Astrophysics of Galaxies
Atomic gas properties at the positions of supernovae Type Ia, II, and Ib/c
Bruno Šlaus, Natalia Gotkiewicz, Michał J. Michałowski et al. (+6 more)
Understanding which
stars explode as which type of
supernovae (SNe) is crucial to measure their contribution to the metal production and feedback halting
star formation. Most of the studies of the gas in the environment of SNe are limited by a small sample size ($<10$). The goal of this paper is to present the first analysis of atomic gas properties at the positions of a statistically significant sample of SNe in order to constrain their nature. We selected 133 SNe (29 Ia, 77 II, 27 Ib/c) which have exploded in
galaxies with existing atomic gas data. In order to test whether SN positions trace enhancements in the atomic gas distribution, we analyzed the fraction of pixels on the {\hi} map which are fainter than the pixel in which SN is located and the fraction of the {\hi} flux contributed by these pixels. All types of SNe deviate from the completely random distribution. From the three types of SNe, Type II showed the largest offset from the {\hi} distribution, preferring even higher concentrations of atomic gas. This type of SNe deviated also from being proportional to the
stellar surface density of the host. The results are, however, complicated by the limits of the survey in size, and in the un-even resolution of the {\hi} observations. Furthermore, by direct comparison between the three SN types, we observed that the distributions of these populations are still consistent with each other. The obtained results fail to ascertain that Ib/c core-collapse SNe, and possibly also Type II SNe, are connected with the densest concentrations of atomic gas in their hosts, unlike what has been suggested for GRBs and Ic-BL SNe. Hence, the birth of progenitors of Type II and Ib/c SNe is still consistent with being connected with the current
star formation in their hosts, whereas the progenitors of GRBs and Type Ic-BL SNe require more special conditions to form, for example low
metallicity.
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All authors Bruno Šlaus, Natalia Gotkiewicz, Michał J. Michałowski, Aleksandra Lesniewska, Przemysław Nowaczyk, Oleh Ryzhov, Martín Solar, Jakub Nadolny, Wojciech Dimitrov
High Energy Astrophysical Phenomena
Inferring the role of binary neutron star mergers in r-process nucleosynthesis with multi-messenger observations using Cosmic Explorer and Einstein Telescope
Aman Agarwal, Suvodip Mukherjee and Daniel M. Siegel
Identifying the
cosmic origin of rapid
neutron-capture (r-process) elements remains an open problem. Binary
neutron-
star (BNS) mergers and rare classes of core-collapse
supernovae (CCSNe) represent the main contenders as major r-process production sites. Although BNS mergers could exclusively account for r-process nucleosynthesis, results from chemical
evolution studies taking into account their delays with respect to
star formation, observed BNS rates by gravitational-wave (GW) detectors, as well as issues with retention in low-mass
halos suggest otherwise. Here, we propose a method to measure the contribution of BNS mergers to
cosmic r-process nucleosynthesis with the third-generation GW detectors
Cosmic Explorer and Einstein
Telescope. It exploits the
redshift-dependent correlation between the total number of BNS GW events and the average r-process abundances at
redshifts $z \lesssim 1$. We apply this correlation technique to mock GW and abundance data, accounting for expected observational uncertainties in two limiting scenarios: GW events with electromagnetic counterpart (multi-messenger 'bright-sirens') and without ('dark-sirens'). Using Fisher forecasts, we demonstrate that the fractional cumulative contribution of BNS mergers to the total
cosmic r-process $F_{\rm{BNS,z0}}$ can be estimated to the $\lesssim 5-6\%$ precision level for both scenarios at $1\sigma$ for fiducial astrophysical scenarios with $F_{\rm{BNS,z0}} \gtrsim 0.1-1$. Furthermore, the method also yields estimates of the BNS delay-time distribution parameters comparable to other approaches. Although
cosmic r-process abundances may be reconstructed from local observations at low
metallicity, this method also provides a science case to identify signatures of
neutron-capture elements beyond the local Universe.
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Cosmology and Nongalactic Astrophysics
Scalable Dark Siren Cosmology with gwcosmo: GPU Acceleration, Validation and Systematics
Alexander Papadopoulos, Christian E. A. Chapman-Bird, Rachel Gray et al. (+2 more)
As the number of confident gravitational-wave detections grows, population-level hierarchical analyses face increasing computational costs. Dark-siren cosmological inference integrates over the localisation volume of each gravitational-wave source. To remain feasible without discarding information from the quieter but more numerous sources in the catalogue, significant efficiency improvements are vital for analysis pipelines. In this work, we present an upgraded version of the cosmological inference pipeline gwcosmo, which leverages vectorisation on graphics processing units to process the entire gravitational-wave catalogue in parallel with each iteration. This new implementation achieves a speed-up of 1000 times over the previous version, facilitating analyses of O5-like numbers of GW events on wall-clock timescales of hours. Our results demonstrate the scalability of the gwcosmo pipeline, specifically its ability to handle the increasing computational load of expanding event catalogues, positioning it as a vital tool for future advances in dark-siren cosmology.
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All authors Alexander Papadopoulos, Christian E. A. Chapman-Bird, Rachel Gray, Christopher Messenger, Tom Bertheas
Instrumentation and Methods for Astrophysics
Design and Development of Cassegrain Module for PARAS-2 Spectrograph (CAMPAS)
Kevikumar A. Lad, Neelam J. S.S.V. Prasad, Kapil Bharadwaj et al. (+5 more)
We present here the design and development of the CAMPAS, the Cassegrain Module for the PARAS-2 spectrograph. PARAS-2 is a high-resolution fiber-fed echelle spectrograph developed for the PRL 2.5m
Telescope. The CAMPAS acts as a coupler between two optical systems, the PRL 2.5m
telescope and the PARAS-2 spectrograph. It has primarily been developed for the precise injection of the light beam into the optical fibers of the PARAS-2 spectrograph. The CAMPAS consists of a focal reducer, beam-guiding optics, an atmospheric dispersion corrector, optical fiber mounts; a calibration unit incorporating calibration lamps and beam-guiding optics; and other auxiliary subsystems. It was developed in-house at PRL, Ahmedabad, between the years 2020-2022 and was installed at one of the two side ports of the PRL 2.5m
telescope in March 2022. It is one of the first light instruments for the PRL 2.5m
Telescope. The CAMPAS serves critical purposes of precise fiber feed, PSF estimation, and atmospheric dispersion correction.
