish, so that the hardware and software know-how acquired during BINGO development will be readily available to take advantage of the much larger signal to noise ratio achieved by SKA (Bull et al. 2015, Abdalla et al. 2015).

## THE INSTRUMENT

Interferometers are the most suitable instruments to perform IM in the angular resolution of ~ 0.5°, covering very large areas of the sky. However, they also require expensive hardware and sophisticated electronics and
<figure><img src="image_4.png" /><figcaption>**Figure 2.** 68% and 95% confidence level constraints on the DE equation of state parameters using BINGO and BINGO + Planck. The results are shown for two different number of redshift bins (Costa et al. 2021).</figcaption></figure>

time-keeping systems to make the necessary correlations. A number of approaches has been proposed to conduct IM surveys using interferometer arrays rather than a single dish (see, for instance, the papers from van Bemmel et al. (2012), Pober et al. (2013), Baker et al. (2011)) and a detailed discussion about advantages and disadvantages for both was published by Bull et al. (2015).

Single-dish telescopes with stable receivers can be a low-cost, good efficiency approach to BAO IM studies at redshifts ($z \lesssim 0.5$) (Battye et al. 2012) and BINGO belongs to this class. No detection of BAOs in radio has been claimed so far, making BINGO an interesting and appealing instrument in the years to come, with a strong potential for a pioneering discovery of the BAO in this wavelength. For comparison, we show some of the IM experiments planned for the near future, or already in operation, in Figure 3, with covered area in the sky as a function of redshift. Albeit operating in the same redshift range of TIANLAI, FAST and SKA telescopes, we believe BINGO can be still be a

strong competitor, producing good quality data before their relatives.

The difficulty in doing a statistically significant BAO detection is due to the high intensity of the Galactic and extragalactic signals in the BINGO frequency band ($980 \le \nu \le 1260$GHz). The HI signal is typically ~100 µK whereas the foreground continuum emission from the Galaxy is ~1 K with spatial fluctuations ~100 mK. Detecting signals of ~100 µK with a non-cryogenic receiver implies that every pixel in our intensity map requires an accumulated integration time larger than 1 day over the course of the observing campaign, which is expected to last a few years. The total integration time can be built up by many returns to the same patch of sky but between these returns the receiver gains need to be highly alike and achieving this stability is a major design concern.

Fortunately, the integrated 21cm emission exhibits characteristic variations as a function of frequency whereas the continuum emission has a very smooth spectrum; this allows for the two signals to be separated (Chang et al.
<figure><img src="image_4.png" /><figcaption>**Figure 2.** 68% and 95% confidence level constraints on the DE equation of state parameters using BINGO and BINGO + Planck. The results are shown for two different number of redshift bins (Costa et al. 2021).</figcaption></figure>

time-keeping systems to make the necessary correlations. A number of approaches has been proposed to conduct IM surveys using interferometer arrays rather than a single dish (see, for instance, the papers from van Bemmel et al. (2012), Pober et al. (2013), Baker et al. (2011)) and a detailed discussion about advantages and disadvantages for both was published by Bull et al. (2015).

Single-dish telescopes with stable receivers can be a low-cost, good efficiency approach to BAO IM studies at redshifts ($z \lesssim 0.5$) (Battye et al. 2012) and BINGO belongs to this class. No detection of BAOs in radio has been claimed so far, making BINGO an interesting and appealing instrument in the years to come, with a strong potential for a pioneering discovery of the BAO in this wavelength. For comparison, we show some of the IM experiments planned for the near future, or already in operation, in Figure 3, with covered area in the sky as a function of redshift. Albeit operating in the same redshift range of TIANLAI, FAST and SKA telescopes, we believe BINGO can be still be a

strong competitor, producing good quality data before their relatives.

The difficulty in doing a statistically significant BAO detection is due to the high intensity of the Galactic and extragalactic signals in the BINGO frequency band ($980 \le \nu \le 1260$GHz). The HI signal is typically $\sim 100 \mu K$ whereas the foreground continuum emission from the Galaxy is $\sim 1 K$ with spatial fluctuations $\sim 100 \text{ mK}$. Detecting signals of $\sim 100 \mu K$ with a non-cryogenic receiver implies that every pixel in our intensity map requires an accumulated integration time larger than 1 day over the course of the observing campaign, which is expected to last a few years. The total integration time can be built up by many returns to the same patch of sky but between these returns the receiver gains need to be highly alike and achieving this stability is a major design concern.

Fortunately, the integrated 21cm emission exhibits characteristic variations as a function of frequency whereas the continuum emission has a very smooth spectrum; this allows for the two signals to be separated (Chang et al.
<figure><img src="image_5.png" /><figcaption>Figure 3. Comparative plot of sky and redshift coverage for different IM experiments. CHIME and FAST are in operation.</figcaption></figure>

2008, Liu & Tegmark 2011, Chang et al. 2010, Olivari et al. 2016). However, while there is a clear-cut statistical signature that allows for the separation of different components, the design of an instrument to measure the HI contribution to the detected signal needs to be very careful. It should contemplate a very clean and symmetric beam, with low sidelobe levels and very good polarisation purity, to avoid systematic effects that can result in leakage of the Galactic foreground emission, which is partially linearly polarised and concentrated towards the Galactic plane, into the HI signal.

A declination strip of ~15°, centered at δ ~ -15° aims at minimising the Galactic foreground contamination and will be the optimal choice for the BINGO survey. The need to clearly resolve structures of angular sizes corresponding to a linear scale of around 150 Mpc at BINGO's chosen

redshift range implies that the required angular
resolution has to be ~ 40'.

The general concept for the BINGO
instrument is described in Battye et al. (2013,
2016) and updated in Wuensche & the BINGO
Collaboration (2019). The current stage of the
instrument construction is as follows: 1) horn
prototype is completed, tested and approved for
electromagnetic and mechanical performance;
2) front end, including polariser, transitions,
OMT ("magic-tees") and rectangular-to-coaxial
transitions are completed, tested and
approved for electromagnetic and mechanical
performance; 3) the LNA and receiver chain
is completed, passed the initial testing and
needs to be improved for a better system
temperature; 4) different LNA types are under
testing to improve the first stage performance; 5)
optical design is nearly completed, with the final
<figure><img src="image_5.png" /><figcaption>Figure 3. Comparative plot of sky and redshift coverage for different IM experiments. CHIME and FAST are in operation.</figcaption></figure>

2008, Liu & Tegmark 2011, Chang et al. 2010, Olivari et al. 2016). However, while there is a clear-cut statistical signature that allows for the separation of different components, the design of an instrument to measure the HI contribution to the detected signal needs to be very careful. It should contemplate a very clean and symmetric beam, with low sidelobe levels and very good polarisation purity, to avoid systematic effects that can result in leakage of the Galactic foreground emission, which is partially linearly polarised and concentrated towards the Galactic plane, into the HI signal.

A declination strip of ~15°, centered at δ ~ -15° aims at minimising the Galactic foreground contamination and will be the optimal choice for the BINGO survey. The need to clearly resolve structures of angular sizes corresponding to a linear scale of around 150 Mpc at BINGO's chosen

redshift range implies that the required angular
resolution has to be ~ 40'.

The general concept for the BINGO
instrument is described in Battye et al. (2013,
2016) and updated in Wuensche & the BINGO
Collaboration (2019). The current stage of the
instrument construction is as follows: 1) horn
prototype is completed, tested and approved for
electromagnetic and mechanical performance;
2) front end, including polariser, transitions,
OMT ("magic-tees") and rectangular-to-coaxial
transitions are completed, tested and
approved for electromagnetic and mechanical
performance; 3) the LNA and receiver chain
is completed, passed the initial testing and
needs to be improved for a better system
temperature; 4) different LNA types are under
testing to improve the first stage performance; 5)
optical design is nearly completed, with the final
dish parameters and focal plane arrangement
simulated and tested in the mission pipeline
data reduction software. The main parameters
describing the telescope can be found in Table I.

<figure><img src="image_6.png" /><figcaption>Figure 4. Optical design schematics as presented in the July 2019 CDR (Abdalla et al. 2021).</figcaption></figure>

The optics

The final optical system consists of an
off-axis dual mirror telescope following the
Dragone-Mizuguchi condition in order to
minimise the cross-polarisation. Combined with
the use of corrugated feedhorns, similarly to CMB
experiments, such configuration allows for low
sidelobes, low spillover and superb polarisation
performance. The focal plane includes 50 feed
horns giving an overall field of view of 13 deg x
10 deg. The forward gain of each beam formed
by the combination of the feedhorn and the
telescope do not vary by more than 1 dB for

all the pixels across the whole focal plane, while
keeping low beam aberration and ellipticity. The
current mirror and focal plane configuration are
found in figure 4. Since the smallest operational
wavelength is 23.8cm, the surface profile of the
telescope mirrors should have an rms error ≲ 15
mm to allow for maximum efficiency. The final
optical design is described in the work of Abdalla
et al. (2021).

The gain of the telescope beams associated
with the feed horns at the edge of the array
are less than 1 dB lower compared with those
from the horns at the centre; optical aberrations
are slight, the edge beams being almost circular.
Various arrangements for the horns in the focal
plane were simulated in order to achieve an
optimal sky coverage with the least distortion
of the outer horns. All the optical analysis was
performed with the GRASP package (TICRA -
Reflector Antenna and EM Modelling Software)¹.
The beam patterns shown in figure 5 correspond
to the best solutions for the horn arrangement
in the focal plane. The corresponding beam
response as a function of declination for both
arrangements are shown in figure 6.

The guiding principle in the design of BINGO
is simplicity. All components should be as simple
as possible to minimize costs. Moreover, since
there will be no moving parts, design, operation
and instrument modelling will also be simpler
than doing the same tasks for a conventional
telescope. Another key advantage of a simple
design is that it is being built in a relatively
small amount of time, allowing for results within
a competitive science time window.

Receiver

Each receiver chain contains a correlation
system, as shown in fig. 7, operating with
room temperature amplifiers. The receiver is
expected to operate at temperature Tsys ~ 70

<footnote>http://https://www.ticra.com/software/grasp/</footnote>
dish parameters and focal plane arrangement
simulated and tested in the mission pipeline
data reduction software. The main parameters
describing the telescope can be found in Table I.

