High Energy Astrophysical Phenomena
Time-dependent multi-energy neutrino emission from symbiotic recurrent novae: the role of accretion disks
Rui Xu, Yudong Cui, Yihan Shi et al. (+1 more)
Symbiotic recurrent novae provide a unique laboratory for studying thermonuclear explosions, shock
evolution, and nonthermal particle acceleration in dense circumstellar environments. In this work, we develop a time-dependent, multi-energy framework to describe
neutrino emission from such systems, consistently incorporating both MeV
neutrinos produced during thermonuclear runaway and GeV
neutrinos generated through hadronic interactions in nova-driven shocks. Using RS Oph as a
benchmark source, we model the
evolution of the shock interacting with both the red
giant wind and a dense
accretion disk surrounding the white
dwarf. We show that the resulting
neutrino signal exhibits a characteristic two-component temporal structure: an early, rapidly rising MeV component tracing
nuclear burning, followed by a delayed GeV component governed by shock propagation and particle acceleration. The presence of an
accretion disk can significantly enhance the early-time GeV
neutrino emission by providing a dense target for
proton-
proton interactions. This leads to a pronounced
neutrino flux within the first few hours after eruption, a feature absent in wind-dominated scenarios. We further evaluate the detectability of these signals and find that while the MeV component remains below current detection thresholds, the GeV
neutrino emission from nearby systems may become accessible to next-generation detectors. Our results highlight the critical role of the circumstellar structure in shaping nova
neutrino emission and demonstrate that symbiotic recurrent novae are promising targets for future multi-messenger observations.
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All authors Rui Xu, Yudong Cui, Yihan Shi, Lili Yang
Solar and Stellar Astrophysics
H-$\alpha$ Integral Carrington Synoptic Maps Produced by NSO/NISP
K. J. Shuman, L. Bertello, O. Burtseva et al. (+1 more)
Monitoring long-term chromospheric activity and large-scale
solar structures like filaments and plages is critical for understanding
solar magnetic cycles and predicting space-weather events. While photospheric
magnetic fields are routinely mapped, a consistent, global reference for chromospheric structures has been absent from H-$\alpha$ observations. This technical report provides a comprehensive description of the methodology used to construct the NSF Global Oscillations Network Group (GONG) H-$\alpha$ Integral Carrington Synoptic Maps from full-disk observations. We outline the processing pipeline developed to transform these observations into 720 x 360 pixel maps binned by Carrington longitude and sine(latitude) and describe characteristics of the final data product.
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All authors K. J. Shuman, L. Bertello, O. Burtseva, A. A. Pevtsov
Instrumentation and Methods for Astrophysics
Performance Analysis of the Asgard/NOTT Nulling Interferometer: Optimizing Observing Modes for High-contrast Detection
J. P. Scott, S. Ertel, T. A. Stuber et al. (+21 more)
We evaluate the performance of three beam-combination schemes, single-Bracewell, asymmetric dual-Bracewell, and symmetric dual-Bracewell, for the forthcoming Asgard/NOTT nulling interferometer at the Very Large
Telescope Interferometer. Utilizing the SCIFYsim end-to-end simulator, we assess the instrument's performance by deriving the precision of calibrated null measurements as a function of
stellar magnitude and simulating observations of varying hot exozodiacal
dust (HEZD) distributions and a hot Jupiter. The study reveals distinct trade-offs for each observing mode. The single-Bracewell mode provides high throughput and preserves spatial information but suffers from poor error suppression. The asymmetric dual-Bracewell mode offers the strongest error suppression for detecting point-like sources, but it inherently suppresses symmetric astrophysical signals such as expected from HEZD. The symmetric dual-Bracewell mode provides a middle ground with modest error suppression while being sensitive to symmetric emission. We conclude that utilizing a combination of all three observing modes provides a robust strategy for detecting HEZD, constraining the structure of its distribution, and identifying false positives from
stellar companions.
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All authors J. P. Scott, S. Ertel, T. A. Stuber, D. Defrère, R. Laugier, J. C. Augereau, P. Chingaipe, G. Garreau, X. Haubois, M. Ireland, F. Kirchschlager, S. Kraus, F. Martinache, M-A. Martinod, K. Missiaen, S. Morel, J. Morren, K. Ollmann, P. Priolet, G. Raskin, M. Salman, N. Schuhler, W. Verstraeten, S. Wolf
Astrophysics of Galaxies
The CMZ Asymmetries: Feeding or Feedback?
