Instrumentation and Methods for Astrophysics
The Cross-Survey Decade: A Call to Action
Gioia Rau, Robert Benjamin, Federica Bianco et al. (+24 more)
By 2027, three flagship wide-field surveys will be operating simultaneously from ground and space, observing overlapping sky and representing more than $6 billion in US and European public investment. Together they will produce overlapping petabyte-scale
datasets across thousands of square degrees. This is a different class of challenge: the observations are no longer the bottleneck; realizing their joint scientific return now depends on shared computational infrastructure and coordination. Decades of community studies show that combining these
datasets does more than improve precision. For science ranging from weak
lensing to transient discovery and
Galactic-plane astronomy, joint processing and analysis can unlock capabilities no single survey provides alone. Yet the required infrastructure – joint pixel-level processing, cross-calibration and validation, interoperable data access, and the people to build and sustain it – falls outside any single mission or institution's mandate. We issue a call to action for cross-survey science infrastructure, built around four pillars: (1) joint pixel-level processing and validation; (2) an AI-ready data substrate for scientific foundation models; (3) standardized, interoperable data access across surveys, democratizing participation in astrophysical discovery; and (4) dedicated personnel and career pathways. We outline concrete steps for policymakers, agencies, observatories, universities, the research community, and philanthropy, and argue that the moment to act is now, while foundational technical choices can still be aligned at a fraction of the cost of reconciling them later.
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All authors Gioia Rau, Robert Benjamin, Federica Bianco, Ranga-Ram Chary, Andy Connolly, Cecilia Garraffo, Suvi Gezari, Leanne P. Guy, Željko Ivezić, Stephanie Juneau, Vicky Kalogera, Mansi M. Kasliwal, François Lanusse, Zack Li, Rachel Mandelbaum, Peter Melchior, Stella Offner, Antonella Palmese, Jason Rhodes, Edward Schlafly, Kartik Sheth, Rachel Street, Michael Troxel, Tony Tyson, Beth Willman, Michael Wood-Vasey, Yuanyuan Zhang
Astrophysics of Galaxies
Osvan M. Portilla-Narvaez, Javier Zaragoza-Cardiel, Gisela N. Ortiz-León et al. (+6 more)
Some interactions between
galaxies produce
tidal tails primarily composed of material from their disks. Within these tails, concentrations of gas and
stars can form, resembling
dwarf galaxies. These
tidal objects often begin to form
stars and become dynamically independent of their parent
galaxies, leading to their classification as
Tidal Dwarf Galaxies (TDGs). By definition, TDGs should consist solely of baryonic material, with a negligible dark matter fraction. In this study, we analyze the dynamics of two TDGs in the Arp 72 system using high-resolution H{\alpha} observations obtained with the MEGARA multi-spectrograph at the GTC (Gran Telescopio Canarias) and neutral hydrogen (HI) data from the GMRT (
Giant Metrewave
Radio Telescope). The HI data were also used to determine the gas mass. We derived the rotation curves and velocity dispersion from the kinematic data, which allowed us to estimate the dynamical mass of the systems. The TDGs were modeled through 3D fitting as rotating disks with additional pressure support, assuming a mass distribution following an exponential law. The gas mass was combined with the
stellar mass to determine the total baryonic mass. Under specific dynamical considerations, we established the relationship between the dynamical mass and the baryonic mass. Additionally, we used the pressure-support corrected circular velocity to compare the behavior of TDGs in the context of the baryonic Tully-Fisher relation (BTFR) with the literature, showing how detached TDGs fall off the relation. The two studied objects are consistent with the expected properties of a TDG.
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All authors Osvan M. Portilla-Narvaez, Javier Zaragoza-Cardiel, Gisela N. Ortiz-León, Y. D. Mayya, Beverly J. Smith, Chandreyee Sengupta, Mark L. Giroux, S. Comerón, Luz I. Alvarez-Cruz
Earth and Planetary Astrophysics · Cross-listed from physics.space-ph
Evolution of lunar wake potentials: structure, energy conversion, and their imprints on velocity distributions
Xin An, Vassilis Angelopoulos, Jasper S. Halekas et al. (+4 more)
We study the
evolution of electric potentials in the lunar wake. The wake potential exhibits two distinct spatial scales. The macroscopic scale arises from
solar wind expansion into the
vacuum, with a potential length-scale growing with distance from the Moon; the microscopic scales arises from ion acoustic shocks near the wake center, with transition layers spanning tens of local Debye lengths. This two-scale potential mediates energy conversion between ions and electrons during wake refilling. The macroscale potential retards electrons and accelerates ions to supersonic velocities, converting electron thermal energy to ion kinetic energy. The microscale potential then decelerates ions to subsonic velocities and heats both species, converting ion kinetic energy back to thermal energy. Together, the two-scale potential imprints distinct signatures on velocity distributions, including ion beams and electron flat-top distributions, consistent with ARTEMIS observations.
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All authors Xin An, Vassilis Angelopoulos, Jasper S. Halekas, Terry Z. Liu, Shaosui Xu, Andrew R. Poppe, Ferdinand Plaschke
Earth and Planetary Astrophysics
The Inbound Gas and Dust Evolution of Interstellar Comet 3I/ATLAS from Optical Spectroscopy and Multi-band Photometry
Toni Santana-Ros, Alexey Sergeyev, Oleksandra Ivanova et al. (+9 more)
Interstellar objects (ISOs) provide direct constraints on the composition and
evolution of extrasolar planetary systems. As the third confirmed ISO, comet 3I/ATLAS offers a rare opportunity to study pristine material from another
star system. We present a systematic multi-band monitoring campaign conducted from 2025 July to September. To minimize systematic uncertainties, we utilized a homogeneous
dataset of SDSS $g', r', i', z_s$ and Johnson-Cousins $BVR$ imaging obtained with MuSCAT3/4 on the 2.0-m Faulkes
Telescopes and the 1.5-m Maidanak
telescope. We employed a novel multi-aperture technique providing a robust, distance-independent characterization of the coma, alongside optical spectroscopy from SALT and the Nordic Optical
Telescope. 3I/ATLAS exhibited a stable reddish color with no significant secular variation during its inbound journey. Spectroscopic analysis reveals carbon-chain depletion, with CN as the only prominent molecular emission. Coma morphology, analyzed via azimuthal averaging and rotational gradient filters, shows a persistent sunward jet at a position angle of $\sim$280$^{\circ}$, indicating sustained and localized outgassing from a high-latitude active region. Light-scattering modeling demonstrates that the observed colors and polarization are consistent with dense aggregates of organic matter and silicate minerals, while water ice sublimation remained insufficient to alter the optical properties. The stability of the coma structures and the homogeneous nature of our
dataset indicate that 3I/ATLAS underwent a steady activation phase, preserving a volatile-rich but carbon-chain-poor composition. This characterization points to an object formed in a distinct protoplanetary environment and provides a definitive record of its pre-perihelion
evolution.
