Astrophysics of Galaxies
Emulator-Assisted Calibration of a Semi-Analytic Galaxy Formation Model for the Roman Galaxy Redshift Survey
Andrew Robertson and Andrew Benson
Mock catalogues for the Roman
Galaxy Redshift Survey benefit from
galaxy populations whose physical properties and emission-line observables are predicted within a single
galaxy-formation framework. We present an emulator-assisted calibration of the semi-analytic model Galacticus for this purpose. Because direct posterior exploration with Galacticus is computationally prohibitive, we train Gaussian-process emulators to predict the observables entering the calibration likelihood. We calibrate the model simultaneously to stellar mass functions, the
star-formation-rate function, size–mass relations, the black-hole mass–velocity-dispersion relation, the mass–
metallicity relation, and H-alpha luminosity functions. Combining these observables breaks parameter degeneracies present in individual fits and can reveal tensions where different observables favour different regions of parameter space. The resulting model provides a broadly successful simultaneous description of the calibration data, including the abundance and
redshift evolution of H-alpha emitters relevant to the Roman
Galaxy Redshift Survey. A direct Galacticus calculation at the maximum a posteriori point gives similarly good agreement with the calibration data, providing a calibrated
galaxy-formation model suitable for constructing physically consistent mock catalogues for Roman.
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Instrumentation and Methods for Astrophysics
A data processing pipeline for the WINTER near-infrared surveyor using the $\texttt{mirar}$ framework
Viraj Karambelkar, Robert Stein, Danielle Frostig et al. (+18 more)
We present the data reduction and transient detection pipeline for the Wide-field Infrared Transient Explorer (WINTER) surveyor and report its on-sky performance. The WINTER camera utilizes cost-effective InGaAs sensors as alternatives to traditional IR sensors, and is mounted on a dedicated 1-m robotic
telescope at Palomar Observatory. The WINTER camera has six detectors producing a combined field-of-view of 1.2 sq. deg. equipped with y, J, and shortened-H bands. WINTER saw first light in June 2023 and has been operating robotically since. The WINTER data processing pipeline ($\texttt{winterdrp}$) has been implemented within the broader framework $\texttt{mirar}$: a modular, open-source $\texttt{python}$ package developed for realtime processing of images from time-domain surveys. $\texttt{winterdrp}$ performs end-to-end data processing implementing data reduction and image subtraction to go from raw dithered WINTER images to transient alerts in the $\texttt{avro}$ format, which are then sent to $\texttt{SkyPortal}$ for vetting and follow-up. During a year of observations in 2024, WINTER achieved J-band median 5-$\sigma$ depths ranging from $18.1-18.8$ mag (AB) on its six detectors in 960 second integrations as part of its survey, with an astrometric accuracy of $\approx0.2$ arcsec (a fifth of a pixel) and a detector-performance limited photometric accuracy ranging from $\approx0.09-0.18$ mag for its six detectors. We present early science results from WINTER, which include the identification of a stellar merger in M31, dust-enshrouded outbursting young stellar objects and classical novae in the Galactic plane, NIR followup of known
supernovae, and multi-messenger follow-up of
neutrinos, gravitational waves, fast X-ray transients and gamma-ray bursts.
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All authors Viraj Karambelkar, Robert Stein, Danielle Frostig, Saarah Hall, Mansi M. Kasliwal, Tomás Ahumada, Michael W. Coughlin, Thomas Culino, Kishalay De, Sulekha Kishore, Theophile Jegou du Laz, Nathan P. Lourie, Geoffrey Mo, Tanishk Mohan, Sam Rose, Benjamin R. Roulston, Aditya Pawan Saikia, Mallika Sheshadri, Robert A. Simcoe, Jamie Soon, Aswin Suresh
Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
Re-examining the sensitivity of JWST to decaying axion dark matter
Caleb Gemmell, Christopher Dessert, Andrea Caputo et al. (+1 more)
An eV-scale QCD
axion comprising the observed dark matter (DM) abundance is expected to generate a
photon line at infrared energies that would be observable or near-observable in data collected by the James Webb Space
Telescope (JWST), as might more general
axion-like particles (ALPs) over a broader range of masses and couplings. This has motivated a number of efforts to either forecast JWST sensitivities to a QCD
axion or realize them through analyses of publicly available
datasets. At present, no consensus exists; leading analyses disagree by as much as an order of magnitude in terms of
axion-coupling sensitivity, implying an orders-of-magnitude discrepancy in raw flux density sensitivity, and consistency between the analyses and prior forecasts is unclear. We address these outstanding discrepancies with a bespoke data reduction and flexible nonparametric inference procedure that lead to well-controlled and robust limits on the decay of eV-scale
axion DM, consistent with previously forecasted sensitivities. We further demonstrate that the strongest previously claimed sensitivities exceed those attainable by any analysis of the
datasets from which they were derived. We exclude QCD
axion DM for masses between $500\,\mathrm{meV}$ and $2.5\,\mathrm{eV}$ using NIRSpec data, while setting limits on ALP DM complementary to other astrophysical constraints at masses between $100\,\mathrm{meV}$ and $500\,\mathrm{meV}$. However, we find the sensitivities to be systematically limited, and therefore unlikely to be improved upon by ongoing data collection or re-analysis unless instrumental modeling and data reduction pipelines improve considerably.
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All authors Caleb Gemmell, Christopher Dessert, Andrea Caputo, Joshua W. Foster
Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
On the Numerical Integration of One-Loop Cosmological Collider Signals
Michael Borinsky, Aidan Herderschee and Qianshu Lu
In a broad class of inflationary models, the leading non-Gaussian bispectrum arises from one-loop rather than tree-level processes. However, realistic one-loop contributions remain largely unexplored for phenomenologically relevant masses beyond the simplest bubble diagrams. This is insufficient for observational purposes because, for generic masses and couplings, triangle contributions need not be suppressed relative to their bubble counterparts. We present a numerical method for evaluating scalar one-loop in-in diagrams contributing to the inflationary bispectrum at fully general external momenta and masses. First, the Witten-Feynman parameterization reduces de Sitter loop integrals to generalized Euler-Mellin integrals governed by Symanzik graph
polynomials. Unfortunately, the exponents of the
polynomials in the integrand become complex for sufficiently heavy masses, leading to sign problems when evaluating the integral using standard numerical techniques. To remedy this problem, we introduce the reduced Schwinger method, which evaluates a highly oscillatory subintegral analytically to obtain a Gauss hypergeometric kernel, leaving the remaining integrals to standard numerical quadrature. We validate the
algorithm by reproducing known analytic results for the tree-level bispectrum in terms of ${}_3F_2$ functions, and then apply it to the one-loop bubble and triangle contributions at general kinematics. This yields the first direct numerical evaluation of the complete one-loop bispectrum, valid across the full kinematic range. Using these numerical results, we construct bispectrum templates and compare them with CMB data.