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All authors Kevikumar A. Lad, Neelam J. S.S.V. Prasad, Kapil Bharadwaj, Nikitha Jithendran, Ashirbad Nayak, Rishikesh Sharma, Abhijit G. Chakraborty, Vishal Joshi
Solar and Stellar Astrophysics
Ensemble asteroseismology: An ensemble approach to detecting signatures of solar-like oscillations in K-dwarfs
William J. Chaplin, Tiago L. Campante, Mikkel N. Lund et al. (+5 more)
Solar-like oscillations have to date been observed in hundreds of main-sequence and sub-
giant stars. However, only a handful of detections have been made in K-type
dwarfs, using ground-based extreme precision radial velocity observations and space-based photometric observations made by the NASA Kepler and TESS missions. Whilst the upcoming ESA PLATO Mission promises to add to these individual detections, it will do so only in a similar, modest number of
stars. Here, we propose a new ensemble strategy to exploit the PLATO data, in which frequency power spectra on hundreds of K-
dwarfs lying in constrained ranges of effective temperature are combined in a weighted manner to significantly improve the detectability of the oscillations. Whilst this approach means it is not possible to extract usable constraints on individual oscillation frequencies, it provides a way to detect and measure the characteristics of the composite envelope of oscillation power given by the ensemble, which in turn provides diagnostics of granulation and magneto-convection and the impact of
magnetic activity on the modes. We use data in the PLATO Input Catalogue (PIC) to make discrete numerical predictions of the detectability of the ensemble spectra. We also derive a simple analytical approximation of our method that obviates the need to perform numerical calculations over a discrete sample of targets, and which serves as a useful tool to make quick predictions for other future or planned missions. Our predictions indicate that PLATO has the potential to provide solid ensemble detections well into the K-
dwarf regime. In summary, PLATO offers an ideal opportunity to exploit this new approach.
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All authors William J. Chaplin, Tiago L. Campante, Mikkel N. Lund, Martin B. Nielsen, Guy R. Davies, Emily Hatt, Rachel Howe, Amalie Stokholm
Astrophysics of Galaxies
Examining extinction distributions for type Ia supernovae in simulated 3D galaxies
João Duarte, Santiago González-Gaitán, Ana M. Mourão et al. (+2 more)
Dust extinction and reddening greatly contribute to type Ia
supernovae (SNe Ia) observed color and magnitude variations. The models used to describe the extinction probability density function (PDF) are often simplistic, which can negatively impact SN simulations and cosmology. We present an analysis of simulated SN Ia extinction in
galaxies along realistic lines of sight and investigate the parameterization of its PDF, as well as its dependence on host properties. We employed SKIRT, a radiative transfer code, to simulate observations of SNe Ia in different environments and generate synthetic extinction distributions. To parameterize and fit these distributions, we used both the commonly assumed single-parameter exponential PDF and some of its two-parameter generalizations. We find that the standard exponential PDF does not adequately describe simulated SN extinction: It underestimates low-extinction events and overestimates high-extinction ones. 2D KS tests show significant differences between the simulated extinction distributions for SNe in different environments, which the exponential parameterization cannot properly distinguish. In contrast, the two-parameter PDFs parameterize SN extinction distributions more accurately across all simulated environments. Variations in host morphology or
dust mass relate to variations in different PDF parameters, meaning that the two effects can effectively be disentangled. We conclude that the two-parameter Weibull or exponentiated exponential PDFs offer the best parameterizations of SN Ia extinction for a wide range of simulated environments. Analyzing observed SN colors from the literature and assuming a Gaussian distribution for the intrinsic component, we conclude that a two-parameter extinction PDF results in intrinsically redder SNe, with their mean intrinsic color shifted ~2$\sigma$ in relation to the standard exponential extinction PDF.
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All authors João Duarte, Santiago González-Gaitán, Ana M. Mourão, Rita P. Santos, Radoslaw Wojtak
Astrophysics of Galaxies
A comparison between Galactic magnetic field models and polarized synchrotron emission with C-BASS at 4.76 GHz and S-PASS at 2.3 GHz
Vasundhara Shaw, S. E. Harper, C. Dickinson et al. (+9 more)
We compare a set of contemporary
Galactic magnetic field (GMF) models with polarized synchrotron observations from the S-PASS and C-BASS
radio surveys and combine them to create a reconstructed 4.76~GHz full sky map. Pixels that potentially have a large Faraday rotation are excluded while small ($< 80\degree$) Faraday corrections derived at the respective frequencies of the two surveys are applied to the rest of the map. Using a template-fitting approach, we evaluate the ability of each model to reproduce the observed polarization amplitudes and polarization angles. We find that while most GMF models match the polarization angles reasonably well, they often fail to reproduce the morphology of the polarized intensity. We find that for most models there is a clear correlation between the data and models in polarization angles on large scales, but this does not hold true for polarized intensity. Our results show that a large portion of the polarized sky is shaped by local “foreground” features such as the North Polar Spur/Loop\,I and the Fan region. We conclude that incorporating such local structures is essential for accurately modelling the polarized synchrotron emission at microwave frequencies.
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All authors Vasundhara Shaw, S. E. Harper, C. Dickinson, J. P. Leahy, Gabriel A. Hoerning, R. Cepeda-Arroita, Gilles Weymann-Despres, Mike Peel, Angela C. Taylor, T. J. Pearson, Jamie Leech, Michael Jones
Solar and Stellar Astrophysics
Imaging spectroscopy reveals spike-like repeating radio burst pairs in the solar corona
Suli Ma, Eduard P. Kontar, Daniel L. Clarkson et al. (+2 more)
Solar radio bursts exhibit complex fine structures that reveal intricate coronal
plasma dynamics. Here, we report detection of spike-like repeating burst pairs, characterized by two short-lived (0.1-2 s), narrowband components separated by about 4 s at frequencies 30-50 MHz. Using high-resolution dynamic spectra and spectroscopic imaging, we analyzed 613 burst pairs, measuring their durations, bandwidths, drift rates, flux densities, and spatial characteristics. Imaging links sources to an active region, with earlier components spatially concentrated above the region while delayed components are displaced and exhibit reduced drift rates.