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All authors Toni Santana-Ros, Alexey Sergeyev, Oleksandra Ivanova, Sofiia Mykhailova, Johannes Markkanen, Igor Luk'yanyk, Tomasz Kwiatkowski, Dagmara Oszkiewicz, Antti Penttilä, Nicolas Erasmus, Kamoliddin Ergashev, Yurij Krugly
Instrumentation and Methods for Astrophysics
The Atacama Cosmology Telescope: Passband Measurements with an Analysis of Systematic Errors
Thomas Alford, Rahul Datta, Erminia Calabrese et al. (+14 more)
We present measurements of the spectral response of the four Advanced ACTPol (AdvACT) multichroic detector arrays, which observed in frequency bands centered near 30, 40, 90, 150, and 220 GHz. The passbands were measured with a
Fourier transform spectrometer (FTS) combined with coupling optics that direct and match the output of the FTS to the AdvACT receiver. We perform optical simulations of the FTS and coupling optics in order to model frequency-dependent systematic effects in this system. We use these simulations to apply corrections to the measurements and evaluate the remaining systematic uncertainty. We combine these systematic estimates with statistical errors to determine the measured passbands and their uncertainties from our FTS measurement, which are typically 0.75 to 1.5% per detector array. We present the passband characteristics for all measurements made by ACT in a common framework. Additionally, we discuss the performance achieved as well as ways to improve passband measurements in the future.
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All authors Thomas Alford, Rahul Datta, Erminia Calabrese, Steve K. Choi, Shannon M. Duff, Adriaan J. Duivenvoorden, Joseph Golec, Matthew Hasselfeld, J. Colin Hill, Johannes Hubmayr, Jeffrey McMahon, Michael D. Niemack, Lyman A. Page, Alex Thomas, Cristian Vargas, Yuhan Wang, Edward J. Wollack
High Energy Astrophysical Phenomena
Modeling the Gravitational Wave Signal from the X-ray Pulsar Her X-1
I. D. Markozov, G. K. Pimenov and A. A. Mushtukov
The paper is devoted to modeling the gravitational waves from the X-ray
pulsar Her X-1. The
neutron star is considered as a freely precessing ellipsoid. The gravitational wave signal is calculated in the quadrupole approximation. The $h_{\times}$ and $h_{+}$ polarization profiles are constructed for the precession parameters of the
neutron star in Her X-1 measured in up-to-date works. The possibility of signal detection with the DECIGO
telescope is assessed. The formulas for the semi-analytical modeling of the gravitational wave signal from precessing
neutron stars by the method of perturbations in the small
neutron star ellipticity parameter are deduced.
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High Energy Astrophysical Phenomena
High-Redshift Type Ia Supernovae Exhibit Enhanced Calcium Abundances
Xingzhuo Chen, Ulisses Braga-Neto and Lifan Wang
Type Ia
supernovae (SNe Ia) are major contributors to
cosmic chemical enrichment, and their elemental abundances provide a probe of progenitor properties and explosion physics across
cosmic time. We employ an artificial intelligence-assisted inversion technique to analyze spectra of high-
redshift SNe Ia from the
Supernova Legacy Survey and of gravitationally lensed SNe Ia observed by the James Webb Space
Telescope, extending the sample to
redshift 2.05. We find a positive correlation between SN Ia calcium abundance and
redshift. The
redshift-dependent variation in calcium abundance exceeds that predicted by SN Ia nucleosynthesis simulations with varying progenitor
metallicities, suggesting that high-
redshift SNe Ia may undergo different explosion mechanisms from nearby SNe Ia.
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Cosmology and Nongalactic Astrophysics
PowerFull: fast and accurate computation of the relativistic angular galaxy power spectrum including local primordial non-Gaussianity
Gregory Lukens and Donghui Jeong
Current and forthcoming wide-field
galaxy surveys, such as SPHEREx and Euclid, provide a unique opportunity to probe the ultra-large scales of structure formation, where
primordial non-Gaussianity, often parameterized by $f_\text{NL}$, is expected to leave its most detectable imprint. At the same time, these surveys inevitably enter regimes where relativistic and wide-angle effects become significant, requiring careful modeling to extract unbiased cosmological information. We address these challenges by applying the total-angular-momentum (TAM) formalism to describe
redshift-space clustering beyond the flat-sky approximation. The standard
Fourier-mode description, which characterizes distortions by the angle between a mode and a line of sight, becomes ill-defined over wide fields, whereas the TAM basis naturally separates radial and angular contributions and incorporates the relevant relativistic effects. Within this framework, we provide a new parameterization of wide-angle predictions that can be compared directly with survey data. We then introduce PowerFull, a modification of the Julia-based 2-FAST package, which enables efficient computation of the full relativistic angular power spectrum. Finally, using Fisher information
matrix-based analyses, we show that a survey like SPHEREx reaches $\sigma(f_\text{NL}) \sim 1$, but that neglecting the relativistic and wide-angle contributions shifts the recovered $f_\text{NL}$ by an amount of order its own uncertainty: at this precision the inferred value is biased unless the clustering is modeled consistently.
