Astrophysics of Galaxies
The JWST Proto-PAH project. Computational modeling of the emission carriers
A. Ricca, G. C. Sloan, E. Peeters et al. (+8 more)
The infrared spectra of many carbon-rich post-asymptotic giant branch
stars are dominated by emission features from aromatic and aliphatic hydrocarbons, but the chemical structure of the carriers remains unidentified. Class D sources show unusual emission profiles with strong aliphatic emission, providing a stringent test of carrier candidates. Here we investigate whether hydrogenated carbonaceous molecular particles can be the carriers of these features. Rather than assuming candidate geometries we generate the initial structures using ab initio molecular dynamics simulations and optimize them using density functional theory. We then compare the computed emission spectra to JWST NIRSpec and MIRI/MRS observations of Class D sources. The structures providing the best agreements contain sizeable domains with defect-bearing aromatics and hydrogenated-aromatics connected by aliphatic bridges, in contrast to the "arophatic" cluster model of isolated two- to three-ring aromatics connected by aliphatic and olefinic bridges. As a representative example, we discuss in detail the molecular particle C130H96 (radius of 5.5 A) and compare its computed spectrum to the JWST spectra of IRAS 05110-6616, a Class D2 source with apparent shifts of the aromatic C-H out-of-plane bands. The calculated spectra are in qualitative agreement with the observed 3 micron profile, the aliphatic C-H bending bands, the broad 8 micron feature, the 11-14 micron C-H out-of-plane region, and the bands at 16 and 21 microns. We hypothesize that UV photo-driven fragmentation of such molecular particles releases aromatics linked by aliphatics, followed by the formation of polycyclic aromatic hydrocarbons and fullerenes as these objects evolve into planetary nebulae.
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All authors A. Ricca, G. C. Sloan, E. Peeters, J. Cami, N. Clark, M. Matsuura, R. Sahai, J. Bernard-Salas, D. A. Garcìa-Hernàndez, J. Li, C. Bhatt
Earth and Planetary Astrophysics
Hot Rocks Survey VI: An anomalously hot dayside for the rocky planet GJ 357 b
Merlin Zgraggen, Brice-Olivier Demory, Hannah Diamond-Lowe et al. (+15 more)
As part of the JWST Hot Rocks Survey, we analyzed a JWST/MIRI F1500W secondary-eclipse observation of GJ 357 b, a rocky
exoplanet orbiting a nearby M dwarf. We also performed a new global analysis of the GJ 357 system, combining TESS photometry, a JWST/NIRSpec transit observation, the MIRI secondary eclipse, radial velocities, and Gaia parallax measurements to obtain a self-consistent set of stellar and planetary parameters. We measure an occultation depth of $200.5 \pm 12.7,\mathrm{ppm}$, corresponding to a dayside brightness temperature at $15,\mu\mathrm{m}$ of $T_{\mathrm{b},15,\mu\mathrm{m}}=923^{+39}_{-38},\mathrm{K}$. The inferred brightness temperature substantially exceeds the zero-Bond-albedo, no-redistribution, disk-integrated bolometric dayside reference temperature of $686 \pm 14,\mathrm{K}$. The measured eclipse depth differs from the tested zero-albedo, grey airless-surface model by $5.2\sigma$ and is also inconsistent with the high-mean-molecular-weight atmospheric models considered here, including pure CO$_2$, pure H$_2$O, and N$_2$ with 100 ppm CO$_2$. Possible explanations for the excess emission in the MIRI/F1500W band include wavelength-dependent surface emissivity, localized hot regions, or atmospheric temperature structures and opacity sources not included in the tested models. Follow-up mid-infrared eclipse spectroscopy would constrain the shape of the dayside emission spectrum and help test the proposed surface and atmospheric explanations.
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All authors Merlin Zgraggen, Brice-Olivier Demory, Hannah Diamond-Lowe, João M. Mendonça, Erik Meier Valdés, Mark Fortune, Kathryn D. Jones, Daniel Kitzmann, Millie Smith, Natalie H. Allen, Prune C. August, Amélie Gressier, Måns Holmberg, Jegug Ih, Lars A. Buchhave, Néstor Espinoza, Neale P. Gibson, Kevin Heng
Astrophysics of Galaxies
Breaking the AGB Color Degeneracy with Variability and H$_2$O: A Consistent Picture of AGB Chemistry, Dust, and the J-Region Across Environments
Caroline D. Huang, Massimo Marengo, Antonio Capodagli et al. (+7 more)
Resolved asymptotic giant branch (AGB) populations present many observational puzzles. We consider three often treated separately: photometric C/O classification boundaries must be redrawn empirically in new environments; hydrostatic model grids are too blue in bands sampling H2O absorption; and J-region (JAGB) luminosities can differ between fields of a single
galaxy. Pulsation connects them into a coherent picture. Using SPHEREx spectroscopy of AGB
stars in the Large Magellanic Cloud (LMC) with JWST/NIRCam photometry and HST time-series of the SN Ia host M101, placed on a common scale by synthetic photometry, we investigate how AGB variability, surface chemistry, and circumstellar dust depend on environment. We develop an F182M index sensitive to 1.9$\mu$m H2O absorption that chemically classifies variable AGB
stars and reveals oxygen-rich (O-rich)
stars degenerate with carbon-rich (C-rich)
stars in broadband colors. Because these features arise in extended atmospheric layers, hydrostatic grids struggle to reproduce them. Pulsation and circumstellar dust are asymmetrically linked: nearly all
stars with substantial infrared excess are variable, while many variables show little dust. This supports mass loss initiated by pulsation and enhanced by dust formation. Variable O-rich AGB
stars in M101 are up to ~0.7 mag redder than their LMC counterparts in dust-sensitive colors, consistent with more efficient silicate-dust production at higher
metallicity, while C-rich populations depend less on environment. Color windows that select C-rich
stars cleanly in the LMC are therefore 33-68% O-rich in the metal-rich M101. This challenges the J-region's universality as a standard candle while evading standard self-consistency checks. We recommend combining variability, or the infrared excess that implies it, with photometry of molecular features to improve AGB classification at 0.75-5.0$\mu$m.