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Cosmology and Nongalactic Astrophysics
The relevance of the cosmic microwave background for cosmology
Pavel Kroupa, Eda Gjergo and Nikolaos Samaras
Within the Hot Big Bang picture, as usually interpreted in the standard LCDM framework and its hierarchical scenario for elliptical
galaxy assembly, the
cosmic microwave background (CMB) is associated with
photon decoupling near z = 1100, and the Planck angular power spectra are taken to constrain primordial 10^{-5}-level fluctuations that seeded later structure formation. We show that, in addition to the LCDM model, two cosmological models based on Milgromian gravitation are also consistent with the Planck CMB power spectra, such that the spectra do not uniquely favor dark matter. We then argue that the published CMB spectra are not direct observables, but reconstructed quantities obtained after foreground subtraction and corrections for weak
lensing,
photon-electron scattering, and gravitational energy
redshifts along the line of sight. Because these steps depend on the assumed growth history of structure, the resulting spectra depend on the cosmological model adopted in the data reduction. We also note that the reported correlation between the hemispherical CMB asymmetry and the excess on-sky distribution of elliptical
galaxies may point to matter inhomogeneities spanning large portions of the observable universe. Motivated by observational tensions in the hierarchical assembly of elliptical
galaxies, we review the consequences of elliptical-
galaxy formation on a downsizing timescale, which implies a significant extragalactic foreground released at 15< z < 20. Under conservative assumptions, this foreground contributes at least 1.4 percent of the observed CMB energy density and has not been included in CMB analyses. It follows that the reported 10^{-5}-level fluctuations is introduced by overly aggressive foreground cleaning.
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Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
Ultralight Axial Dark Matter
Anson Hook, Junwu Huang and Kevin Zhou
Ultralight dark matter could be an axial vector field, a simple possibility which motivates new experiments. Couplings to
fermions, through an axial vector current or a dark electric dipole moment operator, lead to enhanced
spin torques compared to
axion dark matter. An axial vector also has an analogue of the
axion-
photon coupling, though its consistent realization requires a
photon mass. Under this "axial-
photon" coupling, the effect of a background
magnetic field is suppressed, and the strongest experimental probes involve polarimetry, electric fields in superconducting cavities, and the
cosmic microwave background. Since a massive axial vector is dual to a massive two-form, our results also apply to "Kalb-Ramond" dark matter motivated by string theory.
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Cosmology and Nongalactic Astrophysics
Aletheia: Emulating the halo mass function with evolution mapping
Andrea Fiorilli, Ariel G. Sánchez, Andrés N. Ruiz et al. (+1 more)
We present an emulator of the
halo mass function (HMF) based on Gaussian-process regression, that exploits the
evolution mapping framework. This framework splits cosmological parameters into shape parameters ($\mathbf{\Theta}_\mathrm{s}$), which set the shape of the linear power spectrum, and
evolution parameters ($\mathbf{\Theta}_\mathrm{e}$), which only rescale its amplitude, with their net effect entirely captured by the clustering amplitude, $\sigma_{12}$. The emulation acts in two steps: first, an emulator predicts the overall shape of the HMF given $\mathbf{\Theta}_\mathrm{s}$ and $\sigma_{12}$; then, a second emulator applies a small correction accounting for the residual dependence on the integrated growth history of density fluctuations. The emulator is trained on a suite of 100 simulations of flat $\Lambda$CDM cosmologies but, owing to
evolution mapping, can be applied to predict the abundance of
haloes in cosmologies with any extended space of $\mathbf{\Theta}_\mathrm{e}$, such as
curvature, quintessence and dynamical dark energy. We test the emulator against independent $\Lambda$CDM runs and on an additional validation suite of dynamical dark energy simulations, achieving per cent-level accuracy over a wide range of masses and
redshifts, with the performance only slightly degrading at early times, where the training data points are fewer. Compared to other state-of-the-art HMF emulators, its accuracy is higher in nearly all tested cases. Our results demonstrate the broad applicability of the
evolution mapping framework to build very accurate emulators of statistics of the density field. The emulator is publicly available as part of the Aletheia emulator suite.
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All authors Andrea Fiorilli, Ariel G. Sánchez, Andrés N. Ruiz, Facundo Rodriguez
Instrumentation and Methods for Astrophysics
More than half of recent astronomy papers are written with language-model assistance
Serat M. Saad and Yuan-Sen Ting
Language models leave a distinctive vocabulary in the prose they help write, and we measure how much of the astronomy literature now carries it. From the full text of 207,111 astro-ph papers spanning 2015 to mid-2026, we count those words in each paper and model the counts, in proportion to paper length, as a mixture of assisted and unassisted writing in a hierarchical
Bayesian model. Papers from before 2020 calibrate the unassisted rate, and the 392 papers that disclose model use calibrate the assisted one. Our answer depends on how often these words would appear today if nobody used a model, a rate that must be modeled rather than observed, so we extend it past 2020 under three assumptions and report all three. For 2025 that gives $54^{+8}_{-8}\,(\mathrm{stat},\,95\%)\,^{+26}_{-0}\,(\mathrm{sys,\ background})$% of papers, the second error being the spread across the three. The estimate stays at or above 36% when we vary that choice, the calibration, and the requirement that adoption only rises. A word list built from the astro-ph corpus, keeping only words that rose across every subfield, leaves 2025 in the same range. Assisted writing is also getting harder to see, since authors adapt to the words that reveal it and the marker excess more than halves between 2023 and 2026. Our model allows for that fading, so it can separate a fainter trace from reduced use. More than half of recent astro-ph papers therefore carry a
language-model trace, while only 0.81% of 2025 papers disclose it, one declaration for every $\sim$66 papers with a trace.
