Astrophysics of Galaxies
An Off-Nuclear Tidal Disruption Event Discovered At Late Times: The Case Of TDE 2023mfm
Itai Sfaradi, Ryan Chornock, Yuhan Yao et al. (+24 more)
We present the discovery and analysis of the optically selected tidal disruption event (TDE) 2023mfm, which originates from a wandering massive black hole (MBH) in a massive ($\sim 10^{11} \,$M$_{\odot}$)
galaxy hosting a central low-luminosity active galactic
nucleus (AGN). Our analysis of the ZTF, Lick, Keck, Swift, Chandra, XMM-Newton, HST, and VLA observations reveals that TDE 2023mfm is a TDE-H from a $10^{6.2 \pm 0.5}\,$M$_{\odot}$ black hole which is offset by $0.66 \pm 0.02$" from the center of its host
galaxy, corresponding to a projected distance of $1.08 \pm 0.04$ kpc. TDE 2023mfm displays all the traits of optically selected TDEs. The emission remains hot, $T_{\rm bb} \sim 22,000 \pm 1,000$ K, for more than a month after peak, and the $g$-band light curve peaks at $\left( 2.24^{+0.10} _{-0.11} \right) \times 10^{43} \, \rm erg \, s^{-1}$ and stays above half-maximum luminosity for $47.8^{+3.7}_{-3.5}$ days. The late-time optical-to-UV emission observed with the HST suggests the presence of an unresolved stellar population with a stellar mass of $10^7-10^8\,$M$_{\odot}$ at the position of the TDE, possibly being a low-mass dwarf
galaxy or a stripped
galaxy from a previous minor merger. The
radio emission from TDE 2023mfm emerges at least a year after optical discovery, and we find it likely that it originates from a delayed outflow, however, further observations are needed to determine its true origin.
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All authors Itai Sfaradi, Ryan Chornock, Yuhan Yao, Erica Hammerstein, Jean Somalwar, Raffaella Margutti, Huei Sears, Robert Stein, Natalie LeBaron, Adelle J. Goodwin, Sjoert van Velzen, Matthew J. Graham, Kate D. Alexander, Nayana A. J., Edo Berger, Jonathan Carney, Yvette Cendes, Collin T. Christy, Walter W. Golay, Wenbin Lu, James C. A. Miller-Jones, Charlotte Ward, Eli Wiston, Tracy X. Chen, Mansi M. Kasliwal, Frank J. Masci, Jesper Sollerman
Astrophysics of Galaxies
A Systematic Assessment of Total Stellar Mass Measurements with Spatially Resolved Photometry and Medium Bands at 1 < z < 9: The Impact of Mass-to-Light Variations and Outshining
Naadiyah Jagga, Adam Muzzin, Visal Sok et al. (+16 more)
JWST NIRCam spatially resolved photometry enables studies of
galaxies' stellar populations and stellar masses on sub-kpc scales. We use JWST (CANUCS, Technicolor, JUMPS) and HST data, covering wide- and medium-band UV-IR filters to study the stellar mass bias between spatially resolved and integrated photometry of $\sim$3000
galaxies at 1 $<z_{\mathrm{phot}}<$ 9. The 2D parameter maps reveal spatial variations in stellar mass and populations, showing that integrated measurements systematically underestimate stellar masses. We find that the stellar mass bias remains small for
galaxies with specific
star formation rate $\mathrm{sSFR} < 10^{\mathrm{-9}}$ yr$^{\mathrm{-1}}$, but increases for
galaxies with $\mathrm{sSFR} > 10^{\mathrm{-8.5}}$ yr$^{\mathrm{-1}}$. For these high-sSFR
galaxies, the median offset reaches $\Delta \log_{\mathrm{10}} (M_{\ast})$ $\sim$ -0.36 dex with the largest bias occurring in low-mass ($M_{\ast} \leq 10^{\mathrm{ 9.5}} M_{\odot}$)
galaxies. These results are consistent with the outshining of older populations by recent
star formation. High-sSFR
galaxies also show spatial variations in their mass-to-light ratios ($M_{\ast}/L_{V}$): the stellar mass bias decreases with $\sigma[\log_{\mathrm{10}}(M_{\ast}/L_{V})]$ for
galaxies with $10^{\mathrm{-8}} \leq \mathrm{sSFR}[\mathrm{yr}^{\mathrm{-1}}] < 10^{\mathrm{-9}}$, with the strongest trend for $10^{\mathrm{-7}} \leq \mathrm{sSFR}[\mathrm{yr}^{\mathrm{-1}}] < 10^{\mathrm{-8}}$, quantified by the Spearman correlation coefficient $\rho_{\rm S}=-0.37$. While medium bands are important for constraining stellar masses from integrated photometry, spatially resolved photometry reduces the impact of their absence, with dispersion offsets of $\Delta \log_{\mathrm{10}} (M_{\ast})$ = 0.33 dex for integrated photometry but 0.15 dex for resolved photometry when only wide-bands are included.
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All authors Naadiyah Jagga, Adam Muzzin, Visal Sok, Vivian Yun Yan Tan, Ghassan Sarrouh, Kartheik Iyer, Yoshihisa Asada, Chris J. Willott, Maruša Bradač, Nicholas S. Martis, Gaël Noirot, Gregor Rihtaršič, Marcin Sawicki, Sunna Withers, Jacqueline Antwi-Danso, Samantha C Berek, Danilo Marchesini, Maya Merchant, Katherine Myers
High Energy Astrophysical Phenomena
Bayesian Evidence for Inspiraling Hotspot Motion in the Galactic Center
Pablo Ruales, Maciek Wielgus, Delilah E.A. Gates et al. (+1 more)
During flaring episodes, polarimetric observations of the Galactic Center black hole Sagittarius A* (Sgr A*) reveal evolving, loop-like trajectories in the Stokes Q-U plane, the so-called Q-$U loops. Keplerian models of transiently energized orbiting features, hotspots, have been employed to reproduce these polarimetric signatures. In this work, we develop a
Bayesian framework to infer the time-dependent kinematics of the hotspot from polarized light curves, using a general prescription for its motion. We model the emitting region's trajectory as a continuous, piecewise sequence of K kinematic segments, each described by radial and azimuthal velocity parameters. We perform analyses with K=1,2,3 and compare these models to millimeter-wavelength ALMA observations of Sgr A* from 2017 April 11 that include two subsequent Q-U loops, extending the observational constraints on the kinematics. We examine the effects of the local
magnetic field geometry, spectral index, and kinematic profile of the hotspot's trajectory on the polarized signal. We find statistically significant evidence that the emitting region follows a non-geodesic inspiraling trajectory, and this preference over a strictly Keplerian orbit strengthens sharply when a longer data segment is modeled. The inspiraling non-Keplerian models are preferred to a purely Keplerian model based on both the
Bayesian log-evidence comparison and the reduced chi-square statistic. Our results offer new insight into the nature of flaring events in the Galactic Center and the episodically produced hotspots associated with them.