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All authors Caroline D. Huang, Massimo Marengo, Antonio Capodagli, Adam G. Riess, Louise Breuval, Stefano Casertano, Patricia A. Whitelock, Gagandeep S. Anand, Randall K. Smith, Wenlong Yuan
High Energy Astrophysical Phenomena · Cross-listed from gr-qc
Rotating Weyssenhoff fluids in linearized Einstein-Cartan theory
Emmanuele Battista, Salvatore Capozziello and Francesco Giovinetti
The Weyssenhoff fluid expands the ordinary perfect-fluid description of general relativity by taking into account the intrinsic
spin of its constituent particles. Within the linearized regime of Einstein-Cartan theory, we investigate the exterior geometry produced by isolated slowly rotating Weyssenhoff fluids, i.e., sources endowed with both macroscopic and microscopic angular momenta. Our work represents an extension of the foundational analysis of Arkuszewski, Kopczyński and Ponomariev, which was restricted to the static fluid configuration. Under the assumptions of stationarity and axial
symmetry, we derive the explicit expression for the linearized stress-energy tensor of the source and obtain the corresponding metric through a multipole expansion. The ensuing solution exhibits a generalized Lense-Thirring structure, with both the gravitoelectric and gravitomagnetic sectors affected by the
quantum spin and macroscopic rotation. We also discuss some phenomenological implications of the model, including the gyroscope precession and the Sagnac effect, along with potential experimental probes of the predicted corrections.
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Instrumentation and Methods for Astrophysics
FOTO: Figure-Level Semantic Search for Astronomy
Hurum Maksora Tohfa and Francisco Villaescusa-Navarro
Astronomy papers carry much of their content in figures, but literature search indexes text, so there is no way to find a plot by describing what it shows. We present FOTO, a figure-level search tool over 482,750 captions from 53,839 peer-reviewed astro-ph papers. Each figure is indexed once by its title and caption, embedded with a 110M-parameter open model that runs locally, and a large
language model is applied only to the retrieved shortlist, where it verifies real figures rather than generating references to ones that do not exist. Held to the harder figure-level criterion, FOTO recovers the target for 29 to 79% of queries at recall 20 depending on register, against 6 to 20% for Pathfinder and 8 to 16% for Semantic Scholar on the easier paper-level criterion, and it beats the paid
embedding API it replaced. Reranking the shortlist then raises recall at 1 from 0.667 to 0.875 on detailed queries and from 0.071 to 0.571 on vague ones. Openly available models match or beat paid LLM models for verification
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Solar and Stellar Astrophysics
The 91T/99aa-like Type Ia Supernova 2019vrq, Part II: 3D, Non-LTE, Low-Amplitude, Pulsating Delayed-Detonation Models of a Promising Standard Candle
Peter Hoeflich, Yi Yang, J. Craig Wheeler et al. (+11 more)
We analyze the overluminous, 91T/99aa-like Type~Ia SN 2019vrq, based on light curves(LCs) and spectropolarimetric time-series. We employ 3D-radiation-hydrodynamical, full non-LTE simulations of low-amplitude, radially-pulsating-off-center-delayed-detonations(PDD) of a possibly rotating near-M(Ch) mass white dwarf (WD) to reproduce the LCs and spectra. The progenitor originates from a 7 Mo main-sequence
star of solar
metallicity. The explosion yields 0.86Mo of 56Ni and 0.023Mo of 58Ni. The latter falls a factor of 10 below that of `classical' delayed-detonations for 91T/99aa-like SNe, a diagnostic that is directly testable with JWST. The slow deflagration leaves a bound, pulsating WD. The detonation is triggered at 0.8 Mo. LCs and spectra require an outer 0.11 Mo of unburned material with twice-solar Fe, plausibly the ashes of an earlier, unsuccessful explosion, and low-level mixing of nuclear-statistical-
equilibrium(NSE) elements. The spectra reflect early high ionization followed by recombination, with the photosphere shifting from intermediate-mass-element- to NSE-dominated layers about a week before maximum. The early high-velocity (HV) CaII IR3 line (likely produced by an aspherical density shell at 24,000km/s of 0.01 Mo) arises from an ionization sandwich rather than a double structure in abundances. After Ca recombines, the CaII IR3 wing reaches 33,000km/s well beyond the HV component. The low polarization is due to low scattering in an iron-group-dominated photosphere, consistent with asphericities <20% and resulting in a directional luminosity dependence 10-15% from the outer layers, and a dispersion of 35% in total. The LC-shape provides a further probe of asphericity, consistent with the locally tested polarimetry limits and relevant for high-z cosmology.
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All authors Peter Hoeflich, Yi Yang, J. Craig Wheeler, Dietrich Baade, Aleksandar Cikota, Elham Fereidouni, Divya Mishra, Sagiv Shiber, Maximo Marengo, Tyco Mera, Chris Ashall, Kyle Medler Cameron Medler, Lluis Galbany, Mark M. Phillips
Astrophysics of Galaxies
Collisional excitation of E- and Z-ethanimine to model cold molecular clouds
Francesca Tonolo, Vivek Vijay, Ernesto Quintas-Sánchez et al. (+5 more)
Context. Ethanimine is a prebiotically relevant complex organic molecule that has been proposed as a key precursor of amino acids in the interstellar medium. To date, both its E and Z isomers have only been detected toward the Sgr B2(N) molecular cloud. The pronounced non-local thermodynamic
equilibrium (non-LTE) effects predicted for this molecule require accurate collisional rate coefficients for reliable astrophysical modeling and future astronomical searches. Aims. We aim to provide the first collisional
datasets for both ethanimine isomers with the main cold molecular clouds collision partners, He and para-H2, in order to support non-LTE radiative-transfer modeling. Methods. State-to-state rate coefficients for collisions with He were computed by integration over mixed close-coupling (CC) and coupled-states (CS) scattering cross sections at different energy ranges. In addition, comparisons with mixed
quantum-classical theory (MQCT) calculations performed for both He and para-H2 collisions enabled the derivation of transition-specific scaling factors, which were applied to predict collisional rate coefficients for para-H2. Results. We present the first state-to-state collisional
datasets for both E- and Z-ethanimine in collision with He and para-H2, including all rotational transitions involving levels below 50 cm-1 and over the 5-100 K temperature range. Conclusions. The
datasets reported here provide the first collisional information suitable for non-LTE modeling of ethanimine in cold interstellar environments. They represent a key step toward more reliable abundance determinations and may facilitate future astronomical detections of both ethanimine isomers beyond Sgr B2(N).