Radio-wave propagation simulations support the delayed bursts as turbulent echoes of harmonic emission in anisotropic coronal
plasma. The location of the burst sources high in the corona suggests ongoing
magnetic reconnection and electron acceleration well above typical
flare heights. Our findings offer new insights into coronal
turbulence effects while advancing diagnostics of coronal
plasma and the elusive nature of
solar radio echoes from ground-based transmitters.
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All authors Suli Ma, Eduard P. Kontar, Daniel L. Clarkson, Huadong Chen, Yihua Yan
Astrophysics of Galaxies
Disruption of a Giant: Spectroscopic Identification of Members in the Periphery and Tidal Tails of $\omega$ Centauri
P. B. Kuzma, A. M. N. Ferguson, A. L. Varri et al. (+1 more)
$\omega$ Centauri ($\omega$ Cen, NGC\,5139) is one of the most enigmatic globular clusters in the Milky Way, with the recent detection of
tidal tails adding further to its complexity. We report the results of a spectroscopic study of
stars in the outer regions of $\omega$ Cen, which provides an improved characterisation of the cluster periphery and confirms the existence of
tidal tails. Our targets, which lie in six VLT/FLAMES fields sampling six degrees across the sky, are selected using a
Bayesian inference technique. We confirm 157 members of $\omega$ Cen based on line-of-sight velocity and [Fe/H] measurements, indicating an overall success rate of 93 per cent. We trace
stars along the
tidal tails to a cluster-centric radius of 3.2~deg, identifying five members in the debris and additional lower-probability candidates. The analysis of the kinematics and
metallicities of the new members provides evidence of continuity in these properties from the bound component of the progenitor cluster into its
tidal debris. We find that the
metallicities of
stars in the peripheral regions and
tidal tails of $\omega$ Cen are broadly consistent with those in the Fimbulthul stream to which the cluster has been previously linked. Our study provides a glimpse of the promise of new and forthcoming wide-field multi-object spectrographs for advancing understanding of
tidal structures around Milky Way globular clusters.
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All authors P. B. Kuzma, A. M. N. Ferguson, A. L. Varri, P. Bianchini
Earth and Planetary Astrophysics
TOI-7154b: A Close-in Massive Brown Dwarf in an Eccentric Orbit
Rohan Ch. Das, Churchil Dwivedi, Rishikesh Sharma et al. (+12 more)
We report here the discovery and characterization of a high-mass transiting brown
dwarf in a close-in orbit around its host
star, TOI-7154. Initially, the host
star was identified as an exoplanetary candidate from the TESS photometry data. Later, with the mass measurements from the RV follow-up using the PARAS-2 and TRES spectrographs, the companion is found to be sub-
stellar in nature. TOI-7154, is a G-type main-sequence metal-rich
star metallicity $\mathrm{[Fe/H]} = 0.154^{+0.077}_{-0.075}\,\text{dex}$, effective temperature $T_{\mathrm{eff}} = 5564^{+100}_{-110}\,\text{K}$, mass $M_\star = 0.939^{+0.047}_{-0.043}\,M_{\odot}$, radius $R_\star = 0.949^{+0.032}_{-0.030}\,R_{\odot}$, and surface
gravity $\log g = 4.456^{+0.036}_{-0.036}$. With the joint analysis of the TESS photometry and the PARAS-2 and TRES radial velocities we found that TOI-7154b orbits its host
star in $P = 8.860073\pm 0.000029\,\text{d}$, eccentric ($e = 0.2482 \pm 0.0024$) orbit and its radius is smaller than that of Jupiter ($R_{b} = 0.827^{+0.040}_{-0.037}\,R_{\mathrm{J}}$). With a mass near the hydrogen-burning boundary ($M_{b} = 71.7^{+2.4}_{-2.2}\,M_{\mathrm{J}}$) which separates brown
dwarfs from very low-mass
stars, TOI-7154b occupies a critical position in the regime for probing the transition between sub-
stellar and
stellar objects. The system is very old, with its age estimated to be $7.2^{+3.9}_{-3.6}\,\text{Gyr}$ by MIST isochrones, while
Galactic kinematics indicate an age of $\sim4-5\,\text{Gyr}$. {Our
tidal evolution simulations indicate a
stellar dissipation factor of $Q_\star'\lesssim10^6$. Since the presence of any companion is currently ruled out by observations, the presence of eccentricity in this old system is, therefore, indicative of it having
stellar-like fragmentation origins.
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All authors Rohan Ch. Das, Churchil Dwivedi, Rishikesh Sharma, Hareesh G. Bhaskar, K.J. Nikitha, Allyson Bieryla, Boris S. Safonov, Shubhendra N. Das, Abhijit Chakraborty, Lalthakimi Zadeng, David W. Latham, Neelam J.S.S.V. Prasad, Kapil K. Bharadwaj, Kevikumar A. Lad, Ashirbad Nayak
Astrophysics of Galaxies
Cosmic web stripping and starvation of low-mass filament galaxies in TNG50
Daria Zakharova, Gabriella De Lucia, Benedetta Vulcani et al. (+3 more)
Galaxy properties are known to correlate with their location within the
cosmic web. However, the role of filaments remains poorly understood, particularly for low-mass
galaxies, which are expected to be more sensitive to environmental effects. In this work, we use the TNG50-1 simulation to investigate the properties of low-mass $8 \le \log(M_{star}/M_{{sun}}) \le 10$
galaxies in filaments and in the field, when controlling for
stellar and
halo mass and excluding the role of groups and clusters. We find that their integrated properties, including
stellar,
halo mass assembly and quenched fractions, are similar between the two environments. However, we demonstrate that filament
galaxies exhibit smaller and more asymmetric cold gas discs with respect to their field counterparts. We identify two main mechanisms driving these differences. For
galaxies that entered filaments in the early Universe, during the phase of active
accretion,
cosmic web
tidal fields modify the
accretion of gas and dark matter. In some systems,
accretion proceeds at rates comparable to the field but with a different geometry, leading to more tangential motions in the dark matter
halo and, consequently, smaller gas discs. In others, the
tidal field significantly suppresses both gas and dark matter
accretion, leading to a starvation-like
evolution, in which
galaxies gradually exhaust their gas through
star formation and can eventually quench. In contrast,
galaxies that fall into filaments at late times can undergo
cosmic web stripping, a rapid hydrodynamical removal of gas analogous to ram-pressure stripping in clusters. Our results suggest that spatially resolved gas properties are sensitive to several filament-driven environmental mechanisms.