<figure><img src="image_6.png" /><figcaption>Figure 4. Optical design schematics as presented in the July 2019 CDR (Abdalla et al. 2021).</figcaption></figure>

The optics

The final optical system consists of an
off-axis dual mirror telescope following the
Dragone-Mizuguchi condition in order to
minimise the cross-polarisation. Combined with
the use of corrugated feedhorns, similarly to CMB
experiments, such configuration allows for low
sidelobes, low spillover and superb polarisation
performance. The focal plane includes 50 feed
horns giving an overall field of view of 13 deg x
10 deg. The forward gain of each beam formed
by the combination of the feedhorn and the
telescope do not vary by more than 1 dB for

all the pixels across the whole focal plane, while
keeping low beam aberration and ellipticity. The
current mirror and focal plane configuration are
found in figure 4. Since the smallest operational
wavelength is 23.8cm, the surface profile of the
telescope mirrors should have an rms error ≲ 15
mm to allow for maximum efficiency. The final
optical design is described in the work of Abdalla
et al. (2021).

The gain of the telescope beams associated
with the feed horns at the edge of the array
are less than 1 dB lower compared with those
from the horns at the centre; optical aberrations
are slight, the edge beams being almost circular.
Various arrangements for the horns in the focal
plane were simulated in order to achieve an
optimal sky coverage with the least distortion
of the outer horns. All the optical analysis was
performed with the GRASP package (TICRA -
Reflector Antenna and EM Modelling Software)¹.
The beam patterns shown in figure 5 correspond
to the best solutions for the horn arrangement
in the focal plane. The corresponding beam
response as a function of declination for both
arrangements are shown in figure 6.

The guiding principle in the design of BINGO
is simplicity. All components should be as simple
as possible to minimize costs. Moreover, since
there will be no moving parts, design, operation
and instrument modelling will also be simpler
than doing the same tasks for a conventional
telescope. Another key advantage of a simple
design is that it is being built in a relatively
small amount of time, allowing for results within
a competitive science time window.

Receiver

Each receiver chain contains a correlation
system, as shown in fig. 7, operating with
room temperature amplifiers. The receiver is
expected to operate at temperature Tsys ~ 70

<footnote>http://https://www.ticra.com/software/grasp/</footnote>
<table><caption>**Table I. BINGO telescope parameter list.**</caption><tr><td>System temperature (K)</td><td>70</td><td></td></tr><tr><td>Frequency band (MHz)</td><td>980.00 - 1260.00</td><td></td></tr><tr><td>Channels</td><td>40</td><td>used for simulations, real number still TBD</td></tr><tr><td>Sampling time (Hz)</td><td>10.00</td><td>Likely to be 2 × 10<sup>4</sup> for FRB sampling</td></tr><tr><td>Redshift interval</td><td>0.127 - 0.449</td><td></td></tr><tr><td>Instrument noise (mK, 1 second)</td><td>26.5</td><td></td></tr><tr><td>Focal length (m)</td><td>63.2</td><td>TBC by the final design</td></tr><tr><td>Primary reflector F/D ratio</td><td>140</td><td></td></tr><tr><td>Field of view</td><td>13° × 10°</td><td>TBC by the final design</td></tr><tr><td>Primary mirror (parabola)</td><td></td><td></td></tr><tr><td>Major semi-axis (m)</td><td>25.7</td><td>TBC by the final design</td></tr><tr><td>Minor semi-axis (m)</td><td>20.0</td><td>TBC by the final design</td></tr><tr><td>Secondary mirror (hyperbola)</td><td></td><td></td></tr><tr><td>Major semi-axis (m)</td><td>18.3</td><td>TBC by the final design</td></tr><tr><td>Minor semi-axis (m)</td><td>18.0</td><td>TBC by the final design</td></tr><tr><td>Pixel solid angle (sr)</td><td>0.35</td><td></td></tr><tr><td>Optics FWHM (deg)</td><td>0.67</td><td>TBC by the final design</td></tr><tr><td>Survey area (square deg)</td><td>5359.75</td><td>TBC by the final design</td></tr><tr><td>Total # horns (nominal)</td><td>50</td><td></td></tr></table>

K in the frequency interval 980 – 1260 MHz, at ambient temperature. A number of tests were performed at INPE’s Division of Astrophysics, using two different low noise amplifiers (LNA). We tested a radiometer chain, with one LNA, one first stage filter and second stage LNAs. The testing was conducted in the laboratory, with no specific shielding in the amplifier structure. The measured receiver noise temperature was $T_R = (58 \pm 6)$ K, taken as an upper limit, since the environment in which the measurements were made is permeated by RFI. Table II shows the temperature for each component of the BINGO radio telescope. Thus, the system temperature is given by $T_{sys} = T_A + T_R = 89$ K. To estimate the sensitivity of the BINGO using this

simple radiometer, two ratios are used, one for the minimum temperature variation that can be detected by the radiometer and another for the flow density that such temperature represents:

$$ \Delta T_{\min} = \frac{T_{sys}}{\sqrt{B\tau}} \qquad (1) $$

$$ S(\Delta T_{\min}) = \frac{2k}{A_{\text{eff}}} \Delta T_{\min}. \qquad (2) $$

In eq. (1), B is the frequency operating bandwidth, $\tau$ the integration time, k is the Boltzmann constant and $A_{\text{eff}}$ the effective area of the radio telescope. In this work, the bandwidth is 2.8 × 10⁸ Hz and the integration time is 1 s. The effective area used considers that 50 % of the total area of the primary mirror receives electromagnetic
<table><caption>**Table I. BINGO telescope parameter list.**</caption><tr><td>System temperature (K)</td><td>70</td><td></td></tr><tr><td>Frequency band (MHz)</td><td>980.00 - 1260.00</td><td></td></tr><tr><td>Channels</td><td>40</td><td>used for simulations, real number still TBD</td></tr><tr><td>Sampling time (Hz)</td><td>10.00</td><td>Likely to be 2 × 10<sup>4</sup> for FRB sampling</td></tr><tr><td>Redshift interval</td><td>0.127 - 0.449</td><td></td></tr><tr><td>Instrument noise (mK, 1 second)</td><td>26.5</td><td></td></tr><tr><td>Focal length (m)</td><td>63.2</td><td>TBC by the final design</td></tr><tr><td>Primary reflector F/D ratio</td><td>140</td><td></td></tr><tr><td>Field of view</td><td>13° × 10°</td><td>TBC by the final design</td></tr><tr><td>Primary mirror (parabola)</td><td></td><td></td></tr><tr><td>Major semi-axis (m)</td><td>25.7</td><td>TBC by the final design</td></tr><tr><td>Minor semi-axis (m)</td><td>20.0</td><td>TBC by the final design</td></tr><tr><td>Secondary mirror (hyperbola)</td><td></td><td></td></tr><tr><td>Major semi-axis (m)</td><td>18.3</td><td>TBC by the final design</td></tr><tr><td>Minor semi-axis (m)</td><td>18.0</td><td>TBC by the final design</td></tr><tr><td>Pixel solid angle (sr)</td><td>0.35</td><td></td></tr><tr><td>Optics FWHM (deg)</td><td>0.67</td><td>TBC by the final design</td></tr><tr><td>Survey area (square deg)</td><td>5359.75</td><td>TBC by the final design</td></tr><tr><td>Total # horns (nominal)</td><td>50</td><td></td></tr></table>

K in the frequency interval 980 – 1260 MHz, at ambient temperature. A number of tests were performed at INPE’s Division of Astrophysics, using two different low noise amplifiers (LNA). We tested a radiometer chain, with one LNA, one first stage filter and second stage LNAs. The testing was conducted in the laboratory, with no specific shielding in the amplifier structure. The measured receiver noise temperature was $T_R = (58 \pm 6)$ K, taken as an upper limit, since the environment in which the measurements were made is permeated by RFI. Table II shows the temperature for each component of the BINGO radio telescope. Thus, the system temperature is given by $T_{sys} = T_A + T_R = 89$ K. To estimate the sensitivity of the BINGO using this

simple radiometer, two ratios are used, one for the minimum temperature variation that can be detected by the radiometer and another for the flow density that such temperature represents:

$$ \Delta T_{\min} = \frac{T_{sys}}{\sqrt{B\tau}} \qquad (1) $$

$$ S(\Delta T_{\min}) = \frac{2k}{A_{\text{eff}}} \Delta T_{\min}. \qquad (2) $$

In eq. (1), B is the frequency operating bandwidth, τ the integration time, k is the Boltzmann constant and $A_{\text{eff}}$ the effective area of the radio telescope. In this work, the bandwidth is 2.8 × 10⁸ Hz and the integration time is 1 s. The effective area used considers that 50 % of the total area of the primary mirror receives electromagnetic
<figure><img src="image_7.png" /><figcaption>**Figure 5.** Beam pattern response for the Stokes parameters as a function of celestial coordinates, for the focal plane arrangement of a rectangular horn arrangement configuration (left) and for a hexagonal horn arrangement configuration (right). The colour scale on the right refers to intensity (dB) (Abdalla et al. 2021).</figcaption></figure>

waves. For BINGO, this area is 785.40 m². The minimum temperature obtained in this case is $ΔT_{min} = 11$ mK and the corresponding flux, from eq. (2) is $S(ΔT_{min}) = 0.037$ Jy. After one year of observations, BINGO should achieve a 40' pixel noise of 36.9 μK in a 7.5 MHz frequency channel, with the parameters described in Table I. A more detailed discussion of the receiver tests can be found in the M.Sc. dissertation of Vieira (2020).

## Feedhorns and polariser

BINGO will use specially designed conical corrugated horns to illuminate the secondary mirror of the telescope. These need to be corrugated in order to provide the required low sidelobes coupled with very good polarisation performance. Because of the large focal ratio needed to provide the required wide field of view, the horns have ~ 1.9m diameter and ~ 4.9m length. The electromagnetic design of such horns is well understood and the first prototype was successfully developed and tested in the Laboratory of Integration and Tests at INPE. Insertion and return loss, as well as the beam profile, were measured for the frequency interval 900 - 1300 MHz, in 25 MHz steps, for

vertical and horizontal polarisations. A summary of the main properties of the horn prototype is found in Tables III and IV and the main results of the construction and testing of the feed horns and polariser are discussed in Wuensche et al. (Wuensche et al. 2020).

