adsabs/SciX_UAT_keywords huggingface dataset:
Simulating the Detection of the Global 21 cm Signal with MIST for Different Models of the Soil and Beam Directivity

The Mapper of the IGM Spin Temperature (MIST) is a new ground-based, single-antenna, radio experiment attempting to detect the global 21 cm signal from the Dark Ages and Cosmic Dawn. A significant challenge in this measurement is the frequency dependence, or chromaticity, of the antenna beam directivity. MIST observes with the antenna above the soil and without a metal ground plane, and the beam directivity is sensitive to the electrical characteristics of the soil. In this paper, we use simulated observations with MIST to study how the detection of the global 21 cm signal from Cosmic Dawn is affected by the soil and the MIST beam directivity. We simulate observations using electromagnetic models of the directivity computed for single- and two-layer models of the soil. We test the recovery of the Cosmic Dawn signal with and without beam chromaticity correction applied to the simulated data. We find that our single-layer soil models enable a straightforward recovery of the signal even without chromaticity correction. Two-layer models increase the beam chromaticity and make the recovery more challenging. However, for the model in which the bottom soil layer has a lower electrical conductivity than the top layer, the signal can be recovered even without chromaticity correction. For the other two-layer models, chromaticity correction is necessary for the recovery of the signal, and the accuracy requirements for the soil parameters vary between models. These results will be used as a guideline to select observation sites that are favorable for the detection of the Cosmic Dawn signal.

Keywords: population iii stars; reionization; intergalactic medium; h i line emission; radio receivers; bayesian statistics; bayesian information criterion
Richardson-Lucy Deconvolution with a Spatially Variant Point-spread Function of Chandra: Supernova Remnant Cassiopeia A as an Example

Richardson-Lucy (RL) deconvolution is one of the classical methods widely used in X-ray astronomy and other areas. Amid recent progress in image processing, RL deconvolution still leaves much room for improvement under realistic situations. One direction is to include the positional dependence of a point-spread function (PSF), so-called RL deconvolution with a spatially variant PSF (RLsv). Another is the method of estimating a reliable number of iterations and their associated uncertainties. We developed a practical method that incorporates the RLsv algorithm and the estimation of uncertainties. As a typical example of bright and high-resolution images, the Chandra X-ray image of the supernova remnant Cassiopeia A was used in this paper. RLsv deconvolution enables us to uncover the smeared features in the forward/backward shocks and jet-like structures. We constructed a method to predict the appropriate number of iterations using statistical fluctuation of the observed images. Furthermore, the uncertainties were estimated by error propagation from the last iteration, which was phenomenologically tested with the observed data. Thus, our method is a practically efficient framework to evaluate the time evolution of the remnants and their fine structures embedded in high-resolution X-ray images.

Keywords: astronomy data analysis; astronomy image processing; high angular resolution; x-ray astronomy
The Gas Accretion Rate of Galaxies over z ≈ 0-1.3

We present here estimates of the average rates of accretion of neutral gas onto main-sequence galaxies and the conversion of atomic gas to molecular gas in these galaxies at two key epochs in galaxy evolution: (i) z ≈ 1.3-1.0, toward the end of the epoch of peak star formation activity in the Universe, and (ii) z ≈ 1-0, when the star formation activity declines by an order of magnitude. We determine the net gas accretion rate R Acc and the molecular gas formation rate R Mol by combining the relations between the stellar mass and the atomic gas mass, the molecular gas mass, and the star formation rate (SFR) at three epochs, z = 1.3, z = 1.0, and z = 0, with the assumption that galaxies evolve continuously on the star-forming main sequence. We find that, for all galaxies, R Acc is far lower than the average SFR R SFR at z ≈ 1.3-1.0; however, R Mol is similar to R SFR during this interval. Conversely, both R Mol and R Acc are significantly lower than R SFR over the later interval, z ≈ 1-0. We find that massive main-sequence galaxies had already acquired most of their present-day baryonic mass by z ≈ 1.3. At z ≈ 1.3-1.0, the rapid conversion of the existing atomic gas to molecular gas was sufficient to maintain a high average SFR, despite the low net gas accretion rate. However, at later times, the combination of the lower net gas accretion rate and the lower molecular gas formation rate leads to a decline in the fuel available for star formation and results in the observed decrease in the SFR density of the Universe over the last 8 Gyr.

