Peer Revenue An exchange of ideas

Papers

Fresh from arXiv, typeset properly. Highlighted words trade on the market.

Physics Astrophysics

astro-ph Watch Astrophysics

Wednesday 24 June

Earth and Planetary Astrophysics

Architectures of Planetary Systems III: Excitation of Eccentricities and Inclinations

Alex R. Howe, Juliette C. Becker and Fred C. Adams

The current census of planetary systems displays a wide range of architectures. Extending earlier work, this paper investigates the correlation between our classification framework for these architectures and the distribution of eccentricities and inclinations of planetary orbits using both dispersion and normalized angular momentum deficit (NAMD) metrics. Orbital inclinations prove to be too strongly affected by observational biases to yield meaningful results, but the patterns in eccentricities reveal significant correlations. We find that systems with large gaps between planets are more dynamically excited than closely-spaced systems, based on dispersion in eccentricity and an eccentricity-specific NAMD metric. Systems with detected outer planets also appear dynamically excited, to a degree where our own solar system appears to be dynamically colder than expected. We also predict the existence of a population of highly-inclined long-period planets that is likely to be observed by upcoming astrometric surveys.
Read the full abstract

High Energy Astrophysical Phenomena · Cross-listed from gr-qc

Time-domain framework for the Teukolsky equation with a particle source using comoving hyperboloidal coordinates

Aditya Vaswani, Leor Barack, Oliver Long et al. (+1 more)

We present a scheme and implementation code for time-domain integration of the Teukolsky equation in 1+1 dimensions with a point-particle source, based on comoving, spatially compactified hyperboloidal coordinates. We demonstrate that the scheme evades the problem of nonphysical growing modes that plague some numerical evolution schemes without compactification. Our use of comoving coordinates greatly simplifies the application of jump conditions on the particle's worldline. We develop our method and test its performance for a scalar field on a Schwarzschild background, first for a circular geodesic orbit source and then for a scattering geodesic orbit. We then present a test implementation of the method for the $s = -2$ Teukolsky equation, illustrating its long-term stability and absence of growing-mode behavior through comparison with similar results using noncompactified characteristic coordinates. Our method paves the way to calculations of the full gravitational self-force in extreme-mass-ratio scattering.
Read the full abstract

All authors Aditya Vaswani, Leor Barack, Oliver Long, Rodrigo Panosso Macedo

High Energy Astrophysical Phenomena

Debiasing the Observed Fast Radio Burst Population with the CHIME/FRB Selection Function

Kyle McGregor, Jason W. T. Hessels, Victoria M. Kaspi et al. (+26 more)

The recent release of CHIME/FRB Catalog~2 provides the largest sample to date with which to investigate the intrinsic distributions of fast radio bursts (FRBs). Leveraging an expanded campaign of 587,367 synethetic bursts injected into the live CHIME/FRB search pipeline, we perform a population analysis of the fluence, scattering timescale, pulse width, and dispersion measure distributions of Catalog~2 FRBs. We first infer the intrinsic population using a resampling-based framework that accounts for instrumental selection effects following previous CHIME/FRB population studies. A central goal of this work is to constrain the intrinsic distribution of scattering timescales, that remained weakly constrained in Catalog~1 owing to limited statistics at moderate and large scattering times ($\tau \gtrsim 10\,\mathrm{ms}$ at 600~MHz) and sparse injection coverage in this regime. Second, we construct an explicit multidimensional selection function by training a logistic regression model on the injected events. This model estimates the detection probability as a function of FRB observable properties, including higher-order interaction terms. We incorporate this selection function into a simulation-based inference framework to refine the inferred intrinsic scattering-timescale distribution. We find evidence for a slight downturn in the intrinsic FRB scattering timescale distribution, though a flat or slightly rising distribution cannot be ruled out, that is further supported through a comparison with the higher-frequency scattering timescale distribution observed by Commensal Real-time ASKAP Fast Transients (CRAFT) survey.
Read the full abstract

All authors Kyle McGregor, Jason W. T. Hessels, Victoria M. Kaspi, Kaitlyn Shin, Fengqiu A. Dong, Naman Jain, Robert A. Main, Mawson W. Sammons, Michele Woodland, Daniel Amouyal, Derek Bingham, Charanjot Brar, Amanda M. Cook, Radu Craiu, Alice P. Curtin, Gwendolyn Eadie, Bryan M. Gaensler, Jeff Huang, Afrokk Khan, Calvin Leung, Kiyoshi W. Masui, Ayush Pandhi, Swarali Shivraj Patil, Aaron B. Pearlman, Sachin Pradeep E. T., Paul Scholz, Seth R. Siegel, Kendrick Smith, David C. Stenning

Earth and Planetary Astrophysics

DiskMINT-GARDEN: Self-consistent Models to Estimate Disk Masses

Dingshan Deng, Uma Gorti, Ilaria Pascucci et al. (+1 more)

We present DiskMINT-GARDEN, a grid of self-consistent models together with a fast, open source inference tool for disk masses. The grid is built on DiskMINT, a tool which couples hydrostatic disk structure, continuum/line radiative transfer, and a reduced CO chemical network including freeze-out, grain-surface conversion, and isotope-selective photodissociation. DiskMINT-GARDEN model grid spans a large range of stellar mass ($0.1-2.0\,M_\odot$), gas disk mass ($10^{-5}-10^{-1}\,M_\star$), dust-to-gas ratio ($0.003-0.1$), and characteristic radius ($10-300\,{\rm au}$), and provides synthetic ALMA observables. We train a machine-learning regression model to infer the disk mass, dust-to-gas mass ratio, and disk size from the dust continuum and $\mathrm{C^{18}O}$ line observations. Applying DiskMINT-GARDEN to archival ALMA data of 34 disks, we find gas masses in good agreement with dynamical and HD-based estimates. Comparing our results with estimates from chemical modeling using DALI, we find that their need for large-scale elemental or CO depletion can be accounted for by grain-surface chemistry implemented in DiskMINT, with CO conversion to CO$_2$ being one of the main reactions. Therefore, extant data suggest little chemical processing due to disk evolutionary processes.
Read the full abstract

All authors Dingshan Deng, Uma Gorti, Ilaria Pascucci, Maxime Ruaud

Astrophysics of Galaxies

Probing the molecular gas content of galaxies in an over-dense group at z~0.7: A test case for environmental quenching

Jonathan Freundlich, Benoît Epinat, Thierry Contini et al. (+14 more)