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Earth and Planetary Astrophysics
The Tidal Venus Phenomenon: Demographics and Case Studies
Stephen R. Kane and Emma L. Miles
The demographics of terrestrial
planets and their orbits reveal a vast diversity in overall planetary energy budgets. Terrestrial
exoplanets in short-period or eccentric orbits can experience intense
tidal heating that, combined with
stellar irradiation, may trigger runaway greenhouse conditions analogous to Venus. We calculate
tidal heating rates for 143 terrestrial-sized
exoplanets with measured eccentricities and find that, under adopted archive default eccentricities and constant-$Q$ assumptions, 70% exceed the extreme volcanism threshold in
tidal flux and 96% exceed the runaway greenhouse limit in total zero-albedo flux. We develop a three-category taxonomy of
tidal influence on
climate: flux-driven Venus analogs, tidally dominated
planets, and historically compromised Habitable Zone (HZ) worlds, and apply this framework to five case studies. TOI-6716 b and TOI-912 b may have exceptionally high
tidal fluxes, potentially serving as examples where
tidal dissipation alone causes them to exceed the runaway greenhouse threshold. TOI-700 d and LHS 1140 b, though currently below the threshold, were exposed to above-threshold
stellar irradiation during their host
stars' $\sim$0.5–3~Gyr pre-main-sequence phases; whether their atmospheres survived is testable with JWST. GJ 12 b, already above the threshold from
stellar flux alone, experiences a
tidal heat flux of $\sim$5~W/m$^2$ (comparable to Io) that drives an independent volcanic pathway to a runaway greenhouse. Three-dimensional
climate simulations show that a temperate atmosphere for GJ 12 b fails to achieve radiative balance, while a Venus-like CO$_2$-dominated atmosphere converges to a stable state. We consider observational prospects for these systems and connections to forthcoming Venus in-situ missions.
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Astrophysics of Galaxies
Continuum Variability in AGN: Evidence for Systematically Suppressed Fluctuations in the BAL Population
A. Aliaga, P. Arévalo, M.L. Martínez-Aldama et al. (+2 more)
We aim to compare the flux variability of Broad Absorption Line
quasars (BAL) to non-BAL
quasars, controlling for black hole parameters to inform models concerning the generation of the BAL phenomenon. Using SDSS DR16 and ZTF $g$- and $r$-band light curves, we select
quasars with $1.57 \leq z \leq 2.00$ and $18.5 \leq rmag \leq 19.8$. This
redshift range ensures that the $g$-band covers the C IV emission line (and trough in BALs) while the $r$-band probes continuum variability, and allows black hole mass (MBH) estimates via Mg II. We quantify variability using excess variance and damped random walk (DRW) parameters ($\sigma_{\mathrm{DRW}}$, $\tau_{\mathrm{DRW}}$). We also compared the DRW metrics in bins of MBH and Eddington ratio (REdd) to isolate the influence of the BAL phenomenon in objects with the same physical properties. Excess variance and $\sigma_{\mathrm{DRW}}$ are consistently smaller for BALs, confirming lower long-term variability, while the $g$-band exhibits higher variability than the $r$-band across both populations. These differences persist in fixed bins of MBH and REdd, indicating that the suppressed variability in BALs is not simply driven by differences in these properties between BAL and non-BAL samples. These results show that BAL
quasars are systematically less variable than non-BAL
quasars in both bands, confirming that this suppression is an intrinsic feature of the continuum rather than an effect of emission or absorption line contamination. The samples could be made to agree if BAL MBH values were systematically overestimated by a factor $\gtrsim 4$, implying a significantly higher REdd. Alternatively, the lower variability in BALs can be related to their lower X-ray luminosities, or to significant
nuclear obscuration, if the inner part of the
accretion disc were more obscured in BALs and more variable than the rest of the disc.
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All authors A. Aliaga, P. Arévalo, M.L. Martínez-Aldama, W. Zuo, B. Muñoz-Bravo
Cosmology and Nongalactic Astrophysics
CosmoPyro: Gradients for Gravitational-Wave Cosmology
Konstantin Leyde and Elena Colangeli
Gravitational-wave (GW) observations of
stellar-mass compact binary coalescences directly measure the source luminosity distance. Combined with the source
redshift, these measurements constrain the current expansion rate of the Universe, the Hubble constant, $H_0$, or $h=H_0 / [100 \,{\rm km \,s^{-1} \, Mpc^{-1}}]$. For most GW signals no electromagnetic
redshift measurement is expected, but the GW signal itself depends on the redshifted (detector-frame) masses. Assuming a source-frame mass distribution therefore enables a
redshift estimate for each source. Combining the
redshift estimates with the distance measurements provides a weak constraint on $H_0$ for each individual source that tightens with the number of sources in the catalog. However, the shape of the source-frame mass distribution is not known a priori, and previous work has relied on parametric models (piecewise power-laws with Gaussian components), and one-dimensional Gaussian processes. Here, we introduce CosmoPyro, a fully differentiable hierarchical
Bayesian inference code that models the mass distribution using either one- or two-dimensional Gaussian processes. With the latest GW transient catalog (GWTC-5) we find $h = 0.66^{+0.17}_{-0.20}$ and $h = 0.57^{+0.20}_{-0.15}$ (median with $1\sigma$ uncertainty), for the one- and two-dimensional case, respectively. Despite the noticeably different inferred mass distributions, both models yield $H_0$ values consistent with the latest LVK measurements within $1 \sigma$. While our main results marginalize over the Gaussian-process power-spectrum hyperparameters, the measurement is also robust against fixing these hyperparameters over a range comparable to their measured uncertainty.
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Instrumentation and Methods for Astrophysics
The VLA and High-Frequency SETI: Expanding the Search for Life
Talon Myburgh, Noah Stiegler, Chenoa D. Tremblay et al. (+2 more)
The Commensal Open-Source Multimode Interferometer Cluster (
COSMIC) runs software that searches for technologies elsewhere in the Universe ("technosignatures") using the Karl G. Jansky Very Large Array (VLA). Specifically, it searches for narrowband signals that drift in frequency over time as a result of Doppler motions. Although this is the first study of high-frequency technosignatures that has been published from the
COSMIC system on the VLA, it follows closely on previous work completed by an undergraduate research intern. Within the field of view of the VLA, the software on
COSMIC creates coherent beams directed toward
stars that may contain
exoplanets from the
Gaia catalogue. The recorded results follow a real-time software pipeline and are examined for technosignatures. Using a Taylor-Tree De-Dispersion
algorithm to find narrow-band drifting signals, each recorded beam (coherent and incoherent) is searched for signals with a drift-rate with magnitudes up to $\pm$50Hz/s. All detections are stored as "hits" with the relevant snippet of data stored for posterity. The purpose of this work is to extend the high-frequency search by reviewing data from February 2024 to the present. Our study examines the impact of previously implemented and novel filters to find a selection of candidate signals. At the final stage of the pipeline, our objective is to study these resultant candidate signals spatially through imaging. The observations therefore probe regions of frequency and signal parameter space that have received comparatively limited coverage in previous SETI surveys.
