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Research Trends

Latest preprints in space engineering and astrophysics.

physics.plasm-phphysics.space-ph

Numerical investigations of low-latitude ground magnetic fields due to cavity mode oscillations

Khilav Majmudar, Robert L. Lysak, Kazue Takahashi

Pi2 oscillations have been known to be associated with cavity mode oscillations (CMOs) in the inner magnetosphere at low latitudes. CMOs can also be excited by interplanetary shocks on the dayside. We present results from a global linear MHD wave model in spherical coordinates that allows us to analyse these waves at equatorial latitudes. We see that the model reproduces some of the principal CMO harmonics. The standing wave cavity modes are set up due to a dense plasmasphere. The CMOs associate…

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astro-ph.EP

The Tidal Venus Phenomenon: Demographics and Case Studies

Stephen R. Kane, Emma L. Miles

The demographics of terrestrial planets and their orbits reveal a vast diversity in overall planetary energy budgets. Terrestrial exoplanets in short-period or eccentric orbits can experience intense tidal heating that, combined with stellar irradiation, may trigger runaway greenhouse conditions analogous to Venus. We calculate tidal heating rates for 143 terrestrial-sized exoplanets with measured eccentricities and find that, under adopted archive default eccentricities and constant-$Q$ assumpt…

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astro-ph.GA

Continuum Variability in AGN: Evidence for Systematically Suppressed Fluctuations in the BAL Population

A. Aliaga, P. Arévalo, M. L. Martínez-Aldama, W. Zuo, B. Muñoz-Bravo

We aim to compare the flux variability of Broad Absorption Line quasars (BAL) to non-BAL quasars, controlling for black hole parameters to inform models concerning the generation of the BAL phenomenon. Using SDSS DR16 and ZTF $g$- and $r$-band light curves, we select quasars with $1.57 \leq z \leq 2.00$ and $18.5 \leq rmag \leq 19.8$. This redshift range ensures that the $g$-band covers the C IV emission line (and trough in BALs) while the $r$-band probes continuum variability, and allows black…

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astro-ph.IM

The VLA and High-Frequency SETI: Expanding the Search for Life

Talon Myburgh, Noah Stiegler, Chenoa D. Tremblay, Joe S. Bright, Ross A. Donnachie

The Commensal Open-Source Multimode Interferometer Cluster (COSMIC) runs software that searches for technologies elsewhere in the Universe ("technosignatures") using the Karl G. Jansky Very Large Array (VLA). Specifically, it searches for narrowband signals that drift in frequency over time as a result of Doppler motions. Although this is the first study of high-frequency technosignatures that has been published from the COSMIC system on the VLA, it follows closely on previous work completed by…

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astro-ph.SR

Asteroseismic analysis of red giants in eclipsing binaries using two methods: implications for scaling relations and chemical composition

M. Yıldız, S. Örtel, T. Çakır Alsaç

The study of solar-like oscillating red giants in eclipsing binaries (EBs) provides a unique opportunity to advance stellar astrophysics by combining dynamical mass and radius measurements with asteroseismic constraints. EBs provide precise fundamental parameters (e.g. mass, radius, and luminosity) independent of distance, while solar-like oscillations probe stellar interiors and enable tests of asteroseismic scaling relations used to determine stellar masses and radii. {We apply two different m…

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

Accretion of AGN Stars under Influence of Disk Geometry II: The Adiabatic Regime and Runaway Collapse Induced by Self-gravity

Yi-Xian Chen, Yan-Fei Jiang, Jeremy Goodman

Accretion onto massive stars embedded in Active Galactic Nuclei (AGN) disks around supermassive black holes (SMBHs) is regulated to the stellar Eddington rate in the fast-diffusion or radiatively-efficient limit, $c/τ> c_s$, where $τ$ is the optical depth of the accretion flow and $c_s$ the sound speed. However, when the ambient density is sufficiently high, the opposite slow-diffusion limit applies. In this regime, accretion proceeds quasi-adiabatically and forms a hydrostatic circumstellar env…

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physics.opticsphysics.space-ph

A compact low-frequency optomechanical triaxial inertial sensor

Daniel George, Jose D. Hernandez Rivero, Moritz Mehmet, Ramses Miranda Espino, Xiangyu Guo, Andrea Nelson, Jose Sanjuan, Felipe Guzman et al.