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All authors Pablo Ruales, Maciek Wielgus, Delilah E.A. Gates, Alejandro Cardenas-Avendano
High Energy Astrophysical Phenomena
Hierarchical Bayesian Inference on the intrinsic event rate of Type I gamma-ray bursts from the Fermi/GBM catalogue
Cao Tian-Yong, Yi Shu-Xu, Du Yun-Fei et al. (+2 more)
The intrinsic event-rate of Type I gamma-ray bursts (GRBs) as a function of
redshift, provides a probe for binary
neutron star (BNS) mergers population. However, the above-mentioned inference is complicated by instrumental selection effects, the lack of
redshift measurements for the majority of GRBs, and uncertainties in jet geometry. In this work, we applied a hierarchical
Bayesian inference framework to the Fermi/GBM Type I GRB catalogue to reconstruct the underlying event-rate population. This framework accounts for the selection effects and marginalizes over the limited-information posteriors of individual GRB
redshifts and jet structures. The population model uses parameterized luminosity function, distribution of jet structure parameters, the Madau-Dickinson
star-formation rate and a delay-time distribution of BNS mergers. The posterior distribution of the hyperparameters in the model are to be inferred, using a GPU-accelerated MCMC
algorithm. The intrinsic event rate density as function of
redshift is constrained up to $z=5$, which a local rate density of \(R_0 = 22.6^{+15.0}_{-10.6}\,{\rm Gpc^{-3}\,yr^{-1}},\), which is consistent with the latest gravitational-wave measurements.
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All authors Cao Tian-Yong, Yi Shu-Xu, Du Yun-Fei, Yorgancioglu S. Emre, Xiong Shao-Lin
Astrophysics of Galaxies
CHAMPS: The COSMOS High-Redshift ALMA-MIRI Population Survey - A New Census of the Dusty Early Universe
Andreas L. Faisst, Felix Martinez III, Jeyhan S. Kartaltepe et al. (+86 more)
Understanding how dust forms and evolves over
cosmic time is a key open problem in extragalactic astrophysics.
Galaxies in the early Universe were once thought to be mostly dust-poor, but recent discoveries of heavily dust-obscured
galaxies near the Epoch of Reionization challenge models of early dust production and raise new questions about the true
cosmic star formation rate density. In this paper, we present the COSMOS High-
Redshift ALMA-MIRI Population Survey (CHAMPS), which sheds light on the dusty early universe at z>4. CHAMPS is a new 144h ALMA 1.2mm (band 6) large program mapping the combined JWST/NIRCam+MIRI footprint in the COSMOS field. It covers 0.2deg2 with a synthesized beam size of 1.1" and a sensitivity of 0.14mJy/beam. It is complemented, alongside JWST, by ancillary X-ray, UV, optical, sub-mm, and
radio data. CHAMPS, optimized as a blind survey, detects above 5$\sigma$ approximately 385 individual dusty high-
redshift sub-mm sources, 68 dusty AGN, and a dozen dusty
galaxies at z>6. The
galaxies are largely not detected in JWST/F150W, making them prototypical near-IR dark
galaxies. We showcase three of the highest-
redshift most dusty and massive candidate
galaxies detected in CHAMPS with
redshifts up to z=7.5. CHAMPS also enables stacks of thousands of
galaxies grouped in bins of various physical parameters. Its sub-mm coverage of dust-attenuated JWST-identified
galaxies provides robust constraints on dust masses and obscured
star formation rates to study early dust formation and
evolution. In addition, CHAMPS enables a blind search for luminous CO line emitters at z=0.4-2.7 and [CII]158$\mu$m emitters at z=6.7.
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All authors Andreas L. Faisst, Felix Martinez III, Jeyhan S. Kartaltepe, Manuel Aravena, Caitlin M. Casey, John D. Silverman, Sune Toft, Ezequiel Treister, Jorge A. Zavala, Hiddo S. B. Algera, Andrew J. Battisti, Michele Catone, Jaclyn B. Champagne, Yingjie Cheng, Rasha M. Samir, Maximilien Franco, Kyle Finner, Carter Flayhart, Fabrizio Gentile, Ghassem Gozaliasl, Santosh Harish, Shuowen Jin, Yu-Heng Lin, Lun-Jun Liu, Arianna S. Long, Crystal L. Martin, Bahram Mobasher, Francesca Pozzi, Huimin Qu, Chuan Tian, Mattia Vaccari, Wuji Wang, Can Xu, Hollis B. Akins, Micaela B. Bagley, Angela Bongiorno, Kevin C. Cooke, Olivia R. Cooper, Simon Hempel-Costello, Ivan Delvecchio, Nicole E. Drakos, Andrea Enia, Steven L. Finkelstein, Seiji Fujimoto, Steven Gillman, Carlos Gomez-Guijarro, Jorge Gonzalez-Lopez, Michaela Hirschmann, Olivier Ilbert, Kei Ito, Knud Jahnke, Boris S. Kalita, Daichi Kashino, Vasily Kokorev, Thomas S.-Y. Lai, Erini Lambrides, Daizhong Liu, Georgios E. Magdis, Vincenzo Mainieri, Sinclaire M. Manning, Claudia Maraston, Richard Massey, Henry Joy McCracken, Jed McKinney, Wilfried Mercier, Thibaud Moutard, Masafusa Onoue, Louise Paquereau, Alvio Renzini, Jason Rhodes, R. Michael Rich, Brant E. Robertson, Giulia Rodighiero, David B. Sanders, Claudia M. Scarlata, Nick Scoville, Kartik Sheth, Marko Shuntov, Laura Sommovigo, Martin Sparre, Tomoko L. Suzuki, Margherita Talia, Benny Trakhtenbrot, Francesco Valentino, Brittany N. Vanderhoof, Eleni Vardoulaki, Aswin P. Vijayan, Katherine E. Whitaker, Stephen M. Wilkins
Cosmology and Nongalactic Astrophysics
Enhanced density fluctuations: consequences for stellar dynamics and dark matter substructure
Wenzer Qin, David E. Kaplan and Neal Weiner
Enhanced density fluctuations form early dark matter
halos, which serve as early gravitational potential wells for baryons. These baryons can then condense to form
stars and black holes at high
redshifts, $1+z \gtrsim 100$. Larger density fluctuations result in denser
halos with higher virial temperatures; hence, a
halo at a mass that is below the threshold for forming
stars under standard astrophysical expectations may form astrophysical objects if its initial density is higher than expected, although the exact threshold for compact object formation is subject to large astrophysical uncertainties. We outline the conditions under which enhanced density fluctuations form dark (
star-less)
halos, early
galaxies, or even
star clusters. Using toy model enhancements to the primordial power spectrum that have been shown to explain the abundances of “little red dots", along with our fiducial set of astrophysical parameters, we show that the number of clusters initially captured by the Milky Way is highly sensitive to the shape of the enhancement, with the narrowly peaked enhancement resulting in $50$ clusters and the step-function enhancement resulting in $\sim 4.1 \times 10^5$. The initial stellar masses of the clusters is also $O (100) \,M_\odot$, although this range is also dependent on the shape of the enhancement. In addition, the abundance of dark matter subhalos with masses greater than $10^7 \, M_\odot$ can be enhanced by as much as a factor of $\sim 6.5$ and is denser than in $\Lambda$CDM, which will increase their detectability in future stellar stream surveys such as the Via Project.