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All authors Talon Myburgh, Noah Stiegler, Chenoa D. Tremblay, Joe S. Bright, Ross A. Donnachie
Solar and Stellar Astrophysics
Asteroseismic analysis of red giants in eclipsing binaries using two methods: implications for scaling relations and chemical composition
M. Y{\i}ld{\i}z, S. Örtel and T. Çak{\i}r Alsaç
The study of
solar-like oscillating red
giants in eclipsing binaries (EBs) provides a unique opportunity to advance
stellar astrophysics by combining dynamical mass and radius measurements with asteroseismic constraints. EBs provide precise fundamental parameters (e.g. mass, radius, and luminosity) independent of distance, while
solar-like oscillations probe
stellar interiors and enable tests of asteroseismic scaling relations used to determine
stellar masses and radii. {We apply two different methods to estimate the initial chemical composition of the systems. In Method I, the initial helium abundance ($Y_0$) is treated as the free parameter, whereas in Method II the free parameter is the initial
metallicity ($Z_0$), assuming a relation between $Y_0$ and $Z_0$. We construct interior models individually for the components of 11 EBs and obtain coeval solutions for eight systems.} The ages and chemical compositions derived from the two methods are generally consistent with each other. Our results provide important clues about the chemical
evolution of a part of the
Galactic disk. Moreover, using the parameters obtained for two oscillating
stars, Tek Ayak (KIC 8410637) and KIC 9970396, instead of
solar reference values in the scaling relations yields masses and radii that are in much better agreement with the dynamical solutions without requiring additional corrections.
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Astrophysics of Galaxies
Accretion of AGN Stars under Influence of Disk Geometry II: The Adiabatic Regime and Runaway Collapse Induced by Self-gravity
Yi-Xian Chen, Yan-Fei Jiang and Jeremy Goodman
Accretion onto massive
stars embedded in Active
Galactic Nuclei (AGN) disks around supermassive black holes (SMBHs) is regulated to the
stellar Eddington rate in the fast-
diffusion or radiatively-efficient limit, $c/\tau > c_s$, where $\tau$ is the optical depth of the
accretion flow and $c_s$ the sound speed. However, when the ambient density is sufficiently high, the opposite slow-
diffusion limit applies. In this regime,
accretion proceeds quasi-adiabatically and forms a hydrostatic circumstellar envelope (CSE) that stalls further mass inflow in the absence of self-
gravity. We perform 3D hydrodynamic simulations in the adiabatic limit to investigate the structure and
evolution of such envelopes. For low thermal mass ratios, $q_{\rm th} \equiv M_\star/M_{\rm th}$ where $M_{\rm th}=c_s^3/(G\Omega)$ is the thermal mass, the CSE boundary smoothly matches the ambient disk
entropy and density without forming a shock. In contrast, when $q_{\rm th} \gg 1$, a strong shock develops at the envelope boundary, substantially increasing the
entropy of the envelope and thereby regulating its structure and mass, $M_{\rm env}$. In marginally self-gravitating disks with Toomre parameter $Q \sim 1$, we find that at sufficiently large $q_{\rm th}$ the envelope mass satisfies $M_{\rm env}/M_\star \gtrsim 1$. This condition is equivalent to stating that the post-shock material entering the envelope possesses lower radiation
entropy than the characteristic
stellar value, which triggers dynamical runaway growth on a dynamical timescale once envelope self-
gravity is included in our simulations. In realistic AGN disk environments with SMBH mass $\sim 10^8M_\odot$, runaway may occur close to the minimum self-gravitating radii and produce supermassive
stars of $\sim 10^5M_\odot$.
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Cosmology and Nongalactic Astrophysics
Testing MOND-like modifications to gravity using growth-rate measurements and one-loop corrections to the matter power spectrum
Gabriel Hartmann, Emanuelly Silva and Rafael C. Nunes
We develop a perturbative framework for structure formation in a broad class of MOND-like theories characterized by a generalized nonlinear Poisson equation. We derive the modified
evolution equations governing matter perturbations and obtain the corresponding linear growth equation, extending the analysis into the mildly nonlinear regime through one-loop corrections to the matter power spectrum. Beyond the theoretical framework, we perform a cosmological analysis based on two phenomenological scenarios: one parametrized by a quantity controlling the degree of nonlinearity in the generalized Poisson equation, and another describing the interplay between the MOND acceleration scale and the cosmological acceleration associated with the background expansion. We constrain these scenarios using recent measurements of the growth rate of structure, $f\sigma_8$, DESI-DR2
baryon acoustic oscillation data, and Type Ia
supernova compilations. We find no statistically significant evidence for departures from the standard $\Lambda$CDM cosmology. The inferred constraints are fully consistent with the GR + $\Lambda$CDM scenario within the current observational uncertainties. At nonlinear scales, we note that MOND-like modifications can alter $P_{\rm NL}(k)$ and leave signatures that current and future high-precision large-scale-structure observations may probe. Our results establish a systematic connection between MOND-like gravitational dynamics and large-scale structure observations, providing a consistent framework to assess the phenomenological viability of MOND-inspired modifications of
gravity in a cosmological context.