John Bally
Three-fourths of the dense gas and
dust in the CMZ is located at positive longitudes and positive radial velocities. The majority of compact 24 micrometer wavelength sources are at negative longitudes. These two asymmetries indicate either a recent asymmetric injection of gas along the bar
dust lanes, or that most of the molecular gas is contained in a small number of massive, gravitationally bound clouds, or a major feedback episode which dissociated an entire sector of the CMZ's dense gas.
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Instrumentation and Methods for Astrophysics
MORFEO control strategy
Guido Agapito, Lorenzo Busoni, Cédric Plantet et al. (+7 more)
The ESO Extremely Large
Telescope (ELT) will offer unprecedented sensitivity and resolution in the near-infrared, marking a new era for ground-based astronomy. Among its key imaging instruments is MORFEO coupled with MICADO. MORFEO (Multi-conjugate adaptive Optics Relay For ELT Observations), formerly known as MAORY, is the largest astronomical adaptive optics system ever designed. It features 12 wavefront sensors and three deformable mirrors, for a total of over 20,000 subapertures and over 6,000 actuators. MORFEO represents one of the greatest upcoming challenges in the field of astronomical adaptive optics. While the design builds upon the heritage of previous AO systems, several architectural choices are entirely new, driven by the unique scale and requirements of this instrument. One of the main challenges is delivering high and uniform wavefront correction across the MICADO field of view. To meet this goal, the MORFEO control strategy adopts a specific approach: sodium
laser guide
stars are used to sense modes above focus only, since differences in beacon altitude can introduce significant aberrations. Natural guide
stars are instead employed to measure and correct for tip, tilt, plate scale variations, and field-averaged focus. In this work, we present the MORFEO control strategy and provide performance estimates across different observing scenarios.
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All authors Guido Agapito, Lorenzo Busoni, Cédric Plantet, Giulia Carlà, Alfio Puglisi, Jean-Pierre Véran, Marco Falotico, Gabriele Umbriaco, Edoardo Redaelli, Paolo Ciliegi
Astrophysics of Galaxies
Old Disks Die Hard: How Does AGN Feedback Suppress Disk Formation in Milky Way Mass Galaxies?
Patricia Fofie, James S. Bullock, Sarah Wellons et al. (+3 more)
The connection between a
galaxy's visual shape and its
star formation rate is one of the oldest established trends in
galaxy evolution, yet the origin of this trend remains unsettled. We analyze two Milky-Way mass
halos simulated with FIRE-2
galaxy formation physics, each run without AGN and with up to three implementations of AGN feedback. We use them to study how and why AGN
star formation suppression affects morphological
evolution over
cosmic time. Both runs without AGN feedback produce prominent, thin,
star-forming spiral disks at $z=0$. Each of the AGN runs has less late-time
star formation, and ends up with a higher spheroid fraction and a lower thin-disk mass fraction. In two instances, the AGN runs produce quenched lenticular
galaxies with no cool gas at $z=0$. The main reason for these morphological differences is that AGN feedback becomes effective just after the onset of disk formation, at “
spin up," in every run. This time-differentiated impact suppresses the formation of disk
stars, especially thin-disk
stars, preferentially because thin-disk formation occurs late. The spheroidal components are assembled early in all runs, before AGN feedback is effective, and are therefore similar in mass and size across runs.
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All authors Patricia Fofie, James S. Bullock, Sarah Wellons, Jorge Moreno, Francisco J. Mercado, Andrew Wetzel
High Energy Astrophysical Phenomena
The second Arcminute Microkelvin Imager - Large Array Gamma-ray burst radio afterglow catalog
L. Rhodes, D. Ibrahim, N. Sqalli et al. (+13 more)
Radio observations of gamma-ray burst afterglows provide insight in to the different emitting regions within the jet, its hydrodynamics and burst environment. In this paper, we present the second iteration of the Arcminute Microkelvin Imager - Large Array (AMI-LA) Gamma-ray burst (GRB)
radio afterglow catalog. The catalog consists of 1035 observations of 210 bursts. Our observations range from 0.04 to 900days post-burst. We detect
radio emission associated with 19 events with flux densities spanning 0.1-40mJy, and present a detailed analysis of six events whose light curves have not been published elsewhere. In our individual afterglow analyses, we find that our
radio counterparts show evidence of reverse shock emission 60% of the time. Two of the detected afterglows show evidence of scintillation which we use to place source size limits at tens of days. Of the whole catalog, 50 events have
redshift measurements which we use to find the
radio afterglow luminosity distribution for our sample. Our luminosity distribution spans five orders of magnitude, a larger range than seen in optical and X-ray bands, indicative of the strong dependence of the
radio counterparts on the GRB's physical parameters.