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Instrumentation and Methods for Astrophysics
Divergence-free magnetohydrodynamics on a moving mesh
Volker Springel, Alexander C. Mayer and Rüdiger Pakmor
Magnetic fields are ubiquitous in the Universe and play an important role in many astrophysical processes, such as
star formation and the
evolution of
galaxies. Hydrodynamical simulation methods that account for ideal magnetohydrodynamics (MHD) are however challenged by the need to achieve numerical stability and physical consistency. Both can be compromised by the occurrence of non-vanishing local divergence errors in the
magnetic field. Different approaches to either eliminate or reduce these discretization errors are in widespread use, including constrained transport or divergence cleaning techniques. However, thus far a divergence-free Galilean invariant formulation of MHD that can be readily applied in Lagrangian codes has been an elusive goal. Here we revisit the use of the vector potential for evolving the
magnetic field on an unstructured moving-mesh and show how a particular gauge choice combined with a suitably discretized integration scheme provides a stable and accurate formulation of MHD. Our method combines a finite-difference
evolution of a
cell-centred vector potential with a finite volume representation of the other fluid quantities, and is realized in the moving-mesh code AREPO. The new approach is fully Galilean invariant and therefore shows vanishing errors for classic problems such as field loop advection. We demonstrate good accuracy and stability when our scheme is applied to various test problems and to practical applications in 3D, including when local timesteps and adaptive mesh refinement and derefinement are used.
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Cosmology and Nongalactic Astrophysics
Satellite stellar-to-halo mass relations in primordial black hole universes
Patricio Colazo, Nelson Padilla and Federico Stasyszyn
Primordial black holes (PBHs), in particular with a fixed-conformal-time (FCT) extended mass function, can modify small-scale structure through enhanced primordial power and discreteness-driven Poisson fluctuations, altering subhalo abundances and internal structure. We study their effects on satellite stellar-to-
halo mappings, bound-remnant compactness, and the link to compact dark perturbers. We compare two dark-matter-only simulations, a fiducial CDM run and an FCT/PBH run. As these runs form no
galaxies, we construct an approximate abundance-based stellar-to-
halo mapping using the progenitor virial mass at last isolation. The CDM mapping is anchored to a
redshift-dependent abundance-matching stellar-to-
halo relation, and the FCT mapping is derived from the relative cumulative subhalo abundances. We use resolved SOAP (V_max) and (R_max) to characterize present-day subhalo compactness, supplemented by a subgrid estimate of mass segregation in the unresolved PBH population. FCT enhances the subhalo abundance in a mass-dependent way, but abundance-based stellar-mass reassignment makes satellite stellar-mass functions weak discriminants. Internal structure is a stronger test: FCT subhaloes are more compact and have larger NFW-reconstructed enclosed masses at fixed radius, strengthening a Too-Big-To-Fail-like tension if all compact subhaloes host luminous satellites. FCT subhaloes also form earlier, accounting for much of the low-mass compactness difference, while PBH mass segregation adds a central perturbation with typical \mu ~ 0.4-0.5. Neither effect fully explains the resolved FCT compactness enhancement. Changes in the
galaxy–
halo mapping can partly hide the enhanced FCT subhalo abundance in satellite counts, whereas internal dynamics remain more discriminating. Satellite abundances, dynamics, and compact dark perturbers are complementary probes of PBH-induced small-scale structure.
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Astrophysics of Galaxies
COSMOS-3D: Diverse Environments and Hot-dust Signatures among Dusty Star-forming Galaxies at $z$ = 4.9-7.2
Siwei Zou, Manuel Aravena, Shaoze Geng et al. (+20 more)
Dusty
star-forming
galaxies (DSFGs) are expected to trace early massive-
halo assembly, but the connection between dust-obscured
star formation, morphology, hot dust, and environment remains unclear at $z$>4. We combine JWST/NIRCam F444W grism spectroscopy from COSMOS-3D with MIRI F1000W/F2100W imaging and a mixed ALMA-selected and ALMA-followed dusty-
galaxy sample from CRISTAL, CHAMPS, REBELS, and A3COSMOS to study 18 DSFGs or DSFG candidates at z=4.9-7.2. We compare their environments with the parent spectroscopically confirmed emission-line sample and the COSMOS-Web photo-z
galaxy sample using separate and combined overdensity
estimators. The parent narrow-line H$\alpha$ sample has a median observed, dust-uncorrected ${\rm SFR}_{\rm H\alpha}=11.7 M_\odot~{\rm yr^{-1}}$. Within R=0.5 pMpc, DSFGs have a median $\delta_{\rm spec+phot}=0.92^{+0.06}_{-0.16}$, compared with $0.80^{+0.05}_{-0.04}$ for HAEs, with a stronger contrast on smaller scales. The strongest compact overdensities are associated with merger/interacting morphology: merging DSFGs reach $\delta_{\rm spec+phot}=4.70^{+1.61}_{-1.51}$ within R=0.5 pMpc. In contrast, MIRI-bright DSFGs do not show an enhanced number of nearby visible H$\alpha$-emitting companions, and their F2100W fluxes are difficult to explain with the 3.3 $\mu$m PAH feature alone, suggesting an additional hot-dust component. These results are consistent with a possible phase-dependent picture in which the compact line-emitter core, merger-driven dusty phase, and MIRI-bright hot-dust phase need not be spatially or temporally identical during early structure growth.
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All authors Siwei Zou, Manuel Aravena, Shaoze Geng, Romain A. Meyer, Jianwei Lyu, Jaclyn B. Champagne, Jia-Sheng Huang, Andreas L. Faisst, Shuqi Fu, Andrew J. Battisti, Hiddo Algera, Caitlin M. Casey, Xiaohui Fan, Maximilien Franco, Ghassem Gozaliasl, Linhua Jiang, Koki Kakiichi, Darshan Kakkad, Zihao Li, Lun-Jun Liu, Felix Martinez III, Jorge A. Zavala, Rasha M. Samir
Instrumentation and Methods for Astrophysics
Improved Modeling for Moving Sources of Radio Frequency Interference and Impact on Flagging Strategies
Jade M. Ducharme, Jonathan C. Pober and Michael J. Wilensky
Radio frequency interference (RFI) is a major challenge for low-frequency
radio experiments targeting the redshifted 21-cm signal from the Epoch of Reionization. Many important RFI sources, including aircraft and satellites, move across the sky during an observation. The averaging of visibilities for such moving sources over a finite correlator integration produces a distinct sinc-like pattern in the interferometric uv-plane, causing the RFI to appear bright on some baselines and strongly suppressed on others. Here, we develop an analytical model for this effect and validate its qualitative behavior against real MWA observations and numerical simulations. Controlled RFI injections into clean MWA data are then used to compare several flagging treatments in the context of EoR power spectrum recovery. These treatments explore the trade-off between per-baseline flagging, which can miss weak but potentially non-negligible contamination on baselines where the integration effect leads to strong suppression, and baseline-aggregated flagging, which removes more faint residual contamination but reduces the total number of usable uv-modes. We find that the preferred strategy depends on RFI brightness and occupancy, but that flagging all frequencies at contaminated time-steps most consistently minimizes excess power for bright or frequent events. However, none of the tested flagging treatments fully recovers the uncontaminated reference spectrum, motivating future work on direct modeling and subtraction of moving RFI sources.