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All authors Francesca Tonolo, Vivek Vijay, Ernesto Quintas-Sánchez, Adrian Batista Planas, Carolin Joy, Richard Dawes, François Lique, Dmitri Babikov
High Energy Astrophysical Phenomena
Spectral and Polarization Properties of Coherent Radio Emission from Relativistic Magnetized Pair Plasma Shocks
Yuanhong Qu, Joonas Nättilä and Lorenzo Sironi
Fast
radio bursts (FRBs) are millisecond-duration
radio transients whose emission mechanism remains an open question. The so-called synchrotron maser instability in relativistic magnetized shocks is a leading candidate for FRBs produced outside the compact object magnetosphere, yet its spectral and polarization predictions have not been systematically explored. We present three-dimensional particle-in-
cell simulations of relativistic magnetized pair
plasma shocks with upstream magnetization $\sigma > 1$ and bulk Lorentz factor $\gamma_0 = 10$, assuming a plane-parallel shock geometry and neglecting radiative cooling, and compute the spectra and polarization of the precursor maser emission for an arbitrary line of sight. For on-axis observers aligned with the shock-propagation direction, the X-mode dominates the emission. The O-mode power increases at off-axis viewing angles and is primarily associated with currents parallel to the upstream background
magnetic field. Assuming a spherical shock, we find full-width-at-half-maximum fractional bandwidths of $\Delta\nu/\nu_0\simeq0.57$ and $0.82$ for $\sigma=3$ and $6$, respectively. For highly magnetized shocks, the intrinsic emission bandwidth accounts for most of the spectral width, while high-latitude contributions provide additional broadening. The integrated emission remains highly linearly polarized near the spectral peak, with a nearly constant polarization angle due to the dominance of the X-mode. Our results suggest that synchrotron maser emission can produce spectra with bandwidths and high linear polarization degrees compatible with observations of some non-repeating FRBs, and may provide testable signatures for distinguishing shock-powered FRBs from other emission mechanisms.
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High Energy Astrophysical Phenomena
Infrared Cavity Surrounding T Pyxidis: Evidence of a Nova Super-remnant?
Michael W. Healy-Kalesh and Matthew J. Darnley
Nova super-remnants (NSR) are shell-like structures spanning tens of parsecs that are predicted to grow around all recurrent novae as a result of repeated ejecta sweeping up the surrounding material. After the first NSR was discovered in the Andromeda
Galaxy around M31N 2008-12a, a number of Galactic NSRs have been uncovered, as has the first NSR in the Large Magellanic Cloud. Here we report an apparent infrared cavity surrounding the Galactic recurrent nova, T Pyxidis, which we suggest may be a nova super-remnant and discuss the implications.
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Astrophysics of Galaxies
A tidal disruption event in a quasar at redshift 7.19
S. Fujimoto, Q. Fei, G. B. Brammer et al. (+41 more)
We report a long-lived nuclear transient in GNz7q, a red
quasar at $z=7.19$ powered by a $\sim3\times10^{7}\,M_\odot$ black hole and hosted by a compact, dusty starburst
galaxy. The transient was identified in more than two decades of imaging with HST, Spitzer, and JWST. After a rapid rise, the source faded smoothly by $\Delta m\simeq1.1$ mag in the rest-frame ultraviolet over $\sim2$ rest-frame yr, with coherent, wavelength-dependent
evolution across 1–5 $\mu$m that places GNz7q above the 99.9th percentile of the SDSS
quasar variability distribution and is absent at $z\gtrsim5$. The duration and energetics disfavor superluminous
supernovae, and
stochastic quasar variability reproduces the multi-band
evolution with a probability of $\lesssim10^{-5}$. A panchromatic model combining a thermal continuum with a $t^{-5/3}$ decline reproduces the light curves, yielding a peak bolometric luminosity of $\simeq3\times10^{45}$ erg s$^{-1}$ and a radiated energy of $\simeq1.5\times10^{53}$ erg, which imply the tidal disruption of a
star of a few solar masses and place the event among the most energetic tidal disruption events (TDEs) known. A redshifted, extremely broad Balmer-line component in independent JWST/NIRSpec spectroscopy is consistent with a transient, non-virialized broad-line region. JWST/MIRI photometry further reveals delayed mid-infrared emission from $\simeq1500$ K dust at a sub-parsec radius, consistent with a dust echo of the
flare. The relatively low black-hole mass and dense
star-forming
nucleus of GNz7q are conditions under which TDEs are expected to be most efficient. These observations provide a time-domain view of episodic black-hole fueling and its dusty nuclear environment 700 million years after the Big Bang. Wide-field surveys with Roman and Euclid in the near-infrared, complemented by LSST at lower
redshifts, may uncover such transients in large numbers.
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All authors S. Fujimoto, Q. Fei, G. B. Brammer, K. Inayoshi, V. Kokorev, L. C. Ho, R. Li, F. Walter, V. Bromm, L. Colina, P. Dayal, S. L. Finkelstein, M. Ginolfi, Z. Liu, G. C. K. Leung, G. E. Magdis, J. Matthee, R. P. Naidu, P. Oesch, M. Onoue, P. G. Pérez-González, D. Watson, J. Álvarez-Márquez, J. Antwi-Danso, Y. Asada, G. Barro, C. M. Casey, J. Chisholm, S. Gillman, R. Marques-Chaves, J. P. U. Fynbo, T. R. Greve, I. Labbe, R. A. Meyer, F. Rizzo, A. Robbins, R. Schneider, C. L. Steinhardt, S. Toft, A. Trinca, F. Valentino, R. Valiante, M. Vestergaard, M. Xiao
Astrophysics of Galaxies
SN Helios: A Multiply Imaged Type II Supernova Opening Time-Delay Cosmography beyond redshift of 3
Seiji Fujimoto, Conor Larison, Justin D. R. Pierel et al. (+64 more)
We report the discovery and spectroscopic confirmation of SN Helios, a strongly lensed, multiply imaged Type II
supernova (SN) at $z=3.34$ behind the
galaxy cluster RXC J0018.5+1626. The transient was identified as a red F150W-dropout source (F277W = 26.1 mag) in JWST/NIRCam imaging taken on 2026 July 3 for the VENUS survey, with no counterpart in 2024 December imaging. Director's Discretionary Time observations on 2026 August 17 added second-epoch NIRCam imaging and a deep NIRSpec prism spectrum. The spectrum shows a strong, spectrally resolved H$\alpha$ emission line (FWHM $\approx 7900$ km/s) with a P-Cygni absorption blueshifted by 8800 km/s, together with corresponding H$\beta$ and He I $\lambda$10830 features, establishing a hydrogen-rich photosphere at $z=3.34$. Template fits classify SN Helios as a Type II SN, and light-curve comparisons with well-studied local SNe II yield a phase of $27.5\pm2.8$ rest-frame days past B-band maximum. Independent cluster lens models magnify the observed image by $\mu\approx 10$-20 and predict another image within $\simeq 2$-6 yr, offering a rare opportunity for a time-delay measurement of $H_{0}$ with a source at $z>3$. The host
galaxy is undetected in deep rest-frame ultraviolet and optical imaging, in emission lines, and in ALMA 2 mm dust continuum, leaving a heavily obscured counterpart unlikely. Its de-lensed $M_{\rm UV}\gtrsim -13$ places it far below blank-field limits and adds support to an elevated core-collapse rate per unit
star formation in ultra-faint
galaxies. Without the multi-epoch data, SN Helios would masquerade as a convincing $z\approx 16$ Lyman-break
galaxy, with
galaxy-template fits strongly disfavoring any low-
redshift solution even with multiple medium bands. Its spectrum thus provides an empirical SED template with which high-
redshift searches can vet similar dropout candidates.