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Cosmology and Nongalactic Astrophysics
Mapping the Information Geometry of an Unresolved Dark Matter Population using a Differentiable Strong Lensing Simulator
Alexandre Adam
Strong gravitational
lensing is a unique probe of the matter power spectrum on small scales, where the abundance of dark matter subhalos in
galaxies could be used to distinguish the predictions of the concordance cold dark matter model from alternatives such as warm dark matter. Extracting this signal poses major computational challenges, since perturbations of the
lensing potential induced by substructure can be degenerate with both the macro-model of the lens and highly flexible models of the background source. Here, we introduce a framework to quantify these degeneracies using a differentiable strong-
lensing simulator. Substructure is represented in a spectral basis confined to an annular domain surrounding the lensed image, allowing signals from a population of NFW subhalos to be encoded in a finite vector space. We then use the Fisher
matrix to determine how much information about substructure is absorbed by nuisance components of the model. We find that macro-model degeneracies are largely confined to low-order perturbations of the
lensing potential, while degeneracies with the source model can strongly suppress sensitivity across a broad range of scales as the expressivity of the source model is increased. Finally, we introduce the Fisher Graph
Laplacian prior as a diagnostic tool to study how the internal degeneracies of the source model can be used to regulate the sensitivity of the data to an unresolved population of dark matter subhalos.
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Astrophysics of Galaxies
Automated Assignment and Prediction of Molecules in Astronomical Line Surveys Using Machine-Learning-Based Chemical Embeddings
Zachary T. P. Fried, Ryan A. Loomis, Jes K. Jørgensen et al. (+6 more)
Modern
radio telescopes generate vast amounts of observational data, offering valuable insights into the molecular composition of interstellar sources. Identifying the molecules within these
datasets typically involves time-consuming and labor-intensive manual analysis. This paper presents an automated method for assigning molecules in interstellar line surveys. The
algorithm operates in two main stages. First, it automatically determines key parameters of the data, including excitation temperature, line width, and source velocity. Next, it assigns the observed spectral peaks by evaluating the spectroscopic match of the molecular candidates along with analyzing their chemical relevance to the interstellar source. The chemical relevance is determined by leveraging machine-learning-based molecular
embedding techniques to analyze the regions of chemical space occupied by the observed species. Following the line assignment, this information is then used to generate new molecular candidates that occupy the same regions of chemical space. These newly generated species serve as promising targets for further investigation in the observational data. The
algorithm was validated on spectral line surveys of the dark molecular cloud TMC-1 and the
star-forming region IRAS 16293-2422B. In both cases, it identified at least 67 molecular species, accounting for over 90 percent of the analyzed line intensity, in 17 minutes or less while maintaining a high level of accuracy.
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All authors Zachary T. P. Fried, Ryan A. Loomis, Jes K. Jørgensen, Andrew Lipnicky, Ci Xue, Gabi Wenzel, Thomas H. Speak, Michael C. McCarthy, Brett A. McGuire
Instrumentation and Methods for Astrophysics
Radiation damage to the Hubble Space Telescope has been several years out of phase with the Solar cycle
Gavin Leroy, Juan Paolo Lorenzo Gerardo Barrios, Maximilian von Wietersheim-Kramsta et al. (+8 more)
As well as obtaining beautiful images of the Universe, the Hubble Space
Telescope's CCD detectors are sensitive radiation dosimeters that have been monitored in Low Earth Orbit for more than 24 years. The rate of radiation damage they received has varied over each
Solar cycle, but several years out of phase with the appearance of sunspots or coronal mass ejections. We investigate functional forms that successfully fit the time series of damage to
telescopes elsewhere in the
Solar system. We obtain remarkably accurate fits to Hubble data but with physically absurd parameter values. During image post-processing, such fits can be used empirically, to correct more than 99.5% of the radiation damage's effect on image quality. However, fits to the time series with physically reasonable parameters produce worse performance. Our results highlight the diversity of radiation environments in different parts of our
Solar system, and the complexity of Low Earth Orbit in particular. Our results also motivate continued monitoring of radiation damage to currently operational spacecraft, to more reliably predict the rate of degradation in (and useful lifespan of) future missions.
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All authors Gavin Leroy, Juan Paolo Lorenzo Gerardo Barrios, Maximilian von Wietersheim-Kramsta, Richard Massey, Richard G. Hayes, Jacob A. Kegerreis, David Lagattuta, Zane D. Lentz, James W. Nightingale, Jesper Skottfelt, Felix Vecchi
Astrophysics of Galaxies
Quasar Impostors: Two Extremely UV-Bright ($M_{\rm UV}\approx-23.5$) Reionisation-Epoch Galaxies Powered by Very Massive Stars
Daming Yang, Joseph F. Hennawi, Sarah E. I. Bosman et al. (+20 more)
The extreme bright end of the
galaxy UV luminosity function during reionisation remains poorly constrained, particularly where the
galaxy and
quasar luminosity functions overlap and source classification becomes ambiguous. We present JWST/NIRSpec and ALMA Band-6 observations of J1450-0144 ($z=6.627$) and J1429-0104 ($z=6.796$), two $M_{\rm UV}\simeq-23.5$ sources originally classified as faint
quasars by SHELLQs. NIRSpec reveals blue UV continua, strong P Cygni profiles in N V, Si IV, and C IV, broad He II $\lambda1640$ emission with rest-frame equivalent widths of $8.8\pm1.2$ and $3.7\pm1.1$ Å, respectively, and narrow nebular lines, reclassifying both as extremely UV-luminous
galaxies. Standard population-synthesis models cannot simultaneously reproduce the strong He II and wind features, whereas models incorporating very massive
stars (VMS; $M\gtrsim100\,M_\odot$) with dedicated wind prescriptions can. These models favor a
star-formation duration of 2-4 Myr for J1450-0144, with a broader allowed range for J1429-0104,
stellar masses of $\log(M_\star/M_\odot)\approx9.2$-$9.9$, and
star-formation rates of $\simeq300$-$540\,M_\odot\,{\rm yr}^{-1}$. Under the same VMS wind models, equivalent-width diagnostics imply $M_{\rm up}\gtrsim225\,M_\odot$ for J1429-0104, while J1450-0144 lies beyond even the $M_{\rm up}=475\,M_\odot$ grid. ALMA detects luminous [C II] 158 $\mu$m emission in both systems, with $L_{\rm [CII]}\approx0.8$ and $4.1\times10^{9}\,L_\odot$, respectively. J1429-0104 additionally shows bright
dust continuum, with both [C II] and
dust offset by $\sim5.4$ kpc from its UV emission. These sources demonstrate that VMS can power some of the most UV-luminous
galaxies at
cosmic dawn and show that source classifications, and hence the inferred demographics of both
galaxies and
quasars in the crossover regime, need revisiting.
