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Research Trends

Latest preprints in space engineering and astrophysics.

astro-ph.GA

Super-resolving Polarized Dust Emission with Transformer-Based Multi-Tracer Fusion

Minjie Lei, George Halal, S. E. Clark, Alejandro Dobles, Katie Brown, Viraj Manwadkar

Realistic models of polarized Galactic dust emission at high angular resolution are essential for component separation in next-generation cosmic microwave background (CMB) $B$-mode experiments. However, existing dust polarization templates are constrained only to ~1 degrees, and it remains challenging to develop models that can generate realistic small-scale complexity that is also coherently connected to the well-measured large-scale structures. In this work, we develop a data-driven super-reso…

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cs.LGastro-ph.EP

Post-Training Quantization of Autoregressive Weather Models

Ananyo Bhattacharya, Swastik Bhattacharya, Christiane Jablonowski

Advancements in high-resolution numerical weather prediction (NWP) and data assimilation (DA) have shaped the developments in deep learning (DL) architectures emulating atmospheric dynamics. Emulators for weather forecasting exhibit forecast quality comparable to physics based models at forecast horizon scaling from few days to subseasonal time scales. The emulators are driven by hardware-accelerated matrix multiplication in autoregressive inferences, significantly reducing the computation time…

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physics.space-phphysics.ed-phphysics.ins-det

A Student Sounding Rocket Experiment to Probe Electron Density in the Lower Ionosphere

Joshua Goodwill, Timothy Tomaszewski, Jarrod Bieber, Carson P. Brown, Ashton Southwick, Samuel Auerbach, Sreenidhi Banda, Alex Bruce et al.

Earth's ionosphere is primarily generated by the Sun's ionization of atoms in the upper atmosphere. This plasma environment is highly dynamic, exhibits strong spatial and temporal, variations and significantly impacts power systems, navigation, and satellite and ground communications. The University of Delaware Ionospheric Probe (UDIP) was developed as a hands-on learning experience for University of Delaware students on the ionosphere itself and on the development of space technology. Students…

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astro-ph.HEphysics.plasm-ph

Suppression of spiral density waves in collisionless accretion flows

Stephen Majeski, Matthew W. Kunz, Jason Dexter

Spiral density waves are ubiquitous phenomena in differentially rotating flows. They are non-modal, non-axisymmetric perturbations that, due to shear in the background flow, possess time-evolving wavenumbers, frequencies, and amplitudes. In global simulations of optically thin, low-luminosity black-hole accretion flows, the excitation of such waves leads to spiral patterns in the plasma density that influence the morphology of the emission region. As such, the observed variabilities of such accr…

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astro-ph.GA

X-ray Characterization of Galaxy Groups and Hickson Groups in COSMOS-Web to z~3.8 I. X-ray Luminosity Function Evolution

Ghassem Gozaliasl, Günther Hasinger, Gavin Leroy, Alexis Finoguenov, Fatemeh Abedini, Hollis B. Akins, Rafael C. Arango-Toro, Arif Babul et al.

Galaxy groups are the dominant halo environment in the Universe and a sensitive laboratory for feedback and gas-cycling physics, yet a uniform, intermediate-redshift X-ray characterization of the group population has been limited by the availability of deep, wide-area imaging. We present a uniform X-ray characterization of the COSMOS-Web galaxy group population: 1,678 groups (CW-All) identified with the AMICO algorithm applied to the JWST-selected COSMOS-Web photometric catalog ($0.08 \lesssim z…

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astro-ph.GAastro-ph.HE

Separating the Optical to Near-Infrared Light of AGN and Their Host Galaxies

Callum Dewsnap, Pauline Barmby, Sarah C. Gallagher

The properties of galaxies that host active galactic nuclei (AGNs) offer clues to the conditions that enable accretion onto supermassive black holes. A galaxy's morphology can provide significant information on the evolutionary processes underway. By modeling the surface-brightness profiles of galaxies that host AGN, we can characterize physical properties of the host galaxy. With a sample of sources across a wide range of redshifts, we can investigate how both the supermassive black hole and ga…