Keywords: galaxies
The Coupling of an EUV Coronal Wave and Ion Acceleration in a Fermi-LAT Behind-the-Limb Solar Flare

We present the Fermi-LAT observations of the behind-the-limb (BTL) flare of 2021 July 17 and the joint detection of this flare by STIX on board the Solar Orbiter. The separation between Earth and the Solar Orbiter was 99.°2 at 05:00 UT, allowing STIX to have a front view of the flare. The location of the flare was S20E140 in Stonyhurst heliographic coordinates, making this the most distant behind-the-limb flare ever detected in >100 MeV gamma-rays. The LAT detection lasted for ~16 minutes, the peak flux was 3.6 ± 0.8 (10-5) ph cm-2 s-1 with a significance >15σ. A coronal wave was observed from both STEREO-A and SDO in extreme ultraviolet (EUV), with an onset on the visible disk in coincidence with the LAT onset. A complex type II radio burst was observed by GLOSS also in coincidence with the onset of the LAT emission, indicating the presence of a shock wave. We discuss the relation between the time derivative of the EUV wave intensity profile at 193 Å as observed by STEREO-A and the LAT flux to show that the appearance of the coronal wave at the visible disk and the acceleration of protons as traced by the observed >100 MeV gamma-ray emission are coupled. We also report how this coupling is present in the data from three other BTL flares detected by Fermi-LAT, suggesting that the protons driving the gamma-ray emission of BTL solar flares and the coronal wave share a common origin.

Keywords: solar particle emission; solar physics
Wandering Black Hole Candidates in Dwarf Galaxies at VLBI Resolution

Thirteen dwarf galaxies have recently been found to host radio-selected accreting massive black hole (MBH) candidates, some of which are "wandering" in the outskirts of their hosts. We present 9 GHz Very Long Baseline Array (VLBA) observations of these sources at milliarcsecond resolution. Our observations have beam solid angles ~104 times smaller than the previous Very Large Array (VLA) observations at 9 GHz, with comparable point-source sensitivities. We detect milliarcsecond-scale radio sources at the positions of the four VLA sources most distant from the photocenters of their associated dwarf galaxies. These sources have brightness temperatures of >106 K, consistent with active galactic nuclei (AGNs), but the significance of their preferential location at large distances (p-value = 0.0014) favors a background AGN interpretation. The VLBA nondetections toward the other nine galaxies indicate that the VLA sources are resolved out on scales of tens of milliarcseconds, requiring extended radio emission and lower brightness temperatures consistent with either star formation or radio lobes associated with AGN activity. We explore the star formation explanation by calculating the expected radio emission for these nine VLBA nondetections, finding that about five have VLA luminosities that are inconsistent with this scenario. Of the remaining four, two are associated with spectroscopically confirmed AGNs that are consistent with being located at their galaxy photocenters. There are therefore between five and seven wandering MBH candidates out of the 13 galaxies we observed, although we cannot rule out background AGNs for five of them with the data in hand.

Keywords: dwarf galaxies; radio active galactic nuclei; star forming regions; intermediate-mass black holes; radio astronomy
White-light Superflare and Long-term Activity of the Nearby M7-type Binary EI Cnc Observed with GWAC System

Stellar white-light flares are believed to play an essential role in the physical and chemical properties of the atmosphere of the surrounding exoplanets. Here we report an optical monitoring campaign on the nearby flaring system EI Cnc carried out by the Ground-based Wide Angle Camera (GWAC) and its dedicated follow-up telescope. A superflare, coming from the brighter component EI CncA, was detected and observed, in which four components are required to properly model the complex decay light curve. The lower limit of flare energy in the R - band is estimated to be 3.3 × 1032 erg. A total of 27 flares are additionally detected from the GWAC archive data with a total duration of 290 hr. The inferred cumulative flare frequency distribution follows a quite shallow power-law function with a slope of β = - 0.50 ± 0.03 over the energy range between 1030 and 1033 erg, which reinforces the trend that stars cooler than M4 show enhanced superflare activity. The flares identified in EI Cnc enable us to extend the τ-E relationship previously established in the white-light superflares of solar-type stars down to an energy as low as ~1030erg (i.e., by 3 orders): τ ∝ E 0.42±0.02, which suggests a common flare mechanism for stars with a type from M to solar-like and implies an invariant of B 1/3 υ A in the white-light flares.