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All authors L. Rhodes, D. Ibrahim, N. Sqalli, G.E. Anderson, R. Fender, A.J. van der Horst, J.S. Bright, A.K. Hughes, D.R.A. Williams-Baldwin, D.A. Green, D. Haggard, A. Horesh, Y. Perrott, P. Scott, T. Staley, D. Titterington
Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
Gravitational Waves from Dimension-6 Assisted Peccei - Quinn Phase Transitions
Nico Benincasa and Kristjan Müürsepp
We consider a simple model-independent extension of the minimal KSVZ
axion model, augmenting the Peccei - Quinn effective potential with a dimension-6 operator invariant under the Peccei - Quinn
symmetry. We show that this operator can trigger a first-order phase transition and study its cosmological consequences. We map out the parameter space, consistent with present observational constraints, in which the phase transition produces a gravitational wave signal observable at current and future interferometers, and we investigate the resulting dark matter phenomenology. Finally, we present specific ultraviolet completions that generate the dimension-6 operator, each leading to distinct phenomenological signatures, which motivates our model-independent approach.
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High Energy Astrophysical Phenomena
High-Energy Neutrinos from Supernova Shock Breakouts in Circumstellar Media: Light Curves, Spectra, and Contribution to the Extragalactic Neutrino Background
Tal Wasserman, Eli Waxman and Kohta Murase
Enhanced mass loss from core-collapse
supernova (SN) progenitors shortly before explosion appears to be common, creating a compact, optically thick circumstellar medium (CSM) at $\sim10^{14}-10^{15}$ cm. We derive an analytic description of the light curves and spectra of high-energy
neutrinos emitted by nonrelativistic SN shock breakouts through such CSM, as a function of shock velocity and CSM parameters, accounting for the
evolution of the hydrodynamic structure and the electromagnetic (EM) spectrum as the shock transitions from being radiation-mediated to collisionless. This
evolution determines the time-dependent
neutrino production efficiency, the maximum
proton/
neutrino energy, and the pair-production optical depth. A significant fraction of the
neutrino energy is typically emitted within a few days of explosion, during breakout and before the EM light curve peak, with $1-100$ TeV
neutrinos carrying $\approx10\%$ of the energy of shock-accelerated
protons. The escape of high-energy
photons ($>1$~GeV) is suppressed by pair-production for compact CSM configurations. If enhanced mass losses are common, and assuming that shock-accelerated
protons carry $\approx10\%$ of the collisionless shock energy, CSM SN breakouts may significantly contribute to the observed high-energy
neutrino background, without overproducing a corresponding high-energy gamma-ray background. SNe producing $>1$
neutrino events in a $1\left(10\right){\rm km^2}$ detector are expected at a rate of $\sim0.05\left(1\right){\rm yr^{-1}}$.
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Astrophysics of Galaxies
Abundant Heavy Black Hole Seeds from Moderate Lyman-Werner Radiation
Ryan Hazlett, Eli Visbal, Greg L. Bryan et al. (+1 more)
The existence of high-
redshift quasars may indicate that massive black hole seeds formed via supermassive Population III
stars in atomic-cooling
halos with large gas inflow rates; however, the dependence of this process on
halo assembly rate and radiative background remains poorly constrained. We present a large suite of 65 high-resolution cosmological zoom-in simulations of 15 pristine
halos spanning a wide range of Lyman-Werner radiation backgrounds and
halo assembly histories. We introduce a novel method to estimate the final Population III
stellar mass from radial gas infall profiles at the onset of runaway collapse and validate it against simulations from the literature that explicitly follow protostellar
accretion with sink particles, reproducing protostellar masses to within a factor of $\sim2$. We find a clear transition in gas inflow rates between
halos exposed to $J_{\rm 21} \lesssim 1$ and $J_{\rm 21} \gtrsim 10$, with the latter frequently sustaining inflow rates above the adopted threshold for supermassive
star formation and producing estimated
stellar masses up to $10^{5} \, M_{\odot}$. In contrast, the
halo assembly timescale, $M_{\rm Halo}$/$\dot{M}_{\rm Halo}$, shows no statistically significant correlation with predicted
stellar mass, despite
halo assembly rates spanning $0.01$-$7 \, M_{\rm \odot} \, {\rm yr}^{-1}$. The Lyman-Werner radiation field therefore is a stronger predictor of sustained high
accretion within our parameter space. Finally, a semi-analytic model applied to cosmological volumes shows that
halos exposed to intermediate Lyman-Werner backgrounds ($1 \lesssim J_{\rm 21} < 10$) are orders of magnitude more common than those in the high-$J_{\rm 21}$ tail. If sustained high
accretion extends into this intermediate regime, heavy black hole seeds may form in substantially more common environments than required by classical direct-collapse scenarios.
