bluuebunny/crossref_metadata_2025 huggingface dataset:
Ionizing photon production and escape fractions during cosmic reionization in the TNG50 simulation
Authors: Kostyuk Ivan , Nelson Dylan , Ciardi Benedetta , Glatzle Martin , Pillepich Annalisa
Published: March 2023

In this work, we investigate the dependence of the escape fraction of ionizing photons, fesc, on various galaxy and host halo properties during the epoch of reionization. We post-process the TNG50 magnetohydrodynamical simulation from the IllustrisTNG project using the three-dimensional multifrequency radiative transfer code CRASH. Our work covers the stellar mass range of 106 ≲ M⋆/M⊙ ≲ 108 at redshifts 6 < z < 10. Adopting an unresolved, cloud-scale escape fraction parameter of unity, the average halo escape fraction fesc increases with mass from ∼0.3 at M⋆ = 106 M⊙ to ∼0.6 at M⋆ = 107.5 M⊙, after which we find hints of a turnover and decreasing escape fractions for even more massive galaxies. However, we demonstrate a strong and non-linear dependence of fesc on the adopted subgrid escape fraction, resulting in uncertainties for the absolute value of the escape fraction. In addition, fesc has significant scatter at fixed mass, driven by diversity in the ionizing photon rate together with a complex relationship between (stellar) source positions and the underling density distribution. The global emissivity is consistent with observations for reasonable cloud-scale absorption values, and haloes with a stellar mass ≲107.5 M⊙ contribute the majority of escaping ionizing photons at all redshifts. Incorporating dust reduces fesc by a few per cent at M⋆ ≲ 106.5 M⊙, and up to 10  per cent for larger haloes. Our multifrequency approach shows that fesc depends on photon energy, and is reduced substantially at E > 54.4 eV versus lower energies. This suggests that the impact of high-energy photons from binary stars is reduced when accounting for an energy-dependent escape fraction.
The TESS Triple-9 Catalog II: a new set of 999 uniformly vetted exoplanet candidates
Authors: Magliano Christian , Kostov Veselin , Cacciapuoti Luca , Covone Giovanni , Inno Laura , Fiscale Stefano , Kuchner Marc , Quintana Elisa V , Salik Ryan , Saggese Vito , Yablonsky John M , Fornear Aline U , Hyogo Michiharu , Di Fraia Marco Z , Luca Hugo A Durantini , de Lambilly Julien S , Oliva Fabrizio , Pagano Isabella , Ienco Riccardo M , de Lima Lucas T , Andrés-Carcasona Marc , Gallo Francesco , Acharya Sovan
Published: March 2023

The Transiting Exoplanet Survey Satellite (TESS) mission is providing the scientific community with millions of light curves of stars spread across the whole sky. Since 2018, the telescope has detected thousands of planet candidates that need to be meticulously scrutinized before being considered amenable targets for follow-up programs. We present the second catalog of the Planet Patrol citizen science project containing 999 uniformly vetted exoplanet candidates within the TESS ExoFOP archive. The catalog was produced by fully exploiting the power of the Citizen Science Planet Patrol project. We vetted TESS Objects of Interest (TOIs) based on the results of Discovery And Vetting of Exoplanets (dave) pipeline. We also implemented the automatic disposition generator, a custom procedure aimed at generating the final classification for each TOI that was vetted by at least three vetters. The majority of the candidates in our catalog, 752 TOIs, passed the vetting process and were labelled as planet candidates. We ruled out 142 candidates as false positives and flagged 105 as potential false positives. Our final dispositions and comments for all the planet candidates are provided as a publicly available supplementary table.
Can radial motions in the stellar halo constrain the rate of change of mass in the Galaxy?
Authors: Sharma Sanjib , Bland-Hawthorn Joss , Silk Joseph , Boehm Celine
Published: March 2023

A change in the mass of the Galaxy with time will leave its imprint on the motions of the stars, with stars having radially outward (mass-loss) or inward (mass accretion) bulk motions. Here, we test the feasibility of using the mean radial motion of stars in the stellar halo to constrain the rate of change of mass in the Galaxy, e.g. due to decay of dark matter. In the lambda cold dark matter (ΛCDM) paradigm, the stellar halo is formed by accretion of satellites on to the host galaxy and its mean radial motion 〈VR〉 is eventually expected to be close to zero. But due to incomplete mixing most haloes have substructures and this can lead to non-zero 〈VR〉 in them. Using simulations, we measure the mean radial motion of stars in 13 ΛCDM stellar haloes lying in a spherical shell of radius 30 kpc. For most haloes, the shell motion is quite small, with 75 per cent of haloes having $\langle V_\text{R}\rangle \lesssim 1.2 \:{\rm km}\, {\rm s}^{-1}$. When substructures are removed by using a clustering algorithm, 〈VR〉 is reduced even further, with 75 per cent of haloes having $\langle V_\text{R}\rangle \lesssim 0.6 \:{\rm km}\, {\rm s}^{-1}$. A value of $\langle V_\text{R}\rangle \approx 0.6 \:{\rm km}\, {\rm s}^{-1}$ can be attained corresponding to a galactic mass-loss rate of 2 per cent per Gyr. We show that this can place constraints on dark matter decay parameters such as the decay lifetime and the kick velocity that is imparted to the daughter particle. The advent of all-sky stellar surveys involving millions to billions of stars is encouraging for detecting signatures of dark matter decay.
Statistical distribution of HI 21cm intervening absorbers as potential cosmic acceleration probes
Authors: Lu Chang-Zhi , Zhang Tingting , Zhang Tong-Jie
Published: March 2023