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Instrumentation and Methods for Astrophysics
Small-Body Science with the Nautilus Space Observatory: From Cislunar Space Resilience to Mapping the Kuiper-Belt-to-Oort-Cloud Transition
J. de Wit, A. Y. Burdanov, P. McGill et al. (+3 more)
A new generation of space-based observatories can transform small-body science from the local Earth-Moon environment to the Solar System's dynamical frontier, where planetary control gives way to Galactic tides and stellar encounters. Mapping this frontier would reveal how planetesimals were scattered during giant-
planet formation, how many primordial bodies survived in distant reservoirs, and whether large objects remain undiscovered in the inner Oort Cloud. At the same time, meter- to decameter-scale natural objects traversing the Earth-Moon system are frequent but poorly characterized. As human and robotic activity expands, their operational relevance depends not simply on abundance but on object size, encounter geometry, exposed infrastructure, warning time, and available response. Lunar impacts and impact-generated ejecta provide one class of events, while fading objects with unresolved Earth or lunar impact probabilities provide another. Here, we explore a two-layer small-body program combining a 4.0 m-diameter Nautilus Quattro Imaging (NQI) unit with an illustrative distributed cislunar layer of ~50 cm-class wide-field optical
telescopes. The cislunar layer would characterize the nearby natural-object population, support rapid classification and selective custody of high-interest objects, and monitor lunar impacts and ejecta; the NQI deep-search layer would provide precise astrometry and synthetic tracking for faint-object recovery and distant-Solar-System surveys. Together, the two layers would constrain the small-impactor population, resolve fading planetary-defense targets, and survey the distant Solar System to Vmag ~30, enabling tests of the Kuiper-Belt-to-Oort-Cloud transition while advancing Earth-Moon space resilience.
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All authors J. de Wit, A. Y. Burdanov, P. McGill, D. Apai, S. N. Hasler, S. Cambioni
Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
Implications of Inelastic Dark Matter for Primordial Dark-Star Evolution: Kinematic Thresholds and Nonthermal Capture
Qinxun Li and Shengyi Liu
The recent 248-keV nuclear recoil candidate reported by LUX-ZEPLIN has renewed interest in endothermic inelastic dark matter, motivating us to examine its capture in primordial dark
stars. Relative to the conventional elastic-capture picture in dark
star evolution, endothermic capture adds two qualitative features. First, it opens only after the growing
star crosses a compactness threshold, expressed as a kinematic radius $R_{\rm kin}\propto\mu_{\chi}M_\star/\delta$ set by the stellar mass, the dark-matter–
nucleus reduced mass and the mass splitting. The accreting growth carries the
star through the threshold, and the capture rate turns on quadratically above it. Second, although newly captured particles generically begin on nonthermal bound orbits, endothermic kinematics can keep this normally transient population spatially extended, turning it into a persistent reservoir rather than an intermediate step toward a thermal core. Following complete chains of state-changing collisions, we find that the reservoir compacts sharply and then stalls, because a ground state particle below a compactness-dependent orbital energy has no allowed up-scatter anywhere in the
star. A percent-level radius contraction reopens the relaxation. These kinematic results do not depend on whether the excited state decays promptly or is long-lived. As a result, inelastic capture does not replenish a thermal annihilation core. The captured population forms an evolving orbital distribution that sets up the co-evolutionary dynamics between the
star and the dark matter in the core and the reservoir, which we develop in a companion paper.
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Cosmology and Nongalactic Astrophysics
Dark Matter-Baryon Separability Predicts the Dynamics of an Almost-Dark Galaxy
Oem Trivedi and Abraham Loeb
We extend the Dark Matter-Baryon Separability Condition to show that the same framework developed for dark matter deficient
galaxies naturally admits a conjugate branch describing preferential baryonic depletion. Using the recently discovered almost-dark
galaxy TTT J1237327+143535 as a worked example, we derive a family of dynamical consistency relations parameterized by the unknown progenitor ratio $\mu_i$, including thresholds for $\sigma_{\rm los}$, $M_{\rm dyn}$, the enclosed baryonic fraction and the dynamical mass to light ratio. We further connect the separability framework to the expected globular cluster population, providing an independent consistency test of the inferred
halo mass. We also provide some bounds on the baryon ratio using the tidal properties of Virgo Cluster. Future measurements of stellar kinematics, gas content and globular clusters can therefore determine whether this
galaxy occupies the positive separability branch and also test whether dark matter deficient and baryon depleted systems can be described within a common framework.
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High Energy Astrophysical Phenomena · Cross-listed from physics.hist-ph
The Crab Nebula progenitor: recovering the 1054 AD supernova event as galactic Gamma-ray burst
Costantino Sigismondi and Remo Ruffini
In 1054 AD a daytime
star appeared in the constellation of Taurus, for three weeks, and it was reported in various sources from Europe to China/Japan: it was one of the few documented galactic
supernovae of the last two millenia. This paradigm has been established about sixty years ago, as the comprehension of the physics of
supernovae progressed with enough observational data. The Gamma-ray bursts were discovered in the same period, but only in the past few years have their observations become daily and their distances have been fully understood as cosmological. After the explosion, the exponential decay of the luminosity in gamma-rays and X-rays has been followed with
telescopes onboard dedicated satellites. Also the exponential decay of the afterglow's optical and
radio frequencies have been observed with the largest optical and
radio telescopes. Within the binary-driven hypernova framework, successful in explaining all the observed phases of the Gamma-ray bursts, the universal exponential decay can be extended to 1000 years after the burst, to account for the present values of Gamma and X-rays as well as optical and
radio frequencies of the Crab Nebula. Both the daytime visibility of the burst, and the simultaneous radiation plagues appeared in Constantinople and Cairo is a strong evidence of the presence of Gamma-rays in the lower atmosphere, coming from the same source originating the Crab nebula. The association to the daytime visibility of that
star and the following plague meets exactly the etymology of the word dis-aster, bad
star.