We investigated the impact of group environment on molecular gas reservoirs at an intermediate redshift by observing the CO(2-1) emission from the galaxy group COSMOS-Gr30 at $z \sim 0.7$ with the Institut de Radioastronomie Millimetrique (IRAM) NOrthern Extended Millimeter Array (NOEMA) and 30m telescope. This dense environment, located at the intersection of large-scale cosmic web filaments hosts a large ($\sim 10^{4}$ kpc$^{2}$) ionized gas structure revealed by MUSE. We detect CO emission in four galaxies in the group with a signal-to-noise ratio (S/N) greater than five and derive upper limits for the remaining group members with secure spectroscopic redshifts. Stacked measurements indicate that group galaxies exhibit, on average, molecular gas contents reduced by $\sim 0.5$ dex relative to field scaling relations, corresponding to gas fractions that are $20- 40\%$ of those found in typical main-sequence galaxies. Although the uncertainties are significant, this suggests that environmental processes efficiently deplete molecular gas reservoirs in the galaxies of this group. The 30m observations place an upper limit on the molecular gas associated with the extended ionized structure, $M_{\rm gas} < 2 \times 10^{10} \rm M_\odot$, implying that less than a third of the gas in the intragroup medium is in a cold, star-forming phase. Together, these results show how environmental mechanisms in dense group environments act to remove or suppress molecular gas within galaxies, capturing quenching processes in action.
Read the full abstract

All authors Jonathan Freundlich, Benoît Epinat, Thierry Contini, Philippe Salomé, Françoise Combes, Baptiste Jego, Davor Krajnović, Wilfried Mercier, Constanza Muñoz López, Matthieu Béthermin, Leindert Boogaard, Rodrigo Herrera-Camus, Diana Ismail, Fangzhou Jiang, Katarina Kraljic, Florent Renaud, Sandro Tacchella

Astrophysics of Galaxies

Wind Acceleration as a Driver of Detached Blueshifted Absorption in Quasar Disk Winds

Randall C. Dannen, Daniel Proga, Paola Rodríguez Hidalgo et al. (+4 more)

Active galactic nuclei (AGN) unification models often emphasize the viewing angle, $i$, but $i$ alone does not determine quasar properties. This is crucial for quasar outflows: UV absorption in Extremely High Velocity Outflow (EHVO) quasars can reach blueshifted velocities of $\sim0.2~c$. In disk-wind models, both $i$ and internal wind structure shape the emergent spectrum. We test their interplay using biconical quasar disk-wind models with different acceleration lengths, $R_v$, and generate synthetic spectra over a range of $i$. We use Monte Carlo radiative transfer to account for finite continuum sources, wind attenuation, scattering, reprocessing, and emission. Changing $R_v$ greatly alters the ionization structure, continuum shape, and absorption-line profiles. At intermediate viewing angles, sightlines pass through the fastest wind. Even there, highly detached and blueshifted \CIV\ absorption like that observed in EHVO quasars appears only in models with small $R_v$. In these models, the gas reaches high velocity before attaining the ionization and density conditions favorable for \CIV. Models with larger $R_v$ instead produce broader, less detached troughs, even when the terminal velocity is very high. Thus, highly detached and blueshifted absorption requires both a high terminal velocity and small $R_v$, making such features diagnostics of disk-wind acceleration and structure. EHVO quasars provide a clear example, but the same principle applies more broadly to highly detached and blueshifted absorption in quasar outflows. Our results support an extended disk-wind view of AGN unification: $i$ selects the observed wind region, while $R_v$ shapes the emergent spectrum and absorption morphology.
Read the full abstract

All authors Randall C. Dannen, Daniel Proga, Paola Rodríguez Hidalgo, Kara Smith, Anna Ritchie, Liliana Flores, Morrigan Kalet

Solar and Stellar Astrophysics

DKIST Unveils Four-Lobed Stokes U Profiles in a Magnetically Complex Sunspot Penumbra

Ryan James Campbell and Sarah Jaeggli

We present DKIST spectropolarimetric observations of a sunspot penumbra revealing spatially coherent four-lobed Stokes U profiles that persist after polarimetric crosstalk correction. The observed Stokes vectors are well reproduced by stratified inversions containing gradients in velocity and magnetic parameters, including line-of-sight variation of the magnetic azimuth. Forward synthesis experiments in which the magnetic azimuth is artificially held constant with optical depth substantially modify the Stokes U morphology while leaving Stokes I, Q, and V comparatively unchanged, indicating that azimuthal variation is an important contributor to the observed linear polarisation signatures within the tested one-component atmospheres. We explored degeneracies using both two-component atmospheres and one-component constant-azimuth models: the former generally converged toward pathological solutions, while the latter provided a plausible degenerate explanation for much of the observed four-lobed Stokes U morphology. A supervised machine-learning classifier applied to Stokes V profiles shows that the associated magnetic complexity is spatially confined to the penumbra-light-bridge boundary where the four-lobed Stokes U profiles and reverse-polarity fields are observed. These results identify four-lobed Stokes U profiles as a potential spectropolarimetric signature of complex line-of-sight magnetic structuring in sunspot penumbrae, providing new observational constraints on fine-scale penumbral magnetic topology.
Read the full abstract

Instrumentation and Methods for Astrophysics

Indigenizing the Drake Equation: how Indigenous methods can help us understand life in the Milky Way Galaxy

Hilding R. Neilson

The Drake Equation is a thought experiment whose purpose is to understand the ingredients necessary for life and advanced technological civilizations to exist on other worlds in our galaxy. However, beyond reflecting on life on Earth, we have no knowledge of many of these ingredients, such as the number of planets that have life, the number with intelligent life, the number with advanced civilizations, and the lifetimes of these civilizations. In this work, I will review the Drake Equation and the biases that scientists have traditionally had in discussing this equation and how it has led to the current searches of biological and technological signatures. I will discuss how the Drake Equation looks different if we consider it through the lens of Indigenous methods and sciences and how these methods would lead to a dramatically different view of life in our Galaxy.
Read the full abstract

Solar and Stellar Astrophysics

Constraints on Binarity for the Extreme Oe Variable Star AzV 493

M. S. Oey, Irene Vargas-Salazar, Edmund Hodges-Kluck et al. (+6 more)

The extreme Oe star AzV 493 is known to show unusual photometric and spectroscopic variability that suggest the presence of an unseen companion in a highly eccentric and long-period (7.3 or 14.6-year) orbit. We obtained a Chandra/ACIS observation near the putative periastron for the 7.3-year orbit to test for transient X-ray emission that would confirm its binary nature. Our data only place an upper limit to the X-ray luminosity of L_X < 2.5 x 10^33 erg/s based on the 0.5 - 8 keV flux limit. Additionally, we obtained 4 new spectroscopic observations with the M2FS spectrograph at Magellan and 20 archive FLAMES/GIRAFFE and X-Shooter spectra from ESO/VLT to further constrain the possibility of radial velocity (RV) variation. Statistical analysis of the RV measurements yields inconclusive results regarding the existence of variations. We discuss possible mass limits for a potential companion, which may be a black hole, in the event that the variations are real. The violet-to-red (V/R) Balmer ratio has also recently inverted, which may be a further indication of a companion.
Read the full abstract