Keywords: stellar flares
Defining the (Black Hole)-Spheroid Connection with the Discovery of Morphology-dependent Substructure in the MBH-nsph and MBH-Re,sph Diagrams: New Tests for Advanced Theories and Realistic Simulations

For 123 local galaxies with directly measured black hole masses (MBH), we provide the host spheroid's Sérsic index (nsph), effective half-light radius (Re,sph), and effective surface brightness ( ${\mu }_{{\rm{e}}}$ ), obtained from careful multicomponent decompositions, and we use these to derive the morphology-dependent MBH-nsph and MBH-Re,sph relations. We additionally present the morphology-dependent M*,sph-nsph and M*,sph-Re,sph relations. We explored differences due to early-type galaxies (ETGs) versus late-type galaxies (LTGs), Sérsic versus core-Sérsic galaxies, barred versus non-barred galaxies, and galaxies with and without a stellar disk. We detect two different MBH-nsph relations due to ETGs and LTGs with power-law slopes 3.95 ± 0.34 and 2.85 ± 0.31. We additionally quantified the correlation between MBH and the spheroid's central concentration index, which varies monotonically with the Sérsic index. Furthermore, we observe a single, near-linear M*,sph- ${R}_{{\rm{e}},\mathrm{sph}}^{1.08\pm 0.04}$ relation for ETGs and LTGs, which encompasses both classical and alleged pseudobulges. In contrast, ETGs and LTGs define two distinct MBH-Re,sph relations with ${{\rm{\Delta }}}_{\mathrm{rms}| \mathrm{BH}}\sim 0.60\,\mathrm{dex}$ (cf. ∼0.51 dex for the MBH-σ relation and ∼0.58 dex for the MBH-M*,sph relation), and the ETGs alone define two steeper MBH-Re,sph relations, offset by ∼1 dex in the $\mathrm{log}{M}_{\mathrm{BH}}$ direction, depending on whether they have a disk or not and explaining their similar offset in the MBH-M*,sph diagram. This trend holds using 10%, 50%, or 90% radii. These relations offer pivotal checks for simulations trying to reproduce realistic galaxies, and for theoretical studies investigating the dependence of black hole mass on basic spheroid properties.

Keywords: galaxy evolution; supermassive black holes; galaxy structure; galaxy bulges; galaxy spheroids; early-type galaxies; late-type galaxies; spiral galaxies; scaling relations; black hole physics
Blazars at the Cosmic Dawn

The uncharted territory of the high-redshift (z ≳ 3) universe holds the key to understanding the evolution of quasars. In an attempt to identify the most extreme members of the quasar population, that is, blazars, we have carried out a multiwavelength study of a large sample of radio-loud quasars beyond z = 3. Our sample consists of nine γ-ray-detected blazars and 133 candidate blazars selected based on the flatness of their soft X-ray spectra (0.3-10 keV photon index ≤1.75), including 15 with Nuclear Spectroscopic Telescope Array (NuSTAR) observations. The application of the likelihood profile stacking technique reveals that the high-redshift blazars are faint γ-ray emitters with steep spectra. The high-redshift blazars host massive black holes ( $\langle \mathrm{log}\,{M}_{\mathrm{BH},M\odot }\rangle \gt 9$ ) and luminous accretion disks ( $\langle {L}_{\mathrm{disk}}\rangle \gt {10}^{46}$ erg s-1). Their broadband spectral energy distributions are found to be dominated by high-energy radiation, indicating their jets are among the most luminous ones. Focusing on the sources exhibiting resolved X-ray jets (as observed with the Chandra satellite), we find the bulk Lorentz factor to be larger with respect to other z > 3 blazars, indicating faster moving jets. We conclude that the presented list of high-redshift blazars may act as a reservoir for follow-up observations, such as with NuSTAR, to understand the evolution of relativistic jets at the dawn of the universe.