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All authors Daria Zakharova, Gabriella De Lucia, Benedetta Vulcani, Lizhi Xie, Stefania Barsanti, Sean McGee
Astrophysics of Galaxies
Insights from Analytical Theory of Eccentric Circumbinary Disks II. Forced Modes and Resonance for Precessing Binaries
Marcela Grcic, Daniel J. D'Orazio and Martin E. Pessah
An eccentric, unequal-mass binary induces forced eccentricity in a circumbinary disk through the non-axisymmetric component of its gravitational potential. Building on the theory of free (i.e., unforced) eccentric modes, we develop a semi-analytical framework to describe this response in two-dimensional, locally isothermal disks with a power-law surface density profile. We show that the disk eccentricity is governed by the competition between pressure and the binary quadrupole potential, leading to two distinct regimes. In quadrupole-dominated disks, the eccentricity oscillates about the forced eccentricity of a test particle, $E\sim r^{-1}$, with an amplitude and wavelength set by the disk aspect ratio. In pressure-dominated disks, the eccentricity departs qualitatively from the test-particle limit and follows a universal radial scaling $E\sim r^{-2}$, consistent with recent numerical results. Resonant amplification occurs when the binary forcing frequency matches the eigenfrequency of a free eccentric disk mode. In the limit of a non-precessing binary, this reduces to the previously identified zero-frequency resonance, for which we derive an analytic criterion and map its dependence on disk and binary parameters. We extend the framework to massive disks by including the disk's gravitational potential and allowing binary apsidal precession. We
conjecture that the cavity size, for eccentric, non-equal-mass binaries, can be set such that the ground free eccentric mode of the disk has an eigenfrequency equal to the binary precession frequency. In other words, the disk cavity adjusts until the lowest-order trapped eccentric mode resonates with the forcing from the precessing binary.
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High Energy Astrophysical Phenomena · Cross-listed from nucl-th
Quasiradial oscillations of rotating hybrid neutron stars
Zi-Yue Zheng, Ting-Ting Sun, Huan Chen et al. (+4 more)
We investigate fundamental quasiradial oscillations in slow-rotation approximation of pure and hybrid
neutron stars, employing equations of state of
nuclear matter from Brueckner-Hartree-Fock theory or the relativistic mean field model, and of
quark matter from the Dyson-Schwinger
quark model, performing a Gibbs construction for the mixed phase in hybrid
stars. Characteristic differences between
neutron-
star and hybrid-
star fundamental quasiradial oscillation frequencies during
spin-down are pointed out.
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All authors Zi-Yue Zheng, Ting-Ting Sun, Huan Chen, Xiao-Ping Zheng, Jin-Biao Wei, G. F. Burgio, H.-J. Schulze
Solar and Stellar Astrophysics
Nature of HD 251108: an RS CVn binary with a long-term evolving spot
Xinlin Zhao, Song Wang, B. Fuhrmeister et al. (+5 more)
Recently, the Lobster Eye Imager for Astronomy (LEIA) detected the longest-lasting and most energetic
stellar X-ray
flare event from HD 251108. In this work, we re-determined the atmospheric parameters of HD 251108 using three spectroscopic observations obtained with the 2.4 m Lijiang
Telescope. Combined with the
stellar radius derived from spectral energy distribution fitting, we found that HD 251108 contains a K-type
giant with a mass of approximately 1.3 $M_{\odot}$. Long-term photometric monitoring over 12 years reveals a modulation suggestive of a
stellar activity cycle, but inconclusive given the limited time span to date. Light curve fitting indicates that the variations in both amplitude and shape are primarily driven by the
evolution of a large spot. The fitting further indicates that the spot migrated from low latitudes toward the pole between 2014 and 2020, and began to recede from the pole after 2022. Using spot parameters from light curve fitting, we found that the observed radial velocity variations arise from both the spot-induced distortions and the Keplerian orbital motion of the
giant star. Additionally, we detect a possible M-
dwarf companion with a mass of approximately 0.25 $M_{\odot}$. Our finding suggests a notable effect on the radial velocity caused by
stellar magnetic activity.
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All authors Xinlin Zhao, Song Wang, B. Fuhrmeister, J. H. M. M. Schmitt, Xuan Mao, He-Yang Liu, Xiaohong Yang, Jifeng Liu
Astrophysics of Galaxies
ALMA CO-CAVITY I. Resolved Molecular Gas in Void Galaxies
D. Espada, S. B. De Daniloff, S. Duarte Puertas et al. (+21 more)
The environment plays a key role in
galaxy evolution, yet it remains unclear how detailed molecular gas properties and their connection to
star formation and
stellar content are influenced by both large-scale and local environments. Here we introduce the ALMA CO-CAVITY project, the first interferometric CO(1-0) survey of a large sample of 41 void
galaxies (VGs) to characterise in detail their molecular gas properties. It is built over the CAVITY project, offering optical integral field unit (IFU) data, enabling a direct, pixel-to-pixel comparison between molecular gas (from ALMA),
star formation, and
stellar properties, as well as the derivation of their scaling relations. In this work we present ALMA data products for our sample, containing data cubes, moment maps and position-velocity diagrams at angular resolutions of 1 arcsec. We also present molecular gas,
stellar mass, and
star formation rate surface density maps at a common resolution of 2.5 arcsec. We contextualise our sample against representative unresolved and resolved surveys. While our sample provides a good representation of the VG population and follows the distribution of key properties seen in
star-forming
galaxy samples,
galaxies included in resolved studies from the literature tend to be more massive, less isolated, and located in denser large-scale environments. We present global scaling relations for the ALMA CO-CAVITY sample and find that the molecular gas main sequence exhibits the smallest scatter (0.21 dex), followed by the Schmidt-Kennicutt relation and the
star-forming main sequence. From integrated properties alone, we find that these scaling relations for VGs are compatible with those for denser environments. This paper lays the foundation for forthcoming studies exploiting this unique
dataset.