All authors M. S. Oey, Irene Vargas-Salazar, Edmund Hodges-Kluck, Norberto Castro, Michal K. Szymanski, Mario Mateo, Mathieu Renzo, Mark W. Suffak, Maxwell Moe

Solar and Stellar Astrophysics

Six decades of TIGRE and Mount Wilson chromospheric monitoring in the H and K lines: The quest for an understanding of solar-type activity

J. H. M. M. Schmitt, K.-P. Schröder, M. Mittag et al. (+3 more)

The combined time series of the consistently calibrated chromospheric activity indicator, the S-index – derived from Mount Wilson and TIGRE data – now spans more than five decades of monitoring observations of the Sun and of more than one hundred solar-like stars. For the first time, these data allow us to probe the long-term stability of solar-type magnetic cycles as well as their possible transition into other behavioral forms of stellar activity in the time domain. Such variability studies are an important input for solar-stellar connection research and for our empirical understanding of the long-term perspective of solar activity as well as of a wider empirical picture of the coevolution of magnetic activity with stellar structure. We here present and discuss a representative selection of cool main-sequence stars, for which such data are available. The excellent quality of our TIGRE data now more than doubles the number of known cyclic stars. Grading them (i.e., excellent, good, fair, and poor) and putting them into an evolutionary perspective, we find that stars more active than the Sun are also more likely to show cyclic variability than stars below solar activity. Furthermore, more active stars tend to have more regular cycles, while the solar mean S-value fits the lower end of the S-index range found for cyclic stars. This is consistent with the occurrence of solar Maunder minima episodes, hinting at a sometimes already unstable solar cycle. We find eighteen stars with even lower activity and lower variability than the Sun, which provide a preview into the latter's distant future.
Read the full abstract

All authors J. H. M. M. Schmitt, K.-P. Schröder, M. Mittag, A. Hempelmann, J. N. González-Pérez, Dennis Jack

Instrumentation and Methods for Astrophysics

Low Thrust Electric Propulsion Mission Concepts For a 3-Meter Class Space Telescope

Yael M. Brynjegard-Bialik, Mohamed Nassif, Drew Latta et al. (+12 more)

Space-based telescopes benefit from operating in stable orbital environments with reduced exposure to radiation and thermal fluctuations in order to minimize cost and maximize time for high-quality observations. Finding this ideal environment proves beneficial particularly for exoplanet discovery and characterization; direct imaging requires sub-nanometer wavefront stability and multi-hour observations, and transit detection requires parts-per-million photometric accuracy. Our team at University of Arizona's Steward Observatory and the Wyant College of Optical Sciences is evaluating various mission concepts for a 3-meter class telescope design, flying on a spacecraft bus equipped with a low thrust propulsion system. The presented mission analysis focuses on obtaining suitable transfer trajectories to the desired science orbit as well as understanding the radiation environment during the transfer, which is relevant for low thrust missions. The science analysis explores different operating orbits with the purpose of yielding maximum scientific return for detecting exoplanets. In this paper, we evaluate the use of a 2:1 lunar resonant orbit and a Sun-Earth L2 halo orbit for our mission.
Read the full abstract

All authors Yael M. Brynjegard-Bialik, Mohamed Nassif, Drew Latta, Neel Kunjur, Nicholas Rahaim, Paul DeTrempe, Abhi Tripathi, Isaac Saedi-Marghmaleki, Dillon O'Reilly, Justin Hom, Patrick Ingraham, Jeffrey Kingsley, Buell T. Jannuzi, S. Pete Worden, Ewan S. Douglas

Astrophysics of Galaxies

The 10-15 GHz radio continuum survey of the Galactic Plane with SKAO

A. Traficante, C. Mininni, F. Cavallaro et al. (+63 more)

Star formation emerges from the complex interplay between gravity, turbulence, magnetic fields, and stellar feedback, all of which vary across spatial scales and Galactic environments. Over the past decades, extensive multiwavelength surveys of the Galactic Plane have progressively unveiled this complexity. Far-infrared and sub-millimetre surveys have identified and characterized tens of thousands of star-forming regions, revealing their mass, temperature, and evolutionary stage. Complementary molecular-line surveys, spanning several CO transitions and isotopologues, have mapped the gas kinematics from giant molecular clouds down to sub-parsec structures. The advent of interferometers such as ALMA has revolutionized this field, enabling systematic studies of gas dynamics, fragmentation, and collapse in dense clumps at scales of a few thousand astronomical units. At the same time, mid-infrared and radio surveys at frequencies 0.8 <= nu <= 5 GHz have traced ionised gas associated with the earliest and latest phases of massive-star evolution, including thermal radio jets, hypercompact and ultracompact HII regions, supernova remnants, planetary nebulae, and evolved massive stars. Yet, a uniform, Galaxy-wide census of ionised structures and feedback processes remains elusive. A transformational leap forward requires a sensitive, high-resolution radio survey of the Galactic Plane at 10-15 GHz, capable of resolving physical scales smaller than 0.05 pc at distances up to 20 kpc. This is precisely the goal of the SKA-Mid Galactic Plane survey, which will, with its unprecedented sensitivity, angular resolution, and mapping speed, provide the first panoptic view of ionised gas and stellar feedback across the Milky Way.
Read the full abstract

All authors A. Traficante, C. Mininni, F. Cavallaro, G. Umana, C. Trigilio, S. Molinari, L. D. Anderson, M. Audard, C. Bordiu, C. S. Buemi, C. Carrasco-Gonzalez, L. Cerrigone, E. J. Chung, J. Dey, A. Ingallinera, I. Jimenez-Serra, P. Klaassen, S. Loru, K. Mallick, A. Nucara, M. Padovani, J. D. Pandian, K. L. J. Rygl, T. M. Rodríguez, G. Sabatini, S. Reissl, P. Suin, M. A. Thompson, T. L. Bourke, J. S.Urquhart, M. Valeille-Manet, F. Xu, A. Zavagno, M. Benedettini, E. Bianchi, A. Bracco, F. Bufano, C. Codella, N. Cunningham, J. Dawson, D. Galli, M. G. Guarcello, A. Karska, W.-J. Kim, P. Leto, B. Liu, B. Mookerjea, F. Motte, T. Nony, R. Paladini, A. Patel, L. Podio, A. J. T. Ramaila, B. Riaz, S. Riggi, D. A. Roshi, A. Ruggeri, Á. Sánchez-Monge, R. Schödel, O. M. Smirnov, J. D. Soler, S. Sottie, R. Unnikrishnan, A. Y. Yang, K. Wang, T. Wilson

