High Energy Astrophysical Phenomena · Cross-listed from gr-qc
Normalizing Flow Emulator for Gravitational Wave Detection Probability in the LIGO/Virgo/KAGRA O4 Observing Run
Julius Gassert, Ignacio Magaña Hernandez, Ariel J. Amsellem et al. (+2 more)
Efficient and accurate estimation of the detection probability of a gravitational wave event given its source parameters remains a challenging problem because it conventionally requires expensive Monte Carlo injection campaigns. We present a machine learning-based approach using Normalizing Flows (NFs) to estimate the detection probability of gravitational wave events for a LIGO/Virgo/KAGRA O4-like detector network configuration. We utilize the publicly available injection
dataset as training and test data. We test our method and implementation by evaluating the raw NF performance as a generative model based on its ability to recover the correct parameter distributions of detected events. In addition, we compare the detection efficiencies predicted by the NF emulator with those from Monte Carlo importance sampling and find good agreement. Furthermore, estimating the detection efficiency for a wide variety of population models, including those with sharp features, can be more precise than estimates obtained via Monte Carlo importance sampling. We show that the NF emulator can be used in population analysis of gravitational wave sources, similar to previous neural network approaches. The training code and trained models from this work are publicly available.
Read the full abstract ▾
All authors Julius Gassert, Ignacio Magaña Hernandez, Ariel J. Amsellem, Antonella Palmese, Barnabas Póczos
Instrumentation and Methods for Astrophysics
Multi Kernel Gaussian Process Guiding: Predictive Correction for Mounts with Several Gear Stages
Rumen G. Bogdanovski
Gaussian process (GP) based predictive periodic error correction, introduced by Klenske et al., learns a
telescope mount's periodic tracking error online and applies the correction before the error is observed, removing the reaction lag inherent in purely reactive autoguiders. The published model uses a single periodic kernel and therefore represents the error of one gear stage: any repeating shape at one period, harmonics included, but only one period. Mounts with more than one reduction stage – strain-wave drives with a separate input stage, belt-and-worm combinations, transfer gears – produce errors at periods that are mutually incommensurate, which beat against each other and never repeat on a common cycle. We extend the model to a sum over an arbitrary number of quasi-periodic kernels, one per gear stage, each discovered from the residual spectrum, gated on the strength of its own spectral line, and refused if it is commensurate with a period already modelled. We show that a strictly periodic second kernel is unusable in practice because it demands the second period to within 0.2%, and that a squared-exponential envelope of about twenty periods removes that sensitivity at a cost of 0.02 px. On synthetic two-stage errors at realistic periods and amplitudes the extension reduces the residual by 1-40% against the single-kernel model, while leaving single-stage cases numerically unchanged. On a recorded, de-noised session with no second, incommensurate gear frequency, it still improves on the single-kernel model by 6% and on a reactive hysteresis controller by 45%, by absorbing amplitude modulation of the primary that the single kernel cannot. The implementation is dependency-free, multiplatform code in the C programming
language and is released as part of the INDIGO project.
Read the full abstract ▾
Instrumentation and Methods for Astrophysics
Diffusion Models for Polarimetric Reconstruction of Circumstellar Environments in Correlated Speckle Noise
Quentin Villegas, Laurence Denneulin, Simon Prunet et al. (+3 more)
High-contrast polarimetric imaging of circumstellar disks is severely limited by stellar leakage and speckle noise. Building upon the RHAPSODIE framework for polarimetric inverse problems,
diffusion-based methods have shown promising results by replacing classical regularization with learned priors. However, RHAPSODIE's white noise assumption fails to capture the spatial correlation structure of atmospheric and instrumental speckles. We extend this framework to handle speckle fluctuations, which are modeled as a Gaussian field with a stationary covariance
matrix with a Gaussian spectral density. To efficiently apply the dense precision
matrix that includes correlated speckle and heteroskedastic
photon noise, we develop a dedicated preconditioner for conjugate gradient iterations. The
diffusion prior is trained exclusively on disk-only data. While limitations remain at very low SNRs, our method significantly outperforms Tikhonov regularization and competes favorably with a Plug-and-Play baseline in realistic regimes, successfully recovering morphological features masked by correlated noise.
Read the full abstract ▾
All authors Quentin Villegas, Laurence Denneulin, Simon Prunet, André Ferrari, Éric Thiébaut, Maud Langlois
High Energy Astrophysical Phenomena · Cross-listed from math.NA
An Energy-Conserving Unstaggered Electromagnetic-Potential Particle-in-Cell Method, Part II: Fully Relativistic Formulation with an Adapted Higuera–Cary Pusher
Andrew Christlieb, Luis Chacon and Sining Gong
We develop a fully relativistic extension of the energy-conserving, unstaggered electromagnetic-potential particle-in-
cell method introduced in our earlier nonrelativistic work. As in the nonrelativistic generalized-momentum formulation, the fields are advanced by a Crank–Nicolson discretization of the Lorenz-gauge potential equations, the current is deposited from particle orbits, and charge is advanced through the discrete continuity equation. The new ingredient is a generalized-momentum adaptation of the Higuera–Cary relativistic particle pusher. The vector-potential force is decomposed into an orbit-discrete-gradient part, which enforces the same finite-difference chain rule used in our earlier nonrelativistic formulation, and a skew part, which generates a Higuera–Cary
magnetic rotation in mechanical momentum. For prescribed fields and frozen orbit data, this generalized-momentum Higuera–Cary map is a unit-Jacobian conjugacy of the mechanical Higuera–Cary map and preserves particle phase volume in $(\xx,\PP)$. For the fully coupled implicit step, the same orbit data define the current deposit, mesh-to-particle gather, vector-potential chain rule, and relativistic kinetic-energy secant velocity. The resulting particle work cancels the Crank–Nicolson field-energy balance, yielding exact relativistic total-energy conservation up to nonlinear solver tolerance, orbit-quadrature error, and roundoff. A self-adjoint
Fourier projection removes modes on even-grid Nyquist planes while preserving the particle–grid work identity. Numerical tests are organized around cold relativistic two-stream and Weibel/filamentation instabilities, with diagnostics for energy drift, Gauss's law, the Lorenz gauge, particle–grid work, and the orbit chain rule.