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Instrumentation and Methods for Astrophysics
Performance Comparison of the Nonlinear Curvature and Shack-Hartmann Wavefront Sensors in Strong Turbulence
Sam J. Potier, Arlene J. Aleman, Justin R. Crepp et al. (+1 more)
Strong
turbulence induces spatial variations in beam intensity that hinder the reconstruction process of many commonly deployed adaptive optics (AO) systems that use gradient-based wavefront sensors (WFS), such as the Shack-Hartmann wavefront sensor (SHWFS) and pyramid wavefront sensor. The nonlinear
curvature WFS (nlCWFS) uses Fresnel diffraction to extract wavefront phase and amplitude information, suggesting that it may be able to operate under challenging
turbulence conditions. In this work, we investigate nlCWFS reconstruction accuracy as a function of
turbulence strength and relative flux by modeling high spherical-wave Rytov number ($R_{sw}$) environments where scintillation and branch points impact sensing performance. We present open-loop as well as static and dynamic closed-loop results benchmarked against a comparable Shack-Hartmann WFS (SHWFS). In static and weak-to-moderate scintillation regimes, the nlCWFS consistently outperforms the SHWFS by leveraging amplitude-phase coupling inaccessible to gradient-based sensors. However, dynamic closed-loop simulations reveal a crossover behavior at higher scintillation strengths, where deep intensity nulls and proliferating branch points degrade the performance of Gerchberg-Saxton-based nlCWFS reconstruction, while the SHWFS degrades more gradually due to its insensitivity to such topological phase structure. These results highlight the regime-dependent advantages of the nlCWFS and emphasize the need for branch-point-tolerant reconstruction
algorithms to fully realize its potential in strong-
turbulence, low-flux conditions.
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All authors Sam J. Potier, Arlene J. Aleman, Justin R. Crepp, Stanimir Letchev
Cosmology and Nongalactic Astrophysics · Cross-listed from hep-th
For Whom Does Bell Hold?
Daniel Green, Kshitij Gupta and Qiya Zhang
Violations of Bell's inequalities offer a definitive signal of non-classical (
quantum) behavior in local deterministic systems. Yet, in many physical settings where
quantum mechanics is expected to play an important role, one cannot construct a Bell-type test using the available observables. Cosmology offers one concrete example, where
cosmic structure may have originated from
quantum vacuum fluctuations yet all observations are effectively classical. Nevertheless, recent work suggests that
quantum and classical time
evolution may still be differentiated by the pattern of statistical correlations of these observables. In this paper, we explore and generalize the use of correlations as Bell-type test of the nature of time
evolution. We show that
quantum vacuum fluctuations of closed systems undergoing
Hamiltonian evolution produce unique correlations that are not mimicked by classical
Hamiltonian systems. Correlations in the
quantum vacuum are generally time-independent and are controlled by the energy gap between the ground and exited states. Classical systems exhibit apparent poles at physical frequencies that do not arise in the
quantum vacuum. As one approaches the poles, the
evolution becomes dominated by a resonant
Hamiltonian giving rise to time dependent correlations that eventually decay through dephasing. Finally, we show that this behavior is distinct from other signals of
quantum evolution, including applications to
quantum optics,
quantum walks, and
quantum search.
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Astrophysics of Galaxies
The kinematics of tadpole galaxies at intermediate redshift $z \sim 0.4 - 1.5$
Manish Kataria, Kanak Saha and Bruce Elmegreen
Galaxy morphology and kinematics encode complementary information about the assembly history of
galaxies, but the extent to which they evolve in tandem remains unclear. Tadpole
galaxies, characterized by their distinct head-tail morphology and pronounced asymmetry, provide an ideal laboratory for investigating whether strongly asymmetric
galaxies can exhibit ordered
galaxy-scale kinematics. In this work, we present a detailed analysis of the ionized-gas kinematics of 20 morphologically selected tadpole
galaxies at
redshifts $z=0.4 - 1.5$ in the Hubble Ultra Deep Field, using deep VLT/MUSE spectroscopy together with HST and JWST imaging. In 13 out of 20
galaxies, the 2D velocity maps derived from the MUSE [O\,ii] $\lambda\lambda3726,3729$ emission show evidence for ordered motion, characterized by moderate velocity gradients along the kinematic major axis, while the remaining systems show no clear evidence for
galaxy-scale ordered kinematics. In 16
galaxies, the [O\,ii] and rest-frame optical emission, probed by HST/F775W, have spatially coincident centroids, with projected offsets of $<2$~kpc. The morpho-kinematic position angles are also generally well aligned, with a median misalignment of $\Delta{\rm PA}\sim12^{\circ}$. Despite the strongly asymmetric tadpole morphologies, these results indicate that a substantial fraction of these systems retain coherent
galaxy-scale gaseous kinematics, suggesting that morphological asymmetry need not imply a globally disordered dynamical state. Together, our analyses suggest that morphological and kinematic settlement does not occur simultaneously and these tadpole
galaxies might represent a transient evolutionary phase towards the combined morpho-kinematic settlement process.
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Earth and Planetary Astrophysics
A Candidate Innermost Fifth Planet In the HR 8799 System Revealed By JWST NIRISS Aperture Masking Interferometry
Jayke S. Nguyen, Louis Desdoigts, Alexandra Z. Greenbaum et al. (+20 more)
We detect a candidate fifth
planet in the HR 8799 system, directly imaged with the JWST/NIRISS Aperture Masking Interferometer (AMI). The detected source lies just above a $3\sigma$ contrast curve at a contrast of $\sim2\times10^{-4}$ in the F380M filter at a projected separation of $\sim150$ mas, corresponding to a few-to-several Jupiter mass
planet at an orbital radius of $\sim 7$au. The separation of the candidate is compatible with absolute proper-motion constraints from Gaia and Hipparcos assuming it is bound, while its orbital position lies near a stable orbital solution of a fifth
planet in a 3:1 mean motion resonance with
planet e. This detection was made possible by a new JWST/NIRISS AMI data pipeline that reaches the
photon noise limited potential of AMI by accounting for the optical and electronic systematics that limited sensitivity in prior analyses. Confirmation of this candidate would make HR 8799 the first directly imaged five-
planet system and provide insight into the orbital dynamics and the dynamical
evolution of planetary systems with widely-separated gas giants.