Instrumentation and Methods for Astrophysics

A nonrelativistic radiative transfer module for Idefix

Nicolas Scepi and Geoffroy Lesur

Radiation magnetohydrodynamic (RMHD) simulations are essential for comparisons with observations, particularly in the regime where fluids and radiation are dynamically coupled. Although computationally expensive, RMHD is becoming increasingly accessible with the advent of exascale computing. However, only a few public RMHD codes are currently able to fully exploit the diversity of modern accelerated architectures. We present a nonrelativistic radiative transfer module for the public magnetohydrodynamic code IDEFIX; it is built on the Kokkos library to ensure performance portability. Our goal is to provide a user-friendly RMHD code capable of running efficiently on current and future exascale supercomputers. The radiative transfer module is based on the M1 approximation and implemented using a split explicit-implicit scheme. A reduced speed of light approximation is employed to alleviate the timestep constraint imposed by radiation. The module supports several radiation Riemann solvers and Cartesian, cylindrical, and spherical geometries in one, two, and three dimensions. The implicit step relies on a simple matrix inversion, ensuring both robustness and high performance. Users can choose between built-in opacity models or supply tabulated opacities and custom user-defined functions. The radiative module of IDEFIX demonstrates excellent performance on accelerated architectures, including the AMD MI250X and MI300 partitions of the AdAstra supercomputer. On MI250X nodes, it achieves up to $7.\times 10^8$ cell updates per second per node, at a computational cost only 1.6 times higher than a pure magnetohydrodynamic simulation. These results establish IDEFIX as a fast, robust, and portable RMHD code suitable for the wider community.
Read the full abstract

Astrophysics of Galaxies

Quantifying the inside-out formation of disk galaxies at $1.5 \le z \le 3.0$

Laura DeGroot, Swara Ravindaranath, Karmellah Buttler et al. (+1 more)

We examine the properties of galaxies at $1.5\le z\le3.0$ in the Extended Groth Strip (EGS) field to explore inside-out disk growth. We take advantage of the high-resolution James Webb Space Telescope (JWST) imaging and imaging from the Hubble Space Telescope (HST) to measure rest-frame optical and rest-frame UV half-light radii of the galaxies at comparable spatial resolution. We also examine the relation between structural properties and star formation rates, mass, and dust attenuation. While previous studies have inferred inside-out disk formation via the comparison of rest-optical and rest-UV radii using HST images, this study advances this knowledge by using the unprecedented resolution of JWST. We find evidence of inside-out disk formation from, on average, larger UV sizes than optical for galaxies across all redshifts. While previous studies suggested that this could be accounted for due to dust, we find that measurements with the improved resolution of the JWST support this size difference, after accounting for dust attenuation. We also observe that majority of galaxies with clumpy morphologies ($n < 0.5$) exhibit larger UV sizes than rest-optical because the star formation is distributed in multiple star forming clumps or mergers. We observe correlations in both the optical and UV for the size-mass relation, which are consistent with previous results but we find lower values for the slope of the power-law relation of the rest-optical fit, based on robust measurements from JWST images compared to the low resolution HST images used in previous studies.
Read the full abstract

All authors Laura DeGroot, Swara Ravindaranath, Karmellah Buttler, Taliah Lansing

Solar and Stellar Astrophysics

A Stellar Role Reversal: Multiple Features in the Mass and Mass Ratio Distributions of Merging Binary Black Holes from Stable Mass Transfer

Gina Chen, Katelyn Breivik and Lieke A. C. van Son

Observations of gravitational wave events have enabled the measurement of the merging binary black hole (BBH) mass function. This mass function encodes the physical interactions which shape the formation and evolution of BBHs. In this work we investigate how the stable mass transfer (SMT) channel of BBH formation imprints onto the BBH primary mass and mass ratio distributions. We use both an analytic framework and binary population synthesis to show how assumptions about mass transfer accretion efficiency and mass transfer stability affect the BBH mass distribution. Under the assumption of conservative mass transfer, we find that the SMT channel produces two observationally distinct subpopulations: a high primary mass, near equal mass ratio population formed through mass ratio reversal (MRR), and a low primary mass non-MRR subpopulation. The mass range where MRR occurs is determined by assumptions about binary SMT. In particular, we find that the stability criteria for mass transfer at different stellar evolutionary stages carve out complementary regions in the primary-mass–mass-ratio plane, separating the MRR and non-MRR populations into distinct peaks at high and low primary mass respectively. Our results imply that the physics of SMT creates distinct features in gravitational wave populations which current and near future gravitational wave detectors may be able to resolve.
Read the full abstract

Solar and Stellar Astrophysics

Cepheids with giant companions III. Evolutionary modeling of nine binary double Cepheids from the Milky Way and Magellanic Clouds

F. Espinoza-Arancibia, B. Pilecki, M. Catelan et al. (+3 more)

Binary double (BIND) Cepheids are systems comprising two Cepheid components. This feature provides important constraints that allow us to reveal the origin of Cepheids, trace their evolution, and test pulsation theory. Ten BIND Cepheids are now known, with only one having its parameters determined. We aim to estimate the physical parameters of the components of nine BIND Cepheids in the Magellanic Clouds and the Milky Way, investigate their evolutionary configurations, and formation scenarios. We also expand the parameter space of characterized individual Cepheids in mass, radius, period, and metallicity. We extended the recently introduced $q$-PED method to BIND Cepheids, combining observational constraints with theoretical pulsation and evolutionary models. We considered all consistent configurations (first-crossing, blue-loop, and mixed) as viable solutions. Probabilistic and observational constraints, including spectroscopic mass ratios for two systems, were then used to discriminate between them. We obtained new $q$-PED estimates of mass, radius, temperature, luminosity, and age for 18 Cepheids with previously unknown physical parameters. For one Galactic system, the spectroscopic mass ratio $q_s=0.84\pm0.04$ indicates a first-crossing plus a blue-loop Cepheid solution. This mass ratio, along with the predicted mass ratios lower than unity for two other systems, suggests past binary interactions and a likely merger origin for one component. We derive a new period–mass–radius relation and mass–luminosity relation covering the mass range $2.3-4.6$ M$_\odot$. This work provides the first mass estimates for Cepheids in the SMC, extending the lower Cepheid mass limit down to 2.3 M$_\odot$. Binary interactions in the past evolution of Cepheids may be common, affecting up to 40% of our systems with two clear cases and two more if blue loop Cepheids are preferred.
Read the full abstract

All authors F. Espinoza-Arancibia, B. Pilecki, M. Catelan, V. Hocdé, I. B. Thompson, W. Gieren