Read the full abstract ▾
Solar and Stellar Astrophysics
Properties of Circumfacular Regions derived from H$\alpha$ and Ca II K synoptic observations of the Sun
Serena Criscuoli and Andrea Diercke
Circumfacular regions are dark chromospheric structures surrounding
magnetic regions whose properties and contribution to solar activity diagnostics remain poorly understood. We investigate their photometric and
geometric properties using full-disk H$\alpha$ and Ca II K observations acquired by the Chromospheric
Telescope (ChroTel) from 2012 to 2020, spanning the maximum and declining phases of solar cycle 24 and the beginning of cycle 25. We develop an automated segmentation
algorithm to identify circumfacular regions and define a photometric index analogous to existing excess and deficit indices. We compare their temporal
evolution with those of plages, dark features, and filaments on solar-cycle and Carrington-rotation timescales. Circumfacular regions develop after the H$\alpha$ plage brightening become visible and persist into the decay phase of active regions. At activity maximum, they are the most extended chromospheric structures, covering more than half of the visible solar disk. Their mean intensity varies only weakly throughout the solar cycle; consequently, their index variability, as well as that of the other photometric indices, is driven primarily by changes in area coverage. H$\alpha$ and Ca II~K indices are strongly correlated, although their correlations weaken toward solar minimum. This activity-dependent relationship is primarily driven by the decline of the area of H$\alpha$ excess regions during periods of low activity, and the increasing relative contributions of deficit and circumfacular regions. Our results therefore suggest that circumfacular regions should be considered when interpreting disk-integrated chromospheric observations of the Sun and solar-type
stars.
Read the full abstract ▾
Cosmology and Nongalactic Astrophysics
Probing Baryons with the Kinematic Sunyae Zel'dovich Effect and Machine Learning Derived Peculiar Velocities using DESI DR2 and ACT DR6
Yulin Gong, Rachel Bean, Patricio A. Gallardo et al. (+54 more)
We present novel empirical constraints on average optical depths and gas density profiles from combining kinematic Sunyaev Zel'dovich effect (kSZ) measurements and nonlinear peculiar velocities, reconstructed using machine learning, for massive
halos traced by DESI DR2 luminous red
galaxies (LRG). The pairwise kSZ is measured using two ACT DR6
cosmic microwave background (CMB) temperature maps (ILC and 150 GHz maps) for seven luminosity-selected LRG samples. We find consistent results between the two maps and significant detections across the samples. We reconstruct LRG line-of-sight peculiar velocities in two
cosmic epochs, centered on $z=$ 0.55 and 0.8, using a simulation-trained
Transformer machine learning model to extend beyond the linear approximation. Average optical depths are inferred by comparing the kSZ pairwise correlation to the measured pairwise velocity correlation from the reconstructed velocity field and, separately, from a theoretical prediction using the best fit Planck cosmology, with the highest significance reaching SNR = 14.2 and 15.1 respectively. We also obtain velocity-weighted AP-filtered kSZ-stacked cluster density profiles, which show evidence of extended ionized gas around massive LRG groups and no strong
redshift evolution within current measurement uncertainties. These results demonstrate the power of combining spectroscopic
galaxy and CMB data, and employing machine learning methods, to probe diffuse baryons and coherent large-scale velocity fields. They open up new avenues to leverage upcoming
galaxy survey data from Euclid, Roman and Rubin LSST, in tandem with multi-frequency CMB/sub-mm data from CCAT and Simons Observatory.
Read the full abstract ▾
All authors Yulin Gong, Rachel Bean, Patricio A. Gallardo, Boryana Hadzhiyska, Yun-Hsin Hsu, Jenna Moore, Eve M. Vavagiakis, Nicholas Battaglia, J. Aguilar, S. Ahlen, A. Aviles, F. Beutler, D. Bianchi, D. Brooks, A. Carnero Rosell, T. Claybaugh, A. de la Macorra, Arjun Dey, Biprateep Dey, P. Doel, A. Font-Ribera, J. E. Forero-Romero, E. Gaztañaga, G. Gutierrez, K. Honscheid, S. Juneau, T. Karim, R. Kehoe, D. Kirkby, A. Kremin, O. Lahav, M. Landriau, L. Le Guillou, M. Manera, A. Meisner, R. Miquel, S. Nadathur, J. A. Newman, H. E. Noriega, E. Paillas, N. Palanque-Delabrouille, W. J. Percival, F. Prada, I. Pérez-Ràfols, C. Ravoux, G. Rossi, L. Samushia, E. Sanchez, C. Saulder, D. Schlegel, M. Schubnell, H. Seo, J. Silber, M. Siudek, G. Tarlé, B. A. Weaver, R. Zhou
High Energy Astrophysical Phenomena · Cross-listed from gr-qc
Computing gravitational radiation from highly eccentric bound binaries in the small-mass-ratio limit
Diego Andrés Rivera Orona and Scott A. Hughes
Precise strong-
gravity models describing the
evolution of bound compact binary systems provide important information about the gravitational radiation such binaries generate and how they evolve due to the radiation's backreaction. The limit of very high eccentricity, $e \to 1$, is challenging to model: frequency-domain techniques require many harmonics to accurately describe radiation in this limit, and time-domain techniques can be slow to converge due to the systems' long timescales. Many recent astrophysical analyses have nonetheless emphasized the importance of understanding gravitational-wave emission in this regime, highlighting the fact that many systems may evolve through $e \simeq 1$ en route to becoming detectable sources, and may enter the sensitive band of detectors with substantial eccentricity. In this paper, we show how to adapt frequency-domain methods for computing gravitational radiation in the small-mass-ratio limit to effectively handle high eccentricity. The key piece of this analysis is an integral over the source of the frequency-domain Teukolsky equation. We examine features of this integral that make it difficult to evaluate as $e \to 1$, and study methods to circumvent these difficulties. We find a simple fix which allows us to compute gravitational-wave amplitudes and the associated fluxes of energy and angular momentum with ease up to eccentricities $e = 0.99$; with patience (and stamina), we have pushed to $e = 0.999$, though numerical accuracy appears to degrade for such extreme cases. Interestingly, we find that the well-known and often used classic formulas of Peters and Mathews are subject to a systematic error which persists at quite wide separation. This has implications for models of compact binary formation which evolve through $e \simeq 1$.