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All authors Ryan Hazlett, Eli Visbal, Greg L. Bryan, Mihir Kulkarni
High Energy Astrophysical Phenomena
No Evidence for Nearby Circumstellar Material in the Type Ia Supernova 2025rbs
Aravind P. Ravi, Griffin Hosseinzadeh, Stefano Valenti et al. (+28 more)
We present a high-resolution spectral time series of the Type Ia
supernova (SN) 2025rbs discovered in the nearby
galaxy NGC 7331. The Automated
Planet Finder (APF) at Lick Observatory and the MAROON-X/IGRINS-2 at Gemini North were used to obtain echelle spectra between -5 and 15 days with respect to the epoch of maximum light. Several unsaturated NaID absorption components along the line of sight are identified, but there is no evidence of time variance in any of them. We measure the equivalent width of the observed diffuse interstellar band around 5780 A and constrain the extinction along the line of sight to SN 2025rbs as $A_V = 0.64\,\pm\,0.32$ mag, corresponding to a moderate reddening of $E(B-V) = 0.21\,\pm\,0.10$ mag (assuming $R_\mathrm{V}$ = 3.1). The observed Ca II H & K interstellar absorption roughly traces NaID in velocity space, suggesting a common origin. Quantitative comparisons between the column densities of Na and Ca gas in these host clouds ($N_{NaID}$ / $N_{Ca II}$ of order unity) argue against their origin in the
Galactic halo gas and instead support absorption due to the interstellar gas of NGC 7331. Time invariance of all the observed absorption features suggests a lack of nearby circumstellar material ($\lesssim$ 10$^{16}$ cm) around the progenitor system of SN 2025rbs. This supports a progenitor scenario for SN 2025rbs with minimal ambient circumstellar gas, consistent with a double-degenerate CO white
dwarf binary system.
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All authors Aravind P. Ravi, Griffin Hosseinzadeh, Stefano Valenti, Saurabh W. Jha, Jennifer Andrews, David J. Sand, Benjamin J. Fulton, William D. Vacca, Melissa L. Graham, Alexei V. Filippenko, Noah Franz, Jeniveve Pearson, Moira Andrews, K. Azalee Bostroem, Collin Christy, Yize Dong, Sebastian Gomez, Daichi Hiramatsu, Emily Hoang, D. Andrew Howell, Brian Hsu, Daryl Janzen, Lindsey A. Kwok, Michael J. Lundquist, Darshana Mehta, Nicolas Meza-Retamal, Curtis McCully, Manisha Shrestha, Bhagya Subrayan, Lauren Weiss, Weikang Zheng
Solar and Stellar Astrophysics
Radio Properties of RS Canum Venaticorum Variables in VLASS and RACS
Suhasini S. Rao, Gregory R. Sivakoff, Craig O. Heinke et al. (+6 more)
We performed a systematic search for
radio emission from RS Canum Venaticorum (RS CVn) binaries, selected from the International Variable
Star Index (VSX) catalog, in the Very Large Array Sky Survey (VLASS; three epochs) and Rapid ASKAP Continuum Survey (RACS; two epochs) data. We detected 108 candidate
radio-emitting RS CVn in at least one epoch. Several of these systems rank among the most
radio-luminous RS CVn binaries reported to date. The
radio and X-ray luminosities, obtained from cross-matching with the eROSITA and ROSAT X-ray catalogs, are consistent with the Guedel-Benz relation for magnetically active
stars, but are also comparable to
radio-luminous quiescent black hole X-ray binaries, indicating a potential for misidentification between these two classes. Analysis of optical,
radio, and
stellar properties indicates that optically bright RS CVn (i.e., those with at least one
giant component) are
radio-quieter and have periods that are consistent with lower coronal activity. However, two of these optically bright RS CVn systems show persistent and unusually high
radio specific luminosities (>2e17 erg/s/Hz) across all observed epochs, showing that
stellar activity can produce relatively persistent
radio signals as bright as quiescent black hole binaries.