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All authors D. Espada, S. B. De Daniloff, S. Duarte Puertas, M. Argudo-Fernández, U. Lisenfeld, S. Verley, I. Pérez, M. I. Rodríguez, T. Ruiz-Lara, R. García-Benito, L. Sánchez-Menguiano, M. Sánchez-Portal, A. Bongiovanni, S. F. Sánchez, A. Jiménez, R. E. Miura, G. Torres-Ríos, P. Villalba-González, Y. K. González-Koda, B. Bidaran, M. Alcázar-Laynez, A. Zurita, E. Florido, P. Vásquez-Bustos
Astrophysics of Galaxies
Performance analysis of extragalactic classifications in Gaia Data Release 4
Sara Jamal, Coryn A. L. Bailer-Jones, Ruth Carballo et al. (+1 more)
The Discrete Source Classifier (DSC) provides probabilistic classifications of sources in
Gaia Data Release 4 (GDR4) based on empirically-trained
Bayesian classifiers. Using
Gaia astrometry, photometry, and low-resolution spectra (XP), DSC classifies all sources as
quasars,
galaxies, or
stars. DSC comprises three trained neural networks and three combinations of their probabilities. When evaluated as a function of brightness and sky position on a test set excluding the Magellanic Clouds, the DSC purity in GDR4 has improved for a small loss in completeness. The average performance of the best classifiers at magnitudes brighter than G=20 is at least 88% completeness and 96% purity for the extragalactic classes, namely the
quasar and
galaxy classes. At fainter magnitudes, performance is lower due to increased noise. The average performance at magnitudes of 20$\leq$G<20.5 is a minimum of 55% completeness and 71% purity for the extragalactic classes. At G>20.5 mag, completeness is considerably reduced, primarily for the models that depend on the XP spectra. Furthermore, we train additional models on
Gaia optical data together with mid-infrared photometry from the CatWISE2020 catalogue. Inclusion of infrared photometry increases the completeness of extragalactic samples at G>20 mag between 9 and 29 percentage points, at the cost of reducing purity between 1 and 9 percentage points. In GDR4, the best DSC-combined classifier prioritising completeness identifies three million
quasars and two million
galaxies, but with expected high contamination among fainter sources. In contrast, the combined classifiers prioritising purity identify approximately two million
quasars and 1.3 million
galaxies with an expected lower level of contamination. Finally, we provide recommendations for enhancing the purity of the DSC extragalactic selection by applying quality cuts to the
Gaia photometry and astrometry.
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All authors Sara Jamal, Coryn A. L. Bailer-Jones, Ruth Carballo, Orlagh L. Creevey
Cosmology and Nongalactic Astrophysics
Cosmological constraints from neighbor-density-weighted marked correlation functions
Xu Xiao, Zhao Chen, Yu Yu et al. (+3 more)
We investigate whether neighbor-density-weighted marked correlation functions (MCFs) can extract cosmological information beyond the standard
redshift-space two-point correlation function (2PCF). Using the Kun suite of 129 $w_0w_a$CDM$+\sum m_\nu$ simulations in $1~h^{-1}{\rm Gpc}$ boxes, we construct Gaussian-process emulators for the normalized scale statistic $\widehat{W}^{\alpha}(s)$ and the angular statistic $\widehat{W}^{\alpha}_{\Delta s}(\mu)$. We perform joint analyses combining multiple mark parameters $\alpha$ and quantify the information gain using the FoM in the $\Omega_m$–$\sigma_8$ plane. Relative to the 2PCF case, three-mark combinations improve the FoM by factors of $1.7$–$2.5$, while five-mark combinations increase the gain to $1.9$–$2.4$, depending on the statistic and mark definition. We further compare density and normalized-gradient marks, finding that they are nearly redundant for isotropic statistics but complementary for angular statistics, where their combination improves the FoM by up to $43\%$. Tests of scale range and
halo selection show that the marked statistics remain robust under changes in analysis choices, with the angular statistic retaining additional cosmological information that is less sensitive to tracer selection. Our results demonstrate that MCFs substantially enhance cosmological constraints beyond the standard 2PCF and provide a robust probe for next-generation
galaxy surveys.
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All authors Xu Xiao, Zhao Chen, Yu Yu, Xiao-Dong Li, Yiqi Huang, Le Zhang
Earth and Planetary Astrophysics
Size-Dependent Fresh Surface Signatures in Asteroid Families: Observational Evidence from Dual-Band Albedo Analysis
Murat Kaplan
The spectral
evolution of asteroid surfaces reflects the competition between space weathering and impact resurfacing. While previous studies focused primarily on age-dating, the role of family population size remains largely unexplored. We tested whether population-dependent collisional activity affects observable surface properties by analyzing 154 asteroid families using NEOWISE thermal infrared photometry, validated by independent AKARI observations and error propagation analysis. We introduced the V-Dominance Index (VDI) to quantify the incidence of extreme resurfacing signatures within families, defined as the fraction of members with visible-to-infrared albedo ratios p_V/p_IR > 1.2. Among tested parameters, family population size (N) emerged as the dominant correlate of VDI across both silicaceous (S-complex: r_s = 0.58) and carbonaceous (C-complex: r_s = 0.44) taxonomic types, with a full-sample correlation r_s = 0.476 (p = 4.31 x 10^-10). This correlation survived Monte Carlo permutation tests, binomial null model validation, age-matched contrast analyses, and heliocentric independence tests. Percentile sensitivity analysis demonstrated that VDI isolates rare resurfacing events detectable only at extreme thresholds. In families older than 2 Gyr, large populations maintained statistically significant fresh tails (p < 10^-4), whereas small populations were saturated. These results indicate that massive families experience elevated collisional resurfacing rates that counteract space weathering saturation.