## Mission simulations

The assessment of the instrument performance and the reliability with which the cosmological signal can be extracted from the observed data is done through a *Pipeline* developed inside the collaboration and used in previous works (e.g., Bigot-Sazy et al. 2015, Harper & Dickinson 2018). We briefly describe the data processing and component separation algorithm used to obtain the BINGO maps we use for our analysis. Details of the algorithm and data processing can be found in the works of Liccardo et al. (2021) and Fornazier et al. (2021).

The *Pipeline* takes input maps of different emission mechanisms, produced by theoretical models or by observations, as well as various instrument characteristics (such as such as the number of horns and their positioning in the focal plane, receiver system temperature,
<figure><img src="image_7.png" /><figcaption>**Figure 5.** Beam pattern response for the Stokes parameters as a function of celestial coordinates, for the focal plane arrangement of a rectangular horn arrangement configuration (left) and for a hexagonal horn arrangement configuration (right). The colour scale on the right refers to intensity (dB) (Abdalla et al. 2021).</figcaption></figure>

waves. For BINGO, this area is 785.40 m². The minimum temperature obtained in this case is $ΔT_{min} = 11$ mK and the corresponding flux, from eq. (2) is $S(ΔT_{min}) = 0.037$ Jy. After one year of observations, BINGO should achieve a 40' pixel noise of 36.9 μK in a 7.5 MHz frequency channel, with the parameters described in Table I. A more detailed discussion of the receiver tests can be found in the M.Sc. dissertation of Vieira (2020).

## Feedhorns and polariser

BINGO will use specially designed conical corrugated horns to illuminate the secondary mirror of the telescope. These need to be corrugated in order to provide the required low sidelobes coupled with very good polarisation performance. Because of the large focal ratio needed to provide the required wide field of view, the horns have ~ 1.9m diameter and ~ 4.9m length. The electromagnetic design of such horns is well understood and the first prototype was successfully developed and tested in the Laboratory of Integration and Tests at INPE. Insertion and return loss, as well as the beam profile, were measured for the frequency interval 900 - 1300 MHz, in 25 MHz steps, for

vertical and horizontal polarisations. A summary of the main properties of the horn prototype is found in Tables III and IV and the main results of the construction and testing of the feed horns and polariser are discussed in Wuensche et al. (Wuensche et al. 2020).

## Mission simulations

The assessment of the instrument performance and the reliability with which the cosmological signal can be extracted from the observed data is done through a *Pipeline* developed inside the collaboration and used in previous works (e.g., Bigot-Sazy et al. 2015, Harper & Dickinson 2018). We briefly describe the data processing and component separation algorithm used to obtain the BINGO maps we use for our analysis. Details of the algorithm and data processing can be found in the works of Liccardo et al. (2021) and Fornazier et al. (2021).

The *Pipeline* takes input maps of different emission mechanisms, produced by theoretical models or by observations, as well as various instrument characteristics (such as such as the number of horns and their positioning in the focal plane, receiver system temperature,
<figure><img src="image_8.png" /><figcaption>**Figure 6.** Combined beam response for rectangular arrangement (columns 2 and 3, left to right) and hexagonal arrangement (columns 4 and 5, left to right) shown in figure 5 at 1100 MHz (Abdalla et al. 2021).</figcaption></figure>

<figure><img src="image_9.png" /><figcaption>**Figure 7.** Block diagram of the main components of the BINGO correlation receiver. The correlation is achieved by means of the hybrids (in our case, “magic tees”), which in our case will be waveguide magic tees.</figcaption></figure>
<figure><img src="image_8.png" /><figcaption>**Figure 6.** Combined beam response for rectangular arrangement (columns 2 and 3, left to right) and hexagonal arrangement (columns 4 and 5, left to right) shown in figure 5 at 1100 MHz (Abdalla et al. 2021).</figcaption></figure>

<figure><img src="image_9.png" /><figcaption>**Figure 7.** Block diagram of the main components of the BINGO correlation receiver. The correlation is achieved by means of the hybrids (in our case, “magic tees”), which in our case will be waveguide magic tees.</figcaption></figure>
<table><caption>**Table II. Temperature contributions of different components.**</caption><thead><tr><td>Component</td><td>T (K)</td></tr></thead><tbody><tr><td>CMB</td><td>2.7</td></tr><tr><td>Galactic and Extragalactic Astronomical Signals</td><td>5.0</td></tr><tr><td>Ground</td><td>2.0</td></tr><tr><td>Atmosphere</td><td>4.5</td></tr><tr><td>Parabolic Mirror</td><td>1.5</td></tr><tr><td>Hyperbolic Mirror</td><td>1.5</td></tr><tr><td>Horn</td><td>6.8</td></tr><tr><td>Magic Tee</td><td>3.5</td></tr><tr><td>Waveguide</td><td>3.5</td></tr><tr><td>Total</td><td>31</td></tr></tbody></table>

focal length, etc.) and contamination from the environment. Pipeline outputs are time series which can be turned into maps that simulate the signal as measured by the instrument during a defined mission duration.

To detect BAOs in the H1 signal we will need to remove the contributions from much brighter emissions coming from our Galaxy and extragalactic sources, the most relevant emissions at ~ 1 GHz being a combination of extragalactic point sources and diffuse Galactic synchrotron emission. These two foregrounds combined contribute ~ 1 K rms at 1 GHz, while the 21cm signal fluctuations are ~ 100 µK rms. Some very efficient methods of component separation are being tested for BINGO, so that we can recover the cosmological H1 component.

The Pipeline operation makes use of a mission simulator, which processes all the input information described above, producing a time series (TOD), used to produce the maps at each frequency determined by the band and the number of channels. Currently, the set of maps produced is processed by a component separation algorithm to recover the

cosmological H1 signal. Future plans are that this procedure should be integrated in the Pipeline body.

We are currently investigating the instrument performance using a number of different optical arrangements produced by the collaboration Abdalla et al. (2021) and testing component separation methods, such as GNILC, developed for the Planck mission, following the work from Remazeilles et al. (2011) and Olivari et al. (2016).

A detailed description of the instrument performance and capabilities, as well as some discussion regarding the separation of components can be found in the work of Liccardo et al. (2021). A deeper analysis of the component separation process, especially regarding GNILC, and the construction of a non-gaussianity estimator module is presented in the work of Fornazier et al. (2021).

## CURRENT STATUS

BINGO is currently funded, with about 70% of the funding already secured, mostly coming from Brazilian funding agencies (FAPESP, FINEP, MCTIC
<table><caption>**Table II. Temperature contributions of different components.**</caption><thead><tr><td>Component</td><td>T (K)</td></tr></thead><tbody><tr><td>CMB</td><td>2.7</td></tr><tr><td>Galactic and Extragalactic Astronomical Signals</td><td>5.0</td></tr><tr><td>Ground</td><td>2.0</td></tr><tr><td>Atmosphere</td><td>4.5</td></tr><tr><td>Parabolic Mirror</td><td>1.5</td></tr><tr><td>Hyperbolic Mirror</td><td>1.5</td></tr><tr><td>Horn</td><td>6.8</td></tr><tr><td>Magic Tee</td><td>3.5</td></tr><tr><td>Waveguide</td><td>3.5</td></tr><tr><td>Total</td><td>31</td></tr></tbody></table>

focal length, etc.) and contamination from the environment. Pipeline outputs are time series which can be turned into maps that simulate the signal as measured by the instrument during a defined mission duration.

To detect BAOs in the H1 signal we will need to remove the contributions from much brighter emissions coming from our Galaxy and extragalactic sources, the most relevant emissions at ~ 1 GHz being a combination of extragalactic point sources and diffuse Galactic synchrotron emission. These two foregrounds combined contribute ~ 1 K rms at 1 GHz, while the 21cm signal fluctuations are ~ 100 µK rms. Some very efficient methods of component separation are being tested for BINGO, so that we can recover the cosmological H1 component.

The Pipeline operation makes use of a mission simulator, which processes all the input information described above, producing a time series (TOD), used to produce the maps at each frequency determined by the band and the number of channels. Currently, the set of maps produced is processed by a component separation algorithm to recover the

cosmological H1 signal. Future plans are that this procedure should be integrated in the Pipeline body.

We are currently investigating the instrument performance using a number of different optical arrangements produced by the collaboration Abdalla et al. (2021) and testing component separation methods, such as GNILC, developed for the Planck mission, following the work from Remazeilles et al. (2011) and Olivari et al. (2016).

A detailed description of the instrument performance and capabilities, as well as some discussion regarding the separation of components can be found in the work of Liccardo et al. (2021). A deeper analysis of the component separation process, especially regarding GNILC, and the construction of a non-gaussianity estimator module is presented in the work of Fornazier et al. (2021).

## CURRENT STATUS

BINGO is currently funded, with about 70% of the funding already secured, mostly coming from Brazilian funding agencies (FAPESP, FINEP, MCTIC
<table><caption>**Table III. Feedhorn beam measurements.** Left: horizontal polarisation. Right: vertical polarisation. Minimum rejection was not measured at all frequencies.</caption><thead><tr><th>Freq<br>(MHz)</th><th>Directivity<br>(dB)</th><th>FWHM<br>(deg)</th><th>Min.<br>rejection<br>(dB)</th><th>Front to back<br>difference<br>(dB)</th><th>Directivity<br>(dB)</th><th>FWHM<br>(deg)</th><th>Min.<br>rejection<br>(dB)</th><th>Front to back<br>difference<br>(dB)</th></tr></thead><tbody><tr><td>950</td><td>22.4</td><td>14.6</td><td>-</td><td>47.0</td><td>22.7</td><td>13.4</td><td>-</td><td>56.2</td></tr><tr><td>1000</td><td>23.1</td><td>13.8</td><td>22.5</td><td>51.7</td><td>23.0</td><td>13.5</td><td>20.5</td><td>64.7</td></tr><tr><td>1050</td><td>23.5</td><td>13.1</td><td>28.2</td><td>54.2</td><td>23.5</td><td>12.9</td><td>35.9</td><td>57.2</td></tr><tr><td>1100</td><td>23.9</td><td>12.4</td><td>25.6</td><td>58.2</td><td>23.9</td><td>12.4</td><td>30.5</td><td>56.2</td></tr><tr><td>1150</td><td>24.3</td><td>11.8</td><td>20.0</td><td>72.8</td><td>24.4</td><td>11.7</td><td>19.7</td><td>55.4</td></tr><tr><td>1200</td><td>24.7</td><td>11.1</td><td>26.4</td><td>57.2</td><td>24.6</td><td>11.1</td><td>26.0</td><td>63.6</td></tr><tr><td>1250</td><td>25.2</td><td>10.3</td><td>-</td><td>56.1</td><td>24.9</td><td>10.6</td><td>-</td><td>57.1</td></tr></tbody></table>

<table><caption>**Table IV. Horn measurements – summary.**</caption><thead><tr><th rowspan="2"></th><th colspan="2">Insertion loss</th><th colspan="2">Return loss</th></tr><tr><th>measured</th><th>predicted</th><th>measured</th><th>predicted</th></tr></thead><tbody><tr><td>Horn</td><td>-0.14</td><td>-</td><td>26.50</td><td>28</td></tr><tr><td>Polariser</td><td>-0.12</td><td>-0.08</td><td>24.06</td><td>24.44</td></tr><tr><td>WG5 to coax</td><td>-0.075</td><td>-</td><td>&gt; 30</td><td>-</td></tr></tbody></table>

and CNPq) and a smaller amount coming from China, through purchase of components and electronic items for the instrument.