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Solar and Stellar Astrophysics
The long period radio transient ASKAP J1448-68 is a cataclysmic variable
Geoffrey Mo, Akash Anumarlapudi, Iris de Ruiter et al. (+8 more)
Wide-field time-domain
radio surveys have recently unveiled a new class of Galactic
radio emitter: long period
radio transients (LPTs). Despite the rapid pace of discovery, their origins remain poorly understood, with two main theories emerging: slowly spinning magnetars or binary white dwarfs (WDs) with
magnetic interactions. All three LPTs with well-characterised optical counterparts are WDs in binary systems, but even within that class there is diversity, with one accreting and two detached systems. In this Letter, we show that the LPT ASKAP J1448-68 is a cataclysmic variable (CV)—a WD accreting from a low-mass companion—with a spectroscopic orbital period consistent with the
radio pulse period, and specifically, potentially consistent with being a polar. Unlike the other known LPT CV, ASKAP J1448-68 does not exhibit the He II emission that is a hallmark of
magnetic CVs in their high
accretion states. We also present new optical time-series and infrared photometric observations, showing flickering at the 10% level and suggesting a possible period bouncer origin. This identification of ASKAP J1448-68 adds to the small sample of characterised LPT counterparts, and shows that LPTs can arise from WD binaries with a range of
accretion states.
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All authors Geoffrey Mo, Akash Anumarlapudi, Iris de Ruiter, Kareem El-Badry, David L. Kaplan, Antonio C. Rodriguez, Ilaria Caiazzo, Kaitlyn Shin, Anthony L. Piro, Tim Cunningham, Daniel D. Kelson
Earth and Planetary Astrophysics
Toddlers in Resonance I: low masses and eccentricities of the 17 Myr giant planets HIP 67522 bc from transit timing variations
Hannah R. James, Madyson G. Barber, Andrew W. Mann et al. (+28 more)
Infant ($<$100\,Myr) transiting
planet systems provide glimpses into the processes that shape the observed mature
planet population. Masses for these
planets are powerful data points for testing theories of
planet formation and
evolution. Because young systems tend to be in mean-motion resonances (MMR) and show higher rates of transit timing variations (TTVs), we can take advantage of deviations in the expected versus observed transit timings due to gravitational interactions between the
planets to determine the planetary masses and orbital eccentricities. Here we report the TTV analysis of HIP\,67522, a 17\,Myr two-
planet system near a 2:1 orbital resonance. The analysis is based on 55 transit observations (50 epochs) of
planet b and 29 transit observations (22 epochs) of
planet c, taken across 11 facilities. Assuming circular orbits, we determine masses of $M_b=25.0^{+7.6}_{-7.8}M_\oplus$ and $M_c=11.2\pm1.4M_\oplus$. Allowing for eccentric orbits, we find $M_b=23.1^{+15.4}_{-12.4}M_\oplus$ and $M_c=11.8^{+3.0}_{-2.3}M_\oplus$, and low eccentricities ($<0.1$) for both
planets. Adopting a Gaussian prior on $M_b$ from the JWST transmission spectrum tightens the eccentric-solution mass for
planet c to $9.7^{+1.9}_{-1.6}M_\oplus$, which is our recommended solution. The low masses and large radii are consistent with a contracting atmosphere
planet formation model, such as Gas Dwarf formation. Given the challenge of radial-velocity masses and the high rate of TTVs seen in young systems, TTV-masses will be essential for testing theories of the formation and
evolution of super-Earths and sub-Neptunes and determining the conditions that create the most common types of
planets in the
Galaxy.
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All authors Hannah R. James, Madyson G. Barber, Andrew W. Mann, Pa Chia Thao, Adam L. Kraus, Benjamin M. Tofflemire, Andrew Vanderburg, Lyu Abe, Tristan Guillot, Olga Suarez, Djamel Mekarnia, Amaury H. M. J. Triaud, Vincent Deloupy, Mayuko Mori, Jerome P. de Leon, Norio Narita, Akihiko Fukui, John H. Livingston, George Zhou, Camille M. L. Guenée, Juliette Becker, Ana Isabel Lopez Murillo, Karen A. Collins, Richard P. Schwarz, Chris Stockdale, Thiam-Guan Tan, Keith Horne, Leah J. Boff, Mackenna L. Wood, Nidia Morrell, Luke G. Bouma
Cosmology and Nongalactic Astrophysics
JWST lensed quasar dark matter survey V: Hints of self-interacting dark matter from 29 quadruply imaged quasars
D. Gilman, A. M. Nierenberg, J. Gurian et al. (+21 more)
Theories of self-interacting dark matter (SIDM) predict the eventual core collapse of dark matter
halos, a process that transforms these structures into extremely efficient gravitational lenses. We present a population-level inference on the abundance of core collapsed
halos and subhalos in the mass range $10^6 - 10^{10.7} M_{\odot}$ using 29 quadruply imaged
quasars, drawing on the collective
lensing signal of many low-mass perturbers. Our structure formation model predicts the abundance of collapsed (sub)
halos as a function of
halo mass and
redshift. We quantify how our results are affected by systematic uncertainties, including the abundance of globular clusters (GCs) and subhalos, and the internal structure of deeply collapsed
halos. Our data exhibits a strong preference for core collapsed
halos in the lens model, with Bayes factors disfavoring CDM relative to SIDM ranging from 8:1 to 24:1, depending on the assumed SIDM subhalo abundance and the internal structure of collapsed
halos. Explaining our data without core collapse requires both a GC abundance well above expectations and more subhalos than predicted by $N$-body simulations. These results pose a challenge to the CDM paradigm. We present a particle physics interpretation of these results in a companion paper.
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All authors D. Gilman, A. M. Nierenberg, J. Gurian, H. Paugnat, C. Gannon, M. N. Martinez, T. Treu, K. N. Abazajian, T. Anguita, V. N. Bennert, A. J. Benson, S. Birrer, S. G. Djorgovski, S. F. Hoenig, R. E. Keeley, A. Kusenko, M. Millon, T. Morishita, L. A. Moustakas, P. Mozumdar, D. Paris, W. Sheu, D. Sluse, K. C. Wong
High Energy Astrophysical Phenomena · Cross-listed from gr-qc
Black Hole Quasinormal Mode Resonances and Reconnections in Coupled Systems
Leah Jenks, Hayato Motohashi, Kazufumi Takahashi et al. (+2 more)
Black hole quasinormal modes (QNMs) provide a window into the underlying structure of black holes and the environments in which they arise. QNMs have particularly rich dynamics in coupled systems beyond general relativity, in which they are known to undergo avoided crossings, resonant excitation, and mode reconnections. Recent work has shown that reconnecting QNM trajectories can trace out a distinctive double spiral structure in the complex frequency plane. In this work, we study this phenomenology in a concrete model of perturbed dynamical Chern-Simons (dCS) theory, as well as in a minimal toy model. In the former, we characterize the exceptional points, avoided crossings and reconnections for several values of the perturbation parameters, and find that the limiting frequency of the double spiral endpoints is independent of the perturbation strength. We compute the excitation factors and find that they follow the scaling characteristic of a resonance between the scalar and gravitational modes. To determine whether these phenomena depend on the specific features of dCS, we construct a toy model of coupled degrees of freedom with square potential barriers, and find that we can reproduce the avoided crossings and reconnections, indicating that these phenomena can occur more generally in coupled systems and are highly sensitive to the system parameters.