Keywords: high-redshift galaxies; active galactic nuclei; radiative processes; blazars
Radio Emission From a z = 10.1 Black Hole in UHZ1

The recent discovery of a 4 × 107 M ⊙ black hole (BH) in UHZ1 at z = 10.3, just 450 Myr after the Big Bang, suggests that the seeds of the first quasars may have been direct-collapse BHs from the collapse of supermassive primordial stars at z ~ 20. This object was identified in James Webb Space Telescope NIRcam and Chandra X-ray data, but recent studies suggest that radio emission from such a BH should also be visible to the Square Kilometer Array (SKA) and the next-generation Very Large Array (ngVLA). Here, we present estimates of radio flux densities for UHZ1 from 0.1 to 10 GHz, and find that SKA and ngVLA could detect it with integration times of 10-100 hr and just 1-10 hr, respectively. It may be possible to see this object with VLA now with longer integration times. The detection of radio emission from UHZ1 would be a first test of exciting new synergies between near-infrared and radio observatories that could open the era of z ~ 5-15 quasar astronomy in the coming decade.

Keywords: astrophysical black holes
No Detection of Sodium in the Atmosphere of the Warm Neptune HD 106315c

We analyzed archival data of the warm Neptune HD 106315c, an exoplanet with an extended atmosphere orbiting an F-type star with a 21 days period. We used data from the HARPS instrument covering three transits and employed the high-resolution transmission spectroscopy technique. Our analysis yielded a non-detection of sodium with an upper limit of 0.24% on the depth of the planetary feature. This can hint at the presence of Rayleigh scattering in the atmosphere and/or clouds in the upper atmosphere. The HD 106315 system with its two Neptune-sized planets remains an intriguing target for comparative planetology in the starting era of JWST and the upcoming Ariel mission.

Keywords: exoplanet atmospheres; exoplanets
Detection of Interstellar E-1-cyano-1,3-butadiene in GOTHAM Observations of TMC-1

We report the detection of the lowest-energy conformer of E-1-cyano-1,3-butadiene (E-1- ${{\rm{C}}}_{4}{{\rm{H}}}_{5}\mathrm{CN}$ ), a linear isomer of pyridine, using the fourth data reduction of the GBT Observations of TMC-1: Hunting for Aromatic Molecules (GOTHAM) deep spectral survey toward TMC-1 with the 100 m Green Bank Telescope. We perform velocity stacking and matched-filter analyses using Markov chain Monte Carlo simulations and find evidence for the presence of this molecule at the 5.1σ level. We derive a total column density of ${3.8}_{-0.9}^{+1.0}\times {10}^{10}$ cm-2, which is predominantly found toward two of the four velocity components we observe toward TMC-1. We use this molecule as a proxy for constraining the gas-phase abundance of the apolar hydrocarbon 1,3-butadiene. Based on the three-phase astrochemical modeling code NAUTILUS and an expanded chemical network, our model underestimates the abundance of cyano-1,3-butadiene by a factor of 19, with a peak column density of 2.34 × 1010 cm-2 for 1,3-butadiene. Compared to the modeling results obtained in previous GOTHAM analyses, the abundance of 1,3-butadiene is increased by about two orders of magnitude. Despite this increase, the modeled abundances of aromatic species do not appear to change and remain underestimated by one to four orders of magnitude. Meanwhile, the abundances of the five-membered ring molecules increase proportionally with 1,3-butadiene by two orders of magnitude. We discuss the implications for bottom-up formation routes to aromatic and polycyclic aromatic molecules.