Damped Lyman-α absorber (DLA), or HI 21cm absorber (H21A), is an important probe to model-independently measure the acceleration of spectroscopic velocity (vS) via the Sandage–Loeb effect. Confined by the shortage of DLAs and background radio sources (BRSs) with adequate information, the detectable amount of DLAs is ambiguous in the bulk of previous work. After differing the acceleration of scale factor ($\ddot{a}$) from the first-order time derivative of spectroscopic velocity ($\dot{v}_\mathrm{S}$), we make a statistical investigation of the amount of potential DLAs in the most of this paper. Using kernel density estimation to depict general redshift distributions of BRSs, observed DLAs and a DLA detection rate with different limitations (1.4 GHz flux, HI column density, and spin temperature), we provide fitted multiGaussian expressions of the three components and their 1σ regions by bootstrap, with a proportional constant of H21As in detected DLAs, leading to the measurable number predictions of H21As for FAST, ASKAP, and SKA1-Mid in HI absorption blind survey. In our most optimistic condition (F1.4 GHz > 10 mJy, NHI > 2 × 1020 cm−2, and TS> 500 K), the FAST, AKSAP, and SKA1-Mid would probe about 80, 500, and 600 H21As, respectively.
Made-to-measure modelling of globular clusters
Authors: Webb Jeremy J , Hunt Jason A S , Bovy Jo
Published: March 2023

We present the first application of the made-to-measure method for modelling dynamical systems to globular clusters. Through the made-to-measure algorithm, the masses of individual particles within a model cluster are adjusted while the system evolves forward in time via a gravitational N-body code until the model cluster is able to reproduce select properties of an observed cluster. The method is first applied to observations of mock isotropic and anisotropic clusters while fitting against the cluster’s 3D or projected density profile, density weighted mean-squared velocity profile, or its density profile with individual mean-squared velocity profiles assuming $10 {{\ \rm per\ cent}}$ uncertainty in each of these observables. We find that a cluster’s 3D density profile can easily be reproduced by the made-to-measure method, with minor discrepancies in the outer regions if fitting against a cluster’s projected surface density or projected kinematic properties. If an observed cluster is anisotropic, only fitting against the cluster’s density profile and individual mean-squared velocity profiles will fully recover the full degree of anisotropy. Partial anisotropy can be recovered as long as two kinematic properties are included in the fit. We further apply the method to observations of the Galactic globular cluster M4 and generate a complete 6D representation of the cluster that reproduces observations of its surface density profile, mean-squared proper motion velocity profile, and mean-squared line of sight velocity profile. The M2M method predicts M4 is primarily isotropic with a mass of $9.2\pm 0.4\times 10^4\, \mathrm{ M}_{\odot }$ and a half-mass radius of 3.7 ± 0.1 pc.
Gamma-ray bursts, quasars, baryonic acoustic oscillations, and supernovae Ia: new statistical insights and cosmological constraints
Authors: Bargiacchi G , Dainotti M G , Nagataki S , Capozziello S
Published: March 2023

The recent $\sim 4 \, \sigma$ Hubble constant, H0, tension is observed between the value of H0 from the cosmic microwave background (CMB) and Type Ia supernovae (SNe Ia). It is a decade since this tension is excruciating the modern astrophysical community. To shed light on this problem is key to consider probes at intermediate redshifts between SNe Ia and CMB and reduce the uncertainty on H0. Toward these goals, we fill the redshift gap by employing gamma-ray bursts (GRBs) and quasars (QSOs), reaching z = 9.4 and z = 7.6, respectively, combined with baryonic acoustic oscillations (BAO), and SNe Ia. To this end, we employ the ‘Dainotti GRB 3D relation’ among the rest-frame end time of the X-ray plateau emission, its corresponding luminosity, and the peak prompt luminosity, and the ‘Risaliti–Lusso’ QSO relation between ultraviolet and X-ray luminosities. We inquire the commonly adopted Gaussianity assumption on GRBs, QSOs, and BAO. With the joint sample, we fit the flat Λ Cold Dark Matter model with both the Gaussian and the newly discovered likelihoods. We also investigate the impact of the calibration assumed for Pantheon and Pantheon  + SNe Ia on this analysis. Remarkably, we show that only GRBs fulfil the Gaussianity assumption. We achieve small uncertainties on the matter-density parameter ΩM and H0. We find H0 values compatible within 2σ with the one from the Tip of the Red Giant Branch. Finally, we show that the cosmological results are heavily biased against the arbitrary calibration choice for SNe Ia.
A method of photometric data extraction for asteroids from time-domain surveys
Authors: Xu Xiaoyun , Wang Xiaobing , Muinonen Karri , Penttilä Antti , Luo Nanping , Gu Shenghong , Sun Leilei , Xu Fukun , Liu Yisi , Xiang Yue , Cao Dongtao , Wang Jianhua
Published: March 2023