Read the full abstract ▾
High Energy Astrophysical Phenomena
JWST/MIRI Spectroscopy of the Quiescent Black Hole X-ray Binary XTE J1118+480: Constraints on Jet and Circumbinary Dust Contributions to the Mid-infrared Emission
Zihao Zuo, Elena Gallo, Nuria Calvet et al. (+9 more)
We report on JWST/MIRI low-resolution spectroscopy ($5$-$12 \mu$m) and imaging ($15$-$25 \mu$m) of the black hole X-ray binary XTE~J1118+480 in quiescence, at an X-ray luminosity nine orders of magnitude sub-Eddington, together with contemporaneous optical monitoring and a
radio upper limit of $4.5~\mu$Jy at 6 GHz. With the donor subtracted, the $5$-$12 \mu$m continuum is curved, turning over near $6~\mu$m; a single power law is rejected in favor of a $764\pm 9$ K blackbody. Longward of the turnover the spectral index is $\alpha = +1.21\pm0.36$, steeper at the $2\sigma$ level than the flat to slightly inverted spectrum of a compact jet. Interpreted as synchrotron, the turnover implies equipartition fields of $\sim$$10^{4}$ G on scales of tens of gravitational radii, but the MIRI photometry at $15$-$21~\mu$m-taken $2.6$ hr before the spectrum-lies $30$-$90$ per cent above its extrapolation, suggesting a second self-absorbed zone. A single partially self-absorbed jet spectrum can reach the photometry only at the expense of the spectral
curvature and the $25.5~\mu$m upper limit, so a steady compact jet is disfavored, although not excluded. Representative self-consistent irradiated-disk models instead reproduce the principal features of the $5$-$25~\mu$m spectral energy distribution, with a directly illuminated dust wall at $\simeq 5$ binary separations, outside the tidal-truncation radius, and a minimum dust mass of order $10^{22}$ g. This is the first spectroscopic evidence, though not yet conclusive, favoring circumbinary dust over a jet in a quiescent black hole X-ray binary.
Read the full abstract ▾
All authors Zihao Zuo, Elena Gallo, Nuria Calvet, Richard M. Plotkin, David M. Russell, Gabriele Cugno, Rob Fender, Fraser Lewis, Joseph Michail, Jon M. Miller, James C. A. Miller-Jones, Fan Zou
High Energy Astrophysical Phenomena · Cross-listed from gr-qc
What Fraction of Extreme Mass Ratio Inspirals That Merge After the LISA Mission Ends Are Detectable?
Daniel J. Oliver, Aaron D. Johnson, Jonathan E. Thompson et al. (+1 more)
Stellar-mass compact objects spiraling into massive black holes in galactic
nuclei (referred to as "extreme-mass-ratio inspirals", or EMRIs) will be an important class of sources for the
Laser Interferometer Space
Antenna (LISA). A stellar-mass compact object can radiate in the millihertz band for years to decades before it plunges into its massive black hole, so a substantial fraction of the EMRIs that LISA can detect will still be inspiraling when the mission ends. We calculate what fraction of detectable EMRIs will plunge after the mission ends, and for those we calculate how they are distributed as a function of various parameters, such as their post-mission lifetime. To do this, we draw from astrophysically motivated populations, backward-integrate fully relativistic Kerr FastEMRIWaveforms trajectories for a given time to plunge, and compute the full LISA response over both the four-year nominal and ten-year extended observing windows. We calculate the detectable fraction as an explicit function of time to plunge at signal-to-noise ratio (SNR) thresholds of $\rho=10$, 20, and 30. We find that post-mission EMRIs are roughly one in four of the LISA-detectable population at $\rho>20$ over the four-year mission, and roughly one in six over the ten-year extended mission. The in-window detectable fraction varies by nearly a factor of six at $\rho>20$ across the massive black hole
spins and secondary masses we ran, while the share stays between 25% and 33% for the four-year mission and between 13% and 20% for the ten-year one across all of them. The search for EMRIs that plunge more than $\sim 1$ year after the mission ends may require a different
algorithm than the one used for EMRIs that plunge during the mission, and the fact that post-mission detections are a substantial fraction of all detections gives some urgency to developing a detection pipeline suitable for them.
Read the full abstract ▾
All authors Daniel J. Oliver, Aaron D. Johnson, Jonathan E. Thompson, Curt J. Cutler
Earth and Planetary Astrophysics
Whole-disk Photometric and Colorimetric Phase Curves of Earth with the Clementine Lunar Orbiter
Chase Cooper, Tyler D. Robinson, L.C. Mayorga et al. (+2 more)
The phase curve on a planetary object can reveal key details about its atmosphere and surface, including the presence of surface
liquid oceans. Phase curves for Earth can inform the search for habitable surface environments on terrestrial
exoplanets, but such phase curves are quite rare. The Clementine lunar orbiter made 3,744 observations of the Earth between February and May of 1994. These observations spanned phase angles between 3.4 and 139.1 degrees. From these data, we produce phase curves of Earth in 5 distinct bands with wavelengths between 400 nm and 1000 nm. We extrapolate fits to the phase curves to derive the
geometric albedo of Earth in each filter. We examine the Earth's color as a function of phase angle and find the observed values are best fitted by models that include contributions from ocean glint. We also find a number of observations where contributions from glint are minimal but the disk-integrated color is in line with the glinting model predictions; we propose that this can be explained by the presence of optically clouds on the disk. These findings stress the importance of high-phase Earth observations for high-fidelity Earth models and for future efforts to characterize terrestrial
exoplanets via direct imaging.
Read the full abstract ▾
All authors Chase Cooper, Tyler D. Robinson, L.C. Mayorga, Jason W. Barnes, Lily Robinthal
Astrophysics of Galaxies
How well do integral-of-motion distribution functions describe Milky Way-analogue halos?
Jason Kumar and Louis E. Strigari
We study the dark-matter phase space distribution of Milky Way-mass
halos in the Auriga simulations, considering both hydrodynamic and dark-matter-only runs. In a spherically averaged potential, we test whether the coarse-grained distribution function can be approximated as a function of the integrals of motion $E$ and $L$. We find that $f(E,L)$ provides a useful description of the simulated
halos: although the deviations from this form are formally statistically significant, the median fractional residuals between radial shells are typically $\lesssim 15\%$, with 90th-percentile residuals of order tens of percent. An energy-only approximation, $f(E)$, gives similar median residuals but is systematically disfavored by $\chi^2$ tests, indicating that angular momentum dependence is statistically preferred. Ultimately we find that neither $f(E)$ nor $f(E,L)$ fully describes the particle data at high precision. The remaining residuals likely reflect departures from spherical
equilibrium, including anisotropy, triaxiality, substructure, and baryonic effects.