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All authors Daming Yang, Joseph F. Hennawi, Sarah E. I. Bosman, Frederick B. Davies, Rychard Bouwens, Timo Kist, Eduardo Bañados, Jiamu Huang, Alice E. Shapley, Marianne Vestergaard, Hiddo S. B. Algera, Silvia Belladitta, Anna-Christina Eilers, Xiaohui Fan, Francesco Guarneri, Xiangyu Jin, Romain A. Meyer, Elia Pizzati, Huub Röttgering, Jan-Torge Schindler, Mauro Stefanon, Feige Wang, Jinyi Yang
Astrophysics of Galaxies
Recurrent Multi-year Mg II BAL Variability in SDSS J1333+0012
M. Vivek, P. Aromal, R. Srianand et al. (+3 more)
We present a long-term spectroscopic study of Broad Absorption Line (BAL) variability in the
quasar J1333+0012 (\zem = 0.9197) using an extensive multi-epoch
dataset spanning nearly two decades. The
dataset comprises multi-epoch observations from multiple observatories, delivering nearly uniform temporal coverage of the Mg II BAL profile, with close to one spectroscopic observation per year spanning the period from 2008 to 2025. We identify recurrent multi-year variability in the BAL absorption strength, characterized by a rest-frame timescale of $\sim$4 yr. Because the well-sampled baseline covers only a small number of candidate cycles, we present J1333+0012 as a candidate quasi-periodic BAL system. In contrast, contemporaneous optical photometric light curves from CRTS, Pan-STARRS, ZTF, and PTF show no statistically significant correlated variability on comparable timescales. However, ionization-driven variability cannot be ruled out, as the observed optical continuum does not directly trace the unobserved extreme-UV ionizing continuum. The coherence of the variability across distinct velocity components, coupled with the absence of large-scale profile reshaping, is consistent with a
geometric origin. We interpret the observed behavior as modulation of the line-of-sight absorption by the rotation of an inhomogeneous shielding-gas structure.
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All authors M. Vivek, P. Aromal, R. Srianand, K.A. Anjali, S. C. Gallagher, Rachana
High Energy Astrophysical Phenomena
A deep learning algorithm for black hole spin estimation using hot-spot secondary images
Aristomenis I. Yfantis and Rami Al-Belmpeisi
Sagittarius A* exhibits frequent flaring activity across the electromagnetic spectrum that is often associated with a localized region of strong emission known as a hot spot. We aim to train a deep learning model to provide a link between key parameters of this phenomenon - hot-spot emission radius, and black hole inclination and
spin - to the observed angle difference between the primary and secondary image ($\Delta PA$) that present and future interferometric arrays could resolve. Using the general relativistic radiative transfer code IPOLE, we generated a library of $\sim100.000$ models with varying system parameters and computed the position angle difference on the image plane between the primary and secondary images of the hot spot. We explore equatorial and non-equatorial circular orbits and evaluate our models against approximate observational constraints, including partial-orbit visibility and observational errors. Our
algorithm STIHOS shows remarkable accuracy in calculating
spin and inclination from the majority of the observational tests we perform ($\sigma_{a_*}=0.04,\,\sigma_i=2^{\circ}$), even in extreme conditions where only half of the orbit is visible. The off-equatorial estimation provides softer constraints in the absence of prior information. Our results demonstrate the importance of hot-spot observations for spacetime estimations. Given the increasing efforts to detect the
photon-ring, our framework could prove valuable in interpreting the first observations of lensed emission.
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High Energy Astrophysical Phenomena
The fraction of periodic SN Ib/c light curves
Asaf Horowicz, Eran O. Ofek and Avishay Gal-Yam
Periodic luminosity modulations have been recently identified for the stripped-envelope
supernovae SN 2022jli and SN 2022esa, motivating a systematic search for a similar behavior in a larger sample. Such modulations may indicate the explosions arise in binary progenitor systems. We perform the first systematic search for periodic modulation in a sample of 34 Type Ib/c
supernovae with high quality photometry from the Zwicky Transient Facility. We develop and apply a statistically rigorous pipeline for detecting periodic modulation in light curves. The pipeline successfully recovers the previously reported periodic undulations of SN 2022jli and SN 2022esa, and identifies SN 2020sgf as an additional promising periodic candidate. Injection-recovery simulations are used to quantify the survey sensitivity as a function of period and modulation amplitude. Comparing the observed detections with recent population synthesis models shows that, under the adopted assumptions, models predicting intrinsic periodic fractions of order ~20% are consistent with the observations. Our results suggest that periodically modulated SN 2022jli-like events may represent a significant sub-population of stripped-envelope
supernovae rather than being exceptionally rare events, while demonstrating a methodology suitable for future wide-field transient surveys.
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Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
Towards Quantum-Dot Detectors as Barcodes for Dark Matter Interactions
Marek Matas, Andrea Gallo Rosso, Antonio Cammarata et al. (+6 more)
Quantum dots are tunable
semiconductor nanocrystals that can be produced at industrial scales. We present the first ab initio calculation of the scattering of dark matter on electrons bound in
quantum dots. The momentum-dependence of a
quantum dot's electronic response depends on its morphology and on the dark matter mass, interaction operator, mediator coupling, and mediator mass. Therefore, the relative rates across an array of distinct
quantum dot targets form a “barcode” that carries information about the nature of the dark matter interaction. We project the sensitivity of a detector concept in which a collection of independent target subunits, each loaded with silicon
quantum dots of a particular morphology, are read out by Skipper CCDs. Given a future signal, this barcode could discriminate between interaction operators and mediator types. We quantify the discrimination power for a
benchmark pair of models as a function of readout noise and exposure.