The lightcurves of asteroids are essential for determining their physical characteristics, including shape, spin, size, and surface composition. However, most asteroids are missing some of these basic physical parameters due to lack of photometric data. Although a few telescopes or surveys are specially designed for photometric lightcurve observations of asteroids, many ground-based and space-based sky surveys for hunting new exoplanets, transient events, etc., should capture numerous small Solar system objects. This will benefit the physical studies of these objects. In order to extract data of these moving objects from time-domain photometric surveys, we have developed a new method using the model tree algorithm in the field of machine learning. A dedicated module is built to automatically identify moving objects in data set and extract their photometric and astrometric data. As the first application of this novel method, we have analysed data in five fields of the Yunnan-Hong Kong wide field photometric (YNHK) survey, from which 538 lightcurves of 211 asteroids are successfully extracted. Meanwhile, we also tested the method based on the data from NASA’s Transiting Exoplanet Survey Satellite, and the result proves the reliability of our method. With derived lightcurves of 13 asteroids from the YNHK survey, we have determined their synodic spin periods, among which the periods of four asteroids are estimated for the first time. In future, we are going to apply this method to search for small objects in the outer part of the Solar system from the Chinese Space Station Telescope survey.
Neutrino follow-up with the Zwicky transient facility: results from the first 24 campaigns
Authors: Stein Robert , Reusch Simeon , Franckowiak Anna , Kowalski Marek , Necker Jannis , Weimann Sven , Kasliwal Mansi M , Sollerman Jesper , Ahumada Tomas , Amaro Seoane Pau , Anand Shreya , Andreoni Igor , Bellm Eric C , Bloom Joshua S , Coughlin Michael , De Kishalay , Fremling Christoffer , Gezari Suvi , Graham Matthew , Groom Steven L , Helou George , Kaplan David L , Karambelkar Viraj , Kong Albert K H , Kool Erik C , Lincetto Massimiliano , Mahabal Ashish A , Masci Frank J , Medford Michael S , Morgan Robert , Nordin Jakob , Rodriguez Hector , Sharma Yashvi , van Santen Jakob , van Velzen Sjoert , Yan Lin
Published: March 2023

The Zwicky Transient Facility (ZTF) performs a systematic neutrino follow-up programme, searching for optical counterparts to high-energy neutrinos with dedicated Target-of-Opportunity (ToO) observations. Since first light in March 2018, ZTF has taken prompt observations for 24 high-quality neutrino alerts from the IceCube Neutrino Observatory, with a median latency of 12.2 h from initial neutrino detection. From two of these campaigns, we have already reported tidal disruption event (TDE) AT 2019dsg and likely TDE AT 2019fdr as probable counterparts, suggesting that TDEs contribute >7.8 per cent of the astrophysical neutrino flux. We here present the full results of our programme through to December 2021. No additional candidate neutrino sources were identified by our programme, allowing us to place the first constraints on the underlying optical luminosity function of astrophysical neutrino sources. Transients with optical absolutes magnitudes brighter that −21 can contribute no more than 87 per cent of the total, while transients brighter than −22 can contribute no more than 58 per cent of the total, neglecting the effect of extinction and assuming they follow the star formation rate. These are the first observational constraints on the neutrino emission of bright populations such as superluminous supernovae. None of the neutrinos were coincident with bright optical AGN flares comparable to that observed for TXS 0506+056/IC170922A, with such optical blazar flares producing no more than 26 per cent of the total neutrino flux. We highlight the outlook for electromagnetic neutrino follow-up programmes, including the expected potential for the Rubin Observatory.
The hierarchical clustering method: abundance and properties of local satellite populations
Authors: Xi Chengyu , Taylor James E
Published: March 2023

The faint satellites of the local Universe provide an important benchmark for our understanding of structure formation and galaxy formation, but satellite populations are hard to identify beyond the Local Group. We recently developed an iterative method to quantify satellite abundance using galaxy clustering and tested it on a local sample in the COSMOS field, where accurate photometric redshifts are available for a large number of faint objects. In this paper, we consider the properties of these satellite populations in more detail, studying the satellite stellar mass function (SSMF), the satellite-central connection, and quenching as a function of satellite and central mass and colour. Despite the limited sample size, our results show good consistency with those from much larger surveys and constrain the SSMF down to some of the lowest primary masses considered to date. We reproduce several known trends in satellite abundance and quenching, and find evidence for one new one, a dependence of the quiescent fraction on the primary-to-secondary halo mass ratio. We discuss the prospects for the clustering method in current and forthcoming surveys.
Constraining the rotation profile in a low-luminosity subgiant with a surface rotation measurement
Authors: Wilson Tanner A , Casey Andrew R , Mandel Ilya , Ball Warrick H , Bellinger Earl P , Davies Guy
Published: March 2023

Rotationally induced mode splitting frequencies of low-luminosity subgiants suggest that angular momentum transport mechanisms are 1–2 orders of magnitude more efficient in these stars than predicted by theory. Constraints on the rotation profile of low-luminosity subgiants could be used to identify the dominant mechanism for angular momentum transport. We develop a forward model for the rotation profile given observed rotational splittings, assuming a step-like rotation profile. We identify a consistent degeneracy between the position of the profile discontinuity and the surface rotation rate. We perform mock experiments that show the discontinuity position can be better constrained with a prior on the surface rotation rate, which is informed by star spot modulations. We finally apply this approach to KIC 12508433, a well-studied low-luminosity subgiant, as an example case. With the observed surface rotation prior, we obtain a factor of 2 increase in precision of the position of strong rotation gradient. We recover the literature values of the core and surface rotation rates and find the highest support for a discontinuity in the radiative zone. Auxiliary measurements of surface rotation could substantially improve inferences on the rotation profile of low-luminosity subgiants with already available data.
The connection between the escape of ionizing radiation and galaxy properties at z ∼ 3 in the Keck Lyman continuum spectroscopic survey
Authors: Pahl Anthony J , Shapley Alice , Steidel Charles C , Reddy Naveen A , Chen Yuguang , Rudie Gwen C , Strom Allison L
Published: March 2023