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All authors Seiji Fujimoto, Conor Larison, Justin D. R. Pierel, Lukas J. Furtak, Masamune Oguri, Adi Zitrin, Jose M. Diego, Keren Sharon, David A. Coulter, Gabriel Brammer, Vasily Kokorev, Chelsea Nash, Pedram Abedi, Christa DeCoursey, Armin Rest, Andreas L. Faisst, Brenda L. Frye, Tiger Yu-Yang Hsiao, Kohei Inayoshi, Kotaro Kohno, Jorryt Matthee, Matteo Messa, Yoshiaki Ono, Fengwu Sun, Eros Vanzella, Rogier A. Windhorst, Abdurro'uf, Aadya Agrawal, Joseph F. V. Allingham, Yoshihisa Asada, Hakim Atek, Maruša Bradač, Larry D. Bradley, Mateusz Bronikowski, Dan Coe, Christopher J. Conselice, Pratika Dayal, Eiichi Egami, Michael Engesser, Gavin Scott Farley, Qinyue Fei, Ori D. Fox, Yoshinobu Fudamoto, Miriam Golubchik, Yuichi Harikane, Gourav Khullar, Tomokazu Kiyota, Paulo A. A. Lopes, Ray A. Lucas, Guillaume Mahler, Ashish Kumar Meena, Rohan P. Naidu, Gautham Narayan, Gaël Noirot, Pascal A. Oesch, Masami Ouchi, José María Palencia, Massimo Pascale, Luke Robbins, M. R. Siebert, Roberta Tripodi, Francesco Valentino, Darach Watson, Hayley Williams, Hiroto Yanagisawa, Erik Zackrisson, Anita Zanella
High Energy Astrophysical Phenomena
Machine Learning $\beta$-decay Half-lives and Their Application to $r$-Process Observables
Mengke Li, Flora Wang, Jonathan Engel et al. (+3 more)
Accurately modeling $\beta$-decay half-lives of highly
neutron-rich
nuclei is a critical challenge for understanding $r$-process nucleosynthesis and the resulting kilonova light curves. We introduce a data-driven approach to model $\beta$ decay that uses Mixture Density Networks (MDNs) trained on the latest experimental measurements to extrapolate the half-lives of
neutron rich
nuclei. Unlike standard deterministic regression, the MDN directly parameterizes the probability distribution of the half-lives, providing intrinsic (aleatoric) uncertainty. We contrast the intrinsic uncertainty of a single model with the range of models produced by using random variations of the input training data samples. While all models show excellent agreement with experimental data, we find that varying the training data sets produces a wide range of extrapolations, particularly along data-poor regions such as the $N=126$ isotonic chain. We then propagate a selection of model results into $r$-process network calculations to evaluate their impact on isotopic abundances. Finally, by coupling the resulting isotopic abundances with thermalization efficiencies, we translate the effective nuclear heating rates into bolometric light curves. We compare the ranges of outcomes produced from the intrinsic uncertainty of a single model to those produced by multiple independent models trained on different training data sets.
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All authors Mengke Li, Flora Wang, Jonathan Engel, Matthew Mumpowe, Rebecca Surman, Nicole Vassh
High Energy Astrophysical Phenomena
Interaction of stellar dipole and disk magnetic fields in accretion-ejection systems
Somayeh Sheikhnezami and Sarah Aslani
We study jet formation from a magnetically diffusive, sub-Keplerian
accretion disk threaded by different
magnetic field configurations. We present two dimensional, axisymmetric MHD simulations in spherical coordinates employing the PLUTO code. Our results show that the reference simulation, in which the disk is threaded by an initial large scale poloidal
magnetic field, reaches a quasi steady state and produces a well collimated jet.Both kinetic and
magnetic torques are significant and evolve smoothly over time. The
accretion process is established smoothly, with about 26% of the accreting material being delivered into the outflow. Alternatively, applying a purely stellar dipolar
magnetic field produces weak and unstable outflows, characterized by inefficient angular momentum transport and strongly suppressed
accretion. Additionally, in simulations where the stellar dipolar
magnetic field is present alongside the disk's initial poloidal
magnetic field, the disk
magnetic field predominantly stabilizes the system. It also facilitates angular momentum transport from the disk and sustains a significant outflow mass flux. Furthermore, we performed additional simulations that explicitly include an inner gap associated with the disk truncation region. These simulations were designed as a robustness test of the treatment of the innermost disk region and confirm that our main conclusions are not sensitive to the presence of this gap. Overall, our findings demonstrate that although the magnitude of stellar dipole plays an important role in the
evolution of the
accretion-ejection structure, the large scale poloidal
magnetic field threading the disk is essential for launching and sustaining a stable and well collimated magnetized jet.
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Cosmology and Nongalactic Astrophysics
Analyzing $\mu$ Parameter Range and the Duration of Reheating in the Polynomial $\alpha$-attractor Models using CMB Observations
Ajay Atwal and Apurba Samanta
Cosmological $\alpha$-attractor models are renowned for their universal predictions for inflationary observables, largely independent of the detailed form of the inflaton potential. In this work, we investigate the extent to which this universality persists for
polynomial $\alpha$-attractor models, with particular emphasis on the scalar spectral index ($n_s$) and the post-inflationary reheating history. We derive an extended analytical expression for the scalar spectral index ($n_s$) and the tensor-to-scalar ratio ($r$), retaining sub-leading contributions beyond the commonly used universal approximation. Interestingly, we find that these corrections introduce an explicit dependence of $n_s$ on the parameter characterizing the
polynomial attractor potential $\mu$, a dependence that is absent in the leading universal expression. We systematically investigate how this model dependence modifies the predictions in the $(n_s-r)$ plane and affects the model parameter ($\mu$). We further incorporate the Duration of reheating ($\Delta N_{rh}$) and effective equation of state parameter of the reheating epoch ($w_{rh}$), accounting for their impact on the number of e-folds between horizon crossing and the end of inflation ($\Delta N_{\mathrm{CMB}}$). By confronting the resulting predictions with current CMB observations, we identify the viable parameter space and examine the interplay between the model parameter ($\mu$) and reheating. Our results demonstrate that sub-leading corrections can provide a window into the underlying structure of
polynomial attractors, offering a possible way to distinguish different members of the attractor class observationally.