Read the full abstract ▾
High Energy Astrophysical Phenomena
Assessing the detectability and identification of pulsar halos with H.E.S.S. and CTAO
Karim Sabri, Yves Gallant and Justine Devin
Pulsar halos are a class of extended gamma-ray sources, resulting from inverse Compton scattering of ambient
photons by electrons and positrons believed to have escaped confinement in a
pulsar wind nebula. First identified by HAWC towards PSR J0633+1746 and PSR B0656+14, a growing number of
pulsar-powered gamma-ray sources is proposed as candidate
halos. Using a model of isotropic
diffusion, we assessed the ability of current-and-future generation imaging atmospheric Cherenkov
telescopes to characterize the physical properties of such sources in the inner
Galaxy. We constructed template-based
pulsar halo models in the Gammapy library and fitted them to simulated H.E.S.S. and CTAO data of
halos with different physical parameters. The sources were characterized spectro-morphologically using 2D Gaussian components. We assessed the statistical preference between the
halo and 2D Gaussian hypotheses by the simulated data and quantified the impact of the diffuse Galactic emission. A multitude of the
halos' parameters can be constrained simultaneously, including the
pulsar's true age, its proper motion, the
diffusion coefficient, the index of the injected particle spectrum and the injection efficiency. In some cases, the H.E.S.S. array can statistically distinguish between the
halo model and a model containing 2D Gaussian components, while a significant improvement is seen with CTAO. The source's detection significance is drastically reduced with increasing intensity of the Galactic diffuse emission. If the latter is not modeled using the data-generating model, the
halo parameter estimation is biased. A physically-motivated model of
pulsar halos can facilitate the identification and characterization of this class of sources in high-level data analyses. The simulated
halos exhibit properties that may already be found in surveys of current-generation
telescopes with only a modest observation time.
Read the full abstract ▾
Earth and Planetary Astrophysics
Cool, Cloudy Nights on an Ultrahot Neptune: A Panchromatic NIRISS/NIRSpec Transmission Spectrum of LTT 9779 b
Sarah Stamer, Diana Dragomir, Annabella Meech et al. (+13 more)
Studies of
planets that reside in the hot Neptune desert allow us to gain insight into how their atmospheres survive the intense flux from their host
stars. One such member of that population, LTT 9779 b, is unique in that it has a confirmed atmosphere across various multi-wavelength studies, although results regarding the
planet's atmospheric content differ. We present a panchromatic ($\lambda = 0.63 - 5.165$ $\mu$m) JWST transmission spectrum of LTT 9779 b's atmosphere, including a re-reduction of previously obtained NIRISS/SOSS data and a reduction of recent NIRSpec/G395H data. Through atmospheric
retrievals, we find muted spectral features consistent with the presence of clouds and a low terminator temperature ($\sim560 \ \mathrm{K}$ for free chemistry, and $\sim910-950 \ \mathrm{K}$ for
equilibrium chemistry), with a range of possible atmospheric
metallicity values dependent on atmospheric temperature and cloud coverage. Forward modeling suggests that, if clouds are present, small sub-micron particle sizes, moderate-to-high sedimentation efficiency ($f_{\rm sed} = 1 - 3$, corresponding to a relatively compact vertical cloud extent), low particle column densities, and high eddy
diffusion coefficients ($k_{zz} \geq 10^{10}$ cm$^{2}$s$^{-1}$) are preferred. Probing silicate cloud absorption features in the mid-infrared is needed to confirm the cloud species, allowing us to break the cloud-
metallicity degeneracy that is present in this panchromatic transmission spectrum.
Read the full abstract ▾
All authors Sarah Stamer, Diana Dragomir, Annabella Meech, Joshua D. Lothringer, Reza Ashtari, Jonathan Brande, Vivien Parmentier, Ian J. M. Crossfield, Tansu Daylan, Suman Saha, K. Angelique Kahle, Kevin B. Stevenson, David R. Coria, Jared E.J. Splinter, Nicolas B. Cowan, Emma Esparza-Borges
Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
LMC-Perturbed LZ Dark Matter Landscape
Nassim Bozorgnia, Samantha Contreras, Graciela B. Gelmini et al. (+3 more)
The local dark matter (DM) velocity distribution is significantly altered by the gravitational impact of the Large Magellanic Cloud (LMC), which creates a high-velocity tail. We evaluate how the LMC reshapes the DM landscape for a wide variety of theoretical models in light of the recent putative LZ DM event. We show that the LMC-induced velocity shifts substantially modify the parameter space for inelastic endothermic DM models across a broad range of possible interactions, driving the viable regions towards larger mass splittings, which are more susceptible to
collider and indirect detection constraints. By contrast, models for elastically colliding DM are less impacted, and some remain viable candidates – for example, the simple light Singlet-Doublet Majorana DM candidate at the
Higgs blind spot. Our work confirms that accurately accounting for LMC effects is essential when high-velocity DM is probed, rather than relying on the simplified Standard
Halo Model.
Read the full abstract ▾
All authors Nassim Bozorgnia, Samantha Contreras, Graciela B. Gelmini, Alvine C. Kamaha, Javier Reynoso-Cordova, Yongheng Xu
High Energy Astrophysical Phenomena
What We Have Learned from NICER About Neutron Star Radii
M. C. Miller
The cores of
neutron stars have a combination of density, temperature, and
neutron-
proton asymmetry that cannot be replicated in laboratories or understood using first-principles
quantum chromodynamics. Thus, observations of
neutron stars are necessary to understand this regime. In particular, precise and accurate measurements of
neutron star radii are highly informative about cold, catalyzed matter at a few times nuclear saturation density. X-ray observations with NASA's
Neutron star Interior Composition Explorer (NICER) have yielded radius measurements for a few nonaccreting
neutron stars, which have advanced substantially our understanding of dense matter. In this review we discuss the NICER radius measurements and their implications and demonstrate that the systematic errors thus far explored in NICER analyses have at most a minor effect on the inferred radii of
neutron stars.
Read the full abstract ▾
Solar and Stellar Astrophysics
PHAROS: Panchromatic spectral energy distributions of solar-like stars across evolutionary stages
Viktor Sumida, Raissa Estrela, Eric Mamajek et al. (+2 more)
Panchromatic stellar spectral energy distributions (SEDs) provide the wavelength-dependent irradiation fields required for studies of
exoplanet atmospheres, photochemistry, atmospheric escape, and habitability. We present PHAROS, the Panchromatic Habitable-world Archive of Radiation from Observed Solar-like
stars, a first release of fifteen component-traceable SEDs for nearby FGK
stars spanning adopted ages of 0.26–6.5\,Gyr. The catalogue covers 0.5–5000\,nm and combines archival XMM-Newton and Chandra high-energy constraints, semiempirical extreme-ultraviolet (EUV) reconstructions, HST and IUE ultraviolet spectra, Gaia DR3 XP and ancillary optical spectrophotometry, and PHOENIX photospheric extensions. When X-ray data support spectral modelling, target-specific coronal
plasma models define the high-energy segment and anchor the EUV normalisation; otherwise, empirical high-energy templates are scaled to literature luminosity constraints. Each SED preserves segment-level provenance, distinguishing directly observed intervals from reconstructed components, empirical templates, bridges, and model-derived extensions. The largest diversity occurs at X-ray, EUV, and ultraviolet wavelengths. Younger age-context groups generally show stronger high-energy output relative to their photospheric continua, although the dispersion within each group shows that age alone does not uniquely determine the irradiation environment. PHAROS provides traceable panchromatic irradiation fields for studies of planetary atmospheres, photochemistry, atmospheric escape, forward modelling,
retrievals, and interpretation of future direct-imaging observations, including those anticipated for NASA's Habitable Worlds Observatory.