There was a major project review in July 2019, with a committee of five scientists, including two radio astronomers and one HI IM specialist. The result of this review was very positive, with fourteen recommendations in total. Out of these fourteen, four of them requires the close attention of the collaboration working groups and started being addressed immediately after the conclusion of the review. Namely, these four recommendations are: 1) the definition of the final receiver configuration to be used; 2) the final optical design; 3) the recommendation of adopting a full polarisation analysis (or a good motivation to avoid it); and 4) the preparation of

an “end-to-end” pipeline to simulate the mission behaviour well in advance of the beginning of operations. We have solved items 1) and 3) and item 2) is being completed. We are presently working intensely in item 4).

FINAL REMARKS

BINGO is a radio telescope designed to claim the first BAO detection, in the redshift interval $0.13 \le z \le 0.45$, at radio wavelengths around 1 GHz and is currently being constructed in Paraíba, Northeastern Brazil, counting on the local support and expertise of Campina Grande Federal University. The measured signal is produced by the redshifted 21cm HI line, detected through an IM survey covering ~ 1/8
<table><caption>**Table III. Feedhorn beam measurements.** Left: horizontal polarisation. Right: vertical polarisation. Minimum rejection was not measured at all frequencies.</caption><thead><tr><th>Freq<br>(MHz)</th><th>Directivity<br>(dB)</th><th>FWHM<br>(deg)</th><th>Min.<br>rejection<br>(dB)</th><th>Front to back<br>difference<br>(dB)</th><th>Directivity<br>(dB)</th><th>FWHM<br>(deg)</th><th>Min.<br>rejection<br>(dB)</th><th>Front to back<br>difference<br>(dB)</th></tr></thead><tbody><tr><td>950</td><td>22.4</td><td>14.6</td><td>-</td><td>47.0</td><td>22.7</td><td>13.4</td><td>-</td><td>56.2</td></tr><tr><td>1000</td><td>23.1</td><td>13.8</td><td>22.5</td><td>51.7</td><td>23.0</td><td>13.5</td><td>20.5</td><td>64.7</td></tr><tr><td>1050</td><td>23.5</td><td>13.1</td><td>28.2</td><td>54.2</td><td>23.5</td><td>12.9</td><td>35.9</td><td>57.2</td></tr><tr><td>1100</td><td>23.9</td><td>12.4</td><td>25.6</td><td>58.2</td><td>23.9</td><td>12.4</td><td>30.5</td><td>56.2</td></tr><tr><td>1150</td><td>24.3</td><td>11.8</td><td>20.0</td><td>72.8</td><td>24.4</td><td>11.7</td><td>19.7</td><td>55.4</td></tr><tr><td>1200</td><td>24.7</td><td>11.1</td><td>26.4</td><td>57.2</td><td>24.6</td><td>11.1</td><td>26.0</td><td>63.6</td></tr><tr><td>1250</td><td>25.2</td><td>10.3</td><td>-</td><td>56.1</td><td>24.9</td><td>10.6</td><td>-</td><td>57.1</td></tr></tbody></table>

<table><caption>**Table IV. Horn measurements – summary.**</caption><thead><tr><th rowspan="2"></th><th colspan="2">Insertion loss</th><th colspan="2">Return loss</th></tr><tr><th>measured</th><th>predicted</th><th>measured</th><th>predicted</th></tr></thead><tbody><tr><td>Horn</td><td>-0.14</td><td>-</td><td>26.50</td><td>28</td></tr><tr><td>Polariser</td><td>-0.12</td><td>-0.08</td><td>24.06</td><td>24.44</td></tr><tr><td>WG5 to coax</td><td>-0.075</td><td>-</td><td>&gt; 30</td><td>-</td></tr></tbody></table>

and CNPq) and a smaller amount coming from China, through purchase of components and electronic items for the instrument.

There was a major project review in July 2019, with a committee of five scientists, including two radio astronomers and one HI IM specialist. The result of this review was very positive, with fourteen recommendations in total. Out of these fourteen, four of them requires the close attention of the collaboration working groups and started being addressed immediately after the conclusion of the review. Namely, these four recommendations are: 1) the definition of the final receiver configuration to be used; 2) the final optical design; 3) the recommendation of adopting a full polarisation analysis (or a good motivation to avoid it); and 4) the preparation of

an “end-to-end” pipeline to simulate the mission behaviour well in advance of the beginning of operations. We have solved items 1) and 3) and item 2) is being completed. We are presently working intensely in item 4).

## FINAL REMARKS

BINGO is a radio telescope designed to claim the first BAO detection, in the redshift interval $0.13 \le z \le 0.45$, at radio wavelengths around 1 GHz and is currently being constructed in Paraíba, Northeastern Brazil, counting on the local support and expertise of Campina Grande Federal University. The measured signal is produced by the redshifted 21cm HI line, detected through an IM survey covering ~ 1/8
of the sky and will probe the same redshift interval as the most important optical BAO surveys, but with different systematics. BINGO will also provide Galactic foreground maps in the frequency range 980 - 1260 MHz, with its sky coverage overlapping with a number of radio surveys. It will likely be the only radio instrument operating in its redshift range for a few years.

BINGO will provide high quality data, covering a wide range of scientific areas from cosmology to Galactic science. In view of its observation strategy and with some adjustment in the digital backend, BINGO will also be capable to detect transient phenomena, such as pulsars and FRB.

## Acknowledgments

C.A.W. acknowledges the CNPq grant 313597/2014-6 and FAPESP Thematic project grant 2014/07885-0. E.A. acknowledges FAPESP by the grant 2014/07885-0 and FAPESP and CNPq for various other grants. R.G.L. acknowledges CAPES (process 88881.162206/2017-01) and Alexander von Humboldt Foundation for the financial support. M.P. acknowledges funding from a FAPESP Young Investigator fellowship, grant 2015/19936-1. F.A.B acknowledges a CNPq/PRONEX/FAPESQ-PB (Grant no. 165/2018). C.A.W. and F.B.A. acknowledge the UKRI-FAPESP Visiting Professor Grant 2019/05687-0. The authors declare they have no conflicts of interest regarding the contents of this paper.

## REFERENCES

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AGHAMOUSA A ET AL. 2016a. The DESI Experiment Part I: Science, Targeting, and Survey Design. arXiv reprint:astro-ph/1611.00036.

AGHAMOUSA A ET AL. 2016b. The DESI Experiment Part II: Instrument Design. arXiv reprint:astro-ph/1611.00037.

ALBRECHT A ET AL. 2006. Report of the Dark Energy Task Force. arXiv reprint:astro-ph/0609591.

ANDERSON L ET AL. 2014. The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: baryon acoustic oscillations in the Data Releases 10 and 11 Galaxy samples. Mon Not R Astron Soc 441(1): 24-62. doi:10.1093/mnras/stu523.

BAKER T, FERREIRA PG, SKORDIS C & ZUNTZ J. 2011. Towards a fully consistent parameterization of modified gravity. Phys Rev D 84: 124018. doi:10.1103/PhysRevD.84.124018.

BATTYE R ET AL. 2016. Update on the BINGO 21cm intensity mapping experiment. arXiv reprint:astro-ph/1610.06826.

BATTYE RA, BROWN ML, BROWNE IWA, DAVIS RJ, DEWDNEY P, DICKINSON C, HERON G, MAFFEI B, POURTSIDOU A & WILKINSON PN. 2012. BINGO: a single dish approach to 21cm intensity mapping. arXiv reprint:astro-ph/1209.1041.

BATTYE RA, BROWNE IWA, DICKINSON C, HERON G, MAFFEI B & POURTSIDOU A. 2013. H I intensity mapping: a single dish approach. Mon Not R Astron Soc 434: 1239-1256. doi:10.1093/mnras/stt1082.

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CHANG TC, PEN UL, PETERSON JB & MCDONALD P. 2008. Baryon Acoustic Oscillation Intensity Mapping
of the sky and will probe the same redshift interval as the most important optical BAO surveys, but with different systematics. BINGO will also provide Galactic foreground maps in the frequency range 980 - 1260 MHz, with its sky coverage overlapping with a number of radio surveys. It will likely be the only radio instrument operating in its redshift range for a few years.

BINGO will provide high quality data, covering a wide range of scientific areas from cosmology to Galactic science. In view of its observation strategy and with some adjustment in the digital backend, BINGO will also be capable to detect transient phenomena, such as pulsars and FRB.

## Acknowledgments

C.A.W. acknowledges the CNPq grant 313597/2014-6 and FAPESP Thematic project grant 2014/07885-0. E.A. acknowledges FAPESP by the grant 2014/07885-0 and FAPESP and CNPq for various other grants. R.G.L. acknowledges CAPES (process 88881.162206/2017-01) and Alexander von Humboldt Foundation for the financial support. M.P. acknowledges funding from a FAPESP Young Investigator fellowship, grant 2015/19936-1. F.A.B acknowledges a CNPq/PRONEX/FAPESQ-PB (Grant no. 165/2018). C.A.W. and F.B.A. acknowledge the UKRI-FAPESP Visiting Professor Grant 2019/05687-0. The authors declare they have no conflicts of interest regarding the contents of this paper.

## REFERENCES

ABDALLA F, MARINS A, MOTA P, FORNAZIER K ET AL. 2021. Baryon Acoustic Oscillations from Integrated Neutral Gas Observations: optical design. To appear in Astron. Astrophys.