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All authors Suhasini S. Rao, Gregory R. Sivakoff, Craig O. Heinke, Swetha Arumugam, Dougal Dobie, Laura Driessen, David L. Kaplan, Emil Lenc, Joshua Pritchard
Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
Axion Isocurvature Perturbations Survive the Scaling Evolution of Axion Domain Walls
Naoya Kitajima, Junseok Lee, Kai Murai et al. (+2 more)
We revisit the
evolution of
axion domain walls seeded by inflationary fluctuations. In our previous work, we showed that such domain-wall networks retain superhorizon correlations even after entering the scaling regime. We extend our previous analysis to the case with large initial fluctuations, where many minima of the
axion potential are already populated when the
axion starts to oscillate. Although the conventional misalignment contribution can have suppressed long-wavelength isocurvature perturbations when many
vacua are averaged over,
axions produced by domain-wall collapse provide an additional contribution that can dominate when the walls enter the scaling regime before annihilation. In particular, the biased
vacuum energy released during wall annihilation inherits the superhorizon correlations of the inflationary fluctuations and transfers them to the
axion energy density. We find that sizable isocurvature perturbations can therefore survive even after the walls annihilate. We also discuss generic isocurvature constraints on dark matter produced by domain-wall collapse.
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All authors Naoya Kitajima, Junseok Lee, Kai Murai, Fuminobu Takahashi, Wen Yin
High Energy Astrophysical Phenomena
A binary black hole merger rate comparison within the same metallicity-star formation rate framework
Lumen Boco, Michela Mapelli, Michele Bosi et al. (+2 more)
Recent studies have suggested that binary population synthesis models, when coupled with observationally based,
metallicity-dependent SFRD, overpredict the observed local BBH merger rate density. The significance of this tension might vary depending on the specific code and parameters adopted. Thus, a more extensive exploration of the parameter space is required. Here, we perform such an extended analysis. We first carry out a comprehensive analysis by using a large set of BBH merger efficiencies across a wide range of physical assumptions, parameters, and initial conditions. We combine these efficiencies with an observationally motivated SFRD and explore 18
metallicity variations to encompass observational uncertainties. We find that the tension between predicted and observed BBH merger rate density persists: in 17 out of 18
metallicity variations none of the models considered predicts a local BBH merger rate within or below the observed 90% credible interval. Even in the most favorable
metallicity variation, only <10% of the models are consistent with the observational constraints. Then, we perform a full calculation, including a self-consistent delay time distribution, for the models yielding the lowest BBH merger rate densities. This analysis confirms that even the most conservative models overpredict the observed local BBH merger rate for almost all the
metallicity variations. We show that the inclusion of the low-
metallicity tail contributed by low-mass
galaxies and starbursts, together with a treatment of iron rather than oxygen abundance, systematically shift the predicted rates toward higher values. Consequently, even literature models that predict moderate BBH merger rates can instead produce substantially higher rates when coupled to an observationally motivated SFRD.
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All authors Lumen Boco, Michela Mapelli, Michele Bosi, Cecilia Sgalletta, Amedeo Romagnolo
High Energy Astrophysical Phenomena
Observational Constraints on Horizonless Compact Objects from Thermal Emission in AGNs
Ekin Oran, Avery Broderick and Kiana Salehi
The Swift Burst Alert
Telescope Active
Galactic Nuclei Spectroscopic Survey (BASS DR2) provides one of the largest and most complete samples of bright, local (z < 0.1) active
galactic nuclei (AGNs) with high-quality spectroscopic measurements. These sources are typically interpreted within the framework of Kerr black holes; however, a wide range of horizonless compact-object scenarios-including naked singularities, black hole mimickers, and other exotic compact objects-have been proposed as alternatives. Largely independent of the physics of the particular horizonless model invoked, an
accretion powered, thermally radiating photosphere is expected to develop on astronomically short timescales. In this paper, we investigate whether the presence of such a photosphere is consistent with the observed properties of an appropriate subsample of BASS AGNs. We find that in no instances is such a spectral feature present, and can exclude its existence in significant fraction of objects. For the remaining sources, modest improvements in observational sensitivity and spectral coverage could enable robust exclusion. Our results extend previous horizon-scale tests performed for M87* and Sgr A* to a large AGN population, providing strong, population-level evidence against horizonless alternatives. We conclude by outlining future observational strategies that can further tighten these constraints and significantly increase the number of objects for which horizons are required.