Read the full abstract ▾
All authors Viktor Sumida, Raissa Estrela, Eric Mamajek, Pin Chen, Adriana Valio
Astrophysics of Galaxies
MEGATRON: The Physical Origins of Steep UV Slopes at High Redshift
Harley Katz, Nicholas Choustikov, Aayush Saxena et al. (+7 more)
The ultraviolet (UV) spectral slope, $\beta$, serves as a fundamental probe of stellar population properties and interstellar medium conditions in
galaxies. At high
redshift, a small sample of
galaxies have been confirmed to have extremely blue spectral slopes of $\beta<-2.8$, as measured directly from spectroscopy. One explanation for such
galaxies is that they are leaking copious amounts of ionizing
photons such that these
photons are never processed into the nebular continuum and we are observing the bluer intrinsic slopes of the stellar populations. Here, we use a detailed set of radiation hydrodynamics simulations with parsec-scale resolution and non-
equilibrium chemistry to elucidate the physical origin of extremely blue UV slopes at high
redshift. We show that, while some extremely blue
galaxies (EBGs) do indeed have high escape fractions, a second population of EBGs has $f_{\rm esc}<1\%$. In this second population, the ISM gas densities tend to be much lower, and the timescale for ionization fronts to reach their Strömgren radii can be longer than the main-sequence lifetime of massive
stars, leading to a lag in nebular emission. Our results demonstrate that extremely blue UV slopes do not uniquely imply high escape fractions, which highlights the importance of time-dependent (non-
equilibrium) nebular emission for interpreting the spectra of
galaxies in the early Universe.
Read the full abstract ▾
All authors Harley Katz, Nicholas Choustikov, Aayush Saxena, Corentin Cadiou, Martin P. Rey, Jeremy Blaizot, Alex J. Cameron, Fergus Cullen, Taysun Kimm, Kosei Matsumoto
High Energy Astrophysical Phenomena
Fast Radio Bursts from Induced Upscattering. I. Magnetar Polar Fireballs
Rei Nishiura, Kunihito Ioka and Bing Zhang
The extreme brightness temperatures of fast
radio bursts (FRBs) demand a coherent process that converts magnetar burst energy into millisecond
radio emission. We propose that FRBs can be produced within magnetar magnetospheres by induced (stimulated) upscattering in a relativistic fireball outflow. In this paper, we focus on induced Compton upscattering in an electron–positron fireball launched from the polar region of a magnetar. Radiation from the X-ray burst accelerates the polar fireball outflow to Lorentz factors of $\Gamma\sim10$–$10^3$. Low-frequency seed waves, such as fast magnetosonic or Alfvén waves, entering the outflow from the side or against its motion undergo induced scattering and are Lorentz-boosted by the relativistic bulk motion from $\nu_0\sim10\mathrm{kHz}$ to $\nu_{\rm obs}\sim\Gamma^2\nu_0\sim\mathrm{GHz}$. Combining the polar fireball dynamics with the linear growth and nonlinear saturation of the induced scattering instability, we derive the FRB luminosity $L_{\rm FRB}^{\rm iso}$ and fractional spectral bandwidth $\Delta\nu/\nu_{\rm c}$. By considering the possible range of pair densities and temperatures, we find that this polar channel can account for the luminosity of Galactic FRB~20200428 and reach luminosities comparable to those of the brightest extragalactic FRBs. If the pair-loaded region is narrower than the relativistic beaming angle $1/\Gamma$, the model also produces a narrow spectrum and predicts $L_{\rm FRB}^{\rm iso}\propto(\Delta\nu/\nu_{\rm c})^2$, a trend consistent with observations of repeating FRBs. The induced upscattering model thus connects magnetar X-ray bursts to FRBs through a coherent emission process grounded in
plasma physics and makes observationally testable predictions.
Read the full abstract ▾
Earth and Planetary Astrophysics
Binary tidal evolution as a sculptor of circumbinary planet architectures
Mario Sucerquia, Nicolás Cuello and Gaspard Duchêne
Circumbinary
planets (CBPs) are expected to form in circumbinary discs and migrate towards the disc inner cavity, often near the binary stability boundary. Yet the observed population is not strictly marginally stable: excluding extreme systems, the typical offset is $\Delta \equiv a_{\rm p}/a_{\rm crit}=1.22^{+0.18}_{-0.07}$, suggesting post-formation
evolution may shape present-day architectures. We test whether secular
evolution of close binaries can contribute to this displacement. Using high-accuracy $N$-body simulations, we follow coplanar CBPs initially placed near $a_{\rm crit}$ while prescribing binary contraction and eccentricity damping along a track that approximately conserves orbital angular momentum. We quantify how the retreat of $a_{\rm crit}(t)$ affects planetary offsets and survival across binary mass ratios. The moving stability boundary filters the near-boundary population, adding a contraction-driven loss component dominated by ejections. Survivors remain quasi-fossilised, with median changes in $a_{\rm p}$ and $e_{\rm p}$ close to zero and semimajor-axis drifts of only a few per cent. For all valid synthetic survivors, the final offset has median $\Delta_f=1.86^{+0.18}{-0.26}$. Applying the same damping prescription to the observed sample shifts the median from $\Delta{\rm now}=1.22^{+0.18}{-0.07}$ to $\Delta{\rm damp}=1.44^{+0.32}_{-0.10}$. Near-equal-mass binaries undergo stronger filtering, with enhanced ejections and collisions. Binary tidal
evolution can therefore shape non-marginal circumbinary architectures. By removing
planets close to marginal stability while leaving survivors nearly fossilised, the retreat of $a_{\rm crit}$ can widen the inner gap and increase offsets from the present-day stability boundary. This links binary orbital
evolution, dynamical filtering, and transit detectability in a multi-channel interpretation of the CBP desert.