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All authors Leah Jenks, Hayato Motohashi, Kazufumi Takahashi, Takuya Takahashi, Emanuele Berti
Astrophysics of Galaxies
The 1.6 $\mu\mathrm{m}$ $\rm{H^{-}}$ bump as a diagnostic of TP-AGB contributions and recent quenching. I. Insights from stellar population models
Pengjun Lu, Song Huang, Shiying Lu et al. (+3 more)
The 1.6 $\mu\mathrm{m}$ $\rm{H^{-}}$ bump arises from a minimum in the opacity of the negative hydrogen ion in cool stellar atmospheres. Although it is recognized as a common feature in
galaxy spectra, its potential for studying stellar populations and recent quenching remains little explored. Its enhancement at intermediate ages is strong in some stellar population models with substantial thermally pulsing asymptotic giant branch (TP-AGB) contributions but weak or absent in others. This variation makes the feature both a potential age diagnostic and a source of model uncertainty. We use models based on the X-shooter Spectral Library (XSL) and Flexible Stellar Population Synthesis (FSPS) to examine what drives this behavior and what it can reveal about quenching. Controlled FSPS experiments show that the $\rm{H^{-}}$ bump depends on both the amount of TP-AGB light and the stellar template used to represent it. The adopted XSL and TP-AGB-on FSPS models predict a transient enhancement following rapid quenching, with a different age response from optical spectral features. Combining these diagnostics can therefore provide additional information about recent quenching, although the interpretation depends on the population model and
star-formation history. An illustrative comparison with existing JWST spectra shows that models including TP-AGB contributions can describe the observed $\rm{H^{-}}$ region reasonably well. These results motivate further use of the $\rm{H^{-}}$ bump to test TP-AGB prescriptions and investigate quenching with current and forthcoming observations.
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All authors Pengjun Lu, Song Huang, Shiying Lu, Meng Gu, Li Shen, Cheng Li
Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
Constraining dark matter using 20-year INTEGRAL/IBIS observations II: Sub-GeV dark matter
Jordan Koechler and Pedro De la Torre Luque
We present new constraints on sub-GeV dark matter (DM) annihilation and decay using twenty years of diffuse hard X-ray observations from the INTEGRAL/IBIS
telescope. By performing a joint analysis of the spectral and morphological information contained in the IBIS
dataset, we simultaneously fit Galactic longitudinal profiles and energy spectra, exploiting their complementary signatures to disentangle potential DM signals from the dominant astrophysical backgrounds. We use physically motivated background models combining inverse-Compton (IC) emission from Galactic
cosmic-ray electrons with thermal emission from unresolved accreting white dwarfs, and consistently include the secondary IC emission generated by DM-induced electron and positron populations propagated through the
Galaxy. We conservatively derive 95% upper limits on the annihilation cross section $\langle\sigma v\rangle$ and decay half-life $\tau$ for the $e^+e^-$, $\mu^+\mu^-$, and $\pi^+\pi^-$ final states across the mass range 1 MeV to 5 GeV. Our constraints are in the range $10^{-28}$ cm$^3$/s $\lesssim \langle\sigma v\rangle \lesssim 10^{-26}$ cm$^3$/s for annihilation and $\tau \gtrsim 10^{25}$ s for decay at DM masses of a few MeV, improving upon existing X-ray limits by up to two orders of magnitude over much of the mass range. Our bounds are translated into constraints on the kinetic mixing parameter $\epsilon$ of a dark
photon and the scalar-
Higgs mixing angle $\sin\theta$, and compared with existing indirect, direct and accelerator limits available, providing a comprehensive picture of the allowed parameter space for light portal DM.
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Earth and Planetary Astrophysics
GameDev: GPU-accelerated model for dust evolution
Jiaqing Bi
Grain growth and fragmentation through dust collisions in protoplanetary disks are strongly coupled with dust dynamics. This is because the spatial and velocity distributions of dust set the collision rates and outcomes, while dust grain sizes set the aerodynamic coupling with gas. However, existing dust
evolution codes often rely on prescribed dust velocities and are mostly restricted to one or two spatial dimensions. In this work, we present GameDev, a dust
evolution model accelerated by graphics processing units (GPUs) that couples independently evolved three-dimensional dust dynamics with Monte Carlo collisional
evolution of dust. In GameDev, we model dust as Lagrangian representative particles in a prescribed gas disk. We integrate particle trajectories with the staggered semi-analytic method, which remains accurate for both tightly and weakly coupled dust grains. We estimate collision rates from each particle's nearest neighbors rather than on a grid, preventing physically close particles from being excluded from collision sampling because they lie across a grid boundary. Most importantly, we sample collision events against neighborhoods that remain frozen over adaptive intervals, enabling massive parallelization across particles. These implementations make GameDev an accurate and efficient tool for studying dust
evolution in protoplanetary disks. GameDev supports both NVIDIA CUDA and AMD ROCm platforms, provides a smaller-scale standalone Eulerian dust fluid model, and is publicly available on GitHub.
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Instrumentation and Methods for Astrophysics
SIFARI: Self-Supervised Interferometric Fitting for Astronomical Radio Imaging
Shunyuan Mao, Andrea Isella, Paris Perdikaris et al. (+2 more)
Radio-interferometric images are reconstructed from sparsely sampled visibilities, and CLEAN-based imaging can struggle with spatial filtering, complex morphologies, and uncertainty quantification. Alternative methods that fit visibilities directly can address some of these limitations but often require manual choices of image priors and model hyperparameters. We present SIFARI (Self-Supervised Interferometric Fitting for Astronomical
Radio Imaging), a self-supervised neural network workflow that represents sky brightness as a continuous function of position and fits measured visibilities without an external image training set or explicit spatial regularizer. An empirical rule sets the
Fourier feature scale from the visibilities before training, controlling how readily the network fits fine structure. Sampling network weights with
Stochastic Weight Averaging-Gaussian (SWAG) gives approximate brightness uncertainty estimates, which we combine with a thermal-noise floor to construct spatially resolved signal-to-noise maps. In synthetic ALMA tests, SIFARI yields an effective point-source response about eight times narrower than the natural-weighting CLEAN restoring beam and recovers more extended flux than CLEAN when short baselines are missing. It also achieves higher image fidelity than the restored CLEAN images in all three morphology
benchmarks. Applied to ALMA observations of PDS 70, SIFARI recovers the bright outer ring together with faint compact emission in the central cavity. For long-baseline-only WISPIT 2 data, SIFARI supplies a sky model for phase self-calibration where the CLEAN model is inadequate. The restored, self-calibrated SIFARI image has approximately 30% lower RMS noise than the CLEAN image made from the original visibilities without self-calibration.