Triaxial optomechanical accelerometers offer compact, ground-testable alternatives to electrostatic sensors for satellite geodesy, seismometry, and various other applications. We demonstrate a low-CSWaP triaxial sensor using monolithic fused-silica resonators with dual heterodyne interferometric readout. The X axis reaches a 60~pico-g/$\sqrt{\mathrm{Hz}}$ readout noise floor, and the in-plane axes resolve ambient seismic ground motion in agreement with a co-located commercial seismometer from 4~…

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astro-ph.COastro-ph.IM

Mapping the Information Geometry of an Unresolved Dark Matter Population using a Differentiable Strong Lensing Simulator

Alexandre Adam

Strong gravitational lensing is a unique probe of the matter power spectrum on small scales, where the abundance of dark matter subhalos in galaxies could be used to distinguish the predictions of the concordance cold dark matter model from alternatives such as warm dark matter. Extracting this signal poses major computational challenges, since perturbations of the lensing potential induced by substructure can be degenerate with both the macro-model of the lens and highly flexible models of the…

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astro-ph.GA

Automated Assignment and Prediction of Molecules in Astronomical Line Surveys Using Machine-Learning-Based Chemical Embeddings

Zachary T. P. Fried, Ryan A. Loomis, Jes K. Jørgensen, Andrew Lipnicky, Ci Xue, Gabi Wenzel, Thomas H. Speak, Michael C. McCarthy et al.

Modern radio telescopes generate vast amounts of observational data, offering valuable insights into the molecular composition of interstellar sources. Identifying the molecules within these datasets typically involves time-consuming and labor-intensive manual analysis. This paper presents an automated method for assigning molecules in interstellar line surveys. The algorithm operates in two main stages. First, it automatically determines key parameters of the data, including excitation temperat…

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astro-ph.IMastro-ph.EPastro-ph.SRphysics.ins-detphysics.space-ph

Radiation damage to the Hubble Space Telescope has been several years out of phase with the Solar cycle

Gavin Leroy, Juan Paolo Lorenzo Gerardo Barrios, Maximilian von Wietersheim-Kramsta, Richard Massey, Richard G. Hayes, Jacob A. Kegerreis, David Lagattuta, Zane D. Lentz et al.

As well as obtaining beautiful images of the Universe, the Hubble Space Telescope's CCD detectors are sensitive radiation dosimeters that have been monitored in Low Earth Orbit for more than 24 years. The rate of radiation damage they received has varied over each Solar cycle, but several years out of phase with the appearance of sunspots or coronal mass ejections. We investigate functional forms that successfully fit the time series of damage to telescopes elsewhere in the Solar system. We obta…

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astro-ph.GAastro-ph.SR

Quasar Impostors: Two Extremely UV-Bright ($M_{\rm UV}\approx-23.5$) Reionisation-Epoch Galaxies Powered by Very Massive Stars

Daming Yang, Joseph F. Hennawi, Sarah E. I. Bosman, Frederick B. Davies, Rychard Bouwens, Timo Kist, Eduardo Bañados, Jiamu Huang et al.

The extreme bright end of the galaxy UV luminosity function during reionisation remains poorly constrained, particularly where the galaxy and quasar luminosity functions overlap and source classification becomes ambiguous. We present JWST/NIRSpec and ALMA Band-6 observations of J1450-0144 ($z=6.627$) and J1429-0104 ($z=6.796$), two $M_{\rm UV}\simeq-23.5$ sources originally classified as faint quasars by SHELLQs. NIRSpec reveals blue UV continua, strong P Cygni profiles in N V, Si IV, and C IV,…

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astro-ph.IMastro-ph.COastro-ph.GA

The Cross-Survey Decade: A Call to Action

Gioia Rau, Robert Benjamin, Federica Bianco, Ranga-Ram Chary, Andy Connolly, Cecilia Garraffo, Suvi Gezari, Leanne P. Guy et al.