The connection between the escape fraction of ionizing radiation (fesc) and the properties of galaxies, such as stellar mass ($\rm M_{\rm *}$), age, star-formation rate (SFR), and dust content, are key inputs for reionization models, but many of these relationships remain untested at high redshift. We present an analysis of a sample of 96 $z$ ∼ 3 galaxies from the Keck Lyman Continuum Spectroscopic Survey (KLCS). These galaxies have both sensitive Keck/LRIS spectroscopic measurements of the Lyman continuum (LyC) region, and multiband photometry that places constraints on stellar population parameters. We construct composite spectra from subsamples binned as a function of galaxy property and quantify the ionizing-photon escape for each composite. We find a significant anti-correlation between fesc and $\rm M_{\rm *}$, consistent with predictions from cosmological zoom-in simulations. We also find significant anti-correlation between fesc and E(B−V), encoding the underlying physics of LyC escape in our sample. We also find no significant correlation between fesc and either stellar age or specific SFR (= SFR/$\rm M_{\rm *}$), challenging interpretations that synchronize recent star formation and favorable conditions for ionizing escape. The galaxy properties now shown to correlate with fesc in the KLCS are Lyα equivalent width, UV Luminosity, $\rm M_{\rm *}$, SFR, and E(B−V), but not age or sSFR. This comprehensive analysis of galaxy properties and LyC escape at high redshift will be used to guide future models and observations of the reionization epoch.
New insight into the massive eccentric binary HD 165052: self-consistent orbital solution, apsidal motion, and fundamental parameters
Authors: Rosu S , Quintero E A , Rauw G , Eenens P
Published: March 2023

HD 165052 is a short-period massive eccentric binary system that undergoes apsidal motion. As the rate of apsidal motion is directly related to the internal structure constants of the binary components, its study allows getting insight into the internal structure of the stars. We use medium- and high-resolution spectroscopic observations of HD 165052 to provide constraints on the fundamental properties of the binary system and the evolutionary state of its components. We apply a spectral disentangling code to reconstruct artefact-free spectra of the individual stars and derive the radial velocities (RVs) at the times of the observations. We perform the first analysis of the disentangled spectra with the non-local thermodynamic equilibrium model atmosphere code CMFGEN to determine the stellar properties. We derive the first self-consistent orbital solution of all existing RV data, including those reported in the literature, accounting for apsidal motion. We build, for the very first time, dedicated stellar evolution tracks with the Clés code requesting the theoretical effective temperatures and luminosities to match those obtained from our spectroscopic analysis. The binary system HD 165052, consisting of an O6.5 V((f)) primary ($T_\text{eff,P}=37\, 500 \pm 1000$ K) and an O7 V((f)) secondary ($T_\text{eff,S}=36\, 000 \pm 1000$ K), displays apsidal motion at a rate of $(11.30^{+0.64}_{-0.49})^\circ$ yr−1. Evolutionary masses are compared to minimum dynamical masses to constrain the orbital inclination. Evolutionary masses $M_\text{ev,P}=24.8\pm 1.0\, \mathrm{M}_\odot$ and $M_\text{ev,S}=20.9\pm 1.0\, \mathrm{M}_\odot$ and radii $R_\text{ev,P}=7.0^{+0.5}_{-0.4}\, \mathrm{R}_\odot$ and $R_\text{ev,S}=6.2^{+0.4}_{-0.3}\, \mathrm{R}_\odot$ are derived, and the inclination is constrained to 22.1° ≤ i ≤ 23.3°. Theoretical apsidal motion rates, derived assuming an age of 2.0 ± 0.5 Myr for the binary, are in agreement with the observational determination. The agreement with theoretical apsidal motion rates enforces the inferred values of the evolutionary stellar masses and radii.
Synchrotron emission from virial shocks around stacked OVRO-LWA galaxy clusters
Authors: Hou Kuan-Chou , Hallinan Gregg , Keshet Uri
Published: March 2023

Galaxy clusters accrete mass through large-scale, strong, structure-formation shocks. Such a virial shock is thought to deposit fractions ξe and ξB of the thermal energy in cosmic-ray electrons (CREs) and magnetic fields, respectively, thus generating a leptonic virial ring. However, the expected synchrotron signal was not convincingly established until now. We stack low-frequency radio data from the OVRO-LWA around the 44 most massive, high latitude, extended MCXC clusters, enhancing the ring sensitivity by rescaling clusters to their characteristic, R500 radii. Both high (73 MHz) and co-added low (36–68 MHz) frequency channels separately indicate a significant (4–5σ) excess peaked at (2.4–2.6)R500, coincident with a previously stacked Fermi γ-ray signal interpreted as inverse-Compton emission from virial-shock CREs. The stacked radio signal is well fit (TS-test: 4–6σ at high frequency, 4–8σ at low frequencies, and 8–10σ joint) by virial-shock synchrotron emission from the more massive clusters, with $\dot{m}\xi _e\xi _B\simeq (1\!-\!4)\times 10^{-4}$, where $\dot{m}\equiv \dot{M}/(MH)$ is the dimensionless accretion rate for a cluster of mass M and a Hubble constant H. The inferred CRE spectral index is flat, p ≃ 2.0 ± 0.2, consistent with acceleration in a strong shock. Assuming equipartition or using $\dot{m}\xi _e\sim 0.6~{{\ \rm per\ cent}}$ inferred from the Fermi signal yields $\xi _B\simeq (2\!-\!9)~{{\ \rm per\ cent}}$, corresponding to B ≃ (0.1–0.3) $\mu$G magnetic fields downstream of typical virial shocks. Preliminary evidence suggests non-spherical shocks, with factor 2–3 elongations.
The thesan project: Lyman-α emitter luminosity function calibration
Authors: Xu Clara , Smith Aaron , Borrow Josh , Garaldi Enrico , Kannan Rahul , Vogelsberger Mark , Pakmor Rüdiger , Springel Volker , Hernquist Lars
Published: March 2023