Read the full abstract ▾
Instrumentation and Methods for Astrophysics
Comparing Active Anomaly Detection Frameworks: From Light Curves to Images
Sreevarsha Sreejith and Robert C. Nichol
The increasing volume and complexity of data from modern astronomical surveys are making comprehensive visual inspection increasingly impractical, motivating automated methods for identifying rare and unusual objects. Active anomaly detection (A-AD) combines unsupervised anomaly detection with iterative user feedback, allowing searches to adapt to scientific interests while retaining sensitivity to unexpected objects. We systematically compare three A-AD frameworks, Astronomaly, Protege, and PineForest, across Zwicky Transient Facility light curves and Euclid
galaxy images. In baseline experiments, Protege, PineForest, and Astronomaly recovered 83, 78, and 38 variable
stars, respectively, within the first 100 light-curve objects inspected, while PineForest recovered 70 merging or morphologically disturbed
galaxies within the first 100 Euclid images, compared with 29 and 19 for Astronomaly and Protege. Experiments using prior labels show that their effectiveness depends on the composition of the prior sample and varies between A-AD methods. Finally, we combine the complementary behaviour of Protege and PineForest in a hybrid search of 10,000 Euclid images, recovering 799 morphologically unusual objects. These include 29 retained strong lens systems and candidates, of which 9 candidates have no counterparts in the published Euclid Q1 strong lens catalogues searched, and 202 visually classified ring
galaxies. These results highlight the importance of selecting A-AD strategies according to both the scientific objective and
dataset properties, and demonstrate their potential for efficient, discovery-driven exploration of forthcoming astronomical surveys.
Read the full abstract ▾
Cosmology and Nongalactic Astrophysics
Constraining reionization with persistent homology: a novel summary statistic for wide-field Lyman-$\alpha$ emitter observations
Michael M. Wyatt, Nikolaos Triantafyllou, Steven R. Furlanetto et al. (+4 more)
The spatial clustering of Lyman-$\alpha$ emitters (LAEs) is one of the most promising observables for constraining reionization. In this work, we introduce persistent homology, a popular tool in topological data analysis, and specifically the Betti-0 curve as a summary statistic to characterize the clustering of LAEs. We compare the performance of the Betti-0 curve against the angular correlation function (ACF) and void probability function (VPF) by quantifying their ability to constrain the global neutral fraction $x_{\rm HI}$ during reionization using the Fisher information. We forward model observations of LAEs using 21cmFAST by including $\mathrm{Ly}\alpha$ emission as a post-processing step and account for
cosmic variance uncertainties. We focus our analysis within the framework of the SILVERRUSH. catalog at $z=5.7$ and 6.6, and find that the Betti-0 curve performs as well as or better than the ACF and VPF. We also find that the statistics are most sensitive to different physical scales and thus probe complementary information, and as a consequence that simultaneously constraining all three statistics improves constraints by a factor of $\sim 2$ compared with the ACF alone, with predicted minimum uncertainties of $\sigma_{\rm min} \sim$ 0.03 and 0.07 at $x_{\rm HI} = 0.05$ and $z=5.7$ and $x_{\rm HI} = 0.20$ and $z=6.6$, respectively. Our results show that the Betti-0 curve is a promising summary statistic to constrain reionization using LAE clustering and motivate further exploration of persistent homology for the same purpose in other wide-field surveys such as those made possible by the Nancy Grace Roman
Telescope.
Read the full abstract ▾
All authors Michael M. Wyatt, Nikolaos Triantafyllou, Steven R. Furlanetto, Hiroya Umeda, Samuel Gagnon-Hartman, Andrei Mesinger, Masami Ouchi
Astrophysics of Galaxies
CHAMPS: Data Reduction and Detection of ~3300 Dusty Galaxies at 1.2 mm
Felix Martinez III, Jeyhan S. Karaltepe, Andreas L. Faisst et al. (+52 more)
We present the reduction and source catalogs for the \textit{COSMOS High-$z$ ALMA-MIRI Population Survey} (CHAMPS), the largest Atacama Large (Sub)Millimeter Array (ALMA) blank field survey to date at 0.2\,deg$^2$. With observing frequency centered at $250\, $GHz ($1.2\,$mm) and bandwidth of 7.5 GHz, CHAMPS covers the JWST/NIRCam+MIRI footprint in the COSMOS field, taking advantage of the rich, multiwavelength ancillary
datasets in COSMOS ranging from X-ray to
radio. The majority of the CHAMPS survey (90$\%$) has depths at or below 200 $\mu$Jy beam$^{-1}$ and with an average RMS of 146 $\mu$Jy beam$^{-1}$. The reduced CHAMPS mosaic has a beam size of $\theta_{\rm res} = 1.1'' \times 1.1''$. CHAMPS identifies sources via two detection methods, a blind search for high-SNR sources, and a prior-based search involving MIRI detections to identify faint sources. The blind search yields a total of 595 sources down to an SNR $\ge4.5\sigma$ while the prior catalog yields a total of 3162 source down to an SNR $\ge3\sigma$, leading to a full sample of 3355 unique objects detected across both catalogs. We identify a unique population of 385 SNR $\ge5\sigma$ sources across the two catalogs; after excluding 9 likely spurious edge detections we define a robust science sample of 376 sources above $\ge5\sigma$. These sources have a median
redshift of $\langle z_{1.2 \text{ mm}}\rangle = 2.54^{+0.89}_{-1.69}$ based on optical/near-IR/mid-IR photometric
redshifts and high-quality spectroscopic
redshifts, and hold a median stellar mass of $\langle\log (\rm M_\star/M_\odot)\rangle = 10.79^{+0.42}_{-3.08}$. We have further identified 68/376 ($\sim18\%$) sources as candidate AGN through X-ray, UV-optical, infrared and
radio selection techniques.
Read the full abstract ▾
All authors Felix Martinez III, Jeyhan S. Karaltepe, Andreas L. Faisst, Arianna S. Long, Jorge A. Zavala, Caitlin M. Casey, Jed McKinney, Ezequiel Treister, Maximilien Franco, Sune Toft, Manuel Aravena, John D. Silverman, Hollis B. Akins, Hiddo S. B. Algera, Jacqueline Antwi-Danso, Andrew J. Battisti, Yingjie Cheng, Olivia R. Cooper, Nicole E. Drakos, Carter Flayhart, Fabrizio Gentile, Steven Gillman, Ghassem Gozaliasl, Santosh Harish, Simon Hempel-Costello, Michaela Hirschmann, Olivier Ilbert, Bingcheng Jin, Shuowen Jin, Koki Kakiichi, Thresa Kelly, Zihao Li, Daizhong Liu, Lun-Jun Liu, Sinclaire M. Manning, Henry Joy McCracken, Romain A. Meyer, Louise Paquereau, Maria Pudoka, Jason Rhodes, Brant E. Robertson, Giulia Rodighiero, Rasha M. Samir, David B. Sanders, Marko Shuntov, Margherita Talia, Mattia Vaccari, Francesco Valentino, Aswin P. Vijayan, Feige Wang, Wuji Wang, Can Xu, Jinyi Yang, Yongda Zhu, Siwei Zou
High Energy Astrophysical Phenomena
First Detection of the Doppler Shift of X-ray Photons Due to a Telescope's Orbital Motion
Stephen DiKerby and Shuo Zhang
We have detected for the first time the redshifting and blueshifting of X-ray
photons due to the orbital motion of an X-ray
telescope around the Earth. Current and planned X-ray
telescopes like XRISM/Resolve and NewAthena can achieve energy resolutions $R = E / \Delta E \approx 1000$, requiring spectroscopic calibration of physical effects such as the local standard of rest and the orbit of the Earth around the Sun. We construct an a priori method for detecting a heretofore unexamined effect: the modulation of
redshift due to the motion of an X-ray
telescope around the Earth. We apply this pipeline to several XRISM/Resolve observations of narrow iron K$\alpha$ emission lines from galactic center molecular clouds, and we detect evidence of orbital
redshift modulation in the K$\alpha$ emission at the 95% confidence level. Our findings suggest that orbital
redshift modulation is already present and detectable in X-ray data and motivates reexamination of how X-ray
photon data is packaged in the emerging era of high-resolution X-ray spectroscopy.