Astrophysics of Galaxies

Cluster vs Field: Clear Evidence for a Morphology-Density Relation in All Environments at $z\sim1.6$

Westley Brown, Adam Muzzin, Jasleen Matharu et al. (+6 more)

We explore the relationship between galaxy structure, stellar mass, and local galaxy density in three SpARCS clusters at $z\sim1.6$ and compare with field galaxies from the 3D-HST survey. Our cluster and field data include: 1) unprecedented multiband photometry, allowing for accurate stellar mass estimates; 2) extensive slit and grism spectroscopy targeting both star-forming and quiescent galaxies, allowing for high-accuracy local density measurements; and 3) deep imaging in F160W, allowing for accurate rest-frame optical morphologies. Using Sérsic index measured in rest-frame R-band, we classify galaxies as disk-like, bulge-like, and intermediate. Our sample includes 111 cluster galaxies and 458 field galaxies with reliable Sérsic measurements. We find that a morphology-density relation is already in-place in both cluster and field galaxies at $z\sim1.6$, such that as local density increases, the fraction of bulge-like galaxies increases and disk-like galaxies decreases. Both samples show similar positive trends between median Sérsic index and local density. Additionally, we find a general positive relationship between Sérsic index and stellar mass. The majority of galaxies remain disk-like until reaching stellar masses above $10^{10.25} M_\odot$ in the cluster or $10^{10.8} M_\odot$ in the field, however, we cannot conclude whether the differences in stellar mass trends are significant. Overall, our results show clear morphology-density and morphology-mass relations in place at $z\sim1.6$ and oppose the idea that cluster-specific processes are solely responsible the morphology-density relation. Our data further suggest that the morphology-density relation may be independent of global environment at this epoch.
Read the full abstract

All authors Westley Brown, Adam Muzzin, Jasleen Matharu, Gillian Wilson, Julie B. Nantais, Ben Forrest, Ricardo Demarco, Allison Noble, Tracy Webb

Solar and Stellar Astrophysics

Prediction for IMAP: Revealing the Role of the Solar Magnetic Field in the Heliotail

M. Kornbleuth and M. Opher

The classic paradigm of the heliosphere considered the solar magnetic field as having a passive role in the heliosheath, yet Opher et al. (2015) and Drake et al. (2015) suggested that the solar magnetic field plays an active role by collimating the solar wind plasma. Previous work has suggested that high-latitude lobes observed by IBEX-Hi energetic neutral atom (ENA) maps are solely due to the fast/slow solar wind profile, yet other works have found that the solar magnetic field may play a role in organizing the lobes as well. Here, using an MHD solution with and without the solar magnetic field, we find that the fast/slow wind profile largely dictates the ENA profile up to $\sim$10-18 keV. Beyond this energy, the collimation effects are more prominent and the fast/slow solar wind profile no longer organizes the maps. The collimation creates two high latitude lobes. By 80 keV, the heliosphere with collimation yields an enhancement of ENAs of the high-latitude tail lobes compared to the low-latitude region by a factor of $\gtrsim$ 1.3, whereas the uncollimated heliosphere yields a ratio $<$ 1. Therefore, IMAP should be able to identify whether the solar magnetic field collimates the solar wind in the deep heliotail.
Read the full abstract

Earth and Planetary Astrophysics

Using VLTI/GRAVITY+ to determine the identity of a third planet candidate in the PDS 70 system

David Trevascus, Wolfgang Brandner, Olga Balsalobre-Ruza et al. (+75 more)

Detections of protoplanets are rare and protoplanetary disk features mischaracterized as planets are common. PDS 70 is one of only two stars known to host multiple confirmed protoplanets, PDS 70 b and c, and repeat detections of a third point-like source in the system suggest the presence of third inner planet. However, previous observations of this third source are insufficient to distinguish whether it is a planet or a concentrated dust clump in Keplerian motion. Our observations with VLTI/GRAVITY+ did not re-detect this point-like source, suggesting that it is, in fact, a dust clump and not a planet. These observations demonstrate how the angular resolving power of VLTI/GRAVITY+ can be used to distinguish between protoplanets and protoplanetary disk features.
Read the full abstract

All authors David Trevascus, Wolfgang Brandner, Olga Balsalobre-Ruza, Sylvestre Lacour, Karim Abd El Dayem, Nicolas Aimar, Anthony Berdeu, Jean-Philppe Berger, Guillaume Bourdarot, Valentin Christiaens, Carlos Correia, Richard Davies, Denis Defrère, Antonia Drescher, Andreas Eckart, Frank Eisenhauer, Maximilian Fabricius, Helmut Feuchtgruber, Simon Flesch, Natascha M. Förster Schreiber, Arianna Foschi, Quentin Fournier, Paulo Garcia, Rebeca Garcia Lopez, Reinhard Genzel, Stefan Gillessen, Iain Hammond, Sebastian F. Hönig, Mathias Houllé, Simran Joharle, Pierre Kervella, Laura Kreidberg, Lucas Labadie, Olivier Lai, Romain Laugier, Jean-Baptiste Le Bouquin, James Leftley, Ruancun Li, Bruno Lopez, Dieter Lutz, Gabriel-Dominique Marleau, Felix Mang, Antoine Mérand, Florentin Millour, Miguel Montargès, Nuno Morujão, Hugo Nowacki, Mathias Nowak, Juan Osorno, Thomas Ott, Sarah Pappert, Thibaut Paumard, Karine Perraut, Guy Perrin, Romain Petrov, Pierre-Olivier Petrucci, Nicolas Pourré, Sebastian Rabien, Diogo C. Ribeiro, Sylvie Robbe-Dubois, Matteo Sadun Bordoni, Joel Sánchez Bermúdez, Daryl Santos, Jonas Sauter, Jules Scigliuto, Jinyi Shangguan, Taro T. Shimizu, Ferréol Soulez, Christian Straubmeier, Eckhard Sturm, Matthias Subroweit, Calvin Sykes, Linda Tacconi, Paloma Thévenet, Irene Urso, Frédéric Vincent, Julien Woillez, the GRAVITY+ Collaboration

Cosmology and Nongalactic Astrophysics

First full-shape joint analysis of the two- and three-point correlation functions on real data: $\Lambda$CDM cosmological constraints from BOSS DR12

Massimo Guidi, Michele Moresco, Alfonso Veropalumbo et al. (+3 more)