By 2027, three flagship wide-field surveys will be operating simultaneously from ground and space, observing overlapping sky and representing more than $6 billion in US and European public investment. Together they will produce overlapping petabyte-scale datasets across thousands of square degrees. This is a different class of challenge: the observations are no longer the bottleneck; realizing their joint scientific return now depends on shared computational infrastructure and coordination. Deca…

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astro-ph.GA

Recurrent Multi-year Mg II BAL Variability in SDSS J1333+0012

M. Vivek, P. Aromal, R. Srianand, K. A. Anjali, S. C. Gallagher, Rachana

We present a long-term spectroscopic study of Broad Absorption Line (BAL) variability in the quasar J1333+0012 (\zem = 0.9197) using an extensive multi-epoch dataset spanning nearly two decades. The dataset comprises multi-epoch observations from multiple observatories, delivering nearly uniform temporal coverage of the Mg II BAL profile, with close to one spectroscopic observation per year spanning the period from 2008 to 2025. We identify recurrent multi-year variability in the BAL absorption…

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astro-ph.HEastro-ph.IM

A deep learning algorithm for black hole spin estimation using hot-spot secondary images

Aristomenis I. Yfantis, Rami Al-Belmpeisi

Sagittarius A* exhibits frequent flaring activity across the electromagnetic spectrum that is often associated with a localized region of strong emission known as a hot spot. We aim to train a deep learning model to provide a link between key parameters of this phenomenon - hot-spot emission radius, and black hole inclination and spin - to the observed angle difference between the primary and secondary image ($ΔPA$) that present and future interferometric arrays could resolve. Using the general…

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astro-ph.HE

The fraction of periodic SN Ib/c light curves

Asaf Horowicz, Eran O. Ofek, Avishay Gal-Yam

Periodic luminosity modulations have been recently identified for the stripped-envelope supernovae SN 2022jli and SN 2022esa, motivating a systematic search for a similar behavior in a larger sample. Such modulations may indicate the explosions arise in binary progenitor systems. We perform the first systematic search for periodic modulation in a sample of 34 Type Ib/c supernovae with high quality photometry from the Zwicky Transient Facility. We develop and apply a statistically rigorous pipeli…

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astro-ph.HEhep-ph

Heating Up the Black Hole X-ray Binary Accretion Disk by Superradiance

Antonios Kyriazis, Fengwei Yang, Siyu Zhou

A superradiant cloud of ultralight axions around a black hole, that is part of an X-ray binary system, can heat up its accretion disk and be detected by the thermal X-ray spectrum emitted by the disk. We consider a derivative coupling of the axions to the plasma fermions and calculate the emissivity of the inverse bremsstrahlung process that results in a temperature fluctuation of the disk. Based on the thin-disk model and the multicolor disk model, we derive the thermal spectrum with axion heat…

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astro-ph.HE

The Mass Function of Neutron Stars from Core-Collapse Supernova Simulations

Waly M Z Karim, Adam Burrows, David Vartanyan, Anthony Fisher, James Burry

Using the mapping between progenitor core structure and the gravitational mass of neutron stars derived from sophisticated 3D supernova simulations, we determine the theoretical mass distribution of neutron stars at birth and compare it with neutron star mass function measurements. In the process, we explore the effects of islands of black hole formation and subsequent mass accretion. We show that supernova theory can explain the observed neutron star mass function from its lower-mass peak near…

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astro-ph.HEastro-ph.GA

The impact of recombination during tidal disruption events

Simona Pacuraru, Clément Bonnerot, Martin E. Pessah

During a tidal disruption event, the resulting debris stream cools down adiabatically due to the tidal stretching. As the temperature drops, the gas is expected to undergo chemical processes, which can release thermal energy into the stream, potentially affecting the subsequent gas evolution. For the first time, we investigate in detail this effect and its dynamical impact on the early-time evolution of the stream by making use of three dimensional hydrodynamic simulations coupled with a realist…