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Cosmology and Nongalactic Astrophysics
Dissecting the Perseus-Pisces supercluster observed with CFHT-MegaCam: Exploring late-type galaxy shape alignments within the local cosmic web
M. Mondelin, S. Codis, J.-C. Cuillandre et al. (+2 more)
Intrinsic
alignments of
galaxy shapes are a major systematic for weak gravitational
lensing and provide insight into how
galaxies acquire orientations within the
cosmic web. Most studies rely on large statistical samples; here, we probe this signal in a single nearby superstructure, extending to outer regions where secondary infall should dominate. We measure intrinsic
alignments in the Perseus-Pisces supercluster as a function of
galaxy morphology and radial extent into the low surface brightness regime. Using deep CFHT r-band imaging covering 367 deg2 (mainly from the UNIONS survey) and reaching 28 mag/arcsec2, we compute correlation functions at three isophotal radii for 2004
galaxies with log M*/Msun > 8.6, stratified by morphology and
stellar mass in comoving coordinates. We detect positive intrinsic
alignment signals for both early- and late-type
galaxies out to 1 Mpc/h, including a clear signal for spirals. Shape-shape correlations are stronger than position-shape correlations, while comoving measurements increase the fraction of strongly correlated systems. Correlation profiles show little radial dependence across the three isophotes despite ellipticity variations in 10-20% of
galaxies. We find strong morphology dependence: late-type
galaxies dominate the shape-shape signal, preferentially inhabiting filaments and displaying higher ellipticities consistent with edge-on orientations. Early-type
galaxies instead cluster near group and cluster centers, with no comparable excess in position-shape correlations. This segregation suggests distinct
alignment mechanisms:
tidal stretching for early-types in dense environments and
tidal torquing for late-types in filaments. These local-Universe constraints inform intrinsic
alignment modeling for Euclid, DESI, and LSST, highlighting the contribution of blue spiral
galaxies to low-
redshift cosmic shear contamination.
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All authors M. Mondelin, S. Codis, J.-C. Cuillandre, R. Paviot, T. de Boer
High Energy Astrophysical Phenomena · Cross-listed from hep-ph
Enhanced Stellar Production of Weakly Interacting Slim Particles from Non-Thermal Nuclear Cascades
Víctor Fonoll, Maurizio Giannotti and Giuseppe Lucente
Weakly interacting slim particles (WISPs) can be produced in
stars through the conversion of non-thermal
photons generated in
nuclear reactions. Previous studies have generally treated these sources only at the level of their primary injection lines. We show that this picture is incomplete: repeated Compton scatterings redistribute the injected
photons into a broad low-energy spectrum, while associated positrons can thermalize and annihilate into a 511~keV line. Together, these effects define a generic non-thermal
photon reservoir and thus a broadly applicable source term for any
photon-coupled WISP. We develop a general framework for this mechanism and illustrate its impact with the example of dark-
photon production in the
solar pp chain. Our results show that non-thermal
stellar WISP production can be substantially underestimated if Compton reprocessing and positron annihilation are neglected.
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Astrophysics of Galaxies
The dual effect of group-scale environments on galaxy quenching during cluster infall: pre-processing and protection
Haoran Dou, Heng Yu and Xiaolan Hou
Context. It is well established that the cluster environment effectively quenches
star formation in member
galaxies. Amis. We aim to explore how the
accretion path of infalling
galaxies influences the cluster-driven quenching process. Methods. We compiled a large spectroscopic
galaxy sample around 25 low-
redshift, X-ray luminous massive clusters. We identified cluster substructures using the Blooming Tree
algorithm and distinguished between
galaxies accreted as part of group-scale structures and those accreted in isolation. The infall process was quantified using an infall proxy, $d_{\rm R}$, defined in the $R$–$V$ diagram. Results. Along the infall process, the quiescent fraction remains approximately constant at the outskirts and then increases steadily toward cluster center, with a transition occurring around $d_{\rm R}\sim 2.5$. We find that group-associated
galaxies follow a distinct quenching track compared to isolated
galaxies, indicating a dual effect of group-scale environments. At the early infall stages, group
galaxies exhibit a higher quiescent fraction, consistent with “pre-processing” in group-scale
halos. However, after entering the cluster environment, the rise in their quiescent fraction is delayed to smaller $d_{\rm R}$ compared to isolated
galaxies. This suggests a phenomenological “protection” effect, in which group-scale
halos buffer member
galaxies against rapid cluster-driven quenching. Conclusions. We conclude that group-scale environments affect quenching in two ways: via pre-processing prior to cluster infall, and through a subsequent protection effect within the cluster environment.
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Earth and Planetary Astrophysics
Superrotation and Jet Migration in Simulations of Giant Planet Atmospheres
Loren Matilsky, Geoffrey Vallis, Matthew Browning et al. (+1 more)
The mean zonal flow on both Jupiter and Saturn consists of an intricate pattern of jets moving prograde or retrograde compared to the bulk planetary rotation. The strongest jet straddles the equator and is prograde, or superrotating. It is flanked by multiple retrograde/prograde pairs of weaker jets at high latitudes. Two candidate drivers of these jets are "shallow" quasi-two dimensional
turbulence in the outermost stably stratified weather layer (WL) and "deep" buoyantly-driven Busse columns in the underlying convective zone (CZ). To study the respective roles of the WL and CZ, we implement two rotating, three-dimensional, anelastic convection simulations of a
giant planet. In one case, the CZ is isolated, whereas in the other case, the upflows overshoot into a stably stratified near-surface layer, driving
turbulence there. We regard this layer as a simplified WL, although we include the effects of stable stratification only, neglecting
solar irradiation. In each case, we find that homogenization of an appropriately defined potential vorticity initially creates multiple jets at high latitudes, whereas Busse columns in the CZ drive equatorial superrotation. The presence of a simplified WL significantly alters the thermal wind balance, resulting in large deviations of the contours of the zonal flow from
alignment with the rotation axis. Finally, the weaker high-latitude jets slowly migrate poleward and/or merge on a very long time scale (O(10)
diffusion time scales or thousands of eddy turnover times).