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All authors Jayke S. Nguyen, Louis Desdoigts, Alexandra Z. Greenbaum, Benjamin J. S. Pope, Max Charles, Quinn M. Konopacky, Kaitlyn Hessel, Dori Blakely, Matthew De Furio, Clarissa R. Do Ó, René Doyon, Doug Johnstone, Jens Kammerer, David Lafrenière, Bruce A. Macintosh, Michael R. Meyer, Eric L. Nielsen, Anne E. Peck, William Roberson, Anand Sivaramakrishnan, Peter Tuthill, Thomas Vandal, Marie Ygouf
Instrumentation and Methods for Astrophysics
Beyond the BLUE I: the advantage ceiling - how much can any estimator beat the matched filter in mm/submm survey data?
Kaustuv Basu
Papers claiming that convolutional neural networks outperform the matched filter are now common in astronomy. Since that filter is the best linear unbiased
estimator (BLUE) for any noise of given covariance, and the minimum-variance unbiased
estimator under Gaussian noise, such a claim requires that the noise covariance varies from image to image or the noise is non-Gaussian. We introduce the advantage ceiling eta >= 1, which quantifies both cases: the Fisher information for the amplitude in units of the matched filter's, computable from noise-only simulations before any network is trained, and a bound on the variance of any
estimator unbiased at each true amplitude. We compute eta for a suite of millimeter/submillimeter survey noise models and for compact and extended source templates, using a variational score-matching ladder whose rungs are
estimator classes of increasing statistical order, from linear to convolutional. With an instrumental white-noise floor, Gaussian noise returns eta = 0.94-1.06 (+-0.04); covariance mixtures give exact ceilings of 10.2 (spectral tilt, extended source), 2.1 (leaked components) and 1.1-1.8 otherwise; residual artifacts give eta <= 1.09. Source confusion gives the largest advantage, eta >= 3.8 (extended) and >= 2.4 (compact). Three unmodelled channels - a zeroed DC mode, a missing white floor and floating-point rounding - can manufacture spurious advantages of up to two orders of magnitude. A ResNet regressor is 6-15% less efficient than the matched filter on Gaussian noise once prior shrinkage is divided out, and realizes a factor 1.8 of the 10.2 available on the spectral-tilt mixture; a companion paper tests such regressors against these ceilings.
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Astrophysics of Galaxies
ACES VIII: A Survey of Compact, High-Velocity Features Observed in CS(2-1)
Dani R. Lipman, Jakub Poznanski, Savannah R. Gramze et al. (+45 more)
The extreme kinematics of the Milky Way's Central Molecular Zone (CMZ) are influenced by processes such as dynamical shearing, cloud collisions, and stellar feedback. These events are visible in molecular data as vertically spiked features in position-velocity (PV) diagrams referred to as high velocity dispersion compact clouds (HVCCs). Using ALMA CMZ Exploration Survey (ACES) CS (2-1) molecular data, we identify a total of 235 HVCC candidates, 163 of which are visually identified, and an additional 72 identified via automated dendrogram methods. For each HVCC we catalog and report the physical and kinematic properties, explore line ratios of the cold dense gas tracer \HNCO with C-shock tracers, classify the morphology of their PV diagrams, and view their position-position-velocity distribution. The sample includes structures which are compact (d<5 pc) and have large velocity extents (20 km/s $<\Delta \mathrm{V} <$ 140 km/s), with most structures showing thin, `spiked' PV morphologies. We highlight areas of high ratios between HNCO and C-shock tracers along the edge of known orbital streams, implying a buildup of bar lane gas accreting onto the CMZ. We also find a collection of HVCCs overlapping with the 50 km/s cloud and known circumnuclear disk features. This catalog will be used for future investigation of nuclear inflow and determining dominant mechanisms disrupting average CMZ gas flows.
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All authors Dani R. Lipman, Jakub Poznanski, Savannah R. Gramze, Claire E. Cook, Cara Battersby, Jennifer Wallace, Pablo García, Samantha Adams, Xinyu Mai, Kai Smith, Natalie Butterfield, Sophia Kempe, Adam Ginsburg, Rojita Buddhacharya, Tomoharu Oka, Jairo Armijos-Abendaño, John Bally, Ashley T. Barnes, Nazar Budaiev, Alyssa Bulatek, Laura Colzi, Christoph Federrath, Zi-Xuan Feng, Jonathan D. Henshaw, Paul Ho, Pei-Ying Hsieh, Katharina Immer, Izaskun Jiménez-Serra, Ralf S. Klessen, Steven N. Longmore, Xing Lu, Elisabeth A.C. Mills, N. Bijas, Francisco Nogueras-Lara, Dylan M. Paré, Maya A. Petkova, Jaime E. Pineda, Marc W. Pound, Víctor M. Rivilla, Álvaro Sánchez-Monge, Miriam G. Santa-Maria, Anika Schmiedeke, Yoshiaki Sofue, Mattia C. Sormani, Howard A. Smith, Robin G. Tress, Daniel Walker, Qizhou Zhang
Solar and Stellar Astrophysics
Wave Emission and Absorption in a Near-Sun Proton-Cyclotron Wave Storm
Kristopher G Klein, Daniel Verscharen, Mihailo Martinovic et al. (+5 more)
Quantification of energy transport and dissipation in weakly collisional heliospheric
plasmas that are far from local thermodynamic
equilibrium is an outstanding scientific problem. A central challenge is determining how non-Maxwellian velocity-space structure affects damping and emission of coherent ion-scale waves, especially compared to simplified analytical models for background
plasma velocity distributions. In this work, we study the damping and emission of parallel-propagating
proton cyclotron waves for two models of
proton velocity distributions measured by the SPAN-I instrument on board Parker Solar Probe during an extended storm of waves with left-hand polarization in the solar wind at a heliocentric distance of 30.1 solar radii. Using the measured velocity distribution rather than a two-component bi-Maxwellian model predicts instabilities consistent with the observed coherent waves. For intervals in which both models predict net damping, the observed VDF model yields weaker damping in 90% of cases, with a reduction in the integrated heating rate of 0.44 relative to the bi-Maxwellian model. These results suggest that simplified analytical velocity distribution models may overestimate cyclotron damping and underestimate wave emission in the near-Sun solar wind.