The observability of Lyα emitting galaxies (LAEs) during the Epoch of Reionization can provide a sensitive probe of the evolving neutral hydrogen gas distribution, thus setting valuable constraints to distinguish different reionization models. In this study, we utilize the new thesan suite of large-volume ($L_\text{box} = 95.5\, \text{cMpc}$) cosmological radiation-hydrodynamic simulations to directly model the Lyα emission from individual galaxies and the subsequent transmission through the intergalactic medium. thesan combines the arepo-rt radiation-hydrodynamic solver with the IllustrisTNG galaxy formation model and includes high- and medium-resolution simulations designed to investigate the impacts of halo-mass-dependent escape fractions, alternative dark matter models, and numerical convergence. We find important differences in the Lyα transmission based on reionization history, bubble morphology, frequency offset from line centre, and galaxy brightness. For a given global neutral fraction, Lyα transmission reduces when low-mass haloes dominate reionization over high-mass haloes. Furthermore, the variation across sightlines for a single galaxy is greater than the variation across all galaxies. This collectively affects the visibility of LAEs, directly impacting observed Lyα luminosity functions (LFs). We employ Gaussian Process Regression using SWIFTEmulator to rapidly constrain an empirical model for dust escape fractions and emergent spectral-line profiles to match observed LFs. We find that dust strongly impacts the Lyα transmission and covering fractions of MUV ≲ −19 galaxies in $M_\text{vir} \gtrsim 10^{11}\, \text{M}_{\bigodot }$ haloes, such that the dominant mode of removing Lyα photons in non-LAEs changes from low-IGM transmission to high dust absorption around z ∼ 7.
Fast transitions of X-ray variability in the black hole transient GX 339−4: comparison with MAXI J1820+070 and MAXI J1348−630
Authors: Yang Zi-Xu , Zhang Liang , Zhang S N , Méndez M , García Federico , Huang Yue , Bu Qingcui , Liu He-Xin , Yu Wei , Wang P J , Tao L , Altamirano D , Qu Jin-Lu , Zhang S , Ma X , Song L M , Jia S M , Ge M Y , Liu Q Z , Yan J Z , Li T M , Ren X Q , Ma R C , Zhang Yuexin , Xu Y C , Ma B Y , Du Y F , Fu Y C , Xiao Y X , Li P P , Jin P , Zhao S J , Zhao Q C
Published: March 2023

Fast transitions between different types of power density spectra (PDS) happening over time-scales of several tens of seconds are rare phenomena in black hole X-ray binaries. In this paper, we report a broad-band spectral-timing analysis of the fast transitions observed in the 2021 outburst of GX 339−4 using NICER and Insight-HXMT observations. We observe transitions between band-limited noise-dominated PDS and type-B quasi-periodic oscillations (QPOs), and their rapid appearance or disappearance. We also make a detailed comparison between the fast transitions in GX 339−4 with those seen in MAXI J1820+070 and MAXI J1348−630. By comparing the spectra of the periods with and without type-B QPOs, we find that the spectral ratios above 10 keV are nearly constant or slightly decreasing, and the values are different between sources. Below 10 keV, the flux change of the Comptonization component is inversely proportional to the flux change of the thermal component, suggesting that the appearance of type-B QPOs is associated with a redistribution of the accretion power between the disc and the Comptonizing emission region. The spectral ratios between the periods with type-B QPO and those with broad-band noise are significantly different from that with type-B QPO and without type-B QPO, where the ratios (type-B QPO/broad-band noise) show a maximum at around 4 keV and then decrease gradually towards high energies. Finally, we discuss the possible change of the geometry of the inner accretion flow and/or jet during the transitions.
Redshift prediction ofFermi-LAT gamma-ray sources usingcatboostgradient boosting decision trees
Authors: Coronado-Blázquez Javier
Published: March 2023

The determination of distance is fundamental in astrophysics. Gamma-ray sources are poorly characterized in this sense, as the limited angular resolution and poor photon-count statistics in gamma-ray astronomy makes it difficult to associate them to a multiwavelength object with known redshift. Taking the 1794 active galactic nuclei (AGNs) with known redshift from the Fermi-LAT latest AGN catalogue, 4LAC–DR3, we employ machine learning techniques to predict the distance of the rest of AGNs based on their spectral and spatial properties. The state-of-the-art catboost algorithm reaches an average 0.56 R2 score with 0.46 root-mean-squared error, predicting an average redshift value of zavg = 0.63, with a maximum zmax = 1.97. We use the shap explainer package to gain insights into the variables influence on the outcome, and also study the extragalactic background light implications. In a second part, we use this regression model to predict the redshift of the unassociated sample of the latest LAT point-source catalogue, 4FGL–DR3, using the results of a previous paper to determine the possible AGNs within them.
Stellar mass, not dynamical mass nor gravitational potential, drives the mass–metallicity relationship
Authors: Baker William M , Maiolino Roberto
Published: March 2023

The widely known relation between stellar mass and gas metallicity [mass–metallicity relation (MZR)] in galaxies is often ascribed to the higher capability of more massive systems to retain metals against the action of galactic outflows. In this scenario the stellar mass would simply be an indirect proxy of the dynamical mass or of the gravitational potential. We test this scenario by using a sample of more than 1000 star-forming galaxies from the MaNGA (Mapping Nearby Galaxies at Apache Point Observatory) survey for which dynamical masses have been accurately determined. By using three different methods (average dispersion, partial correlation coefficients, and random forest), we unambiguously find that the gas metallicity depends primarily and fundamentally on the stellar mass. Once the dependence on stellar mass is taken into account, there is little or no dependence on either dynamical mass or gravitational potential (and, if anything, the metallicity dependence on the latter quantities is inverted). Our result indicates that the MZR is not caused by the retention of metals in more massive galaxies. The direct, fundamental dependence of metallicity on stellar mass suggests the much simpler scenario in which the MZR is just a consequence of the stellar mass being proportional to the integral of metals production in the galaxy.
Radio emission of tidal disruption events from wind–cloud interaction
Authors: Bu De-Fu , Chen Liang , Mou Guobin , Qiao Erlin , Yang Xiao-Hong
Published: March 2023