Keywords: astrochemistry; polycyclic aromatic hydrocarbons; chemical abundances; dark interstellar clouds; interstellar molecules
Anomalous Bremsstrahlung and the Structure of Cosmic-Ray Electron-Positron Fluxes at the GeV-TeV Energy Range

We reveal that the energy spectra of electrons-positrons in primary cosmic rays measured at atmosphere tops have double structures: an excess component ${{\rm{\Phi }}}_{{e}^{+}}^{s}(E)={{\rm{\Phi }}}_{{e}^{-}}^{s}(E)$ around $400\,\mathrm{GeV}$, which originates from a strong e+ e--source. and the distorted background ${{\rm{\Phi }}}_{{e}^{-}}^{0}(E)$ . We supposed that the difference between AMS-CALET and Fermi-LAT-DAMPE data originates from the energy loss of the fluxes due to the anomalous bremsstrahlung effect at a special window. The evolution of spectra under the anomalous bremsstrahlung effect satisfies an improved electromagnetic cascade equation. The above spectra are parameterized and they can be used for further physics studies. We suggest checking previous applications of the Bethe-Heitler formula when studying the propagation of high-energy electrons and photons.

Keywords: high energy astrophysics; galactic cosmic rays; spectral energy distribution
Drift Performance and Chromatic Thermal Response of a Temperature Stabilized Solid-etalon Calibrator

Etalon-based calibrators have rapidly gained popularity over the past decade in the field of high-precision radial velocity and high-resolution spectroscopy studies. Solid etalons are compact, pressure insensitive, commercially available alternatives to customized air spaced Fabry-Perot etalons. For tight-budget projects and weight-constricted missions, calibration system built from solid etalon is an interesting option to explore. For those, achievable spectral stability becomes the biggest question due to increased thermal sensitivity of the cavity material. Here, the design and performance of a low-cost solid-etalon calibrator is presented. A dual-loop temperature control system keeps the temperature fluctuations to within 1 mK rms when fully stabilized. Drift performance was tracked simultaneously with a laser frequency comb and the chromatic thermal response is measured through temperature tuning. The results indicate that a thermally controlled solid-etalon system can demonstrate sufficient short-term stability (<1 m s-1) for precise wavelength calibration in combination with a hollow-cathode lamp, and the measured drift and chromatic thermal response agree with theoretical predictions. Such systems are plausible candidates for cost-effective calibration of m s-1 level precision radial velocity instruments with improvement in thermal isolation, optimization in data processing, and long-term testing in the foreseeable future.

Keywords: calibration; fabry-perot interferometers; high resolution spectroscopy; radial velocity
Could Quasar Lensing Time Delays Hint to a Core Component in Halos, Instead of H0 Tension?

The time delay measured between the images of gravitationally lensed quasars probes a combination of the angular diameter distance to the source-lens system and the mass density profile of the lens. Observational campaigns to measure such systems have reported a determination of the Hubble parameter H0 that shows significant tension with independent determination based on the cosmic microwave background (CMB) and large-scale structure (LSS). We show that lens mass models that exhibit a cored component, coexisting with a cusp, probe a degenerate direction in the lens model parameter space, being an approximate mass sheet transformation. This family of lens models has not been considered by the cosmographic analyses. Once added to the model, the cosmographic error budget should become dependent on stellar kinematics uncertainties. We propose that a core component coexisting with a cusp could bring the lensing measurements of H0 into accordance with the CMB/LSS value.

Keywords: gravitational lensing; strong gravitational lensing; hubble constant; galaxy structure
An Examination of Galactic Polarization with Application to the Planck TB Correlation

Angular power spectra computed from Planck HFI 353 GHz intensity and polarization maps produce a TB correlation that can be approximated by a power law. Whether the observed TB correlation is an induced systematic feature or a physical property of Galactic dust emission is of interest both for cosmological and Galactic studies. We investigate the large angular scale E- and B-mode morphology of microwave polarized thermal dust emission, and relate it to physical quantities of polarization angle and polarization fraction. We use empirical models of polarized dust to show that dust polarization angle is a key factor in producing the TB correlation. A small sample of both simulated and observed polarization angle maps are combined with 353 GHz intensity and dust polarization fraction to produce a suite of maps from which we compute TB and EB. Model realizations that produce a positive TB correlation are common and can result from large-scale (>5°) structure in the polarization angle. The TB correlation appears robust to introduction of individual intensity, polarization angle, and polarization fraction model components that are independent of the 353 GHz observations. We conclude that the observed TB correlation is likely the result of large-scale Galactic dust polarization properties.

Keywords: observational cosmology; dust continuum emission; galaxy structure