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All authors Shunyuan Mao, Andrea Isella, Paris Perdikaris, Li-Ta Lo, Hui Li
Cosmology and Nongalactic Astrophysics
Current and Future Constraints on the Primordial Power Spectrum
Zachary Cheslog, Emily Finson, Amanda MacInnis et al. (+4 more)
The primordial scalar power spectrum provides a powerful window onto early-universe physics, including a broad class of inflationary scenarios. These models often predict a characteristic scalar spectral index $(n_s)$, nonzero running $(\alpha_s)$, or more general deviations from a pure power-law form. We find that freeing the number of light relic species $(N_{\rm eff})$ and the sum of the
neutrino masses $(\sum m_\nu)$ broadens the $n_s$ error contours enough that key early-Universe models are no longer excluded. In particular, while both Starobinsky inflation and the Bi-thermal Big Bang model are ruled out at about the 95% confidence level in the six-parameter $\Lambda$CDM model, we find that in the nine-parameter $\Lambda{\rm CDM} + \alpha_s + N_{\rm eff} + \sum m_\nu$ model, CMB data from Planck, ACT, and SPT (CMB-PAS) combined with DESI DR2 give $n_s = 0.9758 \pm 0.0064$ and $\alpha_s = 0.0080 \pm 0.0064$, consistent with both models. Future CMB facilities will sharply improve constraints on $n_s$, $\alpha_s$, and, more generally, the binned primordial power spectrum $\mathcal{P}(k)$. For example, CMB-PAS constrains $e^{-2\tau}\mathcal{P}(k = 0.2\,{\rm Mpc}^{-1})$ to 0.5%, while SO-like and CMB-HD-like surveys would tighten this to 0.1%; CMB-HD would also extend this measurement to smaller, previously unprobed scales, constraining $e^{-2\tau}\mathcal{P}(k = 30\,{\rm Mpc}^{-1})$ to within a factor of ten. We release our forecast code and update the public CMB-HD likelihood and Fisher codes to support CLASS in addition to CAMB.
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All authors Zachary Cheslog, Emily Finson, Amanda MacInnis, Neelima Sehgal, Niayesh Afshordi, Simran K. Nerval, Renée Hložek
Cosmology and Nongalactic Astrophysics · Cross-listed from gr-qc
Low Frequency Gravitational Wave Detection with Gravito-Magnetism
Reza Ebadi and Surjeet Rajendran
The detection of gravitational waves in the low-frequency band (10 nHz to 1 micro-Hz) using inner solar system proof masses is severely limited by Newtonian
gravity gradient noise (GGN) sourced by the asteroid belt. In this paper, we propose a novel detection concept that exploits the relativistic nature of gravitational waves to break the degeneracy between the signal and the asteroid GGN background. The non-relativistic motion of asteroids dominantly sources gravito-electric fields, with velocity suppressed gravito-
magnetic components. Relativistic gravitational waves produce gravito-electric and gravito-
magnetic components of equal magnitude. We propose detecting the gravito-
magnetic component of low frequency gravitational waves using the Lorentz acceleration of test bodies. The measurement of this Lorentz acceleration is metrologically possible due to the fact that expected astrophysical sources of low frequency gravitational waves have considerably higher characteristic strains than the strains typically expected at higher frequencies. We show that this measurement allows for unambiguous extraction of the gravitational wave signal from the
gravity gradient noise in a three satellite constellation. The gravito-
magnetic measurement still requires a proof mass that is well isolated from non-gravitational noise. We propose the use of atom interferometers to serve as such a pristine inertial reference.
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Solar and Stellar Astrophysics
Discovery of over a thousand variable stars in Terzan 5 and Liller 1 with JWST
Kevin B. Burdge, Ilaria Caiazzo, Malina M. Desai et al. (+18 more)
The Bulge Fossil Fragments Terzan 5 and Liller 1 host some of the densest stellar environments in the
Galaxy, yet their variable
star populations have remained largely unexplored due to crowding and heavy obscuration. Here, we identify 1,315 variable sources in these two systems in what is to our knowledge the first JWST time-series variability census of a globular cluster-like object. By differencing consecutive non-destructive reads within each NIRCam integration, we transform sample-up-the-ramp imaging into an infrared movie sampled every 21 seconds. More than a century of observations has cataloged 5,604 variables, the majority of them pulsating
stars, across 151 Galactic globular clusters. Our census alone amounts to 23 percent of that total and contains more photometrically variable binaries than had previously been cataloged in all globular clusters combined. The field of Liller 1, with zero previously known variables, now hosts 915, nearly double the count in the runner-up $\omega$ Centauri. We detect dramatic infrared variability from the Rapid Burster, revealing the counterpart sought since 1976 (see Desai et al. 2026), and blindly recover a signal coincident with the prototype redback
pulsar PSR J1748-2446A at its
radio-timed orbital period, identifying the first optical or infrared counterpart to any of Terzan 5's
pulsars. More broadly, we present a technique that recovers group-level time-series photometry from JWST observations, enabling time-domain studies with an observatory whose field of view is naturally matched to the
Galaxy's densest stellar systems.
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All authors Kevin B. Burdge, Ilaria Caiazzo, Malina M. Desai, Cristina Pallanca, Vera L. Berger, Kaley Brauer, Matteo Correnti, Paul Draghis, Kareem El-Badry, Francesco R. Ferraro, Denis González-Caniulef, Kyle Kremer, Barbara Lanzoni, Dongzi Li, Jessica R. Lu, Geoffrey Mo, Mason Ng, Roger W. Romani, Kaitlyn Shin, Daniel R. Weisz, Giorgia Zullo
Cosmology and Nongalactic Astrophysics
LIMFAST. V. Probing Reionization with the Synergy Between 21 cm and Photometric Galaxy Surveys
Guochao Sun, Adam Lidz, Tzu-Ching Chang et al. (+4 more)
Cross-correlating the 21\,cm signal from intergalactic neutral hydrogen with the
galaxy distribution is a powerful probe of the Epoch of Reionization and the physical mechanisms driving it. While upcoming surveys with the SKA-Low
radio telescope and the Roman Space
Telescope offer ideal synergies for this measurement, foreground mitigation of 21\,cm data requires exquisite
redshift precision of
galaxies, effectively excluding the rich photometrically selected samples of Lyman-break
galaxies (LBGs) with typical
redshift uncertainties $\sigma_z \gtrsim 0.1$. We overcome this challenge using a squared statistic of the foreground-cleaned 21\,cm signal. Squaring the filtered 21\,cm signal couples surviving high $k_\parallel$ modes into low $k_\parallel$ fluctuations accessible to photometric LBG surveys. This higher-order cross-correlation statistic remains measurable even when direct cross-correlations are strongly suppressed. Applying Fisher
matrix analysis to this LBG–21\,cm$^2$ cross-correlation signal simulated by the LIMFAST code over $6 \lesssim z \lesssim 10$, we investigate the prospects for constraining EoR physics combining SKA-Low 21\,cm measurements and Roman photometric
galaxy samples. For an overlapping survey area covering 10\,deg$^2$, we find that the LBG–21\,cm$^2$ cross-correlation is detectable at high significance across much of the EoR through 1000\,hours of SKA-Low integration with 15\,MHz bandwidth and a Roman photometric
galaxy sample from the High-Latitude Wide-Area Survey (HLWAS) reaching $m_\mathrm{AB,lim}=27$ and photo-$z$ uncertainties of $\sigma_z \sim 0.1$–0.3. The characteristic sign
evolution of the large-scale cross-power spectrum—driven primarily, though not exclusively, by the evolving neutral fraction—provides strong constraints on the physical parameters governing the ionization and thermal history of the IGM.