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astro-ph.IMastro-ph.HEgr-qc

Learning Approximate Isometric Embeddings for Efficient Template Placement

Alexandra Wernersson, Jessica Irwin, Melissa Lopez, Sarah Caudill

The sphere covering problem has broad applications in science however, exact solutions are computationally infeasible on curved, high-dimensional manifolds because distances must be evaluated using a position-dependent metric. We present $\texttt{isobank}$, a normalizing flow that learns an approximately isometric coordinate transformation, such that Euclidean distances in the latent space approximate metric-induced proper distances in the physical parameter space. This enables template placemen…

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astro-ph.EPastro-ph.IM

TOI-1408: the limb darkening models, photometric and Doppler noises, and the exoplanetary system

Roman V. Baluev

We perform a self-consistent analysis of Doppler and photometric TESS and ground-based transit observations available for TOI-1408, known to host a system with two planets orbiting near 2:1 mean-motion commensurability and a distant companion. In general we confirm its orbital configuration derived in previous studies, however we found that the likelihood function contains multiple local maxima spread over a wider parametric domain, thus making some model uncertainties significantly larger than…

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astro-ph.HE

Extending the Pulsar radio population through Quantum Vacuum Cherenkov Emission

Tales A. O. Gomes, Sergei V. Bulanov, Jaziel G. Coelho, Martin Jirka, Alexander J. Macleod, J. A. Rueda

The presence of some radio pulsars within and below the so-called ``death valley'' in the $P$--$\dot{P}$ diagram challenges the standard pair-cascade models based on curvature radiation (CR) and resonant inverse Compton scattering (RICS) in neutron star polar caps. We show that Cherenkov radiation from the quantum vacuum, a strong-field quantum electrodynamics (QED) phenomenon enabled by vacuum polarization, constitutes a distinct pair-creation channel within the vacuum gap model. Within this mo…

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cs.AIastro-ph.IMmath.NA

FlashSinkhorn 2: Block-Sparse Entropic Optimal Transport

Felix X. -F. Ye, Yu Chin Fabian Lim, Naigang Wang, Davis Wertheimer

Streaming GPU solvers for entropic optimal transport (EOT), such as FlashSinkhorn, avoid storing the dense kernel but still evaluate all $n\times m$ point pairs in every Sinkhorn iteration. We present \textbf{FlashSinkhorn~2} (FS2), a solver for squared-Euclidean cost on low-dimensional point clouds that solves large discrete EOT problems to a prescribed marginal residual on a single GPU by coupling two stages. A coarse stage solves on cell centroids, lifts the potentials to every point and, whe…

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astro-ph.GAastro-ph.COastro-ph.SR

Collapse-accelerated small-scale dynamos in the first stars and galaxies

Muhammed Irshad, Pallavi Bhat

Here, we explore magnetic field amplification by the small-scale dynamo (SSD) during the formation of the first stars and galaxies. Gravitational collapse continuously modifies turbulent velocities and length scales, making the SSD fundamentally different from a dynamo operating in stationary turbulence. In arXiv:2503.19131, we developed a supercomoving formulation of turbulent dynamos and showed that the increasing dynamo growth rate during collapse leads to super-exponential (SE) magnetic fiel…

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astro-ph.SR

Full orbital solution and dynamical masses for a new shell-Be + sdOB binary AN Col

R. Klement, Th. Rivinius, A. C. Carciofi, A. Chaturvedi, D. R. Gies, A. C. Fonseca Silva, P. R. Querido

AN~Col is a shell Be star that has shown transient spectral features caused by a hot, evolved companion on a months-long orbit. If confirmed, this would place it among the growing category of post-mass-transfer spun-up Be + stripped subdwarf OB-type (sdOB) binaries. Characterizing the binary orbit enables obtaining dynamical masses, to provide a rare anchor for models of binary evolution and mass transfer. We present a full 3-dimensional orbital solution, dynamical masses, and dynamical parallax…