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Solar and Stellar Astrophysics
Revealing Optically Hidden Companions to Intermediate-Mass Stripped Stars with Radial Velocities
Alexander Laroche, Maria R. Drout, Ylva Götberg et al. (+7 more)
The recent discovery of a population of intermediate-mass helium
stars ($\sim$2-8 $M_\odot$) in the Magellanic Clouds has opened a new observational window into massive binary
evolution. These hot, helium-rich
stars are thought to be products of binary interaction, and some show no evidence for a luminous companion in their optical spectra. Here, we present multi-epoch radial velocity (RV) measurements for eight of these systems obtained with Magellan/MagE from 2018-2023. Five helium
stars exhibit significant RV variability consistent with binary motion, while three do not. The five helium
stars with evidence of binarity have orbital periods from 16 hours to 300 days, and eccentricities consistent with zero, implying companion mass lower limits from $\sim$0.6-2.9 $M_\odot$. We discuss implications of their orbits for the nature of the unseen companions, and find that low-mass late-pre/early-main sequence
stars ($\lesssim$1.5-3.1 $M_\odot$), low-mass stripped
stars and compact objects are currently viable. We identify an unexpected correlation between surface hydrogen abundance and binarity within this sample: helium
stars in binaries are hydrogen-poor ($X_{\rm H,surf}$ $\sim$ 0.3-0.4), whereas helium
stars without detected binary motion are nearly hydrogen-free ($X_{\rm H,surf}$ $\lesssim$ 0.05). This bimodality suggests that low RV variability in a subset of the sample is not simply due to inclination, but rather a distinct evolutionary pathway. We consider three possible explanations for these objects: wide binaries, disrupted binaries, and stellar mergers. The binary properties of this first sample of intermediate-mass helium
stars is diverse, and provides important empirical constraints for binary
evolution and compact object formation.
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All authors Alexander Laroche, Maria R. Drout, Ylva Götberg, Bethany Ludwig, Dandan Wei, Peter Senchyna, Mathieu Renzo, Debasish Dutta, Anna J. G. O'Grady, Max Pritzkuleit
Instrumentation and Methods for Astrophysics
Selective state space model for photon energy estimation in microwave kinetic inductance detectors
Benjamin A. Mazin
Microwave Kinetic Inductance Detectors (MKIDs) are superconducting
photon counting detectors that simultaneously measure the energy and arrival time of individual
photons and are suitable for large-format arrays. The energy resolving power R = E/$\Delta$E is the primary figure of merit for spectrophotometric applications. It is limited in practice by the assumptions underlying the Wiener optimal filter used to estimate
photon energy: stationary noise, linear response, and energy independent pulse shapes, all of which MKIDs structurally violate. We present Venom (Very Efficient Neural Optimal-filter for MKIDs), a selective state space model based on the Mamba architecture that replaces the coordinate transform and optimal filter, operating directly on raw in-phase/quadrature timestream data, carrying 3,314 trainable parameters, and targeting deployment on the MKIDGen3 and future system-on-chip readout platforms. To deal with the small calibration
datasets typical of MKID experiments, we train on synthetic pulses drawn from a streaming principal component analysis that samples
photon energy continuously between calibration wavelengths. All numbers are reported on a stratified 15% held-out validation set, with R measured from a kernel density estimate. On an InHf bilayer resonator (ten wavelengths, 254-1310nm), Venom reaches a mean R of 26.4 versus 24.2 for the published per-wavelength optimal filter baseline, a 9% improvement from one model in place of ten per-
laser filter templates. The R of 38.6 at 254 nm is the highest ever recorded for an ultraviolet-to-near-infrared MKID suitable for use in a dense array. On a PtSi resonator (five wavelengths, 808-1310nm), where the published analysis used one shared 920nm template, Venom matches the optimal filter, with a mean R of 9.1 versus 8.8 at the three interior wavelengths.
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High Energy Astrophysical Phenomena
Mass and spin properties of black-hole mergers reveal formation in triples
Jakob Stegmann and Aleksandra Olejak
Deciphering the formation channels of the observed binary black hole mergers remains a central open problem in gravitational-wave astronomy. With hundreds of detections, the inferred distribution of masses and
spins reveals a rich diversity which is difficult to reconcile with traditional formation scenarios from isolated binary
stars or dense stellar environments. Here, we consider the large fraction of massive progenitor
stars found in hierarchical triples and investigate black hole mergers driven by gravitational perturbations from tertiary companions. Simulations of their dynamics and stellar
evolution reproduce key features of the merger population, including: i) a sharp primary mass peak at $m_1\sim10\,\rm M_\odot$ dominating the population; ii) substantial fractions of systems with large
spin-orbit angles within and beyond the peak, matching the skewed distributions of the
spin parameters $\chi_{\rm eff}$ and $\chi_p$; iii) a mass-ratio distribution favouring equal masses with matching slopes. We further predict a sharp decline of mergers near $m_1\sim30\,\rm M_\odot$, coincident with the location of inferred features that may signal another channel dominating the high-mass tail. Our models of hierarchical triples demonstrate, for the first time, a formation scenario which simultaneously reproduces the principal properties inferred for the low-mass bulk of binary black hole mergers.