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High Energy Astrophysical Phenomena · Cross-listed from hep-th
Quasinormal modes as exterior probes of black hole interiors in our Universe
Sašo Grozdanov, Vita Movrin and Samuel Valach
We consider a scenario in which a black hole is enclosed in a reflecting timelike cavity and linearly perturbed. For the resulting quasinormal spectra of gravitational, electromagnetic, and other perturbations, in conjunction with our arXiv:2606.11297, we establish a thermal product formula and derive a universal asymptotic expression for high quasinormal overtones. Both results hold in asymptotically flat, de Sitter, and Anti-de Sitter spacetimes (known previously). This spectral signature directly encodes information about the black hole interior and its singularity, and is, at least in principle, accessible to an observer outside the event horizon. We then propose a concrete observational setup in which accreting
plasma plays the role of a partially transmissive mirror. For small, hypothetical,
primordial black holes, we argue that one may thereby be able to extract concrete information about the black hole interior from electromagnetic waves in the radiowave spectrum.
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High Energy Astrophysical Phenomena
Explosions from Rotating Very Massive Star Collapses to Black Holes: Effects of Nuclear Burning
Sho Fujibayashi, Alan Tsz-Lok Lam, Yuichiro Sekiguchi et al. (+1 more)
We investigate the collapse of rotating very massive and supermassive
stellar cores using numerical relativity simulations including an alpha-chain
nuclear reaction network and
neutrino cooling. Our main survey focuses on newly constructed models with initial core masses of $2 \times {10}^{3}-5\times 10^4M_\odot$. The collapse is triggered either by pair instability in lower-mass cores or by general-relativistic instability in higher-mass cores. We find that higher-mass cores undergo a nearly homologous collapse, whereas lower-mass cores show a more runaway-like collapse because
neutrino cooling becomes more efficient at their higher densities and temperatures. Consequently, the black hole formed in lower-mass models initially contains a smaller fraction of the core mass, and disk formation occurs while a larger amount of matter remains outside the black hole. The lower compactness of pair-unstable cores also allows larger dimensionless angular momentum, favoring the formation of rapidly rotating black holes and massive disks. The disk bounce drives mass ejection with ejecta masses of order $10-10^3M_\odot$ and kinetic energies of order $10^{53}-10^{55}\,\mathrm{erg}$. Significant $^{56}$Ni production in the disk-bounce ejecta occurs only in the lowest-mass models. For selected models, we further follow the viscous
evolution of the disk and find that viscosity enhances the ejecta mass and kinetic energy. In models with $\lesssim10^4M_\odot$, the viscosity-driven ejecta can originate from disk matter that has reached
nuclear statistical
equilibrium and can therefore become rich in $^{56}$Ni. These results suggest that rotating very massive
star collapses can produce massive, energetic ejecta and, for sufficiently low core masses, substantial iron-group elements.
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All authors Sho Fujibayashi, Alan Tsz-Lok Lam, Yuichiro Sekiguchi, Masaru Shibata
Astrophysics of Galaxies
Orbital Migration of Interacting Stellar Mass Black Holes in Disks around Supermassive Black Holes. III. Mass Distribution of Hierarchical Mergers
Katherine L. Gonglewski, Amy Secunda, Mordecai-Mark Mac Low et al. (+3 more)
Active
galactic nucleus (AGN) disks are a promising location for the formation of binary black holes (BBHs) that will merge on relatively short timescales and be detected by LIGO-Virgo-KAGRA (LVK). To compare the mass function (MF) of black holes (BHs) undergoing hierarchical mergers in AGN disks to the inferred MFs from LVK observations, we perform 360 simulations with an N-body code augmented to include an analytic model for migration torques and other gas forces. We focus on the region surrounding migration traps in AGN disks where migration torques cancel out and BHs converge. We find that regardless of changes in the initial MF and BBH merger criteria, frequent mergers deplete the number of BHs with masses $\lesssim 10$~$M_\odot$ and fill the upper mass gap with a roughly uniform distribution from 40–100~$M_\odot$, with a slight overabundance around ${\approx}70~M_\odot$ from resonant orbiters. We also find an average merger rate of $\sim 6$~Gpc$^{-3}$~yr$^{-1}$ for migration-trap-aided BBH mergers in our AGN disk model. $\sim 40\%$ of these mergers have uneven mass ratios and 16% have a primary mass $\in[50-100]~M_\odot$. Therefore, AGN disks could easily be the source of BBH mergers observed by LVK that are difficult to produce through traditional
stellar evolution channels. Our simulations also form a separate higher-mass intermediate mass black hole (IMBH) population $>200~M_\odot$ after $\sim 2$~Myr. Future gravitational wave detectors can use observations of this IMBH population to constrain models of AGN
accretion disks.