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astro-ph.HEastro-ph.GAastro-ph.SR

Neutrino flavor instabilities intermediate between slow and fast

Nicolas Viaux, Lucas Johns

The neutrino flavor composition in supernovae and neutron star mergers is shaped by flavor instabilities, which are commonly classified into three types: slow (SFI), fast (FFI), and collisional (CFI). The focus here is on mixed-type instabilities combining attributes of the standard varieties. We examine instability growth rates in two-dimensional parameter spaces (``phase diagrams'') whose axes correspond to instabilities of pure type. We find critical curves connecting the pure-type instabilit…

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astro-ph.GAastro-ph.CO

Inferring magnetic field strengths in high-redshift lensing galaxies from Faraday rotation measure observations

Stefan Reissl, Ralf S. Klessen, Annalisa Pillepich, Sui Ann Mao, Rüdiger Pakmor, Dylan Nelson

Observations of Faraday rotation in the lensing galaxy of CLASS B1152+199 at z = 0.439 suggest that efficient dynamo mechanisms had already amplified galactic magnetic fields by this epoch. We assess the reliability of this method for deriving magnetic field strengths and the likelihood of observing similarly large Faraday rotation differences. We select 64 star-forming disk galaxies from the TNG50 cosmological magnetohydrodynamical simulation, matched to CLASS B1152+199 in mass and redshift, an…

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gr-qcastro-ph.HEhep-ph

Chaotic signatures in extreme-mass-ratio systems surrounded by bosonic environments

Qi-Xuan Xu, Kyriakos Destounis, Yin-Da Guo, Richard Brito, Taillte May

Extreme-mass-ratio inspirals are key gravitational-wave sources for testing strong gravity and the environments of massive black holes. While orbital motion in Kerr black hole spacetimes is integrable, realistic black holes may be surrounded by environments that break integrability. We investigate conservative orbital dynamics around rotating black holes surrounded by scalar clouds using fully nonlinear numerical solutions and an analytical post-Newtonian model. Poincaré sections and rotation cu…

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astro-ph.COastro-ph.IM

Point spread function requirements for dark matter subhalo detection with the Habitable Worlds Observatory

Georgios N. Vassilakis, Susan F. Redmond, Jason D. Rhodes, Richard J. Massey, Qiuhan He

Different theories of dark matter predict different populations and morphologies of galactic subhaloes below about $10^8M_{\odot}$. The planned angular resolution and optical stability of the Habitable Worlds Observatory (HWO) should enable it to detect subtle subhalo perturbations in strongly lensed galaxy images. We simulate 2000-second exposures with its High Resolution Imager (HRI) under the fiducial Exploratory Analytic Case 1 (EAC1) design, assuming known source structure and omitting lens…

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astro-ph.GA

Towards robust simulations of the galactic dynamo: a cross-code comparison between Eulerian and Lagrangian schemes

Mark Ivan Ugalino, Benedikt Diemer, Vadim A. Semenov, Jin Young Kim, Federico Marinacci, Christoph Pfrommer, Matthieu Schaller, Nikyta Shchutskyi et al.

Galactic magnetic fields are thought to be seeded by microscopic processes such as the Biermann battery and are primarily amplified to observed microgauss strengths by dynamo processes. Much of this amplification likely occurs within proto-galaxies, where turbulent and rotational kinetic energy is converted into magnetic energy via dynamo action. However, two aspects of this process remain poorly constrained in simulations: the saturation level of the amplified field and the timescale on which i…

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astro-ph.IMastro-ph.CO

Optimizing spectral-matching component separation for measuring CMB B-mode polarization with a satellite mission