The three-point correlation function (3PCF) encodes cosmological information beyond the two-point correlation function (2PCF), yet a full-shape joint analysis in redshift space using real data has so far been lacking. We present the first full-shape cosmological constraints from a joint analysis of 2PCF and 3PCF in redshift space, using BOSS DR12 data, extending to real data, including Alcock–Paczyński and redsfhit space distortions, the full-shape configuration-space framework validated in real space for the first time by Euclid Collaboration: Guidi et al (2026). We model both statistics adopting the velocity difference generating function (VDG) framework, incorporating non-perturbative Fingers-of-God damping, a complete Eulerian galaxy bias expansion, and infrared resummation. Fast and accurate theoretical predictions are obtained using dedicated emulators, which enable a full-shape likelihood analysis of the 3PCF and its combination with the 2PCF, varying the cosmological parameters $10^9 A_s, \omega_{\rm cdm}$ and $h$, while the baryon fraction density $\omega_{b}$ is fixed to its fiducial value. The covariance matrix is estimated from 2048 MultiDark-Patchy mocks, and an optimal data-vector compression ensures a stable covariance inversion. The perturbative model is validated against goodness-of-fit tests across different scales, and provides a good description of the joint data vector down to $r_{\rm min}^{\rm 3PCF} \sim 60\,h^{-1}{\rm Mpc}$. We find that the joint 2PCF+3PCF analysis yields significant improvements over the 2PCF-only baseline, with gains of approximately 29%, 10%, and 24% on $\sigma(h)$, $\sigma(\omega_{\rm cdm})$, and $\sigma(A_s)$, respectively. The improvements mainly arise from the additional BAO cosmological information encoded in the 3PCF triangle configurations.
Read the full abstract

All authors Massimo Guidi, Michele Moresco, Alfonso Veropalumbo, Lorenzo Cavazzini, Antonio Farina, Andrea Labate

Cosmology and Nongalactic Astrophysics

Lyman-Alpha Forest and its Cross-Correlation with High-Redshift Galaxies in Effective Field Theory at the Field Level

Roger de Belsunce, Mikhail M. Ivanov, James M. Sullivan et al. (+2 more)

We present a field-level perturbative forward model for the Lyman-alpha (Lya) forest flux decrement. We validate it on two simulation suites: large-volume AbacusSummit N-body simulations with the Lya forest painted onto the dark matter field, and the Sherwood hydrodynamic simulations. Across the redshift range of the simulations (z=2.0-3.2), the 3D and 1D power spectra of the model match the simulated Lya fields at the 1% (5%) level up to k <= 0.3 (1.0) h/Mpc, with similar performance for the cross-correlation with massive dark matter halos. The counts-in-cells statistic shows excellent agreement down to cell radii of 2 Mpc/h. Leveraging cosmic variance cancellation, the model enables precision measurements of Lya bias parameters and robustly detects the full set of quadratic line-of-sight bias operators, consistent with the notion of naturalness in effective field theory (EFT). We quantify the stochasticity of the Lya forest (the analog to the one-halo term), and find it to be white (scale- and orientation-independent) on large scales, matching EFT predictions. We further find that phenomenological flux power spectrum models, based on modulations of the linear-theory power spectrum, fail at the field level even on quasi-linear scales. For the currently observing Dark Energy Spectroscopic Instrument (DESI), we generate large-scale clustering mocks of the Lya forest to validate cosmological parameter inference pipelines. Looking ahead to its successor, DESI-II, we produce large-volume mocks of representative samples of Lyman-break galaxies (LBGs) and Lya emitters (LAEs), calibrated on Astrid hydrodynamic simulations and matched to observations at z=3, enabling joint analyses of Lya forest and high-redshift galaxy data.
Read the full abstract

All authors Roger de Belsunce, Mikhail M. Ivanov, James M. Sullivan, Shi-Fan Chen, Kazuyuki Akitsu

Solar and Stellar Astrophysics

Modeling the curved dust sublimation front in protoplanetary disks: a potential probe of midplane turbulence

Ezequiel Manzo-Martínez, Ramiro Franco-Hernández, Nuria Calvet et al. (+3 more)

We present a new approach to calculate the geometry and emission of the dust inner wall in disks around T Tauri stars. This calculation follows a self-consistent approach given the disk structure and adopts a density-dependent sublimation temperature for the dust. We built spectral energy distributions (SEDs) of disk models with curved walls around a $0.5\,M_\odot$ star, finding that the curved wall starts at a radius of $\sim 0.11$ au and extends to $\sim 0.38$ au. The dependence on mass accretion rate, dust settling, and disk inclination on the resulting SEDs is explored, as well as the impact of the height of the midplane layer containing large millimeter-sized grains. To test our models, we compare synthetic near-IR colors from a grid of disk models with observed colors for a large sample of disk-bearing T Tauri stars located in Taurus, IC 348, and the Orion complex. Most of the observed colors can be explained by combinations of mass accretion rates, dust settling, and inclinations within the expected ranges for T Tauri stars. However, populating the regions where observed JHK colors are most concentrated, requires the millimeter-size grains be spread up to 0.5–3 scale heights above the midplane. This result contradicts expectations of rapid dust settling and suggests a high degree of turbulence capable of lifting large grains toward the upper disk layers. These findings provide insight into the dynamical conditions of the disk midplane near the star.
Read the full abstract

All authors Ezequiel Manzo-Martínez, Ramiro Franco-Hernández, Nuria Calvet, Jesús Hernández, Paola D'Alessio, Rosa M. Torres

High Energy Astrophysical Phenomena

3D Kinematic Reconstruction of the Crab Nebula That Includes the Northern Ejecta `Jet'

Ziwei Ding, Dan Milisavljevic, Thomas Martin et al. (+4 more)

We present new detailed three-dimensional kinematic reconstructions of the Crab Nebula created from hyperspectral cubes obtained with the SITELLE instrument mounted on the Canada–France–Hawaii Telescope. Our data cubes span a wavelength range from 3600Å to 7000Å, covering major emission lines including [O II] $\lambda\lambda$3726, 3729, H$\beta$, [O III] $\lambda\lambda$4959, 5007, [N II] $\lambda$5755, He I $\lambda$5876, [N II] $\lambda\lambda$6548, 6584, [S II] $\lambda\lambda$6717, 6731, and H$\alpha$. The field of view encompasses the “chimney" or “jet," a 45-arcsec-wide funnel-shaped structure that extends 100 arcsec beyond the northern limb of the nebula. Our 3D reconstructions confirm and geometrically resolve a cavity at the jet's base that was suggested by earlier kinematic studies, establishing a direct physical connection between the filamentary network and the jet funnel. The morphology and kinematics indicate that the early pulsar wind nebula (PWN) played a central role in forming the jet. Several formation scenarios, which are not necessarily mutually exclusive, remain viable, including a bipolar outflow shaped by a circumstellar disk, a breach or underdensity in the ejecta shell, and a pre-existing progenitor mass-loss trail acting as a low-density channel. Collectively, these scenarios exhibit differing abilities to account for the jet's pronounced collimation, the absence of a southern counterpart, and its near-ballistic motion. Discriminating among them will require fully three-dimensional hydrodynamic simulations that trace the remnant's evolution from the progenitor phase through late-time PWN expansion.
Read the full abstract