Read the full abstract ▾
Earth and Planetary Astrophysics
The Dense, Rocky Core of Haumea Revealed by Satellite Dynamics
Benjamin Proudfoot, Darin Ragozzine, Will Grundy et al. (+2 more)
The icy dwarf
planets in the outer solar system are among the most enigmatic bodies known, showing activity ranging from atmospheric resurfacing to possible cryovolcanism. Yet the study of their interiors remains largely theoretical, with few empirical measurements to guide our understanding. The orbits of their moons offer a way to break this deadlock, providing a direct probe of dwarf
planet interiors. Here we present a detailed investigation of Haumea's interior derived from the motion of its satellite system. Fitting a new dynamical model to two decades of precise Hubble Space
Telescope astrometry, we simultaneously measure Haumea's dynamical oblateness, $J_2$, and the masses of its satellites. Our analysis of the $J_2$ measurement combined with occultation-derived shape models conclusively shows that Haumea has a dense rocky core overlaid with an ice-rich mantle. However, the current
dataset is not constraining enough to fully determine the detailed internal structure (core/mantle density, two-layer vs. three-layer, etc.). We do find a slight preference for models where Haumea retains a frozen-in fossil figure, but more data are needed to statistically confirm this. Future observations of the satellite system, as well as observations of stellar occultations, are needed to fully test this hypothesis and should substantially tighten constraints on Haumea's interior. Taken together with other recent evidence for geophysical and geochemical
evolution of dwarf
planets, our work shows that dense rocky cores and subsurface oceans are likely to be ubiquitous among the trans-Neptunian dwarf
planets.
Read the full abstract ▾
All authors Benjamin Proudfoot, Darin Ragozzine, Will Grundy, Flavia Rommel, Bryan Holler
Astrophysics of Galaxies
Snapshots of r-process production in the Milky Way disk
Sarah G. Kane, Stephanie Monty, Madeleine McKenzie et al. (+9 more)
Stars enhanced in heavy
neutron capture elements like europium (Eu) provide a window into the rarest and most exotic nucleosynthetic events. Most Eu-enhanced
stars discovered thus far are found among metal-poor populations, with $\mathrm{[Fe/H]}<-1.0$. Here, we report the discovery of $17$ vetted Eu-enhanced
stars ($\mathrm{[Eu/Fe]}>0.7$) in the Milky Way disk with
metallicities in the range $-0.87<\mathrm{[Fe/H]}<-0.21$ identified from among $74\,717$
stars in the GALAH survey. 14 of these
stars additionally have $\mathrm{[Ba/Eu]}<0$, marking enhancement from the rapid
neutron capture ($r$-) process and making these r-II
stars. Included in their number is a
star with a remarkably high $\mathrm{[Eu/H]}=1.01\pm0.09$ at $\mathrm{[Fe/H]}=-0.21$. In addition to Eu, all 17
stars show enhancements in other
neutron capture elements, especially in Nd, while otherwise appearing chemically consistent with typical disk
stars, particularly in their $\alpha$-element abundances. Two of the Eu-enhanced
stars exhibit indications of binarity with strong enrichment in Ba and Y, marking potential signatures of the slow or intermediate
neutron capture processes. This sample of 17 Eu-enhanced
stars, which span both the high- and low-$\alpha$ disks, are valuable tracers of
neutron capture processes, including the $r$-process, at high
metallicities. Although we use criteria for Eu-enhanced
stars typically applied to the
halo to enable comparison to literature studies of $r$-process enhanced
stars, we propose a new,
metallicity-dependent selection for Eu enhancement that is better-suited to the regime of the Galactic disk.
Read the full abstract ▾
All authors Sarah G. Kane, Stephanie Monty, Madeleine McKenzie, HanYuan Zhang, Sven Buder, Terese Hansen, Tadafumi Matsuno, Jason Sanders, Anke Ardern-Arentsen, Vasily Belokurov, Zofia Kaczmarek, Andrew Garner
Cosmology and Nongalactic Astrophysics · Cross-listed from gr-qc
Stochastic gravitational-wave background from subsolar neutron stars in collapsar disks
Valerio De Luca, Loris Del Grosso and Emanuele Berti
The fragmentation of the
neutrino-cooled
accretion disks that surround the black holes formed in collapsars has recently been proposed as an astrophysical channel for the production of
neutron stars with masses well below the standard core-collapse floor. These disk-born objects merge either with one another or with the central black hole, and the superposition of all such mergers across
cosmic history sources a
stochastic gravitational-wave background. In this work we compute the energy density of this background for both merger channels, adopting a formation history tied to the observed rate of long gamma-ray bursts. We find that the merger of a subsolar
neutron star with the central black hole is the loudest channel, already constrained by current data and within reach of next-generation observatories, while the binary
neutron-
star channel is at most two orders of magnitude fainter, with its widest binaries remaining accessible to next-generation detectors. Confronting these predictions with the fourth observing run of the LIGO–Virgo–KAGRA Collaboration, we derive two upper bounds on the fraction of collapsars whose disks produce such mergers: a robust one from the non-detection of an isotropic background, and a tighter one that could be achieved by a dedicated search for resolvable subsolar events in current data. Gravitational waves from non-axisymmetric deformations of the collapsar disk itself would provide an additional independent signature for the collapsar scenario, enabling cross-correlation studies with future deci-Hz detectors. Overall, the background computed here provides a population-level probe of disk-born subsolar
neutron stars, which next-generation detectors could bring firmly into view.