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astro-ph.IMastro-ph.SR

Variable Star Polarimetry with PICSARR-2

Daniel V. Cotton, Jeremy Bailey, Logan Barrett, Glenn Henderson, Kim Sumagang, Eric C. Haase

We describe the upgraded Polarimeter using Imaging CMOS Sensor and Rotating Retarder 2 (PICSARR-2), describe its applications, and characterize its performance for stellar polarimetry on a 36-inch and 14-inch telescope. On the larger telescope in the SDSS $g^\prime$, $r^\prime$ and $i^\prime$ filters a precision of $σ_p=$ 5.7 ppm on bright stars is recorded using a fast modulation rate corresponding to frame exposures of 12 ms; accounting for the internal errors in the individual observations gi…

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astro-ph.HE

Generalized Non-linear Bayesian Pulsar Timing with Enterprise

Andrew R. Kaiser, Jeffrey S. Hazboun, Maura A. McLaughlin, H. Thankful Cromartie, Emmanuel Fonseca, Joseph Simon, Stephen R. Taylor, Michele Vallisneri et al.

In this study, we use the Bayesian methods in the Enterprise package to examine the fully general parameterization of pulsar timing models in tandem with noise. We investigate four pulsars, PSR J1600$-$3053, PSR J2043+1711, PSR J0740+6620, and PSR J1640+2224, through the lens of Bayesian timing. These four are selected as they are well-studied, but exhibit interesting characteristics under the lens of Bayesian timing. Our new pulsar mass constraints (medians and 68\% confidence intervals) for ou…

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nucl-thastro-ph.SRhep-ph

Confining density functional approach to the QCD phase diagram at low temperatures and thermal twin stars

David Blaschke, Oleksii Ivanytskyi

We present a density functional-based equation of state for warm, dense nuclear matter with a transition to deconfined quark matter for applications to simulations of supernova explosions and neutron star mergers, but also for the cosmological evolution of Q-balls. For the quark matter equation of state, we employ a recently developed confining density functional approach while nuclear matter is described within a relativistic density functional model of the DD2 class. The phase transition is ob…

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astro-ph.SR

The instantaneous mass accretion rate of novae in quiescence: - an archival ultraviolet optical spectral analysis

Patrick Godon, Edward M. Sion, Tim Naylor, Frederick A. Ringwald

Based on archival spectra, we derive the quiescent instantaneous mass transfer rates in novae using synthetic disk spectra generated with tlusty, Gaia parallax-derived distances, and updated color excess values. Our results for nine novae, based on ultraviolet spectra and on a number of optical spectra, yield mass accretion rates that are higher than those derived from simple integration of the UV and optical luminosity. HR Del, 20 years after its eruption, has a mass transfer rate of $4\times 1…

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astro-ph.HE

Supernova remnant 0509-67.5 is consistent with an explosion inside an old planetary nebula (SNIP)

Noam Soker

I critically examine claims in the paper arXiv:2608.11978 that the double-detonation (DDet) scenario explains the type Ia supernova (SN Ia) remnant (SNR Ia) SNR 0509-67.5, and find the arguments supporting the DDet scenario weak; hence, I reiterate my claim that the core-degenerate (CD) scenario, where a lonely white dwarf (WD), which is the merger product of a lower-mass WD and the core of an asymptotic giant branch star, exploded inside an old planetary nebula, i.e., an SNIP, best explains SNR…

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astro-ph.IMastro-ph.EP

The Roman Coronagraph Community Participation Program: data reduction pipeline astrometric calibration

Amanda Chavez, Jason Wang, Vanessa P. Bailey, Maxwell Millar-Blanchaer, Julien Girard, John Krist, Julia Milton, Marie Ygouf et al.