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Astrophysics of Galaxies
Saturation Mechanism of Cosmic Ray Streaming Instabilities with a Shell Distribution
Mohamad Shalaby, Rouven Lemmerz and Christoph Pfrommer
Cosmic rays (CRs) drive galactic winds and regulate
galaxy growth while contributing to heating the central cooling
plasma in dense
galaxy clusters, making the nonlinear saturation of the instabilities that govern their transport a problem of central importance in astrophysics. Using fully kinetic particle-in-
cell (PIC) simulations, we find that the streaming instability driven by CRs with a shell momentum distribution saturates through gyro-phase bunching around driven Alfvén waves. Fluid-PIC (FPIC) simulations with both ideal and Landau closures reproduce the PIC saturation amplitude, and the same gyro-phase bunching mechanism, indicating that nonlinear Landau damping (NLLD) does not determine the saturation level at our simulation parameters ($v_{\rm A} = 0.01c$, $n_{\rm CR}/n_i = 0.01$). Notably, the CR ions fully isotropize in the Alfvén-wave frame in all simulations, including the FPIC run with an ideal closure in which NLLD is entirely absent, showing that this isotropization does not require NLLD. We additionally confirm, using the FPIC ideal closure, that this saturation amplitude is unchanged across a tenfold increase in domain size, indicating that the mechanism is local rather than dependent on domain-scale processes. Together, these results indicate that, at least in this regime, NLLD is not the dominant saturation mechanism for the CR streaming instability, in tension with common assumptions built into CR transport models used in
galaxy formation and interstellar medium simulations. Whether this conclusion extends to the lower CR densities and Alfvén speeds characteristic of the interstellar medium remains an open question that we address in an upcoming work.
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Astrophysics of Galaxies
TRICEPS. I. Tracing cold gas, dust, and stars at sub-kpc scales in massive star-forming galaxies at z = 4-5
Federico Lelli, Lingrui Lin, Zhi-Yu Zhang et al. (+11 more)
We introduce the TRICEPS (Tracing Resolved Ionized Carbon Emission in Primeval Systems) survey. TRICEPS focuses on a sample of 16 massive
galaxies at z = 4 - 5 with top-quality data: (i) ALMA band-7 observations of the [CII]-158 micron line, tracing the cold gas distribution and kinematics at spatial resolutions of about 0.1" (~0.8 kpc), (ii) ALMA maps of the rest-frame 160 micron continuum emission, tracing the dust distribution at similar spatial resolutions, (iii) multi-band JWST images from NIRCam and MIRI, tracing the stellar mass distribution and
star formation activity at spatial resolutions of 0.1"-0.2", and (iv) multi-line CO observations from ALMA and the VLA, including the CO(1-0) line, tracing the molecular gas content. In this first paper, we describe the TRICEPS scientific goals, the basic properties of the
galaxy sample, and the ALMA band-7 observations. TRICEPS
galaxies were selected based only on bright [CII] fluxes (>2 Jy km/s). They lie on the top-end of the
star-forming main sequence at z = 4-5, having stellar masses between about 10^10.5-10^12 Msun and
star-formation rates between about 100 - 3000 Msun/yr. To date, TRICEPS is the largest sample of
galaxies at z = 4-5 for which the gas distribution and kinematics are exceptionally well resolved: on average, 46 resolution elements per
galaxy with signal-to-noise ratio higher than 3. By survey design, half of the TRICEPS targets are in
galaxy pairs; clear signs of tidal interactions are present in three of the four pairs. In all
galaxies, the [CII] velocity fields display regular rotation, albeit the interacting
galaxies tend to be somewhat more disturbed. The TRICEPS observations suggest that regular rotation is ubiquitous among massive
star-forming
galaxies when the Universe was less than ~1.5 Gyr old.
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All authors Federico Lelli, Lingrui Lin, Zhi-Yu Zhang, Cecilia Bacchini, Davide Bevacqua, Joe Bhangal, Marco Castellano, Carlos De Breuck, Giovanni Gandolfi, Allison W. S. Man, Antonino Marasco, Diego Paris, Borja Pérez-Díaz, Paola Santini
Astrophysics of Galaxies
Hidden in the Halo: New Diffuse Star Clusters in the M82 Starburst with JWST
Deepthi S. Prabhu, David J. Sand, Burcin Mutlu-Pakdil et al. (+12 more)
Diffuse
star clusters (DSCs) occupy a poorly explored region of the size-luminosity plane between classical globular clusters (GCs) and dwarf
galaxies. Here we report the discovery of four faint DSCs in the
halo of the nearby starburst
galaxy M82 using archival JWST/NIRCam imaging. We resolve individual
stars in all four systems, whose color-magnitude diagrams are consistent with predominantly old ($\sim10$ Gyr) stellar populations, based on comparison with isochrones. DSC 1 hosts a metal-poor population ($[\mathrm{M/H}]\sim-2$), while DSCs 2, 3 and 4 are better represented by $[\mathrm{M/H}]\sim-0.8$ isochrones. To establish their nature, we measure their sizes and integrated magnitudes using curve-of-growth and radial profile fits, which yield consistent results between these methods. The sizes of DSCs range from $\sim$ 5.4 to 10.5 pc, making them more extended than typical GCs (2-3 pc). Their luminosities span M$_{\rm V}\simeq-4.1$ to $-6.4$, reaching $\sim$ 1 mag fainter than the previously known M82
star cluster (SC) population. At these low luminosities, the systems occupy a sparsely sampled region of the size-luminosity plane where the distinction between SCs and dwarf
galaxies becomes increasingly ambiguous. Most notably, DSC 3 is the faintest SC candidate identified in M82 to date and approaches the regime occupied by Milky Way ultra-faint compact satellites. These faint DSCs were identified through visual inspection alone, suggesting they are likely underrepresented in existing
star cluster catalogs, and that a JWST-based archival search of nearby
galaxies would be fruitful.
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All authors Deepthi S. Prabhu, David J. Sand, Burcin Mutlu-Pakdil, Adam Smercina, Denija Crnojevic, Michael G. Jones, Paul Bennet, Amandine Doliva-Dolinsky, Kristine Spekkens, Debasish Hazarika, Laura Congreve Hunter, Jaclyn Jensen, Benjamin N. Velguth, Dennis Zaritsky, Sasha N. Campana
Cosmology and Nongalactic Astrophysics · Cross-listed from hep-th
Tracing out massive fields in cosmology
Guanhao Sun and Sam S.C. Wong
Cosmological correlators are calculated through the in-in formalism in (quasi-)de Sitter background. Its effective description is best represented by a reduced density
matrix. In this work, we study how integrating out a massive field in de Sitter space determines the reduced density
matrix of a light field at a finite observation time. Starting from a quasi-single-field model with non-linear couplings, we first evaluate the massive field wavefunctional at fixed final value and then trace over this value. The trace generates branch-mixing terms which are generally present in the Schwinger–Keldysh description. For a conformally coupled massive field, we show explicitly that the light field bispectrum from the effective description agrees with a full theory calculation. This example also shows that decay of a field at the future boundary does not by itself justify discarding its contribution to the trace. We discuss the differences between an exact nonlocal effective description and the local effective field theory obtained through a large mass expansion. We then identify which local cubic terms affect the late-time probability and which contribute only a wavefunctional phase. Finally, we organize the resulting kernels by response, noise, and Schwinger–Keldysh consistency conditions, and discuss the
symmetry constraints on the reduced density
matrix.