Read the full abstract ▾
Astrophysics of Galaxies
MOCSS: Multi-Object Coronagraphy for JWST/NIRSpec Slitless Spectroscopy
Mason S. Huberty, Claudia Scarlata, Matthew J. Hayes et al. (+10 more)
We present an experimental JWST/NIRSpec observational method to obtain $R\gtrsim1000$ G140M/F100LP slitless spectroscopic observations. This "Multi-Object Coronagraphy for Slitless Spectroscopy" (MOCSS) technique involves opening essentially all microshutters on NIRSpec simultaneously while closing shutters corresponding on-sky with known bright objects. Through observations of the Hubble Ultra Deep Field, we demonstrate the discovery potential of these deep, high resolution observations without the need for target pre-selection. We obtain a catalog of 22 secure multi-line emitters at $1.3<z<4.6$, with observations of [OII], [OIII], H$\alpha$, H$\beta$ and [NII] lines, accounting for $\sim80\%$ of the emission lines identified directly in the dispersed images. The MOCSS survey provides first time spectroscopic
redshifts for 18 of these sources. We also demonstrate that first order traces of the NIRSpec/G140M/F100LP observing mode extend substantially beyond the nominal $\sim1.89\rm \mu m$ red cutoff, as far as $2.94\rm \mu m$ in the most extreme case. Compared to existing NIRISS WFSS of similar exposure times, we find that the MOCSS technique can observe very faint lines while covering the full $1-2 \rm \mu m$ regime without gaps in wavelength coverage. This study describes the highest-resolution slitless spectroscopy campaign of the $1-2 \rm \mu m$ regime and emphasizes the discovery potential of this unorthodox observational technique.
Read the full abstract ▾
All authors Mason S. Huberty, Claudia Scarlata, Matthew J. Hayes, Alaina Henry, Danielle A. Berg, Vieri Cammelli, Richard Ellis, Anne E. Jaskot, Matilde Mingozzi, Pierluigi Monaco, Alberto Saldana-Lopez, Jonathan C. Tan, Alice Young
Cosmology and Nongalactic Astrophysics
Connecting the Dots: Prospects for Detecting Multi-Source Inflation through Scale-Dependent and Stochastic Bias of Little Red Dots
Peter L. Taylor, Xinyi Chen, Christopher M. Hirata et al. (+1 more)
Recent work has proposed using the spatial clustering of Little Red Dots (LRDs) as a high-
redshift cosmological probe. In this paper, we investigate the feasibility of obtaining a LRD sample with a future space experiment, and forecast LRD constraints on primordial local-type non-Gaussianity, $f^{\rm loc}_{\rm NL}$, and the collapsed-limit trispectrum amplitude, $\tau^{\rm loc}_{\rm NL}$. LRDs are ideally suited to probe these inflationary parameters because they span a large cosmological volume, have high bias and are easily identifiable. We perform idealised joint $f_{\rm NL}^{\rm loc}$–$\tau_{\rm NL}^{\rm loc}$ Fisher forecasts assuming the universality relation, Gaussian covariance, Poisson shot-noise and a normalised
redshift dispersion, $\sigma(z) / \left( {1+z} \right)= 0.03$. We quantify the significance at which one would detect multi-source inflation under the Suyama–Yamaguchi relation, $\tau^{\rm loc}_{\rm NL} > \left( 6/5 f_{\rm NL}\right)^2$, across the $f_{\rm NL}^{\rm loc}$–$\tau_{\rm NL}^{\rm loc}$ plane. We find that a LRD analysis could robustly detect multi-source inflation at high-significance over a large region of parameter space, and would be more constraining than all other past or present experiments.
Read the full abstract ▾
All authors Peter L. Taylor, Xinyi Chen, Christopher M. Hirata, Charuhas Shiveshwarkar
Cosmology and Nongalactic Astrophysics
Cosmological-perturbation equations from the total-angular-momentum formalism
Marc Kamionkowski and Robert R. Caldwell
We derive the equations for the linear
evolution of cosmological perturbations using total-angular-momentum (TAM) waves. The
cosmic microwave background temperature and polarization transfer functions are first derived as integral equations and from these the usual Boltzmann hierarchy of differential equations are then obtained for both scalar and tensor perturbations. We include the effects of isotropic
cosmic birefringence and discuss anisotropic
cosmic birefringence. We note a subtle effect of
cosmic birefringence on temperature fluctuations. The TAM derivation of the equations provides physical insights to results obtained previously.
Read the full abstract ▾
Solar and Stellar Astrophysics
Beyond what's observed: hierarchical inference of Gaia astrometric compact-object binaries
Natsuko Yamaguchi, Kareem El-Badry, Reed Essick et al. (+3 more)
Astrometry from the Gaia mission has revealed a large and homogeneous population of binaries containing compact objects, including more than 3000 white dwarf–main sequence (WDMS) binaries with orbital periods of $P_{\rm orb}\sim100$–$1000$ d. Most of these binaries likely underwent mass transfer from asymptotic giant branch donors, but their evolutionary histories remain uncertain. We develop a hierarchical
Bayesian inference model to constrain the intrinsic properties of the Gaia WDMS binary population while accounting for measurement uncertainties and the survey selection function. We infer the distributions of orbital period, component masses, and eccentricity, as well as the total space density. We find that the intrinsic orbital-period distribution follows a declining power law, $p(P_{\rm orb})\propto P_{\rm orb}^{-0.445\pm0.048}$, and the WD mass distribution is sharply peaked near $0.6\,M_\odot$, with only ~1% of systems hosting WDs more massive than $0.8\,M_\odot$. The inferred MS-
star mass distribution is relatively flat down to ~$0.3\,M_{\odot}$, which is unexpected if the population is dominated by products of stable mass transfer with a fixed critical mass ratio. The eccentricity distribution peaks at a nonzero value, $e=0.046\pm0.001$, suggesting incomplete circularization or eccentricity excitation. We infer a midplane space density of ~$3\times10^4\,{\rm kpc}^{-3}$ for WDMS binaries in the parameter space probed by Gaia DR3. These properties provide empirical
benchmarks for future work to constrain binary
evolution models. We also apply the framework to Gaia black hole and
neutron star binaries, inferring that $30^{+66}_{-20}$ and $614^{+203}_{-149}$ such systems exist within 2 kpc, respectively. This framework will enable detailed population-level constraints on a wide range of systems identified from the much larger catalog of astrometric orbits expected from Gaia DR4.
Read the full abstract ▾
All authors Natsuko Yamaguchi, Kareem El-Badry, Reed Essick, Amanda Farah, Cheyanne Shariat, Sahar Shahaf