The Nancy Grace Roman Space Telescope will be equipped with a Technology Demonstration Coronagraph Instrument that will push the current limits of high contrast imaging for exoplanets ($10^{-9}$ contrast). The Roman Coronagraph Community Participation Program has developed corgidrp, a python-based data reduction pipeline for the Roman Coronagraph Instrument that will perform essential data processing and calibration steps for coronagraphic observations. The astrometric calibration function withi…

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astro-ph.GAastro-ph.HEgr-qc

The Spin Angular Momentum and Black Hole Mass Components of Sagittarius A*

Ruth A. Daly

The dimensionless spin angular momentum, dimensionless spin function, and blackhole mass components of Sagittarius A* (Sgr A*) were obtained by Daly et al. (2024) by applying the outflow method to six independent sets of simultaneously or contemporaneously obtained X-ray and radio data. Here, results obtained for Sgr A* with the outflow method are reviewed. Consistent results were obtained with each data set. Set I (the preferred data set) indicates that Sgr A* has a dimensionless spin angular m…

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astro-ph.HE

Evidence of self-organized criticality in the prompt emission of a bright gamma-ray burst

Wen-Long Zhang, Wen-Jun Tan, Hao-Tian Lan, Shuang-Xi Yi, Shao-Lin Xiong, Chen-Wei Wang, Shuang-Nan Zhang, C. Guidorzi et al.

Gamma-ray bursts (GRBs) are the most energetic explosive events in the Universe, yet the physical mechanism of their prompt emission remains a mystery. Especially, it is unclear whether the energy dissipation mechanism in the GRB jet is dominated by kinetic energy or magnetic energy. Here, we studied the pulses in the prompt emission of the second brightest GRB to date, GRB 230307A, which was accurately measured by the Gravitational wave high-energy electromagnetic counterpart all-sky monitor (G…

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astro-ph.SR

Observations of Disrupted CME Material Falling Back Into the Low Corona

Brian E. Wood, Jason E. Kooi

We present an empirical study of a disrupted CME, parts of which fall back to the Sun, using observations from SOHO, STEREO-A, and SDO. At UT 18:00 on 2024 August 16, a slow CME is overtaken by a faster CME. A leg of the second CME carries part of the slower CME out with it, resulting in an unusually well-defined flux rope leg for this CME. This second CME is observed in radio by the VLA, with Faraday rotation measurements showing a clear magnetic flux rope signature. A strong response is also l…

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astro-ph.IMastro-ph.GAastro-ph.SR

Vera C. Rubin LSST Synthetic Magnitudes derived from Gaia XP Spectra

Oleksandra Razim, Krešimir Tisanič, Lovro Palaversa

Context. In the context of Milky Way studies, the Vera C. Rubin Observatory's Legacy Survey of Space and Time is often described as a deep extension of the Gaia survey. In the future, joint analysis of the Gaia and LSST data promises to bring new insights into our understanding of the Galaxy's structure and formation history. However, the relatively small overlap in the magnitude ranges of the two surveys raises the question of how to perform a joint calibration of these datasets. Aims. In this…

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astro-ph.EPastro-ph.SR

Hydrodynamics modeling of the water snow line in young protoplanetary disks with dust-size-dependent opacities

Eduard I. Vorobyov, Anastasiia Topchieva, Aleksandr Skliarevskii, Yaroslav Pavlyuchenkov, Konstanze Zwintz

Aims. We investigated the properties of the water snow line during the early stages of disk evolution, paying particular attention to the effects of gravitational instability and dust growth on the snow line's shape and position. Methods. We used the FEOSAD numerical hydrodynamics code to simulate the disk formation and evolution in the thin-disk limit. The simulations incorporate the coevolution of gas, dust, and volatiles, including dust growth, volatile phase transitions, and dust-size-depend…

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astro-ph.GA

The segmented spiral structure of the Solar neighbourhood traced by young clustered populations

M. Carmen Sánchez-Gil, Emilio J. Alfaro

The Milky Way spiral pattern remains poorly constrained, and the youngest tracers in the solar neighbourhood do not always follow a few smooth, continuous logarithmic arms. We analyse young open clusters, both independently and combined with young stellar object (YSO)-based groups, to test whether they define continuous spiral-arm ridges or shorter, partially connected structures. In the (theta_G, ln R_G) plane, we identify local overdensities using a density-supported Bayesian Gaussian Mixture…

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