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All authors Katherine L. Gonglewski, Amy Secunda, Mordecai-Mark Mac Low, K. E. Saavik Ford, Barry McKernan, Fabian R. N. Schneider
Instrumentation and Methods for Astrophysics
Laser Metrology for Precision Alignment of Transmission Gratings in the REDSoX Soft X-ray Polarimeter
Swati Ravi, Alan Garner, Jill Juneau et al. (+4 more)
The Rocket Experiment Demonstration of a Soft X-ray Polarimeter (REDSoX) is a NASA sounding-rocket mission designed to perform the first astrophysical spectropolarimetry in the 0.2-0.4 keV energy band. The instrument uses critical-angle transmission (CAT) gratings to disperse incident X-rays onto laterally graded multilayer (LGML) mirrors, requiring 48 individual gratings to be co-aligned to within 6 arcminutes in yaw, pitch, and roll. To support the systematic assembly of the grating array, we adapted a scanning
laser-reflection metrology technique in which normal-reflected, angled-reflected, and diffracted ultraviolet
laser beams are measured using three position-sensitive detectors (PSDs). Changes in the measured beam positions are used to reconstruct the local yaw, pitch, and roll of each grating and provide real-time feedback during mechanical adjustment. We demonstrate the system using a prototype miniature grating structure containing two gratings. Following co-
alignment, the assembly underwent a flight-level random-vibration test followed by a qualification-level sine sweep. Measurements obtained before and after testing showed that the relative grating orientations were retained to within 1 arcminute, less than 17% of the REDSoX co-
alignment tolerance. This work establishes a reproducible and scalable approach to the assembly and verification of large transmission-grating arrays for REDSoX and future X-ray spectroscopic instruments.
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All authors Swati Ravi, Alan Garner, Jill Juneau, F. Elio Angile, Ralf K. Heilmann, Herman L. Marshall, Sarah N.T. Heine
Earth and Planetary Astrophysics
Effects of Pebble Accretion Isolation Mass on Observable Exoplanet Properties
Lucas Brefka, Rebekah I. Dawson, Mariah G. MacDonald et al. (+2 more)
The Kepler Mission has discovered a plethora of planetary systems with super-Earth sized
planets. These systems exhibit many properties, from widely-spaced
planets with non-negligible eccentricities and inclinations, to tightly-spaced, coplanar, and nearly circular multi-
planet systems. The observable properties of these systems, such as
planet-
planet spacings, multiplicity and orbital morphology, can be strongly influenced by the initial conditions of formation. These conditions affect the early growth of planetary embryos in the gas disk phase through pebble and/or planetesimal
accretion, which then affects the final growth of
planets during the
giant impact stage. In this work, we investigate how assumptions of different limiting embryo isolation masses during early stages of
planet formation affect the final properties of super-Earth
planets within the inner disk, comparing our mock-observed results to each other, as well as to the Kepler sample. We test several models of pebble
accretion isolation mass, including pebble isolation, flow isolation, and migration feedback isolation and otherwise adopt the same parameters for the gas disk. We find that while each model can match at least one distribution of observables in the Kepler catalog, they fall short of matching all distributions simultaneously, even with extreme reweighting. Our inability to match all observations suggests that the initial conditions and/or modeled effects in our simulations that we held fixed should be investigated. This exploration sheds light on how planetary systems evolve and the processes that influence the wide range of system parameters we observe today, helping place our own
Solar System in context.
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All authors Lucas Brefka, Rebekah I. Dawson, Mariah G. MacDonald, Phoebe Sandhaus, Eric B. Ford
Earth and Planetary Astrophysics · Cross-listed from physics.hist-ph
From the Earth to the Sun
Dieynaba Young
This year marks 360 years since the founding of the French Academy of Sciences. This is the story of the academy's daring 17th century expedition to measure the Earth-sun distance. A truncated version first appeared in National Geographic Magazine; the following is closer to the original draft, with updated information and references.