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All authors Marek Matas, Andrea Gallo Rosso, Antonio Cammarata, Nora Hoch, Carlos Blanco, Jan Conrad, Rouven Essig, Tim Linden, Lindley Winslow
High Energy Astrophysical Phenomena
The impact of recombination during tidal disruption events
Simona Pacuraru, Clément Bonnerot and Martin E. Pessah
During a
tidal disruption event, the resulting debris stream cools down adiabatically due to the
tidal stretching. As the temperature drops, the gas is expected to undergo chemical processes, which can release thermal energy into the stream, potentially affecting the subsequent gas
evolution. For the first time, we investigate in detail this effect and its dynamical impact on the early-time
evolution of the stream by making use of three dimensional hydrodynamic simulations coupled with a realistic equation of state. We find that a few days after disruption, the energy injected by hydrogen recombination and molecular hydrogen formation causes the stream thickness to grow much more rapidly. In the bound debris, this effect stops the stream's confinement by self-
gravity before the gas reaches apocentre. As a result, the maximum stream thickness increases by a factor that ranges from a few, for the most bound gas, to a few tens for the near-
parabolic gas, reaching $\approx 30 \, R_{\star} $ around the peak of the mass fallback rate. We discuss how this accelerated stream expansion may affect the subsequent
evolution of the gas, estimate the luminosity powered by recombination in the unbound debris, and evaluate the potential influence of non-ideal magneto-hydrodynamic effects. By characterizing the thermodynamic and hydrodynamic properties of the stream before its return near pericentre, our results provide physically motivated initial conditions to self-consistently model the later stages of
tidal disruption events, offering a promising pathway to unveiling the physical origins of their observed emission.
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High Energy Astrophysical Phenomena
Heating Up the Black Hole X-ray Binary Accretion Disk by Superradiance
Antonios Kyriazis, Fengwei Yang and Siyu Zhou
A superradiant cloud of ultralight
axions around a black hole, that is part of an X-ray binary system, can heat up its
accretion disk and be detected by the thermal X-ray spectrum emitted by the disk. We consider a derivative coupling of the
axions to the
plasma fermions and calculate the emissivity of the inverse bremsstrahlung process that results in a temperature fluctuation of the disk. Based on the thin-disk model and the multicolor disk model, we derive the thermal spectrum with
axion heating, which shows an enhanced thermal
photon flux and a red-/blue- shifted peak spectral frequency. A single bump hunting search of the
axion heating signature in the thermal spectrum of a $10M_\odot$ black hole X-ray binary with a spectral measurement sensitivity of 10% (1%) can derive the constraint on
axion-electron coupling $|g_{ae}|\gtrsim7.5\times 10^{-12} ~(2.4 \times 10^{-12})$ for
axion mass $m_a=5.2\times 10^{-12}\,$eV in a saturated $|211\rangle$ state, and $|g_{ae}|\gtrsim4.5\times 10^{-12} ~(1.4 \times 10^{-12})$ for
axion mass $m_a=1.0\times10^{-11}\,$eV in a saturated $|322\rangle$ state. The projected sensitivities are competitive with those from XENONnT. A detailed continuum fitting can further improve the detectability and provide a complementary bound to the black hole
spin-down measurement.
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High Energy Astrophysical Phenomena
The Mass Function of Neutron Stars from Core-Collapse Supernova Simulations
Waly M Z Karim, Adam Burrows, David Vartanyan et al. (+2 more)
Using the mapping between progenitor core structure and the gravitational mass of
neutron stars derived from sophisticated 3D
supernova simulations, we determine the theoretical mass distribution of
neutron stars at birth and compare it with
neutron star mass function measurements. In the process, we explore the effects of islands of black hole formation and subsequent mass
accretion. We show that
supernova theory can explain the observed
neutron star mass function from its lower-mass peak near $\sim$1.35 $M_{\odot}$ to its higher-mass tail. Moreover, the lower predicted kick speeds expected during the birth of lower-mass
neutron stars and the higher expected kick speeds expected on average for higher mass
neutron stars both sculpt the observed mass function in desired directions. The upshot of all these influences is to imprint upon the measured
neutron star mass function features that reflect the varied physics of both
neutron star origins and the
neutron-
star/black-hole dichotomy. Very approximately, we derive a black hole birth fraction of $\sim$21%. In summary, we suggest that
supernova theory can now be used to explain, however provisionally, various measured attributes of the population of compact objects and that an era of productive engagement between
supernova theory and observation is at hand.
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All authors Waly M Z Karim, Adam Burrows, David Vartanyan, Anthony Fisher, James Burry
High Energy Astrophysical Phenomena
Supernova remnant 0509-67.5 is consistent with an explosion inside an old planetary nebula (SNIP)
Noam Soker
I critically examine claims in the paper arXiv:2608.11978 that the double-detonation (DDet) scenario explains the type Ia
supernova (SN Ia) remnant (SNR Ia) SNR 0509-67.5, and find the arguments supporting the DDet scenario weak; hence, I reiterate my claim that the core-degenerate (CD) scenario, where a lonely white
dwarf (WD), which is the merger product of a lower-mass WD and the core of an asymptotic
giant branch
star, exploded inside an old planetary nebula, i.e., an SNIP, best explains SNR 0509-67.5. I find that the flat edge of the SNR in the north-northeast, which in the DDet scenario is due to a shadow by the companion to the WD that exploded, is not unique in this SNR, and that the circumstellar matter, i.e., an old planetary nebula, shaped this edge, as well as other structures on the edge of this SNR. I emphasize that analyses of SNRs Ia and SNe Ia at late stages must consider the claim that most normal SNe Ia are SNIPs, implying that old planetary nebulae can heavily shape their morphologies. The bulk velocity inferred from an iron emission line in SNR 0509-67.5, which the DDet explosion attributes to the orbital motion of the exploding WD around its companion, can be an outcome of the explosion of a near-Chandrasekhar lonely WD; an off-center delayed-detonation transition explosion can form asymmetrical nucleosynthesis, while leading to a bulk motion of nickel that decays to iron. I repeat my claim that the CD scenario of a SNIP is the most likely scenario for SNR 0509-67.5.