ABDALLA FB, BLAKE C & RAWLINGS S. 2010. Forecasts for Dark Energy Measurements with Future HI Surveys. Mon Not R Astron Soc 401: 743. doi:10.1111/j.1365-2966.2009.15704.x.

ABDALLA FB, BULL P, CAMERA S, BENOIT-LÉVY A, JOACHIMI B, KIRK D, KLOECKNER HR, MAARTENS R, RACCANELLI A & SANTOS MG. 2015. Cosmology from HI galaxy surveys with the SKA. In: Advancing Astrophysics with the Square Kilometre Array (AASKA14). p. 17.

AGHAMOUSA A ET AL. 2016a. The DESI Experiment Part I: Science, Targeting, and Survey Design. arXiv reprint:astro-ph/1611.00036.

AGHAMOUSA A ET AL. 2016b. The DESI Experiment Part II: Instrument Design. arXiv reprint:astro-ph/1611.00037.

ALBRECHT A ET AL. 2006. Report of the Dark Energy Task Force. arXiv reprint:astro-ph/0609591.

ANDERSON L ET AL. 2014. The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: baryon acoustic oscillations in the Data Releases 10 and 11 Galaxy samples. Mon Not R Astron Soc 441(1): 24-62. doi:10.1093/mnras/stu523.

BAKER T, FERREIRA PG, SKORDIS C & ZUNTZ J. 2011. Towards a fully consistent parameterization of modified gravity. Phys Rev D 84: 124018. doi:10.1103/PhysRevD.84.124018.

BATTYE R ET AL. 2016. Update on the BINGO 21cm intensity mapping experiment. arXiv reprint:astro-ph/1610.06826.

BATTYE RA, BROWN ML, BROWNE IWA, DAVIS RJ, DEWDNEY P, DICKINSON C, HERON G, MAFFEI B, POURTSIDOU A & WILKINSON PN. 2012. BINGO: a single dish approach to 21cm intensity mapping. arXiv reprint:astro-ph/1209.1041.

BATTYE RA, BROWNE IWA, DICKINSON C, HERON G, MAFFEI B & POURTSIDOU A. 2013. H I intensity mapping: a single dish approach. Mon Not R Astron Soc 434: 1239-1256. doi:10.1093/mnras/stt1082.

BENNETT CL ET AL. 2013. Nine-year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Final Maps and Results. Astrophys J Supp 208: 20. doi:10.1088/0067-0049/208/2/20.

BEUTLER F, BLAKE C, COLLESS M, JONES DH, STAVELEY-SMITH L, CAMPBELL L, PARKER Q, SAUNDERS W & WATSON F. 2011. The 6dF Galaxy Survey: baryon acoustic oscillations and the local Hubble constant. Mon Not R Astron Soc 416(4): 3017-3032. doi:10.1111/j.1365-2966.2011.19250.x.

BIGOT-SAZY MA, DICKINSON C, BATTYE RA, BROWNE IWA, MA YZ, MAFFEI B, NOVIELLO F, REMAZEILLES M & WILKINSON PN. 2015. Simulations for single-dish intensity mapping experiments. Mon Not R Astron Soc 454(3): 3240-3253. doi:10.1093/mnras/stv2153.

BULL P, FERREIRA PG, PATEL P & SANTOS MG. 2015. Late-time Cosmology with 21 cm Intensity Mapping Experiments. Astrophys J 803(1): 21. doi:10.1088/0004-637X/803/1/21.

CHANG TC, PEN UL, PETERSON JB & MCDONALD P. 2008. Baryon Acoustic Oscillation Intensity Mapping
as a Test of Dark Energy. Phys Rev Lett 100: 091303.
doi:10.1103/PhysRevLett.100.091303.

CHANG TC, PEN UL, BANDURA K & PETERSON JB. 2010. An
intensity map of hydrogen 21-cm emission at redshift z ~
0.8. Nature 466: 463-465. doi:10.1038/nature09187.

CORDES JM & CHATTERJEE S. 2019. Fast radio bursts: an extragalactic enigma. Ann Rev Astron Astrophys 57: 417–465.

COSTA A ET AL. 2021. Baryon Acoustic Oscillations from Integrated Neutral Gas Observations: cosmological forecasts. To appear in Astron. Astrophys.

EISENSTEIN DJ ET AL. 2005. Detection of the Baryon Acoustic Peak in the Large-Scale Correlation Function of SDSS Luminous Red Galaxies. Astrophys J 633: 560-574. doi:10.1086/466512.

FENG C, WANG B, ABDALLA E & SU R. 2008. Observational constraints on the dark energy and dark matter mutual coupling. Phys Lett B 665(2-3): 111-119. doi:10.1016/j.physletb.2008.05.066.

FERREIRA EGM, QUINTIN J, COSTA AA, ABDALLA E & WANG B. 2017. Evidence for interacting dark energy from BOSS. Phys Rev D 95(4): 043520. doi:10.1103/PhysRevD.95.043520.

FORNAZIER K ET AL. 2021. Baryon Acoustic Oscillations from Integrated Neutral Gas Observations: component separation and bispectrum analysis. To appear in Astron. Astrophys.

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HE JH, WANG B & ABDALLA E. 2011. Testing the interaction between dark energy and dark matter via the latest observations. Phys Rev D 83: 063515. doi:10.1103/PhysRevD.83.063515. URL https://link.aps.org/doi/10.1103/PhysRevD.83.063515.

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KOVETZ ED ET AL. 2017. Line-Intensity Mapping: 2017 Status Report. arXiv reprint:astro-ph 1709.09066.

LEVI ME, KIM AG, LAMPTON ML & SHOLL MJ. 2011. Science Yield of an Improved Wide Field Infrared Survey Telescope (WFIRST). arXiv reprint:astro-ph 1105.0959.

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as a Test of Dark Energy. Phys Rev Lett 100: 091303.
doi:10.1103/PhysRevLett.100.091303.

CHANG TC, PEN UL, BANDURA K & PETERSON JB. 2010. An
intensity map of hydrogen 21-cm emission at redshift z ~
0.8. Nature 466: 463-465. doi:10.1038/nature09187.

CORDES JM & CHATTERJEE S. 2019. Fast radio bursts: an extragalactic enigma. Ann Rev Astron Astrophys 57: 417–465.

COSTA A ET AL. 2021. Baryon Acoustic Oscillations from Integrated Neutral Gas Observations: cosmological forecasts. To appear in Astron. Astrophys.

EISENSTEIN DJ ET AL. 2005. Detection of the Baryon Acoustic Peak in the Large-Scale Correlation Function of SDSS Luminous Red Galaxies. Astrophys J 633: 560-574. doi:10.1086/466512.

FENG C, WANG B, ABDALLA E & SU R. 2008. Observational constraints on the dark energy and dark matter mutual coupling. Phys Lett B 665(2-3): 111-119. doi:10.1016/j.physletb.2008.05.066.

FERREIRA EGM, QUINTIN J, COSTA AA, ABDALLA E & WANG B. 2017. Evidence for interacting dark energy from BOSS. Phys Rev D 95(4): 043520. doi:10.1103/PhysRevD.95.043520.

FORNAZIER K ET AL. 2021. Baryon Acoustic Oscillations from Integrated Neutral Gas Observations: component separation and bispectrum analysis. To appear in Astron. Astrophys.

GREEN J ET AL. 2011. Wide-Field InfraRed Survey Telescope (WFIRST) Interim Report. arXiv reprint:astro-ph 1108.1374.

HARPER SE & DICKINSON C. 2018. Potential impact of global navigation satellite services on total power H I intensity mapping surveys. Mon Not R Astron Soc 479(2): 2024-2036. doi:10.1093/mnras/sty1495.

HE JH, WANG B & ABDALLA E. 2009. Stability of the curvature perturbation in dark sectors' mutual interacting models. Phys Lett B 671(1): 139-145. doi:10.1016/j.physletb.2008.11.062.

HE JH, WANG B & ABDALLA E. 2011. Testing the interaction between dark energy and dark matter via the latest observations. Phys Rev D 83: 063515. doi:10.1103/PhysRevD.83.063515. URL https://link.aps.org/doi/10.1103/PhysRevD.83.063515.

KAZIN EA ET AL. 2014. The WiggleZ Dark Energy Survey: improved distance measurements to z = 1 with reconstruction of the baryonic acoustic feature. Mon Not R Astron Soc 441: 3524-3542. doi:10.1093/mnras/stu778.

KOVETZ ED ET AL. 2017. Line-Intensity Mapping: 2017 Status Report. arXiv reprint:astro-ph 1709.09066.

LEVI ME, KIM AG, LAMPTON ML & SHOLL MJ. 2011. Science Yield of an Improved Wide Field Infrared Survey Telescope (WFIRST). arXiv reprint:astro-ph 1105.0959.

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PEEL MW ET AL. 2019. Baryon Acoustic Oscillations from Integrated Neutral Gas Observations: Radio Frequency Interference Measurements and Telescope Site Selection. Journal of Astronomical Instrumentation 8(1): 1940005. doi:10.1142/S2251171719400051.

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PERLMUTTER S, ALDERING G, DELLA VALLE M, DEUSTUA S, ELLIS RS, FABBRO S, FRUCHTER A, GOLDHABER G, GROOM DE & HOOK IM. 1998. Discovery of a supernova explosion at half the age of the Universe. Nature 391(6662): 51-54. doi:10.1038/34124.

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PLANCK COLLABORATION ET AL. 2016. Planck 2015 results. I. Overview of products and scientific results. Astron Astrophys 594: A1. doi:10.1051/0004-6361/201527101.

PLANCK COLLABORATION ET AL. 2018. Planck 2018 results. VI. Cosmological parameters. arXiv reprint:astro-ph 1807.06209: arXiv:1807.06209.

POBER JC, PARSONS AR, DEBOER DR, MCDONALD P, MCQUINN M, AGUIRRE JE, ALI Z, BRADLEY RF, CHANG TC & MORALES MF. 2013. The Baryon Acoustic Oscillation Broadband and Broad-beam Array: Design Overview and Sensitivity Forecasts. Astron J 145: 65. doi:10.1088/0004-6256/145/3/65.

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REMAZEILLES M, DELABROUILLE J & CARDOSO JF. 2011. CMB and SZ effect separation with constrained Internal Linear Combinations. Mon Not R Astron Soc 410: 2481-2487. doi:10.1111/j.1365-2966.2010.17624.x.