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Solar and Stellar Astrophysics
Non-linear dynamo waves in magnetized shear flows: a candidate mechanism for the solar cycle
Uddipan Banik
Large-scale
magnetic reversals in
planets,
stars, and
accretion disks require a non-linear theory coupling the
magnetic field to its sustaining flow. We derive exact non-linear solutions to incompressible magnetohydrodynamics in background rotational shear, with large-scale velocity and
magnetic fields linear in position (affine form). They reveal a cyclic feedback between meridional circulation, shear,
magnetic tension, induction, and the Coriolis force. The steady-circulation reversal orbit, or dynamo wave, periodically reverses all
magnetic components and supports slower modulations. In the solar near-surface shear layer (NSSL), moderate shear permits stable 11-year reversals with poleward speeds of 8-12 m/s and poloidal and toroidal amplitudes of 4-11 G and 2.2-3.8 kG near 1 Mm depth, in reasonable agreement with regional observations. At stronger shear, an 88-year reversal exhibits a 203-207-year modulation, reproducing the Gleissberg and Suess-de Vries activity timescales but requiring weaker poloidal fields. Such reversals, however, remain observationally unestablished. At tachocline density, an 11-year reversal and the inferred return flow require toroidal fields of hundreds of kilogauss over a broad shear range, exceeding large-scale-field reconstructions but partly permitted by seismic upper limits. This favors a shallow NSSL origin for a local cycle, while leaving open the issue of a global dynamo. Toroidal dominance prolongs the cycle because shear acting on a weak poloidal field changes only a small fraction of the stronger toroidal field per rotation. Balancing the weak
magnetic torque against advection and the Coriolis force also requires slow circulation, which gradually turns the poloidal field and reverses toroidal induction. Efficient poloidal regeneration would shorten this delay. A long solar cycle therefore favors a primarily shear-driven dynamo.
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Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
Hybrid Partial Dressing: Correct Effective Potentials at All Temperatures
Raphaël Berthiaume, David Curtin, Michael Luke et al. (+2 more)
We develop Hybrid Partial Dressing (HPD), a simple diagrammatic resummation scheme for finite-temperature effective potentials in scalar field theory which is valid at all temperatures. HPD improves on earlier resummation schemes such as Daisy Resummation and Partial Dressing by being two-loop exact at all temperatures and free of the overlapping momentum problem. Renormalization group improvement is straightforward to implement. We illustrate the scheme in multi-scalar theories with a spontaneously broken $\mathbb{Z}_2$
symmetry, and compare it against existing approaches, showing in particular that it reproduces the two-loop Dimensional Reduction (DR) potential exactly in the high-temperature regime where DR applies, while remaining valid at all temperatures. This makes HPD suitable for the general study of strong first order phase transitions beyond the Standard Model, as we demonstrate through gravitational wave predictions from HPD and its RG-improved version, RGHPD.
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All authors Raphaël Berthiaume, David Curtin, Michael Luke, Andrija Rasovic, Jyotirmoy Roy
Astrophysics of Galaxies
A Self-Consistent Jeans Analysis of the Milky Way Rotation Curve
Yongjun Jiao, Francois Hammer, Istiak Akib et al. (+2 more)
Jeans-based measurements of the Milky Way (MW) rotation curve (RC) have revealed a declining outer RC. The interpretation, however, depends sensitively on the tracer selection, the tracer density profile, gradient terms in the Jeans equation, and non-axisymmetric perturbations in the outer disk. We present a more self-consistent Jeans analysis of the MW RC and reassess whether the outer decline remains after a revised treatment of the main Jeans terms and their associated systematic uncertainties, including those related to non-axisymmetric perturbations. We select a kinematically homogeneous disk tracer sample designed to retain
stars on nearly circular disk orbits, removing only 12% of the original sample. We estimate the tracer density profile from the same
stars used for the kinematic moments, rather than adopting an external scale length. We find that the tracer density profile is better described by a double exponential over the validated range 12.5 < R < 21 kpc. We also assess the main systematic uncertainties associated with the fiducial Jeans equation terms, including the often neglected cross term, and account for different rotational velocities in the outer disk substructures. The derived RC remains nearly flat in the inner disk and declines at large radii. Over the adopted outer interval, $R\gtrsim16\,\mathrm{kpc}$, the RC slope is consistent with a Keplerian decline even after accounting for the systematic uncertainties. The corresponding mass modeling gives an extrapolated dynamical mass of $2.01^{+0.10}_{-0.08}\times10^{11}\,M_\odot$.
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All authors Yongjun Jiao, Francois Hammer, Istiak Akib, Yanbin Yang, Haifeng Wang
Earth and Planetary Astrophysics
Tails and Trails: Comets and NEOs Survive Co-addition in Rubin Early Data Preview 2
Colin Orion Chandler, Joseph Murtagh, Ian Chow et al. (+11 more)
We identify effectively single-visit imaging hidden within the deep co-added images of the NSF-DOE Vera C. Rubin Observatory Early Data Preview 2 (EDP2). These shallow regions contain only one or two contributing visits, providing access to single-visit-depth imaging ahead of the full Data Preview 2 (DP2) release in late 2026. We develop a workflow to locate known small Solar System bodies in these data, using our Ponder orchestrator with the Sorcha survey simulator to predict their positions and the Rubin Science Platform (RSP) to identify shallow coadds and extract image cutouts. Because cometary activity and near-Earth-object (NEO) trails produce extended morphologies, both remain identifiable in these shallow coadds. From approximately 700 comet and active-object cutouts, we identify 59 activity detections spanning 32 objects. We discover activity in 2025 NC6, previously unknown to be active; identify the first reported pre-perihelion activity of 2008 QZ44; and independently rediscover known comets 243P/NEAT and 510P/Boattini through their activity. We also recover 336 NEO cutouts, including 29 with predicted trails longer than 25 pixels. We provide accompanying galleries and tabular data, and highlight 99P/Kowal 1, 510P, and 303P/NEAT as targets for immediate follow-up. Shallow coadds are a relatively unexplored facet of Rubin data with applications beyond the Solar System examples presented here: regions with varying numbers of contributing visits will persist throughout the Legacy Survey of Space and Time (LSST).