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All authors Loren Matilsky, Geoffrey Vallis, Matthew Browning, Nicholas Brummell
Astrophysics of Galaxies
Rotation-curve residuals reveal a suppressed acceleration branch in dwarf galaxies
Hosik Lee
Galaxy rotation curves exhibit systematic deviations from the Newtonian expectation inferred from visible matter alone. Existing phenomenological descriptions capture many aspects of these deviations, but a common residual structure across massive disks and
dwarf irregular
galaxies remains unclear. We investigate whether rotation-curve residuals organize into a simple empirical form across the SPARC and LITTLE THINGS samples. We analyze 175 SPARC
galaxies and 22 LITTLE THINGS
dwarf irregular
galaxies in velocity-squared space after subtracting a leading Newtonian-like term. We fit a generalized residual family, v^2-A/r=B+Cr^{q+1}, and examine which radial scaling is selected by the data. The
galaxy population systematically favors the limit \(q\simeq0\), corresponding to an approximately linear residual relation, \(v^2-A/r=B+Cr\). SPARC
galaxies generally occupy a high-\(B\) branch, whereas LITTLE THINGS
dwarf galaxies show suppressed residual intercepts, including several systems consistent with \(B=0\). For the SPARC sample, the high-\(B\) branch approximately follows \(B\propto M_{\rm bar}^{0.72}\). {Rotation-curve residuals are not featureless scatter beyond the leading Newtonian-like contribution, but instead show a simple population-dependent empirical organization across massive and
dwarf galaxy systems.}
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Astrophysics of Galaxies
Suppression of star formation at the centre of barred AGN galaxies
Takashi Yamamoto, Nario Kuno, Daisuke Iono et al. (+5 more)
We measured the Concentration (C) index of H\alpha and CO (J = 2-1) in 17 nearby
star-forming
galaxies from the PHANGS survey. We have found four barred spiral
galaxies with a C(H\alpha)/C(CO) ratio of ~ 0.3-0.4, while the other 13
galaxies exhibit ratios of ~ 1 (range from 0.7 to 1.3). All four barred
galaxies with low ratios host active
galactic nuclei (AGNs), consistent with a scenario in which
star formation is suppressed by mechanical and radiative feedback from the AGN. Therefore, negative feedback is effective in these four barred
galaxies with a low molecular gas mass fraction (< 0.1), even when AGN activity is relatively weak. The formation of bar structures causes molecular gas to collect in the central region, leading to starburst activity. However, after the starburst, the remaining gas becomes inefficient for
star formation rapidly due to AGN feedback. It can mean the quenching process occurs more rapidly in AGN-barred
galaxies. Furthermore, since gas remains in the central region, AGN activity is likely to continue. These quenching processes are a unique mechanism found in barred spiral
galaxies and are essential to understanding
galaxy evolution.
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All authors Takashi Yamamoto, Nario Kuno, Daisuke Iono, Takuya Hashimoto, Sophia K. Stuber, Daizhong Liu, Thomas G. Williams, Akio K. Inoue
Solar and Stellar Astrophysics
TESS Observations of Stochastic Low-frequency Variability in Extreme Helium Stars
Courtney L. Crawford, C. Simon Jeffery, May G. Pedersen et al. (+4 more)
Extreme helium
stars (EHes) are low-mass hydrogen-deficient
stars thought to be the products of double white
dwarf mergers. Despite prolonged ground-based observations, there is no consensus on the properties of their photometric variability. In this article, we present an analysis of TESS light curves for all known EHe
stars, constituting the first population-level study of EHe photometric variability. We present updated TESS light curves for the two confirmed large-amplitude pulsators, V652 Her and BX Cir, and discuss the potential r-mode pulsators BD+37 442 and BD+37 1977. Notably, we found that the majority of EHe
stars exhibit
stochastic low-frequency (SLF) variability, or a signal with power increasing smoothly towards low frequencies, rather than peaks in the power spectrum corresponding to oscillation modes. We characterised the SLF variability of EHe
stars using Gaussian process regression with a stochastically-driven/damped simple harmonic oscillator kernel and measured the characteristic timescale, low-frequency amplitude, and quality factor for each
star. The variability timescales range from approximately 0.5 to 10 d and correlate strongly with
stellar parameters such as density and radius. Further theoretical work is needed to determine the physical driving mechanism for the variability, but 1-D models of EHe
stars suggest that thin subsurface convection zones may play a role.
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All authors Courtney L. Crawford, C. Simon Jeffery, May G. Pedersen, Timothy R. Bedding, Benjamin T. Montet, Geoffrey C. Clayton, Patrick Tisserand
Solar and Stellar Astrophysics
An Improved HDBSCAN-based Detection and Tracking Method for Solar Active Regions in Magnetograms
C. X. Shi, Q. Hao, P. F. Chen et al. (+1 more)
Solar active regions (ARs) are the primary source of
solar eruptions and space weather. Accurate detection and tracking of ARs is crucial for understanding their
evolution and predicting
solar activities. In the previous work, based on the density-based spatial clustering of applications with noise (DBSCAN) approach, we proposed the DBSCAN-based
solar active region detection (DSARD) framework. To overtake its limitations, in this paper we applied the hierarchical density-based spatial clustering of applications with noise (HDBSCAN) approach to the detection of
solar active regions, which is called the HDBSCAN-based
solar active region detection and tracking (HARDAT) method. This enables the
algorithm to handle multi-density
magnetic structures dynamically, eliminating the need for fixed thresholds. Consequently, the
algorithm can detect diffuse and small ARs more effectively while preserving morphological integrity. We have also developed a
solar differential rotation based tracking
algorithm that integrates physical motion models and Hamming distance similarity metrics to achieve robust multi-object tracking. Additionally, we propose a novel polarity inversion line extraction method that uses support vector classification, which offers superior generalization for complex AR boundaries. Processing line-of-sight magnetograms from SOHO/MDI (1996–2011) and SDO/HMI (2010–2024) and evaluating them against the National Oceanic and Atmospheric Administration (NOAA) and DSARD catalogues demonstrates that HARDAT is superior in terms of sensitivity, accuracy, and stability of detection and tracking. This is particularly evident when resolving clustered ARs and maintaining identity continuity. HARDAT therefore offers a comprehensive solution for the long-term analysis of AR
evolution and space weather prediction.