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All authors Kristopher G Klein, Daniel Verscharen, Mihailo Martinovic, Niranjana, Ali Rahmati, Roberto Livi, Davin Larson, Michael Stevens
Instrumentation and Methods for Astrophysics
Wide Field Localization Using Fixed Modulation Collimators
Steven E. Boggs
Rapid, precise localization of gamma-ray bursts (GRBs) requires continuous wide-field imaging at hard X-ray and soft gamma-ray energies. We develop a fixed (non-rotating) modulation-collimator architecture to address this challenge. A bigrid collimator, a pair of aligned, periodic slit grids in front of a simple, non-imaging
photon-counting detector, transmits an off-axis source through a triangular fringe pattern whose local angular position, the source phase, is recovered from simultaneous count rates in several grid pairs at fixed relative phase offsets, rather than by mechanically rotating a single grid pair as in the classical rotating modulation collimator. Four-phase demodulation of these count rates robustly cancels detector background and grid leakage without requiring rotation. Because the fringe pattern repeats across the sky, a phase measurement corresponds to many candidate source positions; we resolve this ambiguity over an arbitrarily wide field of view using a cascade of progressively coarser-pitched grid stages, generalizing the two-grid vernier-scale technique originally used to localize Sco X-1. This vernier cascade technique reduces the required
photon counts and grid-calibration accuracy required to achieve fine angular resolution over a broad field of view. Generalized to two dimensions with orthogonal cascades, the resulting architecture achieves wide-field localization with no moving parts, no time modulation, and only simple
photon-counting detectors, a promising candidate for simple, inexpensive, continuous-monitoring instruments supporting time-domain and multi-messenger astrophysics.
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Earth and Planetary Astrophysics
From spirals to rings: dust dynamics in gravitoturbulent protoplanetary discs after late infall
Clément Baruteau, Steven Rendon Restrepo, Gaylor Wafflard-Fernandez et al. (+7 more)
Substructures appear to be a common trait of all extended protoplanetary discs. They are found notably in discs still surrounded by ambient, possibly infalling material. In this study, we revisit the observational signatures of gravitational instability (GI) in the dust and gas emission of protoplanetary discs. We focus on discs undergoing a short-lived episode of late infall that triggers spirals via GI, in order to investigate the long-term dynamics of millimetre-sized dust. We performed 2D hydrodynamical simulations modelling gas and millimetre-sized dust in a self-gravitating disc, with a simplified treatment of stellar irradiation and infall. Results were post-processed by 3D radiative transfer calculations. During infall, GI sets in and the disc develops a gravitoturbulent state characterised by the continuous formation of spirals. Shortly after infall ends, the millimetre-sized dust remains well coupled to the gas, and the dust emission exhibits large-scale spirals in both near-infrared scattered light and continuum emission. Even long after infall has ceased, two-armed spirals are persistently excited by GI in specific regions of the disc. Their dissipation entails the formation of multiple long-lasting pressure maxima, which can be viewed as vestiges of shocks induced by the spirals. They form persistent dust rings that are more or less axisymmetrical. Consequently, once late infall ends, a massive disc can gradually evolve from a disc with spirals in the continuum into one featuring multiple, potentially lopsided bright rings in the continuum. In near-infrared scattered light, the disc initially displays multiple spirals during infall or shortly after it ceases, before ultimately exhibiting multiple rings. The persistent excitation of spirals implies, however, that the residual line-of-sight velocity, derived from line emission, shows large-scale spirals across the disc.
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All authors Clément Baruteau, Steven Rendon Restrepo, Gaylor Wafflard-Fernandez, Sebastián Pérez, Zhaohuan Zhu, Hans Baehr, Farzana Meru, Jean-François Gonzalez, Sergei Nayakshin, Sahl Rowther
Cosmology and Nongalactic Astrophysics · Cross-listed from gr-qc
Universal Secular External Leg Corrections for Gauge Independent Scalar Self-Mass on de Sitter
D. Glavan, S. P. Miao, T. Prokopec et al. (+1 more)
This work concerns a procedure for removing gauge dependence from graviton corrections to the effective field equations for a massless, minimally coupled scalar on de Sitter background. The procedure involves combining diagrams in the same way as the scattering amplitude for the $t$-channel exchange of the massless scalar between two massive particles, but without taking the asymptotic limits which are problematic in cosmology. Implementing this at 1-loop on flat space background requires five classes of diagrams, in addition to the naive exchange, and the combination of those diagrams does eliminate dependence on the graviton gauge fixing functional. When those same diagrams are generalized to de Sitter background, their combination cancels the most important (“nonlocal”) secular gauge dependence, but it leaves (“local”) secular gauge dependence that is associated with external legs. Local secular gauge dependence can be removed by adding two additional classes of diagrams, and making secular corrections to the external wavefunctions. The purpose of this paper is to include these additional corrections on de Sitter background in order to derive fully gauge independent effective field equations at 1-loop order.
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All authors D. Glavan, S. P. Miao, T. Prokopec, R. P. Woodard
Solar and Stellar Astrophysics
On the 3D Magnetic Structure of Coronal Mass Ejections Through the Solar Corona
Erika Palmerio, Michal Ben-Nun, Tibor Török et al. (+2 more)
The
magnetic fields that make up the internal structure of coronal mass ejections (CMEs) are thought to be organised in a flux rope configuration, consisting of twisted
magnetic fields that wind about a central axis. Remote-sensing observations of CMEs show a wide range of morphologies, dynamics, and
evolution, including rotation, non-uniform expansion, deflection, and interaction with the ambient solar wind. In-situ measurements, however, typically consist of a single 1D spacecraft trajectory through a large 3D structure (or few at best), restricting our ability to determine how CME
magnetic structure varies in space and time. In this work, we analyse the
magnetic configuration of two idealised CMEs during their early
evolution in the range 1-30 $R_{\odot}$ using the Magnetohydrodynamic
Algorithm Outside a Sphere code. The initial flux ropes differ only in their orientation with respect to the global dipole and erupt from a bipolar active region below the streamer belt in a simplified coronal environment. We deploy a fleet of synthetic spacecraft throughout the CMEs' paths at different combinations of latitudes, longitudes, and heliocentric distances. We identify and examine flux rope signatures in the synthetic in-situ profiles to characterise radial variations as well as latitudinal/longitudinal ones. We find that, even in a simplified CME erupting under solar minimum-like conditions, the sampling location significantly affects the global structure that would be deduced from common flux rope reconstruction and analysis techniques used for in-situ measurements. Additionally, we consider possible in-situ signatures that may serve as indicators of the source region's
topology.