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All authors Colin Orion Chandler, Joseph Murtagh, Ian Chow, Maxine West, A. Fraser Gillan, Peter S. Ferguson, Michael S. P. Kelley, Jacob A. Kurlander, Henry H. Hsieh, Pedro H. Bernardinelli, Wilson Beebe, Jeremy Kubica, Andrew Connolly, James R. A. Davenport
Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
Metastable Neutron Stars as Transient-Rate Detectors of Heavy Dark Matter
Ziwen Yin and Hong-Yi Zhang
Metastable
neutron stars can undergo catastrophic conversion to
quark-containing
stars when a localized energy deposition nucleates a critical bubble. We show that dark-matter-induced conversions can be constrained by the present transient rate of the
neutron star population, rather than by the survival of any individual hadronic
star as often assumed in previous literature. Population depletion makes the present transition rate nonmonotonic: weak triggering produces few transitions, whereas sufficiently rapid triggering predominantly converts
stars formed in the past. Consequently, transient observations can exclude a finite interval of interaction rates, qualitatively different from conventional one-sided survival bounds. Using the beaming-corrected short gamma ray burst rate as a
benchmark, we derive constraints on dark matter annihilation, decay, inelastic particle scattering, and elastic scattering of macroscopic dark matter, including parameter space not covered by existing probes. Transient demographics thus provide a new population level probe of dark sector interactions and the phase structure of ultradense matter.
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Astrophysics of Galaxies
Igniting Galaxy Formation in the Postreionization Universe, II: Nature versus Nurture
Jorge Moreno, Defne Aluç, Eisha López et al. (+7 more)
Although the ultraviolet background from reionization is thought to conspire against the smallest
halos, some gas-rich
halos in the post-reionization Universe still form
stars. We ask which properties, environmental or intrinsic, determine ignition. Using the FIREbox cosmological volume, we compare recently-ignited
halos to a mass- and gas-matched sample of gas-resolved starless
halos at $z=2$–6. We test three families of "third axis" properties beyond $M_{\rm vir}$, $M_{\rm gas}$, and $z$:
geometric environment (the Perturbation Index and local
galaxy density $\rho_5$), hydrodynamic environment (the $1$–$2,R_{\rm vir}$ gas-supply shell), and intrinsic
halo properties (concentration and the neutral-gas reservoir). A nested random-forest classification finds that
geometric environment adds little, while the hydrodynamic shell is modestly informative. Three complementary properties each discriminate ignited from starless
halos beyond the mass–gas–
redshift baseline (AUC $=0.635$, where $0.5$ is chance): total HI mass ($M_{\rm HI}$, AUC $=0.739$), the extent of the neutral gas ($r_{\rm HI,50}/R_{\rm vir}$, AUC $=0.738$), and the central HI density ($\rho_{\rm HI,0}$, AUC $=0.700$); jointly they reach AUC $=0.823$, the highest of any combination we test. At fixed
halo mass, gas mass and
redshift, recently-ignited
halos harbor more HI over a larger radius than their matched controls, and these two enhancements are uncorrelated. The same reservoir sets when ignition can happen: from $z=6$ to $z=0$ the median starless
halo keeps its gas ($+0.05$ dex) while its neutral fraction falls by $3.9$ dex, so the reservoir is ionized rather than exhausted and the ignition window closes below $z\simeq2$. In sum, a
halo's own neutral-gas reservoir discriminates ignited from starless
halos more sharply than its location in the
cosmic web – nature over nurture.
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All authors Jorge Moreno, Defne Aluç, Eisha López, Vivienne Wood, Emmanuel Santiago, Francisco J. Mercado, Caleb R. Choban, Coral Wheeler, M. Katy Rodriguez Wimberly, Robert Feldmann
Astrophysics of Galaxies
The geometric origin of the thermal eccentricity law
Václav Pavlík
The distribution $f(e)=2e$ is commonly referred to as the `thermal eccentricity distribution' of Keplerian binaries. However, the result does not require thermal
equilibrium, and its usual derivations obscure why the distribution is linear in eccentricity. We seek a simple geometrical interpretation of this result and its relation to more general eccentricity distributions. We consider bound Kepler orbits in a Euclidean space of dimension $D\geq2$, with a phase-space distribution depending only on energy, and derive the eccentricity distribution from the Liouville measure. We obtain $f_D(e)=(D-1) e (1-e^2)^{(D-3)/2}$, so that, within this family, $D=3$ is the only case for which the distribution function is linear in $e$. This follows from the $D-1$ transverse momentum dimensions and the Kepler period degeneracy. We further show that two known generalisations – namely a power-law weighting of the normalised angular momentum and a constant velocity anisotropy – are, in fact, two representations of the same one-parameter family of eccentricity distributions.
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Earth and Planetary Astrophysics
Simulating the thermodynamics of gas, radiation, and multispecies dust: Method and applications to protoplanetary disks
Dhruv Muley, David Melon Fuksman, Prakruti Sudarshan et al. (+2 more)
The thermodynamics of protoplanetary disks, governed by a complex interplay between gas, dust, and radiation, exerts a strong influence on their morphology and dynamics at both large and small scales. Historically, hydrodynamical simulations have treated thermodynamics with approximate prescriptions, such as local isothermality, parametrized $\beta$-cooling, and radiation hydrodynamics with gas-dust thermal
equilibrium. However, a more comprehensive and self-consistent approach would more accurately reproduce the wealth of features found in observations, which in modern times have reached unprecedented spectral, angular, and vertical resolution. With this motivation, we have devised a radiation-hydrodynamics scheme for the PLUTO code with energy exchange (via absorption, emission, and collisions) for gas, radiation, and multiple species of dust. Dust-gas dynamics are handled by treating each dust species as a pressureless, diffusive fluid, ensuring that our scheme can represent changes in disk illumination caused by grain settling and trapping. We demonstrate the effectiveness of our scheme in several test problems, and conclude by discussing its relevance to open questions in protoplanetary disk studies.
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All authors Dhruv Muley, David Melon Fuksman, Prakruti Sudarshan, Alexandros Ziampras, Mario Flock
Cosmology and Nongalactic Astrophysics
Statistics of large-scale structure from the transition probability of Lagrangian trajectories
Lawrence Dam
We describe a probabilistic approach to gravitational clustering. Working purely in configuration space, we show that the two-point function can be formulated in terms of a transition probability describing the likely final position of a particle given its initial position. The transition probability is initially sharply peaked and then over time broadens out in a
diffusion-like manner. The effect is more pronounced for widely-separated particles (e.g.\ at the baryon acoustic scale), leading to an effective suppression of the two-point function in what is normally referred to as infrared resummation.
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