Winds can be launched in tidal disruption event (TDE). It has been proposed that the winds can interact with the cloud surrounding the black hole, produce bow shocks, accelerate electrons, and produce radio emission. We restudy the wind–cloud interaction model. We employ the properties of winds found by the radiation hydrodynamic simulations of super-Eddington circularized accretion flow in TDEs. We can calculate the peak radio emission frequency, the luminosity at the peak frequency, and their time-evolution based on the TDEs wind–cloud interaction model. We find that the model predicted peak radio emission frequency, the luminosity at peak frequency, and their time evolution can be well consistent with those in TDEs AT2019dsg and ASASSN-14li. This indicates that in these two radio TDEs, the wind–cloud interaction mechanism may be responsible for the radio emission.
A multiphase study of theoretical and observed light curves of classical Cepheids in the Magellanic Clouds
Authors: Kurbah Kerdaris , Deb Sukanta , Kanbur Shashi M , Das Susmita , Deka Mami , Bhardwaj Anupam , Randall Hugh Riley , Kalici Selim
Published: March 2023

We present an analysis of the theoretical and observed light-curve parameters of the fundamental mode (FU) classical Cepheids in the Magellanic Clouds in V- and I- photometric bands. The state-of-the-art 1D non-linear radial stellar pulsation (RSP) code in mesa (mesa-rsp) has been utilized to generate the theoretical light curves using four sets of convection parameters. Theoretical light curves with two chemical compositions: Z = 0.008 and Z = 0.004 appropriate for the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC), respectively, covered a wide range of periods ($3\lt P (\rm {d})\lt 32$). The observed light curves are taken from the OGLE-IV data base. We compare theoretical and observed Fourier parameters (FPs), and investigate the period–luminosity (PL), period–colour (PC), and amplitude–colour (AC) relations as a function of pulsation phase for short (log P < 1), long (log P > 1), and all periods. The multiphase relations obtained from theoretical and observed light curves in the PL/PC/AC plane are found to be dynamic in nature, with the effect more pronounced at Φ ∼ 0.75–0.85. Furthermore, a contrasting behaviour of the theoretical/observed multiphase PL and PC relations between the short and long periods has been found for both LMC and SMC. The analysis shows that multiphase PL relations are more stringent to test the models with observations over the FPs. Distances to the LMC/SMC determined using long period Cepheids are found to be in good agreement with the literature values when the term R21 is added to the PL relation.
GPU-based framework for detecting small Solar system bodies in targeted exoplanet surveys
Authors: Burdanov A Y , Hasler S N , de Wit J
Published: March 2023

Small Solar system bodies are pristine remnants of Solar system formation, which provide valuable insights for planetary science and astronomy. Their discovery and cataloguing also have strong practical implications to life on Earth as the nearest asteroids could pose a serious impact threat. Concurrently with dedicated observational projects, searches for small bodies have been performed on numerous archival data sets from different facilities. Here, we present a framework to increase the scientific return of an exoplanet transit-search survey by recovering serendipitous detections of small bodies in its daily and archival data using a GPU-based synthetic tracking algorithm. As a proof of concept, we analysed $12\, \times 12\, \mathrm{arcmin^2}$ sky fields observed by the 1-m telescopes of the SPECULOOS survey. We analysed 90 sky fields distributed uniformly across the sky as part of the daily search for small bodies and 21 archival fields located within 5 deg from the ecliptic plane as part of the archival search (4.4 deg2 in total). Overall, we identified 400 known objects of different dynamical classes from Inner Main-belt Asteroids to Jupiter Trojans and 43 potentially new small bodies with no priors on their motion. We were able to reach limiting magnitude for unknown objects of V = 23.8 mag, and a retrieval rate of ∼80 per cent for objects with V < 22 mag and V < 23.5 mag for the daily and archival searches, respectively. SPECULOOS and similar exoplanet surveys can thus serve as pencil-beam surveys for small bodies and probe parameter space beyond V = 22 mag.
Age-divided mean stellar populations from full spectrum fitting as the simplified star formation and chemical evolution history of a galaxy: methodology and reliability
Authors: Lee Joon Hyeop , Pak Mina , Jeong Hyunjin , Oh Sree
Published: March 2023

We introduce a practical methodology for investigating the star formation and chemical evolution history of a galaxy: age-divided mean stellar populations (ADPs) from full spectrum fitting. In this method, the mass-weighted mean stellar populations and mass fractions (fmass) of young and old stellar components in a galaxy are separately estimated, which are divided with an age cut (selected to be 109.5 yr ≈3.2 Gyr in this paper). To examine the statistical reliability of ADPs, we generate 10 000 artificial galaxy spectra, each of which consists of five random simple stellar population components. Using the Penalized PiXel-Fitting (ppxf) package, we conduct full spectrum fitting to the artificial spectra with noise as a function of wavelength, imitating the real noise of Sydney-Australian Astronomical Observatory Multi-object Integral field spectrograph (SAMI) galaxies. As a result, the Δ (= output − input) of age and metallicity appears to significantly depend on not only signal-to-noise ratio (S/N), but also luminosity fractions (flum) of young and old components. At given S/N and flum, Δ of young components tends to be larger than Δ of old components; e.g. σ(Δ[M/H]) ∼ 0.40 versus 0.23 at S/N = 30 and flum = 50 per cent. The age-metallicity degeneracy appears to be insignificant, but Δlog(age/yr) shows an obvious correlation with Δfmass for young stellar components ($\mathcal {R}\sim 0.6$). The impact of dust attenuation and emission lines appears to be mostly insignificant. We discuss how this methodology can be applied to spectroscopic studies of the formation histories of galaxies, with a few examples of SAMI galaxies.
Data science methodology for time-delay estimation and data preprocessing of the time-delay challenge
Authors: Leon-Anaya Luis , Cuevas-Tello Juan C , Valenzuela Octavio , Puente César A , Soubervielle-Montalvo Carlos
Published: March 2023