RIESS AG, FILIPPENKO AV, CHALLIS P, CLOCCHIATTI A, DIERCKS A, GARNAVICH PM, GILLILAND RL, HOGAN CJ,

JHA S & KIRSHNER RP. 1998. Observational Evidence from Supernovae for an Accelerating Universe and a Cosmological Constant. Astron J 116(3): 1009-1038. doi:10.1086/300499.

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SWITZER ER ET AL. 2013. Determination of z ~ 0.8 neutral hydrogen fluctuations using the 21 cm intensity mapping autocorrelation. Mon Not R Astron Soc 434: L46-L50. doi:10.1093/mnrasl/slt074.

TOJEIRO R, ROSS AJ, BURDEN A, SAMUSHIA L, MANERA M, PERCIVAL WJ, BEUTLER F, BRINKMANN J, BROWNSTEIN JR & CUESTA AJ. 2014. The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: galaxy clustering measurements in the low-redshift sample of Data Release 11. Mon Not R Astron Soc 440(3): 2222-2237. doi:10.1093/mnras/stu371.

TYSON T, WITTMAN D, HENNAWI J & SPERGEL D. 2002. LSST as a precision probe of dark energy. In: APS April Meeting Abstracts. APS Meeting Abstracts. p. Y6.004.

VAN BEMMEL IM, VAN ARDENNE A, GERALT BIJ DE VAATE J, FAULKNER AJ & MORGANTI R. 2012. Mid-frequency aperture arrays: the future of radio astronomy. PoS RTS2012: 037. doi:10.22323/1.163.0037.

VIEIRA FAS. 2020. Protótipo de radiômetro simples para pesquisa em Fast Radio Bursts com o radiotelescópio BINGO. Master's thesis. INPE.

WANG B, GONG Y & ABDALLA E. 2005. Transition of the dark energy equation of state in an interacting holographic dark energy model. Phys Lett B 624(3-4): 141-146. doi:10.1016/j.physletb.2005.08.008.

WANG B, ZANG J, LIN CY, ABDALLA E & MICHELETTI S. 2007. Interacting dark energy and dark matter: Observational constraints from cosmological parameters. Nucl Phys B 778(1-2): 69-84. doi:10.1016/j.nuclphysb.2007.04.037.

WEINBERG DH, MORTONSON MJ, EISENSTEIN DJ, HIRATA C, RIESS AG & ROZO E. 2013. Observational probes of cosmic acceleration. Phys Rep 530: 87-255. doi:10.1016/j.physrep.2013.05.001.

WUENSCHE CA & THE BINGO COLLABORATION. 2019. The BINGO telescope: a new instrument exploring the new 21 cm cosmology window. In: Journal of Physics Conference Series. Journal of Physics Conference Series, vol. 1269. p. 012002. doi:10.1088/1742-6596/1269/1/012002.
intensity power spectrum. Mon Not R Astron Soc 447(4): 3745-3755. doi:10.1093/mnras/stu2702.

PEEL MW ET AL. 2019. Baryon Acoustic Oscillations from Integrated Neutral Gas Observations: Radio Frequency Interference Measurements and Telescope Site Selection. Journal of Astronomical Instrumentation 8(1): 1940005. doi:10.1142/S2251171719400051.

PERCIVAL WJ ET AL. 2010. Baryon acoustic oscillations in the Sloan Digital Sky Survey Data Release 7 galaxy sample. Mon Not R Astron Soc 401(4): 2148-2168. doi:10.1111/j.1365-2966.2009.15812.x.

PERLMUTTER S, ALDERING G, DELLA VALLE M, DEUSTUA S, ELLIS RS, FABBRO S, FRUCHTER A, GOLDHABER G, GROOM DE & HOOK IM. 1998. Discovery of a supernova explosion at half the age of the Universe. Nature 391(6662): 51-54. doi:10.1038/34124.

PETERSON JB, BANDURA K & PEN UL. 2006. The Hubble Sphere Hydrogen Survey. arXiv reprint:astro-ph 0606104.

PLANCK COLLABORATION ET AL. 2014. Planck 2013 results. XVI. Cosmological parameters. Astron Astrophys 571: A16. doi:10.1051/0004-6361/201321591.

PLANCK COLLABORATION ET AL. 2016. Planck 2015 results. I. Overview of products and scientific results. Astron Astrophys 594: A1. doi:10.1051/0004-6361/201527101.

PLANCK COLLABORATION ET AL. 2018. Planck 2018 results. VI. Cosmological parameters. arXiv reprint:astro-ph 1807.06209: arXiv:1807.06209.

POBER JC, PARSONS AR, DEBOER DR, MCDONALD P, MCQUINN M, AGUIRRE JE, ALI Z, BRADLEY RF, CHANG TC & MORALES MF. 2013. The Baryon Acoustic Oscillation Broadband and Broad-beam Array: Design Overview and Sensitivity Forecasts. Astron J 145: 65. doi:10.1088/0004-6256/145/3/65.

REFREGIER A, AMARA A, KITCHING TD, RASSAT A, SCARAMELLA R & WELLER J. 2010. Euclid Imaging Consortium Science Book. arXiv reprint:astro-ph 1001.0061.

REID B ET AL. 2015. SDSS-III Baryon Oscillation Spectroscopic Survey Data Release 12: galaxy target selection and large-scale structure catalogues. Mon Not R Astron Soc 455(2): 1553-1573.

REMAZEILLES M, DELABROUILLE J & CARDOSO JF. 2011. CMB and SZ effect separation with constrained Internal Linear Combinations. Mon Not R Astron Soc 410: 2481-2487. doi:10.1111/j.1365-2966.2010.17624.x.

RIESS AG, FILIPPENKO AV, CHALLIS P, CLOCCHIATTI A, DIERCKS A, GARNAVICH PM, GILLILAND RL, HOGAN CJ,

JHA S & KIRSHNER RP. 1998. Observational Evidence from Supernovae for an Accelerating Universe and a Cosmological Constant. Astron J 116(3): 1009-1038. doi:10.1086/300499.

SQUARE KILOMETRE ARRAY COSMOLOGY SCIENCE WORKING GROUP ET AL. 2020. Cosmology with Phase 1 of the Square Kilometre Array Red Book 2018: Technical specifications and performance forecasts. Publ of the Astr Soc Asia 37: e007. doi:10.1017/pasa.2019.51.

SWITZER ER ET AL. 2013. Determination of z ~ 0.8 neutral hydrogen fluctuations using the 21 cm intensity mapping autocorrelation. Mon Not R Astron Soc 434: L46-L50. doi:10.1093/mnrasl/slt074.

TOJEIRO R, ROSS AJ, BURDEN A, SAMUSHIA L, MANERA M, PERCIVAL WJ, BEUTLER F, BRINKMANN J, BROWNSTEIN JR & CUESTA AJ. 2014. The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: galaxy clustering measurements in the low-redshift sample of Data Release 11. Mon Not R Astron Soc 440(3): 2222-2237. doi:10.1093/mnras/stu371.

TYSON T, WITTMAN D, HENNAWI J & SPERGEL D. 2002. LSST as a precision probe of dark energy. In: APS April Meeting Abstracts. APS Meeting Abstracts. p. Y6.004.

VAN BEMMEL IM, VAN ARDENNE A, GERALT BIJ DE VAATE J, FAULKNER AJ & MORGANTI R. 2012. Mid-frequency aperture arrays: the future of radio astronomy. PoS RTS2012: 037. doi:10.22323/1.163.0037.

VIEIRA FAS. 2020. Protótipo de radiômetro simples para pesquisa em Fast Radio Bursts com o radiotelescópio BINGO. Master's thesis. INPE.

WANG B, GONG Y & ABDALLA E. 2005. Transition of the dark energy equation of state in an interacting holographic dark energy model. Phys Lett B 624(3-4): 141-146. doi:10.1016/j.physletb.2005.08.008.

WANG B, ZANG J, LIN CY, ABDALLA E & MICHELETTI S. 2007. Interacting dark energy and dark matter: Observational constraints from cosmological parameters. Nucl Phys B 778(1-2): 69-84. doi:10.1016/j.nuclphysb.2007.04.037.

WEINBERG DH, MORTONSON MJ, EISENSTEIN DJ, HIRATA C, RIESS AG & ROZO E. 2013. Observational probes of cosmic acceleration. Phys Rep 530: 87-255. doi:10.1016/j.physrep.2013.05.001.

WUENSCHE CA & THE BINGO COLLABORATION. 2019. The BINGO telescope: a new instrument exploring the new 21 cm cosmology window. In: Journal of Physics Conference Series. Journal of Physics Conference Series, vol. 1269. p. 012002. doi:10.1088/1742-6596/1269/1/012002.
WUENSCHE CA ET AL. 2020. Baryon acoustic oscillations from Integrated Neutral Gas Observations: Broadband corrugated horn construction and testing. Experimental Astronomy 50(1): 125-144. doi:10.1007/s10686-020-09666-9.

## How to cite

WUENSCHE CA ET AL. 2021. Baryon Acoustic Oscillations from Integrated Neutral Gas Observations: an instrument to observe the 21cm hydrogen line in the redshift range 0.13 < z < 0.45 – status update. An Acad Bras Cienc 93: e20201096. DOI 10.1590/0001-3765202120201096.