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Instrumentation and Methods for Astrophysics · Cross-listed from cs.LG
Safe Domain Adaptation for Physics: Overcoming Nuisances, Label Shifts, and Simulation Priors
Ivan Kharuk
Domain adaptation is widely used to make neural networks trained on simulations applicable to experimental data. Its premise is that the two domains differ only in nuisances, and that the quantity of interest is distributed identically in both. In physics neither assumption holds: simulations can be wrong about the physics, and the distribution of the target quantity - an energy spectrum, a
redshift distribution - is often the measurement itself. We study the consequences of such mismatches on a toy air-shower
benchmark in which a detector-response nuisance, a physical simulation shift, and an energy-spectrum shift can be switched on separately or together. Standard
adversarial adaptation handles the conditional shifts, but once the two spectra differ it aligns them, replacing an uncontrolled bias by one anchored on the simulation prior. We present adaptive domain adaptation, which reweights the simulated events so as to focus domain adaptation on the genuine physical mismatch alone. Since the predicted spectrum depends on model training configuration, we provide a label-free model selection rule for selecting the near-the-best operation point.
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Instrumentation and Methods for Astrophysics
Variable Star Polarimetry with PICSARR-2
Daniel V. Cotton, Jeremy Bailey, Logan Barrett et al. (+3 more)
We describe the upgraded Polarimeter using Imaging CMOS Sensor and Rotating Retarder 2 (PICSARR-2), describe its applications, and characterize its performance for
stellar polarimetry on a 36-inch and 14-inch
telescope. On the larger
telescope in the SDSS $g^\prime$, $r^\prime$ and $i^\prime$ filters a precision of $\sigma_p=$ 5.7 ppm on bright
stars is recorded using a fast modulation rate corresponding to frame exposures of 12 ms; accounting for the internal errors in the individual observations gives a limiting precision of $e_p=$ 1.3 ppm. Longer frame rates are required for
stars with $m > 5$, but the recorded errors only underperform a
photon shot noise derived extrapolation for $m > 8$, when even longer frame exposures are required.
Stars as faint as $m = 11$ were observed. The position angle precision is measured as 0.0845 degrees, and there is very good agreement between observations made by both the PICSARR-2 and HIPPI-2 polarimeters. On the smaller
telescope the instrument's performance approaches similar levels, and there is good cross-platform stability in the observation of standard
stars. PICSARR-2 is therefore an excellent instrument to explore
stellar variability due to a range of phenomena; examples from our ongoing pulsating
star campaign and other variable
star programs are presented.
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All authors Daniel V. Cotton, Jeremy Bailey, Logan Barrett, Glenn Henderson, Kim Sumagang, Eric C. Haase
High Energy Astrophysical Phenomena
Generalized Non-linear Bayesian Pulsar Timing with Enterprise
Andrew R. Kaiser, Jeffrey S. Hazboun, Maura A. McLaughlin et al. (+56 more)
In this study, we use the
Bayesian methods in the Enterprise package to examine the fully general parameterization of
pulsar timing models in tandem with noise. We investigate four
pulsars, PSR J1600$-$3053, PSR J2043+1711, PSR J0740+6620, and PSR J1640+2224, through the lens of
Bayesian timing. These four are selected as they are well-studied, but exhibit interesting characteristics under the lens of
Bayesian timing. Our new
pulsar mass constraints (medians and 68% confidence intervals) for our fully general non-linear
Bayesian timing models are $m_{\mathrm{p}}=1.6(1)~\mathrm{M}_{\odot}$ for PSR J2043+1711 and $m_{\mathrm{p}}=2.3^{+0.9}_{-0.7}~\mathrm{M}_{\odot}$ for PSR J1600$-$3053 both using the NANOGrav 12.5-yr data release, and $m_{\mathrm{p}}=2.06(6)~\mathrm{M}_{\odot}$ for PSR J0740+6620 using the data from Fonseca, et al., 2021. We investigate the effects on placing physical priors on timing model parameters, including restricting the upper limit on the
pulsar mass for PSR J1640+2224, which has a mass often estimated to be greater than $3~\mathrm{M}_{\odot}$. We find \ark{that restricting the allowed sampling space of the
pulsar mass for PSR J1640+2224 to} $m_{\mathrm{p}}<3~\mathrm{M}_{\odot}$ results in a
pulsar mass of $m_{\mathrm{p}}=2.2(5)~\mathrm{M}_{\odot}$ for PSR J1640+2224 using the NANOGrav 12.5-yr data release. For the first time, we find evidence for intrinsic red noise in PSR J2043+1711. We show how fully general
Bayesian timing can better model the interplay of the intrinsic noise and the timing parameters.
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All authors Andrew R. Kaiser, Jeffrey S. Hazboun, Maura A. McLaughlin, H. Thankful Cromartie, Emmanuel Fonseca, Joseph Simon, Stephen R. Taylor, Michele Vallisneri, Sarah J. Vigeland, Zaven Arzoumanian, Paul T. Baker, Harsha Blumer, Paul R. Brook, Ismael Cognard, Megan E. DeCesar, Paul B. Demorest, Timothy Dolch, F. Adam Dong, Justin A. Ellis, Robert D. Ferdman, Elizabeth C. Ferrara, William Fiore, Nate Garver-Daniels, Peter A. Gentile, Deborah C. Good, Lucas Guillemot, Ross J. Jennings, Megan L. Jones, David L. Kaplan, Victoria M. Kaspi, Matthew Kerr, Aida Yu. Kirichenko, Michael T. Lam, Duncan R. Lorimer, Jing Luo, Ryan S. Lynch, Alexander McEwen, James W. McKee, Natasha McMann, Bradley W. Meyers, Arun Naidu, Cherry Ng, David J. Nice, Aditya Parthasarathy, Timothy T. Pennucci, Benetge B. P. Perera, Nihan S. Pol, Henri A. Radovan, Scott M. Ransom, Paul S. Ray, Brent J. Shapiro-Albert, Renée Spiewak, Ingrid H. Stairs, Kevin Stovall, Joseph K. Swiggum, Chia Min Tan, Shriharsh P. Tendulkar, Haley M. Wahl, WeiWei Zhu