The vast amount of astronomical information that has become available over this decade has far exceeded that of the last century. The heterogeneity of the data and its overwhelming magnitude have made it impossible to perform manual analysis. As a consequence, new techniques have been developed and different strategies have been amalgamated, such as data science and data mining, in order to carry out more in-depth and exhaustive analyses in search of the extraction of the knowledge contained in data. This paper introduces a data science methodology that consists of successive stages, with the core of this proposal being the step of data preprocessing, with the aim of reducing the complexity of the analysis and enabling hidden knowledge in the data to be uncovered. The proposed methodology was tested on a set of data consisting of artificial light curves that try to mimic the behaviour of the strong gravitational lens phenomenon, as supplied by the Time Delay Challenge 1 (TDC1). Under the data science methodology, diverse statistical methods were implemented for data analysis, and cross-correlation and dispersion methods were applied for the time-delay estimation of strong lensing systems. With this methodology, we obtained time-delay estimations from the TDC1 data set and compared them with earlier results reported by the COSmological MOnitoring of GRAvItational Lenses project (COSMOGRAIL). The empirical evidence leads us to conclude that, with the proposed methodology, we achieve a greater accuracy in estimating time delays compared with estimations made with raw data.
SRG/eROSITA discovery of a radio-faint X-ray candidate supernova remnant SRGe J003602.3+605421 = G121.1−1.9
Authors: Khabibullin I I , Churazov E M , Bykov A M , Chugai N N , Sunyaev R A
Published: March 2023

We report the discovery of a candidate X-ray supernova remnant SRGe J003602.3+605421 = G121.1−1.9 in the course of the SRG/eROSITA all-sky survey. The object is located at (l, b) = (121.1°, −1.9°), is ≈36 arcmin in angular size, and has a nearly circular shape. Clear variations in the spectral shape of the X-ray emission across the object are detected, with the emission from the inner (within 9 arcmin) and outer (9–18 arcmin) parts dominated by iron and oxygen/neon lines, respectively. The non-equilibrium plasma emission model is capable of describing the spectrum of the outer part with an initial gas temperature 0.1 keV, final temperature 0.5 keV, and ionization age ∼2 × 1010 cm−3 s. The observed spectrum of the inner region is more complicated (plausibly due to the contribution of the outer shell) and requires a substantial overabundance of iron for all models that we have tried. The derived X-ray absorption is equal to (4–6) × 1021 cm−2, locating the object at a distance beyond 1.5 kpc, and implying its age ∼(5–30) × 1000 yr. No bright radio, infrared, H α, or gamma-ray counterpart of this object has been found in the publicly available archival data. A model invoking a canonical 1051 erg explosion (either SN Ia or core collapse) in the hot and tenuous medium in the outer region of the Galaxy ∼9 kpc away might explain the bulk of the observed features. This scenario can be tested with future deep X-ray and radio observations.
Properties and evolution of dual and offset AGN in the ASTRID simulation at z ∼ 2
Authors: Chen Nianyi , Di Matteo Tiziana , Ni Yueying , Tremmel Michael , DeGraf Colin , Shen Yue , Holgado A Miguel , Bird Simeon , Croft Rupert , Feng Yu
Published: March 2023

We examine the dual [both black hole (BH) active] and offset (one BH active and in distinct galaxies) active galactic nucleus (AGN) population (comprising ∼ 2000 pairs at $0.5\, \text{kpc}\lesssim \Delta r\lt 30\, \text{kpc}$) at z = 2 ∼ 3 in the ASTRID simulation covering (360 cMpc)3. The dual (offset) AGN make up 3.0(0.5) per cent of all AGN at z = 2. The dual fraction is roughly constant while the offset fraction increases by a factor of 10 from z = 4 ∼ 2. Compared with the full AGN population, duals are characterized by low MBH/M* ratios, high specific star formation rates (sSFR) of $\sim 1\, \text{Gyr}^{-1}$, and high Eddington ratios (∼0.05, double that of single AGN). Dual AGNs are formed in major galaxy mergers (typically involving $M_\text{halo}\lt 10^{13}\, M_\odot$), with simular-mass BHs. At small separations (when host galaxies are in the late phase of the merger), duals become 2 ∼ 8 times brighter (albeit more obscured) than at larger separations. 80  per cent of the bright, close duals would merge within $\sim 500\, \text{Myr}$. Notably, the initially less-massive BHs in duals frequently become the brighter AGN during galaxy mergers. In offset AGN, the active BH is typically ≳ 10 times more massive than its non-active counterpart and than most BHs in duals. Offsets are predominantly formed in minor galaxy mergers with the active BH residing in the centre of massive haloes ($M_\text{ halo}\sim 10^{13-14}\, \mathrm{M}_\odot$). In these deep potentials, gas stripping is common and the secondary quickly deactivates. The stripping also leads to inefficient orbital decay amongst offsets, which stall at $\Delta r\sim 5\, \text{kpc}$ for a few hundred Myrs.
Effects of folate on telomere length and chromosome stability of human fibroblasts and melanoma cells in vitro: a comparison of folic acid and 5-methyltetrahydrofolate
Authors: Wang Han , Ni Juan , Guo Xihan , Xue Jinglun , Wang Xu
Published: March 2023