Manuscript received on July 14, 2020; accepted for publication on August 10, 2020

### CARLOS A. WUENSCHE¹

https://orcid.org/0000-0003-1373-4719

### ELCIO ABDALLA²

https://orcid.org/0000-0002-9814-1690

### FILIPE ABDALLA³,⁴

https://orcid.org/0000-0003-2063-4345

### LUCIANO BAROS¹

https://orcid.org/0000-0002-5455-2682

### BIN WANG⁶,⁷

https://orcid.org/0000-0003-3419-9153

### RUI AN⁷

http://orcid.org/0000-0003-4931-6105

### JOÃO A. M. BARRETOS²

https://orcid.org/0000-0002-3111-1331

### RICHARD BATTYE⁸

https://orcid.org/0000-0002-4269-515X

### FRANCISCO A. BRITO⁵

https://orcid.org/0000-0001-9465-6868

### IAN BROWNE⁸

https://orcid.org/0000-0002-0743-8430

### DANIEL CORREIA²

https://orcid.org/0000-0002-8733-8535

### ANDRÉ A. COSTA⁶

https://orcid.org/0000-0002-3670-9826

### JACQUES DELABROUILLE⁹,¹⁰

https://orcid.org/0000-0002-7217-4689

### CLIVE DICKINSON⁸

https://orcid.org/0000-0002-0045-442X

### CHANG FENG¹¹

http://orcid.org/0000-0001-7438-5896

### ELISA G. M. FERREIRA¹²

https://orcid.org/0000-0002-5032-8368

### KARIN FORNAZIER²,³

https://orcid.org/0000-0003-0578-9533

### GIANCARLO DE GASPERIS¹³,¹⁴

https://orcid.org/0000-0003-2899-2171

### PRISCILA GUTIERREZ²

https://orcid.org/0000-0001-9997-8313

### STUART HARPER⁸

https://orcid.org/0000-0001-7911-5553

### RICARDO G. LANDIM¹⁵

https://orcid.org/0000-0001-6801-3519

### VINCENZO LICCARDO¹,⁸

https://orcid.org/0000-0001-5506-5125

### YIN-ZHE MA¹⁶,¹⁷

https://orcid.org/0000-0001-8108-0986

### TELMO MACHADO¹

https://orcid.org/0000-0002-6631-1245

### BRUNO MAFFEI¹⁸

http://orcid.org/0000-0002-2214-5329

### ALESSANDRO MARINS²

https://orcid.org/0000-0002-6519-6038

### MILENA M. MENDES²

https://orcid.org/0000-0002-4646-4762

### EDUARDO MERICIA¹

https://orcid.org/0000-0002-4672-5467

### CHRISTIAN MONSTEIN¹⁹

https://orcid.org/0000-0002-3178-363X

### PABLO MOTTA²

https://orcid.org/0000-0002-3416-6258

### CAMILA NOVAES¹

https://orcid.org/0000-0002-5845-3649

### CARLOS H. OTOBONE²

https://orcid.org/0000-0001-7482-262X

### MICHAEL PEEL²⁰,²¹

https://orcid.org/0000-0003-3412-2586

### AMILCAR R. QUEIROZ⁵

https://orcid.org/0000-0002-4785-5589

### CHRISTOPHER RADCLIFFE²²

https://orcid.org/0000-0001-8338-6356

### MATHIEU REMAZEILLES⁸

https://orcid.org/0000-0001-9126-6266

### RAFAEL M. G. RIBEIRO²

https://orcid.org/0000-0003-2903-0679

### YU SANG⁶

http://orcid.org/0000-0002-2631-7781

### JULIANA F. R. SANTOS²

https://orcid.org/0000-0002-5549-5747
WUENSCHE CA ET AL. 2020. Baryon acoustic oscillations from Integrated Neutral Gas Observations: Broadband corrugated horn construction and testing. Experimental Astronomy 50(1): 125-144. doi:10.1007/s10686-020-09666-9.

### How to cite

WUENSCHE CA ET AL. 2021. Baryon Acoustic Oscillations from Integrated Neutral Gas Observations: an instrument to observe the 21cm hydrogen line in the redshift range 0.13 < z < 0.45 – status update. An Acad Bras Cienc 93: e20201096. DOI 10.1590/0001-3765202120201096.

Manuscript received on July 14, 2020; accepted for publication on August 10, 2020

### CARLOS A. WUENSCHE¹

https://orcid.org/0000-0003-1373-4719

### ELCIO ABDALLA²

https://orcid.org/0000-0002-9814-1690

### FILIPE ABDALLA³,⁴

https://orcid.org/0000-0003-2063-4345

### LUCIANO BAROS¹

https://orcid.org/0000-0002-5455-2682

### BIN WANG⁶,⁷

https://orcid.org/0000-0003-3419-9153

### RUI AN⁷

http://orcid.org/0000-0003-4931-6105

### JOÃO A. M. BARRETOS²

https://orcid.org/0000-0002-3111-1331

### RICHARD BATTYE⁸

https://orcid.org/0000-0002-4269-515X

### FRANCISCO A. BRITO⁵

https://orcid.org/0000-0001-9465-6868

### IAN BROWNE⁸

https://orcid.org/0000-0002-0743-8430

### DANIEL CORREIA²

https://orcid.org/0000-0002-8733-8535

### ANDRÉ A. COSTA⁶

https://orcid.org/0000-0002-3670-9826

### JACQUES DELABROUILLE⁹,¹⁰

https://orcid.org/0000-0002-7217-4689

### CLIVE DICKINSON⁸

https://orcid.org/0000-0002-0045-442X

### CHANG FENG¹¹

http://orcid.org/0000-0001-7438-5896

### ELISA G. M. FERREIRA¹²

https://orcid.org/0000-0002-5032-8368

### KARIN FORNAZIER²,³

https://orcid.org/0000-0003-0578-9533

### GIANCARLO DE GASPERIS¹³,¹⁴

https://orcid.org/0000-0003-2899-2171

### PRISCILA GUTIERREZ²

https://orcid.org/0000-0001-9997-8313

### STUART HARPER⁸

https://orcid.org/0000-0001-7911-5553

### RICARDO G. LANDIM¹⁵

https://orcid.org/0000-0001-6801-3519

### VINCENZO LICCARDO¹,⁸

https://orcid.org/0000-0001-5506-5125

### YIN-ZHE MA¹⁶,¹⁷

https://orcid.org/0000-0001-8108-0986

### TELMO MACHADO¹

https://orcid.org/0000-0002-6631-1245

### BRUNO MAFFEI¹⁸

http://orcid.org/0000-0002-2214-5329

### ALESSANDRO MARINS²

https://orcid.org/0000-0002-6519-6038

### MILENA M. MENDES²

https://orcid.org/0000-0002-4646-4762

### EDUARDO MERICIA¹

https://orcid.org/0000-0002-4672-5467

### CHRISTIAN MONSTEIN¹⁹

https://orcid.org/0000-0002-3178-363X

### PABLO MOTTA²

https://orcid.org/0000-0002-3416-6258

### CAMILA NOVAES¹

https://orcid.org/0000-0002-5845-3649

### CARLOS H. OTOBONE²

https://orcid.org/0000-0001-7482-262X

### MICHAEL PEEL²⁰,²¹

https://orcid.org/0000-0003-3412-2586

### AMILCAR R. QUEIROZ⁵

https://orcid.org/0000-0002-4785-5589

### CHRISTOPHER RADCLIFFE²²

https://orcid.org/0000-0001-8338-6356

### MATHIEU REMAZEILLES⁸

https://orcid.org/0000-0001-9126-6266

### RAFAEL M. G. RIBEIRO²

https://orcid.org/0000-0003-2903-0679

### YU SANG⁶

http://orcid.org/0000-0002-2631-7781

### JULIANA F. R. SANTOS²

https://orcid.org/0000-0002-5549-5747
LARISSA SANTOS<fnref n="6" />

https://orcid.org/0000-0001-7015-998X

MARCELO. V. SANTOS<fnref n="5" />

https://orcid.org/0000-0002-1408-6947

CHENXI SHAN<fnref n="6" />

http://orcid.org/0000-0002-7114-8139

GUSTAVO B. SILVA<fnref n="2" />

https://orcid.org/0000-0002-4746-2013

FREDERICO VIEIRA<fnref n="1" />

https://orcid.org/0000-0003-3839-9814

JORDANY VIEIRA<fnref n="2" />

https://orcid.org/0000-0001-8283-5295

THYRSO VILLELA<fnref n="1" />,²³

https://orcid.org/0000-0002-4284-8988

LINFENG XIAO<fnref n="7" />

http://orcid.org/0000-0003-3198-3591

WEIQIANG YANG²⁴

https://orcid.org/0000-0002-6486-6765

JIAJUN ZHANG²⁵

https://orcid.org/0000-0002-4117-343X

XUE ZHANG<fnref n="6" />

http://orcid.org/0000-0002-5840-9349

ZENGHAO ZHU²⁶

http://orcid.org/0000-0001-8443-6095

¹³Dipartimento di Fisica, Università degli Studi di Roma Tor Vergata, Via della Ricerca Scientifica, 1 I-00133 Roma, Italy

¹⁴INFN Sez. di Roma 2, Via della Ricerca Scientifica, 1 I-00133 Roma, Italy

¹⁵Technische Universität München, Physik-Department, James-Franck-Strasse 1, 85748 Garching, Germany

¹⁶School of Chemistry and Physics, University of KwaZulu-Natal, Westville Campus, Private Bag X54001, Durban 4000, South Africa

¹⁷NAOC-UKZN Computational Astrophysics Centre (NUCAC), University of KwaZulu-Natal, Durban, 4000, South Africa

¹⁸IAS, Université Paris-Saclay, 91405 Orsay Cedex, France

¹⁹ETH Zürich, Institute for Particle Physics and Astrophysics, HIT J13.2, Wolfgang-Pauli-Strasse 27, 8093 Zürich, Switzerland

²⁰Departamento de Astrofísica, Universidad de La Laguna (ULL), 38206 La Laguna, Tenerife, Spain

²¹Instituto de Astrofísica de Canarias, 38200 La Laguna, Tenerife, Canary Islands, Spain

²²Phase2 Microwave Ltd., Unit 1a, Boulton Rd, Pin Green Ind. Est., Stevenage, SG1 4QX, UK

²³Universidade de Brasília, Instituto de Física, ICC Centro, Direção do IF, entrada BT 297 (térreo), Asa Norte 70919-970 Brasília, DF, Brazil

²⁴Liao Ning Normal University, No.850 Huanghe Road Shahekou District, Dalian, Liaoning, P.R.China 116029

²⁵CTPU-IBS, Theory building, 4th Floor, 55, Expo-ro, Yuseong-gu, Daejeon, Korea

²⁶School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, P. R. China

Correspondence to: Carlos A. Wuensche

E-mail: ca.wuensche@inpe.br

## Authors contributions

Carlos A. Wuensche and Elcio Abdalla are, respectively, the PI and the general coordination of the project. Filipe Abdalla, Luciano Barosi, Bin Wang, Amilcar Queiróz, Francisco Brito and Thyrso Villela belong to the management team, who are working in various aspects of logistics and construction to make BINGO a reality. Richard Battye, Clive Dickinson and Stuart Harper worked heavily in the initial stages of BINGO. Mike Peel, Ian Browne and Christian Monster have a strong participation in the receiver construction, which is led by Carlos A. Wuensche; Mike Peel is the first author of the site selection paper and Telmo Machado has worked in many aspects of the receiver construction. Christopher Radcliffe produced the filters and the simulations of the BINGO horns and front end. Jacques Dellabrouile, Mathieu Remazeilles, Larissa Santos, Karin Fornazier, Eduardo Mericia, Giancarlo de Gasperis and Vincenzo Liccardo are the contributors to the mission simulation and component separation aspects of the data analysis. André Costa, Ricardo Landim, Elisa Ferreira, Jianjun Zhang, Camila Novaes and Yin-Zhe