Hoang Viet Tran, Guillaume Patanchon, Michele Citran, Benjamin Beringue

The measurement of primordial CMB B-mode polarization is fundamentally limited by our ability to separate this faint signal from bright and complex Galactic foregrounds. Spectral Matching Independent Component Analysis (SMICA) offers a flexible, semi-blind approach to this foreground-cleaning problem. However, its standard implementation relies on a physically unrealistic assumption of non-spatially varying foreground emission, reducing the efficiency of the method. In this work, we develop two…

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astro-ph.SR

A New Framework for Modeling Solar Flares from MHD to Kinetic Processes

Joel C. Allred, Graham S. Kerr, Silvina E. Guidoni, Joel T. Dahlin, Marc Swisdak, Judith T. Karpen, Valeriy Tenishev

Physical processes in solar flares span many orders of magnitude in spatiotemporal scales, so a single unified model accounting for all relevant processes remains computationally intractable. Instead, specialized codes have been developed, targeting specific domains that tackle specific aspects of the solar flare problem. Here, we present a comprehensive framework that links three models to capture flare initiation and energy release, the subsequent particle acceleration, the propagation and the…

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astro-ph.IM

A comprehensive simulation framework for multi-modal kilonova observations from all-sky surveys

Felipe Fontinele Nunes, Andrew Toivonen, Farhana Taiyebah, Leonard Lupin-Jimenez, Skylar Callis, Malhar Kulkarni, Soumi De, Michael W. Coughlin et al.

Current all-sky surveys such as Vera Rubin's Legacy Survey of Space and Time and the Zwicky Transient Facility (ZTF) promise a wealth of scientific gains that are contained in the millions of astrophysical transient candidates produced each night. Kilonovae, one such transient of interest, will be challenging to identify in the alert stream and will require efficient artificial intelligence models to parse the large, real-time influx of data. In order to build these large models, comprehensive m…

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astro-ph.IM

Bayesian Image Reconstruction with Spatially Variant PSFs in X-ray Astronomy

Vincent Eberle, Matteo Guardiani, Margret Westerkamp, Philipp Arras, Philipp Frank, Julia Stadler, Torsten Enßlin

X-ray observatories introduce unwanted instrumental effects into photon count data that must be accurately accounted for. In particular, the spatially variant point spread function (PSF) and shot noise pose a non-trivial inverse problem. We apply Bayesian inference grounded in information field theory (IFT) combined with a fast spatially variant PSF representation to infer the posterior mean and uncertainty of the X-ray flux under a minimal set of physically motivated prior assumptions, thereby…

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astro-ph.IM

Spurious sources in high-resolution VLA surveys

Eric F. Jiménez-Andrade, Emmanuel Momjian, Eric J. Murphy, James J. Condon, Miguel Vega

Blind extragalactic radio continuum surveys are increasingly conducted at sub-arcsecond angular resolutions. However, these surveys contain substantially more spurious sources than expected from purely Gaussian noise statistics. We investigate the origin of these false detections using the 10GHz GOODS-N mosaic obtained with the Karl G. Jansky Very Large Array (VLA), which reaches a native angular resolution of 0.22arcsec and exhibits a nearly Gaussian pixel-noise distribution. We show that part…

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astro-ph.EP

Interpreting effective homogeneous rheologies through a local differential map with application to the Moon

Yeva Gevorgyan

Layered viscoelastic interiors control the frequency dependence of planetary tidal dissipation, but repeated layered Love-number calculations are expensive in long-term orbital and spin integrations. Equivalent homogeneous rheologies provide a cheaper representation of the same response, but their effective parameters do not by themselves identify the interior layers they represent. We develop a local interpretation of such parameters by differentiating the layered-to-homogeneous construction ab…