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All authors Guochao Sun, Adam Lidz, Tzu-Ching Chang, Claude-André Faucher-Giguère, Steven R. Furlanetto, Aritra Kundu, Jordan Mirocha
High Energy Astrophysical Phenomena
Discovery of the Infrared Counterpart of the Rapid Burster with JWST
Malina M. Desai, Kevin B. Burdge, Cristina Pallanca et al. (+8 more)
The Rapid Burster (MXB 1730$-$335) is the only known
neutron star to produce both Type I and Type II X-ray bursts, making it a key system for understanding
accretion physics onto
neutron stars. It resides in Liller 1, a dense, metal-rich stellar system whose crowded core and $\sim$11 magnitudes of visual extinction have concealed the Rapid Burster's optical/infrared (OIR) counterpart for nearly five decades. Here, we present infrared observations of Liller 1 obtained with JWST/NIRCam that, for the first time, reveal the unambiguous OIR counterpart to the Rapid Burster. Caught in an X-ray active state, the counterpart exhibits dramatic infrared variability, fading by $\sim$ 2.5 magnitudes in JWST's F200W band (1.755$-$2.227 $\mu$m) with strong fluctuations on minute timescales. These observations provide an infrared anchor for the Rapid Burster and open the way for future spectroscopy and simultaneous IR and X-ray monitoring to constrain the donor's spectral type and the system's
accretion physics.
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All authors Malina M. Desai, Kevin B. Burdge, Cristina Pallanca, Saul Rappaport, Francesco R. Ferraro, Barbara Lanzoni, Mason Ng, Paul Draghis, Emma T. Chickles, Ilaria Caiazzo, Deepto Chakrabarty
Astrophysics of Galaxies
GA-NIFS view of LAP1: Assembly of Pop~III stellar clusters during EoR
J. Scholtz, R. Maiolino, S. Carniani et al. (+28 more)
Lensed and Pristine 1 (LAP1) is one of the most promising candidates for the detection of so-called Pop~III
stars at $z\sim6.6$. In this work, we present new high-spectral-resolution ($R \sim 2700$) \jwst NIRSpec-IFS observations of the system along with a detailed re-analysis of all archival \jwst and VLT/MUSE data. We confirm the very low
metallicity of the system, with $12+\log(\text{O/H})=6.5\text{--}6.8$ (1–2% Z$_{\odot}$), and its low stellar mass, with $M_{*}= 10^{3\text{--}4}$ \Msun, based on the non-detection in \jwst/NIRCam filter stacks and the \Hbeta luminosity. The high-resolution IFS data allow us to constrain the upper limits on the dynamical masses ($\log_{10}(M_{*}/M_{\odot})$) of the A and B components to $<6.6\text{--}7.6$ and $<5.6\text{--}6.6$, respectively. Based on the
metallicity and the high equivalent width of \Halpha (EW $>1200$\,Å), we estimate the possible range of the LAP1 stellar population ages to be $2\text{--}5$~Myr, consistent with the first burst of
star formation in a pristine environment. Based on the size ($<10$~pc) and mass of the system, we discuss the nature of LAP1 as representing the formation of the first stellar clusters in a larger undetected
galaxy, similar to other low-
metallicity Pop~III candidates in the literature.
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All authors J. Scholtz, R. Maiolino, S. Carniani, E. Vanzella, R. J. Terlevich, H. Übler, M. Perna, S. Arribas, E. Bertola, P. Bergamini, T. Böker, A. Bolamperti, A. Bunker, S. Charlot, M. Curti, F. D'Eugenio, C. Grillo, L. R. Ivey, X. Ji, G. C. Jones, M. Meneghetti, M. M. Messa, R. Pascalau, B. Rodríguez Del Pino, P. Rosati, E. Rusta, S. Salvadori, E. Terlevich, G. Venturi, S. Zamora, A. Zanella
Astrophysics of Galaxies
Massive Population III Galaxies Near a GN-z11 Analog: The Role of the Baryon-Dark Matter Streaming Velocity
Eli Visbal, Greg L. Bryan and Ryan Hazlett
Recently the James Webb Space
Telescope (JWST) detected Hebe, a Population III (Pop III) candidate located ${\sim}3$ kpc in projection from the massive $z=10.6$
galaxy GN-z11. This raises the question of whether Pop III
star formation is expected in the vicinity of massive high-
redshift galaxies or whether it would be prevented by early metal enrichment. We address this with a semi-analytic model of Pop III and metal-enriched
star formation applied to a zoom-in N-body simulation of a highly overdense region surrounding a GN-z11 analog. The zoom-in region resolves the minihalos where the first
stars form. We find that Pop III and metal-enriched
star formation both occur earlier, and with a higher
star formation rate density, than in a typical mean-density environment. The majority of Pop III
star formation in minihalos ends by $z\sim15$; however, we identify a distinct population of late-forming Pop III
galaxies that form near the central
galaxy. These systems have their
star formation delayed due to ionizing feedback from the central GN-z11 analog and experience a Lyman-Werner (LW) intensity of ${\sim}10$ - $100~J_{21}$, potentially leading to massive Pop III starbursts similar to Hebe. Interestingly, the abundance of these Pop III
galaxies depends strongly on the baryon-dark matter streaming velocity, $v_{\rm bc}$, because a higher streaming velocity allows
halos to remain chemically pristine for longer. None of these late-forming Pop III sources occur for $v_{\rm bc}=0$, while many form at high $v_{\rm bc}$. Averaging over the expected distribution of streaming velocities, we predict that of order four GN-z11-like
galaxies would need to be surveyed at $z\sim11$ to expect to find one such source. We also note these environments may provide a natural formation site for heavy black hole seeds.
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Astrophysics of Galaxies
Photoelectron and electron microscopy investigation of laboratory grown Mg-silicate space dust analogues
Steffen Friis Holleufer, Mie Andersen, Frederik Granzow Doktor et al. (+9 more)
The atomic structure at the surface of interstellar silicate dust particles likely plays a key role in a variety of chemical processes occurring in
star- and
planet-forming regions of the interstellar medium (ISM). Here, we use the photoelectric effect to characterize, in situ, the local chemical structure of Mg-silicate nanoparticulate films, and ex situ electron microscopy to trace changes to morphology resulting from different starting compositions. Nanoparticulate films are prepared via co-deposition of Si, Mg and O atoms on a graphitic substrate under ultra-high
vacuum (UHV) and are characterised with X-ray photoelectron spectroscopy and near edge X-ray absorption fine structure measurements. Analysis, supported by density functional theory calculations, shows that adjusting the Mg-to-Si ratio from 3.5 to 1.8 changes particle composition from a mixture of MgO and Mg-silicate towards predominantly Mg-silicate. Annealing in UHV also pushes the composition towards Mg-silicate, however, non-stoichiometric chemical motifs are always observed, presenting a distribution of potentially catalytically active sites. Electron microscopy images show composition-dependent film morphologies that restructure differently upon thermal annealing. The Mg-silicate nanoparticulate films presented here are characterised as a 2D version of ISM analogue dust particles prepared via
laser ablation and are therefore a more readily suitable model for surface science investigations into the catalytic properties of interstellar Mg-silicate dust.