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All authors C. X. Shi, Q. Hao, P. F. Chen, Y. Guo
Instrumentation and Methods for Astrophysics
A Gaia-linked High-purity QSO Candidate Catalog in Selected Fields with Extinction-binned Calibration and Spectrum-informed Training
Zi-Huang Cao, Zhao-Xiang Qi, Juan-Juan Ren et al. (+11 more)
We present an extinction-calibrated,
Gaia-source-level QSO candidate catalog for selected fields, designed as a high-purity input catalog for fiber-spectroscopic follow-up rather than as an all-sky QSO census. The deployed selector uses
Gaia astrometry and photometry, optical/infrared catalog features, and E(B-V)-binned threshold calibration; spectra are used only during training via a source-grouped spectrum-teacher model. The sample definition is layered: a four-field core domain ladder provides the main validation baseline, four application/stress-test fields probe portability, and COSMOS is treated separately as an Extreme Deep boundary case. At the recommended conservative operating point, calibrated to a validation-set purity of 0.98, the P3 spectrum-informed catalog selector achieves a measured test-set purity of 0.9809 and a spectroscopic-label completeness of 0.8869 within the frozen
Gaia-linked
benchmark, whereas the
Gaia official QSO probability yields a spectroscopic-label completeness of 0.4493 under the same threshold protocol. The evaluation protocol excludes downstream validation/test
Gaia source IDs from teacher fitting and checkpoint selection, and uses teacher probabilities only for downstream training rows. Relative to the earlier P2 teacher, P3 yields a modest mean completeness gain across five seeds, with a small decrease in purity and a small increase in false positives; the gain is most evident in higher-extinction and faint-source diagnostics. The released product is a catalog and empirical selection-function data product with source identifiers, field-layer assignments, input-coverage flags, calibrated scores, threshold flags, validation metadata, and provenance/QC fields. In COSMOS, the
Gaia-linked parent set is much shallower than COSMOS2020; the robust 39-object subset is interpreted as a purity-oriented priority list rather than a completeness measurement.
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All authors Zi-Huang Cao, Zhao-Xiang Qi, Juan-Juan Ren, Bo Zhang, Dongwei Fan, Shi-Long Liao, Yuzhou Wang, Yong-Heng Zhao, Yong Zhang, Meng-Xin Wang, Yihan Tao, Gao-Yuan Zhang, Yong Yu, A-Li Luo
Astrophysics of Galaxies
Evidence of radial-migration driven Galactic disc expansion with the U-shape stellar age profile
Jianhui Lian, Qinhao Shao and Yuze Zhao
Canonical theory predicts
galaxies grow "inside-out", producing their observed negative radial age gradient. This picture is challenged by
galaxies' `U-shaped' colour profiles – indicating reversed age gradient – explained by either outside-in formation or radial migration. Extragalactic observations cannot disentangle these two possibilities, but temporally and spatially resolved observations in the Milky Way offer a solution. Here we report a more complex U-shaped age profile of the Milky Way extending to 20 kpc, featuring an outer positive gradient followed by an age plateau of $\sim$5 billion year beyond 12 kpc. Age and chemical abundance distributions of outer disk
stars rule out outside-in formation and confirm radial migration as the primary driver of the outer positive age gradient and plateau. Our results suggest local
star formation in the
Galaxy truncates around 12 kpc and radial migration has expanded the Milky Way far beyond its native
star formation regime out to 20 kpc – a growth mode likely common to disk
galaxies. The Milky Way thus provides a critical template to understand disk assembly in external
galaxies, improving our understanding of
galaxy growth.
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Cosmology and Nongalactic Astrophysics
Increasing the Precision of Surrogate Models for Weak Lensing Mass Maps with Flow Matching
Guangjian Li and Tomasz Kacprzak
Weak gravitational
lensing maps compactly encode the
evolution of
cosmic large-scale structure and are a key tool for cosmological analyses. Performing inference directly at the map level allows flexible choices of statistics and can increase constraining power. Conventional methods rely solely on N-body simulations and are computationally expensive. Generative machine-learning emulators can accelerate map-level theory prediction. However, existing GAN-based map-level surrogates still have limited statistical fidelity. They can produce over-smoothed maps, may fail to capture the full distribution of generated map sets and can be difficult to train. Continuous normalizing flows trained with flow matching have recently emerged as a powerful class of generative models. We present a residual label-conditional flow matching generative network that conditions explicitly on the matter density $\Omega_m$ and clustering amplitude $\sigma_8$ for a fixed source
redshift distribution $n(z)$. The model learns a continuous probability flow in a residual space from label-specific noise distributions to convergence maps. We evaluate it using pixel and peak statistics, the power spectrum, bispectrum, power-spectrum correlation
matrices, and other validation metrics. Compared with the previous GAN
benchmark, the proposed method improves the typical fidelity of generated maps from below 10% and below 20% to below 1% and below 5% for basic and higher-order statistics, respectively. The agreement at the level of map distributions is also very good: maps generated from random noise match well the distribution of maps generated with N-body simulations from random initial conditions. This work brings us closer to a practical mass-map emulator that captures the cosmological signal while supporting multiple forms of data analysis.
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