Telomere length (TL), which is maintained by human telomerase reverse transcriptase (hTERT; component of telomerase) and/or TRF1/TRF2 (core components of shelterin) via different mechanisms, is essential for chromosomal stability and cell survival. Folates comprise a group of essential B9 vitamin that involve in DNA synthesis and methylation. This study aimed to evaluate the effects of folic acid (FA) and 5-methyltetrahydrofolate (5-MeTHF) on TL, chromosome stability, and cell survival of telomerase-negative BJ and telomerase-positive A375 cells in vitro. BJ and A375 cells were cultured in modified medium with FA or 5-MeTHF (22.6 or 2260 nM) for 28 days. TL and mRNA expression were determined by RT-qPCR. Chromosome instability (CIN) and cell death were measured by CBMN-Cyt assay. Results showed that abnormal TL elongation was observed in FA- and 5-MeTHF-deficient BJ cells. The TL of A375 cells showed no obvious alterations under the FA-deficient condition but was significantly elongated under the 5-MeTHF-deficient condition. In both BJ and A375 cells, FA and 5-MeTHF deficiency caused decreased TRF1, TRF2, and hTERT expression, increased CIN and cell death; while a high concentration of 5-MeTHF induced elongated TL, elevated CIN, increased TRF1 and TRF2 expression, and decreased hTERT expression, when compared with the FA counterpart. These findings concluded that folate deficiency induced TL instability in both telomerase-negative and -positive cells, and FA was more efficient in maintaining TL and chromosome stability compared with 5-MeTHF.
Single-molecule visualization of stalled replication-fork rescue by the Escherichia coli Rep helicase
Authors: Whinn Kelsey S , Xu Zhi-Qiang , Jergic Slobodan , Sharma Nischal , Spenkelink Lisanne M , Dixon Nicholas E , van Oijen Antoine M , Ghodke Harshad
Published: March 2023

Genome duplication occurs while the template DNA is bound by numerous DNA-binding proteins. Each of these proteins act as potential roadblocks to the replication fork and can have deleterious effects on cells. In Escherichia coli, these roadblocks are displaced by the accessory helicase Rep, a DNA translocase and helicase that interacts with the replisome. The mechanistic details underlying the coordination with replication and roadblock removal by Rep remain poorly understood. Through real-time fluorescence imaging of the DNA produced by individual E. coli replisomes and the simultaneous visualization of fluorescently-labeled Rep, we show that Rep continually surveils elongating replisomes. We found that this association of Rep with the replisome is stochastic and occurs independently of whether the fork is stalled or not. Further, we visualize the efficient rescue of stalled replication forks by directly imaging individual Rep molecules as they remove a model protein roadblock, dCas9, from the template DNA. Using roadblocks of varying DNA-binding stabilities, we conclude that continuation of synthesis is the rate-limiting step of stalled replication rescue.
Scale effect of circularly polarized luminescent signal of matter
Authors: Sun Siyu , Li Xiaolin , Xu Chen , Li Yan , Wu YongZhen , Feringa Ben L , Tian He , Ma Xiang
Published: March 2023

Circularly polarized luminescence (CPL) is an important part in the research of modern luminescent materials and photoelectric devices. Usually, chiral molecules or chiral structures are the key factors to induce CPL spontaneous emission. In this study, a scale-effect model based on scalar theory was proposed to better understand the CPL signal of luminescent materials. Besides chiral structures being able to induce CPL, achiral ordered structures can also have a significant influence on CPL signals. These achiral structures are mainly reflected in the particle scale in micro-order or macro-order, i.e. the CPL signal measured under most conditions depends on the scale of the ordered medium, and does not reflect the inherent chirality of the excited state of the luminescent molecule. This kind of influence is difficult to be eliminated by simple and universal strategies in macro-measurement. At the same time, it is found that the measurement entropy of CPL detection may be the key factor to determine the isotropy and anisotropy of the CPL signal. This discovery would bring new opportunities to the research of chiral luminescent materials. This strategy can also greatly reduce the development difficulty of CPL materials and show high application potential in biomedical, photoelectric information and other fields.
Dynamics of synthetic yeast chromosome evolution shaped by hierarchical chromatin organization
Authors: Zhou Sijie , Wu Yi , Zhao Yu , Zhang Zhen , Jiang Limin , Liu Lin , Zhang Yan , Tang Jijun , Yuan Ying-Jin
Published: March 2023

Synthetic genome evolution provides a dynamic approach for systematically and straightforwardly exploring evolutionary processes. Synthetic Chromosome Rearrangement and Modification by LoxP-mediated Evolution (SCRaMbLE) is an evolutionary system intrinsic to the synthetic yeast genome that can rapidly drive structural variations. Here, we detect over 260 000 rearrangement events after the SCRaMbLEing of a yeast strain harboring 5.5 synthetic yeast chromosomes (synII, synIII, synV, circular synVI, synIXR and synX). Remarkably, we find that the rearrangement events exhibit a specific landscape of frequency. We further reveal that the landscape is shaped by the combined effects of chromatin accessibility and spatial contact probability. The rearrangements tend to occur in 3D spatially proximal and chromatin-accessible regions. The enormous numbers of rearrangements mediated by SCRaMbLE provide a driving force to potentiate directed genome evolution, and the investigation of the rearrangement landscape offers mechanistic insights into the dynamics of genome evolution.