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All authors Steffen Friis Holleufer, Mie Andersen, Frederik Granzow Doktor, Lars Eric Borchert, Martin Wibrand Larsen, Duncan S. Sutherland, Zheshen Li, Alexei Preobrajenski, Jeppe Vang Lauritsen, Cornelia Jäger, Liv Hornekær, Andrew Cassidy
Instrumentation and Methods for Astrophysics
Reconstructing Implicit Scientific Knowledge: Evaluating LLM Agents through End-to-End Reproduction of Astronomy
Yuehui Wang, Xinyu Qi, Guirong Xue et al. (+4 more)
The integration of large
language models (LLMs) into scientific workflows is accelerating, yet their ability to reconstruct the
reasoning underlying published research remains unexplored. Papers specify explicit procedures while leaving many methodological dependencies-data selection, calibration corrections, priors, and domain assumptions-implicit. This ambiguity complicates the evaluation of LLM-based
agents, since a failure to reproduce a result may reflect either limitations of the
agent or underspecification in the source. We present a framework that evaluates
agents through end-to-end reproduction, separating execution from verification and computational failure from methodological ambiguity. We apply it to fourteen astronomy studies: a case study from The Astrophysical Journal and thirteen papers published in Nature. Eleven of the thirteen contained an ambiguity preventing a uniquely specified reproduction path. In a controlled case study, twelve predefined paths, a 3x2x2 sensitivity analysis over sample definition, sky masking, and parallax zero-point treatment-gave estimates from 2.16 to 3.53 kpc for the same quantity, with only one recovering the published value (about 2.70 kpc). The published value was never used as an optimization target, selection criterion, or stopping condition; the matching path was found only after all twelve had run. Crucially, the decisive information (a +0.02 mas parallax zero-point correction) was already in the paper, but the
agents did not recognize its causal relevance until the analysis made the effect visible. Matching a published outcome therefore does not validate reconstruction of the underlying
reasoning, and the bottleneck is as often a failure to connect relevant information as to retrieve it. End-to-end reproduction thus serves both as a test of reproducibility and as a framework for evaluating implicit scientific knowledge in AI systems.
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All authors Yuehui Wang, Xinyu Qi, Guirong Xue, Cheng Wang, Yangbin Xie, Xiaoyu Tang, Cong Sun
Astrophysics of Galaxies · Cross-listed from gr-qc
From Density to Mass: A New Parametrized Framework for Dark Matter Environment Around Black Holes
Rajes Ghosh, Nicholas Speeney, Avijit Chowdhury et al. (+3 more)
Astrophysical black holes (BHs) are not isolated
vacuum objects but are expected to reside within complex environments, such as dark matter (DM)
halos and baryonic distributions. Such environments can modify the spacetime geometry surrounding the BH and leave observable imprints on gravitational-wave (GW) signals, including shifts in the quasinormal mode (QNM) spectrum, tidal Love numbers (TLNs), and the inspiral dynamics of extreme-mass-ratio inspirals (EMRIs). We develop a general framework for describing DM-dressed BH spacetimes by parameterizing the geometry directly in terms of the enclosed mass function, rather than the traditional density-based profile. This mass-based formulation is naturally connected to the total gravitational field, accommodates several common
halo profiles as limiting cases, and incorporates basic physical consistency requirements such as regularity, causality, and appropriate asymptotic behavior. Within this framework, we investigate the environmental imprints on QNMs, TLNs, and GW fluxes from EMRIs. We find a complementary sensitivity to the
halo structure: QNMs predominantly probe the inner regions of the environment, whereas static TLNs are more sensitive to its outer structure. EMRI fluxes, in contrast, probe the matter distribution through its influence on the orbital motion and GW propagation. Our results establish the enclosed-mass formulation as a flexible and physically controlled framework for connecting astrophysical environment models with precision GW observables.
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All authors Rajes Ghosh, Nicholas Speeney, Avijit Chowdhury, Chiranjeeb Singha, Miguel A. S. Pinto, Emanuele Berti
Cosmology and Nongalactic Astrophysics
Can Fingers of God be Resummed?
Shi-Fan Chen and Alejandro Aviles
Fingers of God (FoGs), Doppler shifts due to the small-scale virial motions of
galaxies, are one of the most significant challenges for analytic models of
galaxy clustering in
redshift surveys. In the effective field theory approach, the characteristic scale of these shifts introduces a new, large length scale, limiting the reach of the theory. This has motivated many phenomenological models of FoGs in the literature where their effect is approximated by a single damping function of the line-of-sight wavenumber $\lambda=k\mu$, effectively resumming powers of $\lambda$ due to single-point contractions of small-scale velocities. The goal of this work is to investigate whether such a resummation can be rigorously constructed. We show that common damping models can be understood as the mean-field limit of the single-particle characteristic function (SPCF) of FoG velocities, but that the environmental dependence of the SPCF generates equally large corrections that break the simple damping form. We develop the long-wavelength theory of the SPCF, showing that it admits an expansion in anisotropic bias operators closely related to those derived for selection effects, but with $\lambda$-dependent coefficients satisfying selection rules. We estimate these coefficients using the
halo model for DESI-like
galaxies, showing that they make significant contributions at the level of the 2- and 3-point functions of
galaxies. To answer the titular question: potentially, but at the cost of significantly expanding the operator basis and promoting free coefficients to free functions.
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Cosmology and Nongalactic Astrophysics
Gauge Backreaction in Standard Model Warm Inflation
Rafid H. Dejrah and Anish Ghoshal
Standard-Model warm inflation (SMWI) makes QCD the microscopic origin of inflationary dissipation, so the real-time response of the gauge
plasma enters the cosmological prediction. We show that a slowly relaxing gauge-helicity response cannot, in general, be absorbed into an effective friction coefficient and must instead remain dynamical. We therefore evolve the
quark axial densities and a matched hard-helicity mode, with QCD sphalerons and an effective $2\leftrightarrow3$ channel generating both charge transfer and correlated
stochastic sources in the full perturbation covariance system. The resulting backreaction is substantial but mainly indirect: gauge-helicity screening can reduce the warm dissipation ratio by an order-one fraction on the strong branch, while the $2\leftrightarrow3$ channel contributes only $0.2\%-0.7\%$ of the zero-density sphaleron friction directly, shifting the amplitude-normalized trajectory in both $n_s$ and $r_{\rm vac}$. The relevant trajectories, however, lack a parametrically broad hard-soft hierarchy and extend beyond strict linear response. The predictions should therefore be understood within the stated local Gaussian transport closure; a parameter-free Standard-Model (SM) result requires finite-affinity real-time $SU(3)$ drift, susceptibility, and noise kernels.
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