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astro-ph.HEastro-ph.IMgr-qc

Testing internal dynamics in neutron stars with radio pulsar timing

Reginald Christian Bernardo

Rotational variations in pulsars reflect either internal angular momentum exchange via equal and opposite torques (stationary spin noise) or independent torques causing diffusive changes in total angular momentum (nonstationary spin noise). We compare two models of a radio-emitting crust and interior superfluid to test the stationarity of angular velocity fluctuations through observed pulsar phases. We present results for three isolated pulsars with measurable timing noise, demonstrating distinc…

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nucl-thastro-ph.HEhep-ph

Trace-anomaly decomposition and universal dark matter scaling in compact stars

Adamu Issifu, Constança Providência, Tobias Frederico

We investigate how dark matter (DM) admixture modifies the conformal properties and phase structure of dense neutron-star matter within a self-consistent single-fluid framework, with the global DM fraction $F_χ=N_χ/N_B$ fixing the local relation $n_χ=F_χn_B$. We derive an exact decomposition of the total trace anomaly, $Δ_{\rm tot}$, into microscopic contributions. For collider-motivated Higgs-portal benchmarks, explicit Higgs, vector-mediator, and contact-interaction contributions are negligibl…

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astro-ph.HEastro-ph.GA

The Impact of a Clumpy Ambient Medium on the Dynamics and Synchrotron Emission of AGN Jets

Ivan Almeida, Christian Fendt, Bhargav Vaidya

Relativistic jets from AGN are expected to propagate through an inhomogeneous ISM, but the role of small-scale gas inhomogeneities in shaping their early evolution remains uncertain. We investigate this problem using 3D special-relativistic magnetohydrodynamic simulations with PLUTO, following a jet with a Lorentz factor of 10 propagating through a pc-scale medium. We compare a homogeneous ambient medium with two clumpy ambient-medium models, motivated by dense gas in the nuclear ISM, in which c…

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astro-ph.HEastro-ph.IM

Intrinsic versus observation induced spin nonstationarity in pulsar timing

Reginald Christian Bernardo

Whether spin noise of a neutron star is stationary is, in two-component models, a question of whether stellar angular momentum is conserved internally or exchanged externally through independent stochastic torques on the crust and superfluid. The question is posed in the two components' angular velocities, but radio pulsar timing observes only the crust, through its rotational phase after a deterministic timing model is fitted. We develop a Gaussian process method for testing spin noise stationa…

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astro-ph.SR

Wolf-Rayet formation through L/M-dependent superwinds

Aisling McKeown, Ciarán Furey, Gautham N. Sabhahit, Jorick S. Vink

Mass-loss in red supergiants (RSGs) is poorly understood and stellar evolution models rely on empirical prescriptions. In recent years, new superwind mass-loss ideas, including an $L/M$ dependence have been proposed, unlike traditional RSG wind recipes which are formulated on a $L$ dependence alone. We investigate how contrasting RSG mass-loss prescriptions affect the late-time evolution of massive stars from their RSG phase onwards. We used MESA to create a series of stellar evolution models wi…

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astro-ph.SR

LACHESIS: Robust stellar parameters through Bayesian model averaging of isochrone grids

Jose I. Vines, Austin T. Ware

Accurate stellar parameters underpin much of astrophysics, from exoplanetary systems to Galactic archaeology. For isolated field stars, masses and especially ages are usually inferred from stellar evolution models, yet these inferences depend on the chosen model grid, and the systematic differences between grids can rival the statistical uncertainties of any single pipeline. We present LACHESIS, a Python package that determines stellar masses, radii, and ages from photometry and spectroscopy whi…

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astro-ph.HEastro-ph.IMcond-mat.stat-mech

Stationarity and angular momentum conservation in pulsar spin noise

Reginald Christian Bernardo

We present an analysis of pulsar spin noise based on physically-motivated two-component models of spin wandering. We focus on two models, distinguished by their total angular momentum dynamics: a singular, nonstationary model with a diffusive total angular momentum, and a minimal, stationary model anchored on a conserved total angular momentum. We develop scalable Gaussian process methods and, using mock data, show that the two models are fully testable and distinguishable with full-state observ…

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