<footnote n="1">¹Divisão de Astrofísica, Instituto Nacional de Pesquisas Espaciais. Av. dos Astronautas 1758, Jd. da Granja, CEP 12227-010, São José dos Campos, SP, Brazil</footnote>

<footnote n="2">²Instituto de Física, Universidade de São Paulo, R. do Matão, 1371, Butantã, 05508-090 São Paulo, SP, Brazil</footnote>

<footnote n="3">³Unidade Acadêmica de Física, Universidade Federal de Campina Grande, R. Aprigio Veloso, Bodocongó, 58429-900 Campina Grande, PB, Brazil</footnote>

<footnote n="4">⁴University College London, Gower Street, London, WC1E 6BT, UK</footnote>

<footnote n="5">⁵Department of Physics and Electronics, Rhodes University, PO Box 94, Grahamstown, 6140, South Africa</footnote>

<footnote n="6">⁶Center for Gravitation and Cosmology, College of Physical Science and Technology, Yangzhou University, 225009, Yangzhou, China</footnote>

<footnote n="7">⁷School of Aeronautics and Astronautics, Shanghai Jiao Tong University, Shanghai 200240, China</footnote>

<footnote n="8">⁸Jodrell Bank Centre for Astrophysics, Department of Physics and Astronomy, The University of Manchester, Oxford Road, Manchester, M13 9PL, U.K.</footnote>

<footnote n="9">⁹Laboratoire Astroparticule et Cosmologie (APC), CNRS/IN2P3, Université Paris Diderot, 75205 Paris Cedex 13, France</footnote>

<footnote n="10">¹⁰IRFU, CEA, Université Paris Saclay, 91191 Gif-sur-Yvette, France</footnote>

<footnote n="11">¹¹School of Astronomy and Space Science, University of Science and Technology of China, Hefei, 230026, China</footnote>

<footnote n="12">¹²Max-Planck-Institut fr Astrophysik, Karl-Schwarzschild-Str. 1, 85748 Garching, Germany</footnote>
LARISSA SANTOS<fnref n="6" />

https://orcid.org/0000-0001-7015-998X

MARCELO. V. SANTOS<fnref n="5" />

https://orcid.org/0000-0002-1408-6947

CHENXI SHAN<fnref n="6" />

http://orcid.org/0000-0002-7114-8139

GUSTAVO B. SILVA<fnref n="2" />

https://orcid.org/0000-0002-4746-2013

FREDERICO VIEIRA<fnref n="1" />

https://orcid.org/0000-0003-3839-9814

JORDANY VIEIRA<fnref n="2" />

https://orcid.org/0000-0001-8283-5295

THYRSO VILLELA<fnref n="1" />,²³

https://orcid.org/0000-0002-4284-8988

LINFENG XIAO<fnref n="7" />

http://orcid.org/0000-0003-3198-3591

WEIQIANG YANG²⁴

https://orcid.org/0000-0002-6486-6765

JIAJUN ZHANG²⁵

https://orcid.org/0000-0002-4117-343X

XUE ZHANG<fnref n="6" />

http://orcid.org/0000-0002-5840-9349

ZENGHAO ZHU²⁶

http://orcid.org/0000-0001-8443-6095

¹³Dipartimento di Fisica, Università degli Studi di Roma Tor Vergata, Via della Ricerca Scientifica, 1 I-00133 Roma, Italy

¹⁴INFN Sez. di Roma 2, Via della Ricerca Scientifica, 1 I-00133 Roma, Italy

¹⁵Technische Universität München, Physik-Department, James-Franck-Strasse 1, 85748 Garching, Germany

¹⁶School of Chemistry and Physics, University of KwaZulu-Natal, Westville Campus, Private Bag X54001, Durban 4000, South Africa

¹⁷NAOC-UKZN Computational Astrophysics Centre (NUCAC), University of KwaZulu-Natal, Durban, 4000, South Africa

¹⁸IAS, Université Paris-Saclay, 91405 Orsay Cedex, France

¹⁹ETH Zürich, Institute for Particle Physics and Astrophysics, HIT J13.2, Wolfgang-Pauli-Strasse 27, 8093 Zürich, Switzerland

²⁰Departamento de Astrofísica, Universidad de La Laguna (ULL), 38206 La Laguna, Tenerife, Spain

²¹Instituto de Astrofísica de Canarias, 38200 La Laguna, Tenerife, Canary Islands, Spain

²²Phase2 Microwave Ltd., Unit 1a, Boulton Rd, Pin Green Ind. Est., Stevenage, SG1 4QX, UK

²³Universidade de Brasília, Instituto de Física, ICC Centro, Direção do IF, entrada BT 297 (térreo), Asa Norte 70919-970 Brasília, DF, Brazil

²⁴Liao Ning Normal University, No.850 Huanghe Road Shahekou District, Dalian, Liaoning, P.R.China 116029

²⁵CTPU-IBS, Theory building, 4th Floor, 55, Expo-ro, Yuseong-gu, Daejeon, Korea

²⁶School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, P. R. China

Correspondence to: Carlos A. Wuensche

E-mail: ca.wuensche@inpe.br

## Authors contributions

Carlos A. Wuensche and Elcio Abdalla are, respectively, the PI and the general coordination of the project. Filipe Abdalla, Luciano Barosi, Bin Wang, Amilcar Queiróz, Francisco Brito and Thyrso Villela belong to the management team, who are working in various aspects of logistics and construction to make BINGO a reality. Richard Battye, Clive Dickinson and Stuart Harper worked heavily in the initial stages of BINGO. Mike Peel, Ian Browne and Christian Monster have a strong participation in the receiver construction, which is led by Carlos A. Wuensche; Mike Peel is the first author of the site selection paper and Telmo Machado has worked in many aspects of the receiver construction. Christopher Radcliffe produced the filters and the simulations of the BINGO horns and front end. Jacques Dellabrouile, Mathieu Remazeilles, Larissa Santos, Karin Fornazier, Eduardo Mericia, Giancarlo de Gasperis and Vincenzo Liccardo are the contributors to the mission simulation and component separation aspects of the data analysis. André Costa, Ricardo Landim, Elisa Ferreira, Jianjun Zhang, Camila Novaes and Yin-Zhe

<footnote n="1">¹Divisão de Astrofísica, Instituto Nacional de Pesquisas Espaciais. Av. dos Astronautas 1758, Jd. da Granja, CEP 12227-010, São José dos Campos, SP, Brazil</footnote>

<footnote n="2">²Instituto de Física, Universidade de São Paulo, R. do Matão, 1371, Butantã, 05508-090 São Paulo, SP, Brazil</footnote>

<footnote n="3">³Unidade Acadêmica de Física, Universidade Federal de Campina Grande, R. Aprigio Veloso, Bodocongó, 58429-900 Campina Grande, PB, Brazil</footnote>

<footnote n="4">⁴University College London, Gower Street, London, WC1E 6BT, UK</footnote>

<footnote n="5">⁵Department of Physics and Electronics, Rhodes University, PO Box 94, Grahamstown, 6140, South Africa</footnote>

<footnote n="6">⁶Center for Gravitation and Cosmology, College of Physical Science and Technology, Yangzhou University, 225009, Yangzhou, China</footnote>

<footnote n="7">⁷School of Aeronautics and Astronautics, Shanghai Jiao Tong University, Shanghai 200240, China</footnote>

<footnote n="8">⁸Jodrell Bank Centre for Astrophysics, Department of Physics and Astronomy, The University of Manchester, Oxford Road, Manchester, M13 9PL, U.K.</footnote>

<footnote n="9">⁹Laboratoire Astroparticule et Cosmologie (APC), CNRS/IN2P3, Université Paris Diderot, 75205 Paris Cedex 13, France</footnote>

<footnote n="10">¹⁰IRFU, CEA, Université Paris Saclay, 91191 Gif-sur-Yvette, France</footnote>

<footnote n="11">¹¹School of Astronomy and Space Science, University of Science and Technology of China, Hefei, 230026, China</footnote>

<footnote n="12">¹²Max-Planck-Institut fr Astrophysik, Karl-Schwarzschild-Str. 1, 85748 Garching, Germany</footnote>
Ma are the main developers of the cosmological forecast module in the data analysis effort. The optical design was led by Filipe Abdalla and Bruno Maffei, with the heavy involvement of Alessandro Marins and Pablo Motta, and the participation of João A. M. Barreto, Daniel Correia, Priscila Gutierrez, Milena M. M. Mendes, Juliana F. R. Santos, Carlos H. Otobone, Rafael M. G. Ribeiro, Karin Fornazier and Gustavo B. Silva, who ran the simulations of the optical system and produced the fits for the horn positions. The Fast Radio Bursts and the pulsar working group is led by Ricardo Landim, with the strong participation of Marcelo. V. Santos, Frederico Vieira, Jordany Vieira, Chenxi Shan, Yu Sang and Linfeng Xiao. Rui An, Chang. Feng, Weiqiang Yang, Xue Zhang and Zenghao Zhu are working on different aspects of the cosmological parameter estimation effort.

<figure><img src="image_10.png" /></figure>
Ma are the main developers of the cosmological forecast module in the data analysis effort. The optical design was led by Filipe Abdalla and Bruno Maffei, with the heavy involvement of Alessandro Marins and Pablo Motta, and the participation of João A. M. Barreto, Daniel Correia, Priscila Gutierrez, Milena M. M. Mendes, Juliana F. R. Santos, Carlos H. Otobone, Rafael M. G. Ribeiro, Karin Fornazier and Gustavo B. Silva, who ran the simulations of the optical system and produced the fits for the horn positions. The Fast Radio Bursts and the pulsar working group is led by Ricardo Landim, with the strong participation of Marcelo. V. Santos, Frederico Vieira, Jordany Vieira, Chenxi Shan, Yu Sang and Linfeng Xiao. Rui An, Chang. Feng, Weiqiang Yang, Xue Zhang and Zenghao Zhu are working on different aspects of the cosmological parameter estimation effort.

<figure><img src="image_10.png" /></figure>