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All authors Erika Palmerio, Michal Ben-Nun, Tibor Török, Cooper Downs, Viacheslav S. Titov
Cosmology and Nongalactic Astrophysics
Primordial turbulence from inflation: a new inflaton-driven turbulent regime
Oksana Iarygina and Axel Brandenburg
For the first time, we establish a direct connection between inflationary dynamics and the subsequent magnetohydrodynamic
evolution. Starting from
vacuum fluctuations, we self-consistently evolve the coupled inflaton-
plasma system through inflation, reheating, and into the radiation-dominated era. We find an inflaton-driven inverse cascade followed by freely decaying
turbulence, with kinetic energy dominating over
magnetic energy and driving dynamo amplification. The inflaton-driven
turbulence causes steeper
magnetic energy decay than helical
turbulence and should therefore be accounted for subsequent
evolution of primordial fields and their present-day observables.
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Astrophysics of Galaxies
Extending the Little Red Dot population at intermediate redshift with VIPERS
Krzysztof Lisiecki, Krzysztof Hryniewicz, Francesco Pistis et al. (+7 more)
Little red dots (LRDs) are a recently identified population of compact, red sources characterised by a distinctive V-shaped UV-to-optical continuum and broad emission lines. Their physical structure and
evolution remain uncertain, while their properties at intermediate
redshifts are largely unexplored. We identify and characterise LRD-like sources at 0.5<z<1.75 using the VIMOS Public Extragalactic
Redshift Survey (VIPERS), extending observational studies to a previously poorly explored
cosmic epoch. We select candidates from their UV and optical slopes measured from broadband photometry and refine the sample using broad emission lines in VIPERS spectroscopy. We investigate their photometric, spectroscopic, and morphological properties, constrain their physical sizes with HSC imaging, measure their comoving number density and
evolution, and characterise their local environments using the VIPERS
galaxy density field. We also model the multi-wavelength emission of the unique X-ray-detected source with CIGALE, including X-ray and AGN emission. We identify 14 LRD-like sources, including one X-ray-detected object, whose HSC morphology remains unresolved. We measure their number density in two
redshift bins, 0.5<z<1 and 1<z<1.75, and combine our results with literature measurements. We find a rapid decline in number density after
cosmic noon. The two sources with sufficiently constrained environments are located in underdense regions. The SED of the X-ray-detected source is best reproduced by a radiatively efficient
accretion disk viewed at low inclination. Our results demonstrate that LRD-like sources are present at z>0.5, bridging local and high-
redshift studies. Their abundance, compact morphology, environmental properties, and multi-wavelength emission provide new constraints on the
evolution and physical origin of this population.
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All authors Krzysztof Lisiecki, Krzysztof Hryniewicz, Francesco Pistis, Michał J. Michałowski, Aidan P. Cotter, Maciej Koprowski, Miguel Figueira, Agnieszka Pollo, Katarzyna Małek, Olga Cucciati
Astrophysics of Galaxies
From stardust to interstellar grain growth in the first galaxies: a cosmological transition in dust evolution near z ~ 8.9
Denis Burgarella, Tom J. L. C. Bakx, Raffaella Schneider et al. (+7 more)
When and how did dust begin to shape
galaxies? Motivated by the identification of an apparent
redshift break in
galaxy dust masses, suggesting substantially lower dust masses at $z \gtrsim 9$, we investigate dust enrichment during the first billion years of
cosmic history. We aim to determine whether the observed
evolution marks a transition in the dominant dust-production mechanism and to identify the physical conditions under which such a transition is expected to occur. Using JWST, ALMA, and NOEMA observations, we measure ultraviolet dust attenuation and dust masses. We apply a censored change-point analysis and compare the observations with dust
evolution modelling. The analysis identifies a preferred transition near
redshift z ~ 8.9, corresponding to about 570 Myr after the Big Bang. The evidence for a break is strongest in dust mass and dust-to-stellar mass ratio, mostly estimated from JWST NIRSpec spectrophotometric fitting but also partly from sub-mm data. The ultraviolet attenuation measurements are consistent with a transition at the same epoch but do not independently require one. The models are consistent with the onset of efficient interstellar grain growth above a characteristic
metallicity. We interpret the transition near z ~ 8.9 as the emergence of grain-growth-dominated dust
evolution from an earlier regime dominated by
supernova-produced grains. Population III enrichment can modify the earliest chemical-enrichment history but leaves the timing of the dust transition nearly unchanged and is not required for its emergence.
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All authors Denis Burgarella, Tom J. L. C. Bakx, Raffaella Schneider, Hiddo S. B. Algera, Chloe Aurin, Tim Dewachter, Clarke Esmerian, Luca Graziani, Kirsten Knudsen, Koki Otaki
High Energy Astrophysical Phenomena
Associating binary black holes with galactic centres using lensed gravitational waves
Laura Uronen, Tian Li, Qiuhan He et al. (+4 more)
Binary black holes (BBHs) have been theorised to form through various different channels, but current LIGO-Virgo-KAGRA (LVK) sky locations make the direct study of formation channels a challenge. Association of strongly lensed BBHs to their hosts has been shown to be possible with current detector networks at upgraded sensitivity and survey
telescopes like Euclid, with localisations that can reach sub-galactic scales in the source plane. With Hubble Space
Telescope-like high-resolution imaging, we report that strong-
lensing localisation of BBHs allows us to confidently associate the BBH with specific structures within their host
galaxies, specifically, galactic centres (GCs). We demonstrate that a BBH localised to the GC of the
galaxy can reject light-tracing BBH populations ($p < 5\%$) in a single observation, and in most cases demonstrate high confidence rejection ($p < 1\%$), providing a conservative basis to exclude light-tracing spatial distributions associated with field-like or non-central formation channels. Such association therefore directly supports formation channels confined to GCs, such as active galactic
nuclei and nuclear stellar clusters.