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Cosmology and Nongalactic Astrophysics · Cross-listed from physics.data-an
Unknown Unknowns: Model Misspecification in Machine Learning for Physics
Juan Cruz-Martinez, Carolina Cuesta-Lazaro, Alexander Held et al. (+1 more)
Machine learning is now a central tool for solving inverse problems in particle physics and astronomy. Models are trained on simulation and deployed on real data, raising the question not just of whether they fit, but of whether they are wrong in ways we did not anticipate: the unknown unknowns. This challenge of model misspecification is not unique to machine learning. In physics, misspecification is sometimes exactly what we want to find: new discoveries appear as failures of existing models. At other times, we want such effects absorbed into the analysis without biasing the measurement. A robust analysis is one that absorbs the misspecifications we are not interested in, while preserving sensitivity to the ones we are. Machine learning can both amplify misspecification and provide new tools to address it. We discuss the challenges of model misspecification, diagnostics for detecting it, and strategies for mitigation. No single diagnostic can confirm that a model is correctly specified: detection and mitigation are two halves of an iterative loop, in which a battery of complementary diagnostics is applied, the model is updated, and the process repeated. Robustness against unknown unknowns is ultimately less about any single technique than about a disposition: a willingness to suspect one's own model, and to design analyses that can survive being wrong in ways one did not anticipate.
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All authors Juan Cruz-Martinez, Carolina Cuesta-Lazaro, Alexander Held, Michael Kagan
Cosmology and Nongalactic Astrophysics · Cross-listed from gr-qc
Vector Perturbations in Ghost-Free Quasidilaton Massive Gravity
Ekapob Kulchoakrungsun and Daris Samart
We study transverse vector perturbations in ghost-free extended quasidilaton massive
gravity without a quasidilaton kinetic term, in the presence of minimal matter. In
vacuum, we recover the known result that the kinetic coefficient $K_V$ of the gravitational vector modes vanishes on the self-accelerating branch $J=0$, so those modes are infinitely strongly coupled at linear order. We then add a canonical scalar field and a single Abelian vector (Maxwell or Proca). After integrating out the auxiliary shift, we find the same $K_V$ as in
vacuum. The scalar matter has no transverse perturbation; it enters the unsimplified shift constraint, but those terms cancel once the Friedmann equation is used. A Maxwell or Proca field with vanishing isotropic background does not mix with the gravitational vectors at quadratic order. Minimal matter therefore leaves $K_V=0$ on Branch II. We do not claim that the modes are absent from the nonlinear theory. We do conclude that ordinary minimal matter is not enough to make the vector sector perturbatively healthy on this branch. If we need healthy gravitational vector modes at the linear level, Branch I is the branch to use.
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Earth and Planetary Astrophysics
The sensitivity of TESS to transiting planets in TOIs with close-in stellar companions
Colin Littlefield, Kathryn V. Lester, David R. Ciardi et al. (+1 more)
High resolution imaging with optical speckle interferometry has revealed that many transiting
exoplanet host
stars possess close-in
stellar companions. The objective of this study is to quantify how the presence of these companions impacts the ability of TESS to detect the transits of small
planets. We accomplish this by examining 2052 TESS Objects of Interest (TOIs) that appear to be single-
star systems based on speckle interferometric observations as well as 188 TOIs in unresolved ($< 1.2\arcsec$)
stellar binaries. For each
planet, we take its transit signal-to-noise ratio (SNR), radius, and orbital period from the TOI catalog and, for
planets in
stellar binaries, we correct the radius for dilution by the companion. By applying a scaling relation to the measured transit SNR of each TOI in our sample, we determine the detectability of transits in each TOI as a function of both
planet radius and orbital period. When applied to the full sample, this procedure elucidates the sensitivity of TESS to transiting
planets as a function of binarity, host-
star spectral type,
planet radius, and
planet orbital period. These sensitivity grids quantify the bias against the detection of small
planets in unresolved binaries by TESS and show that there is a particularly low sensitivity to
planets transiting secondary
stars in unresolved binaries, especially as the magnitude difference between the
stars increases. These sensitivity grids are available for download to facilitate their use in other studies.
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All authors Colin Littlefield, Kathryn V. Lester, David R. Ciardi, Steve B. Howell