All authors Ziwei Ding, Dan Milisavljevic, Thomas Martin, Tea Temim, John C.Raymond, Soham Mandal, Laurent Drissen

Cosmology and Nongalactic Astrophysics

Cutting with precision – Leveraging Collapse Volumes to generate the next generation of zoom-in initial conditions

Benjamin Seidel, Klaus Dolag and Jenny G. Sorce

Astrophysical processes happen across a wide range of scales. This poses a significant challenge from the perspective of modeling these processes. Modern cosmological simulations attempt to maximize the simulation volume to capture the full range of the density power spectrum while simultaneously optimizing spatial resolution for improved modeling of dynamics at galactic scales. Performing zoom-in simulations of galaxy clusters is a way to reconcile computational cost, mass resolution, and large-scale realism in simulations. To study the baryonic evolution of structures it is critical to ensure that the volume of interest is uncontaminated by high-mass particles from outside the zoom-in region. We introduce a new method of constructing stable boundaries for layered zoom-in initial conditions. Applying this method to clusters from the SLOW constrained simulation, we introduce the SLOW cluster zoom-in initial conditions. We select regions using a forward run of a gravity-only version of the parent box. We performed test simulations for a set of 20 regions created from the SLOW constrained simulations containing 30 local clusters. The simulations demonstrate these initial conditions to be stable against deformation and mixing of the boundary region. Consequently, they are uncontaminated to an unprecedented degree, reaching pristine regions of sizes exceeding 6 virial radii. These simulations will provide the basis for the first high-resolution simulations of a large set of directly comparable local galaxy cluster analogues and their environment to date. Their high fidelity in terms of stability and resolution in combination with the accuracy of the underlying local Universe model makes these simulations the first of their kind. They will enable comparisons with state-of-the art observations targeting both cluster properties and ICM physics as well as galaxy evolution in the local Universe.
Read the full abstract

Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph

Magnetic monopole plasma oscillations and implications for TeV blazars

Mariia Khelashvili, Takeshi Kobayashi and Andrew J. Long

Magnetic monopoles arise in many beyond Standard Model scenarios, symmetrize Maxwell's equations, and their existence would be tied to the quantization of electric charge. It has been argued that, when placed in an astrophysical magnetic field, monopoles can induce a magnetic version of plasma oscillations. In this work, we explore monopole-induced oscillations of the intergalactic magnetic field (IGMF). We show that monopole-induced oscillations of the magnetic field lead to collimation of electrically charged particle trajectories, reducing the usual deflection by the magnetic field. The collimation effect impacts the deflection angle in the electromagnetic cascades of TeV blazars and leads to a decrease in the angular size of blazar secondary GeV halos. Therefore, the constraints on the secondary halo angular size from combined H.E.S.S. and Fermi-LAT observations translate into bounds on the magnetic monopole abundance. The bounds on the magnetic monopole flux obtained in this work from blazar 1ES 0229+200, depending on the IGMF strength, can be as strong as $F \lesssim 6 \times 10^{-23}\, \text{cm}^{-2} \text{s}^{-1} \text{str}^{-1}$ for low-mass monopoles $m \lesssim 10^6\, \text{GeV}$, stronger than existing laboratory and astrophysical bounds. The bound becomes subdominant to current constraints if the present-day IGMF value is stronger than $B \gtrsim 10^{-12}\, \text{G}$. At the same time, in the case of non-zero monopole abundance, the IGMF lower bound from TeV observations itself should be revised, resulting in a stronger lower bound at higher monopole number density.
Read the full abstract

Astrophysics of Galaxies · Cross-listed from physics.data-an

Interpreting "Interpretability" and Explaining "Explainability" in Machine Learning in Physics

Rikab Gambhir, Luisa Lucie-Smith and Jesse Thaler

We review the concepts of interpretability and explainability as they apply to machine learning in physics. We define interpretability as concerning the structural transparency of a model (the ability to understand or approximate its inner workings) and explainability as concerning the scientific content of a model (the ability to map it onto domain knowledge). We discuss the trade-offs each entails (interpretability vs. expressivity; explainability vs. adaptability), the contexts in which each is needed, and the intrinsic and post-hoc tools available for achieving them. Throughout, we emphasize that machine-learned models are subject to the same scientific questions as classical models, differing only in scale, and that interpretability and explainability are best understood as deliberate modeling choices rather than inherent properties. We also emphasize the importance of task specification and intervention plans as a core aspect of model design.
Read the full abstract

Astrophysics of Galaxies

Latent thermal instability

Prakriti Pal Choudhury and Archie F. A. Bott

Multiscale temperature fluctuations are abundant in the intracluster medium (ICM) outside of galaxy cluster cores ($\sim 100~{\rm kpc}$). Their origin is often attributed to turbulent stirring by subhalos or accreting baryons crossing the virial radius. However, their apparent resistance to mixing and thermal conduction in a collisional medium has not been explained. We propose a new mechanism by which steady-state temperature fluctuations can form and persist outside the cluster core. Local thermal instability, or Field instability, is used to explain filamentary condensates in cluster cores but is usually dismissed outside them because thermal conduction should suppress instability. In weakly collisional or collisionless plasmas, however, thermal conduction can be anomalously suppressed by heat-flux-driven plasma instabilities triggered in presence of a local magnetic field, leading to two effects: (i) condensates form in a new parameter regime that overlaps with conditions outside the core, and (ii) condensates reach a steady state as in the hydrodynamic limit. This extends the regime of instability-driven fluctuations to over $\gtrsim50\%$ (depending on hot plasma temperature) of the cluster. We use one-dimensional hydrodynamic simulations of condensates to test our analytical ideas.
Read the full abstract