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All authors Laura Uronen, Tian Li, Qiuhan He, Justin Janquart, Thomas Collett, Léon V.E. Koopmans, Otto Hannuksela
Astrophysics of Galaxies
Cosmic-ray electron propagation in the peculiar barred spiral galaxy NGC 2442
Shengtao Wang, Xiaohui Sun, Volker Heesen et al. (+13 more)
Face-on spiral
galaxies offer a favorable geometry for studying
magnetic-field structures and
cosmic-ray (CR) propagation because projection effects and structural overlap are reduced. We investigate
cosmic-ray electron (CRE) transport in the nearby face-on spiral
galaxy NGC 2442 and assess how its environment and
magnetic-field structure influence propagation. We combine
radio continuum (RC) observations from ASKAP at 943 MHz, MeerKAT at 1.28 and 1.7 GHz, and ATCA at 5 GHz with optical H$\alpha$ and infrared data, and compare them with 2D CRE transport simulations. NGC 2442 has a steep integrated RC spectrum, with $\alpha=-0.96\pm0.04$ for the total emission and $\alpha_{\rm nt}=-1.21\pm0.04$ for the synchrotron emission over 408 MHz-5 GHz. A break near 1 GHz indicates substantial radiative aging. Under equipartition, we derive a mean
magnetic-field strength of $10.8\,\mu{\rm G}$. RC-SFR smoothing gives effective CRE propagation lengths of $\sim0.65$-$0.89$ kpc at 943-1700 MHz and $\sim0.44$ kpc at 5 GHz, corresponding to
diffusion coefficients of order $10^{28}\,{\rm cm^2\,s^{-1}}$. We identify a steep-spectrum synchrotron “island” in the southeast, with $\alpha\sim-1.09$ and no clear H$\alpha$, infrared, FUV, or NUV counterpart, indicating that CREs are unlikely to be injected in situ. Our 2D CRPropa simulations show that anisotropic
diffusion along ordered
magnetic fields enables CREs to reach the island more efficiently than isotropic
diffusion. NGC 2442 therefore shows that environmental disturbances and ordered
magnetic fields can strongly regulate CRE propagation in disturbed spiral
galaxies.
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All authors Shengtao Wang, Xiaohui Sun, Volker Heesen, George Heald, Jiangtao Li, Chao-Wei Tsai, Stefan W. Duchesne, Andrew J. Battisti, Yik Ki Ma, Amit Seta, Jun Xu, Naomi McClure-Griffiths, Christopher J. Riseley, Sam Taziaux, Jacco Th. van Loon, Tayyaba Zafar
Astrophysics of Galaxies
The solar Galactocentric distance and local kinematic parameters from Gaia DR3 using Bottlinger's equations
D. V. Odynets, V. S. Akhmetov and S. I. Denyshchenko
The solar Galactocentric distance, $R_0$, together with the local kinematic parameters of the Milky Way, provides fundamental constraints on the Galactic structure and rotation. Their accurate determination has become possible with the hight astrometric precision of Gaia DR3 catalogue. We determine the Galactocentric distance, the Solar peculiar motion components $(u_0,v_0,w_0)$, and the local angular velocity of Galactic rotation, $\omega_0$, using a self-consistent approach based on Bottlinger's equations within a nonlinear least-squares framework. Bottlinger's equations were applied to approximately 13 million luminous giant
stars $(M_G<4)$ selected from Gaia DR3. The analysis was carried out for two subsamples: a thin disk dominated sample (|z|<0.5 kpc) and a mixed thin and thick disk sample (|z|<1.0 kpc). The kinematic parameters were estimated using a nonlinear generalized least-squares method. We obtained $R_0=8.165\pm0.024$kpc and a local angular velocity of Galactic rotation $\omega_0=28.477\pm0.002$ km/s/kpc for the thin disk dominated sample. The Solar peculiar motion components are $(u_0,v_0,w_0)=(9.261\pm0.006,16.593\pm0.008,7.686\pm0.008)$km/s. Including mixed thin and thick disk
stars resulted in a systematic shift in $R_0$, yielding $R_0=8.333\pm0.022$kpc, while the Solar peculiar motion and local angular velocity remain consistent within uncertainties. The Galactic kinematic parameters derived are consistent with recent independent determinations. The Solar peculiar motion parameters and the local angular velocity remain stable for different vertical selections, the recovered Galactocentric distance exhibits a systematic dependence on the adopted stellar sample, indicating that the vertical structure of the tracer population should be taken into account when determining $R_0$.
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Cosmology and Nongalactic Astrophysics · Cross-listed from gr-qc
Pulsar Timing Response and Spatial Correlations of Shear Modes in Torsionless Palatini Spacetime
Tian-Shi Li, Yu-Mei Wu and Chang Liu
In the nanohertz band, spatial correlations between
pulsar timing residuals provide a key observable for characterizing
stochastic gravitational-wave backgrounds and probing their polarization content. In torsionless Palatini spacetime, nonmetricity can generate two additional shear modes, referred to as the shear-$x$ and shear-$y$ modes. In this work, we investigate the
pulsar timing response produced by the shear-induced motions of the emitting
pulsar and the receiving Earth. Assuming that the electromagnetic field is minimally coupled to the physical metric and that the Earth and
pulsar possess non-negligible effective hypermomentum responses, we derive the single-
pulsar redshift, the frequency-domain two-point correlation function, and the corresponding spatial correlation. For a stationary and isotropic
stochastic shear background, the normalized overlap reduction function (ORF) for distinct
pulsars reduces in the short-wavelength limit to the pure dipolar form $\Gamma_{ab}^{\mathrm{sh}}(\zeta)=\cos\zeta$, where $\zeta$ is the angular separation between the two
pulsars. The same dipolar correlation can also be produced by isotropic Solar System ephemeris errors, leading to a spatial degeneracy between the two signals. This degeneracy highlights the importance of information beyond the angular correlation for identifying Palatini shear signatures in PTA data.
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