Cosmology and Nongalactic Astrophysics

Cross-correlation of SPT-3G D1 CMB lensing and DES Y3 galaxy lensing

A. Ouellette, Y. Omori, E. Anderes et al. (+92 more)

Measurements of the weak lensing of galaxies and of the cosmic microwave background (CMB) provide direct probes of the cosmic matter density field, but the two observables are sensitive to different spatial scales, redshift ranges, and survey systematics. Their cross-correlation thus enables consistency checks of the theoretical model and of potential systematics in either dataset. We present measurements of the cross-correlation between CMB lensing and cosmic shear over $\sim$1,300 deg$^2$ of the sky using the SPT-3G D1 CMB lensing maps and the Dark Energy Survey Year 3 (DES Y3) shear catalogs. For the first time, we measure this cross-correlation at high significance ($\sim 14\sigma$) when using a polarization-only CMB lensing reconstruction that is expected to be robust against biases induced by extragalactic foregrounds. We test a variety of other CMB lensing estimators that include temperature information and exhibit different tradeoffs between foreground biases and noise, as well as a shear sample that consists of blue, star-forming galaxies and has been shown to be less impacted by galaxy intrinsic alignments. Assuming $\Lambda$CDM and marginalizing over uncertainties in intrinsic alignments, baryonic feedback, and various nuisance parameters, we obtain a constraint on the amplitude of matter clustering $S_8 \equiv \sigma_8 \sqrt{\Omega_m / 0.3} = 0.833^{+0.047}_{-0.061}$, consistent with both the primary CMB results from Planck and shear-only results from DES Y3. By combining our measurement with Planck, we find mild constraints on the astrophysical processes that impact the cross-correlation. We obtain a constraint on the intrinsic alignment amplitude of the DES sample that is competitive with that from shear-only analyses, and we find a lower limit on the strength of baryonic feedback.
Read the full abstract

All authors A. Ouellette, Y. Omori, E. Anderes, A. J. Anderson, B. Ansarinejad, M. Archipley, L. Balkenhol, D. R. Barron, K. Benabed, A. N. Bender, B. A. Benson, F. Bianchini, L. E. Bleem, S. Bocquet, F. R. Bouchet, E. Camphuis, M. G. Campitiello, J. E. Carlstrom, J. Carron, C. Chang, C. L. Chang, P. M. Chichura, A. Chokshi, T.-L. Chou, A. Coerver, T. M. Crawford, C. Daley, T. de Haan, K. R. Dibert, M. A. Dobbs, M. Doohan, D. Dutcher, C. Feng, K. R. Ferguson, N. C. Ferree, K. Fichman, A. Foster, S. Galli, A. E. Gambrel, A. K. Gao, F. Ge, F. Guidi, S. Guns, N. W. Halverson, E. Hivon, G. P. Holder, W. L. Holzapfel, J. C. Hood, A. Hryciuk, N. Huang, T. Jhaveri, F. Kéruzoré, A. R. Khalife, L. Knox, K. Kornoelje, C.-L. Kuo, K. Levy, Y. Li, A. E. Lowitz, C. Lu, G. P. Lynch, T. J. Maccarone, A. S. Maniyar, E. S. Martsen, F. Menanteau, M. Millea, J. Montgomery, Y. Nakato, T. Natoli, Z. Pan, P. Paschos, K. A. Phadke, A. W. Pollak, K. Prabhu, W. Quan, M. Rahimi, A. Rahlin, C. L. Reichardt, M. Rouble, J. E. Ruhl, A. C. Silva Oliveira, A. Simpson, J. A. Sobrin, A. A. Stark, J. Stephen, C. Tandoi, C. Trendafilova, J. D. Vieira, A. G. Vieregg, A. Vitrier, Y. Wan, N. Whitehorn, W. L. K. Wu, M. R. Young, J. A. Zebrowski

Solar and Stellar Astrophysics

Connecting Stellar Population Surveys to Stellar Evolution with Delay-time Distributions: Application to LMC Classical Cepheids

Sumit K. Sarbadhicary

The progenitors of many stellar-origin phenomena such as supernovae, evolved giants and supergiants, planetary nebulae, AGB stars and other post-main-sequence exotica remain poorly understood due to stellar evolution uncertainties such as mass-loss, binary evolution, rotation, mixing, and overshooting. A promising technique for investigating stellar progenitor scenarios with resolved stellar population surveys of galaxies is the delay-time distribution (DTD). Given a survey of stellar phenomena of interest, the DTD extracts the progenitor age distribution and production rates of the phenomena from star-formation history (SFH) maps of galaxies. Here we test the potential of DTDs as a stellar evolution diagnostic by applying to stars with known ages – Classical Cepheids in the LMC. We use the high-completeness OGLE-IV survey of Cepheids, and LMC SFH maps from optical and near-infrared surveys. The measured DTDs from optical SFH maps show significant detections at ages of 20-200 Myr for FU Cepheids, and 125-200 Myr for FO Cepheids. These are consistent with independently measured ages from the period-age-color relations, with the DTD peak being more consistent with relations from non-canonical models that include effects of overshooting, rotational mixing etc. An outlier population of 0.5-0.8 Gyr of FU Cepheids is also detected in the DTD, though its veracity is debatable given the brightness and pulsation periods of FU Cepheids, and because the signal is not recovered with DTDs derived from near-infrared SFH. For upcoming surveys (e.g. with Roman), DTDs of stars with well-constrained progenitors such as Cepheids and RR Lyrae can provide independent verification of the derived SFHs.
Read the full abstract

Astrophysics of Galaxies

Dark Matter in Draco and Boötes I: Hints of a Core in an Ultra-Faint Dwarf from Simulation-Based Inference

Tri Nguyen, Lina Necib, Ting S. Li et al. (+8 more)

The density profiles of dwarf spheroidal galaxies are among the most sensitive probes of dark matter physics, yet extracting them from noisy stellar kinematics remains a fundamental obstacle. We present GraphNPE, a simulation-based inference method for dynamical mass modeling that incorporates measurement uncertainties and spectroscopic selection functions in the forward model. Using mock data, we show that methods relying solely on line-of-sight velocity dispersion are biased toward cuspy density profiles, even in the absence of the mass-anisotropy degeneracy. By accessing higher-order velocity moments, particularly line-of-sight kurtosis, GraphNPE breaks key degeneracies and recovers density profiles with substantially less bias. We apply GraphNPE to Draco and Boötes I using MMT/Hectochelle and DESI for Draco, and the S5 survey for Boötes I. For each, we report density profiles and dark matter $J$- and $D$-factors. For Draco, GraphNPE yields consistent results across datasets, marginally preferring a cuspy inner profile ($\rho_{150} \sim 1.6-1.9 \times 10^8\,\mathrm{M}_\odot\,\mathrm{kpc}^{-3}$) in agreement with literature. On DESI, however, second-order Jeans modeling fits the dispersion but fails to reproduce the kurtosis, demonstrating higher-order moments are essential. For Boötes I, limited statistical power prevents definitive determination of the inner slope. GraphNPE recovers $\rho_{150} = 0.36^{+0.15}_{-0.11} \times 10^8\,\mathrm{M}_\odot\,\mathrm{kpc}^{-3}$, significantly lower than literature and consistent with a cored inner profile. This places Boötes I among the lowest density dwarfs at comparable stellar masses.
Read the full abstract

All authors Tri Nguyen, Lina Necib, Ting S. Li, Justin Read, Andrés Bañares-Hernández, Claude-André Faucher-Giguère, Kohei Hayashi, Kevin McKinnon, Andrew B. Pace, Nathan R. Sandford, Hao Yang