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Research Trends

Latest preprints in space engineering and astrophysics.

astro-ph.SR

The umbrella effect: Magnetic canopy topology modulates spatially averaged chromospheric three-minute power

Shahin Jafarzadeh, David B. Jess, Marco Stangalini, Bernhard Fleck, Richard J. Morton, Samuel D. T. Grant, Peter H. Keys, Luc Rouppe van der Voort et al.

Three-minute ($\sim$5 mHz) oscillations are a prominent signature of wave propagation in the solar chromosphere, but their measured power can vary substantially between full-disc observations and small, high-resolution fields of view. We investigate whether chromospheric magnetic canopy topology, particularly its lateral continuity and areal filling, modulates field-of-view-averaged three-minute power. We analyse H$α$ and Ca II 8542 Å spectral imaging from the Swedish 1-m Solar Telescope, compar…

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astro-ph.GA

Constraining Baryonic Feedback at $z\sim 1$ with the H$α$ Luminosity Function

Ivan Rapoport, Vincent Desjacques, Ehud Behar, Shmuel Bialy

Baryonic feedback remains one of the primary uncertainties in galaxy formation models because of its impact on the interstellar medium (ISM) and star formation. We investigate its effect on the H$α$ luminosity function (LF) using the Illustris and IllustrisTNG simulations, incorporating direction-dependent dust attenuation and a physically motivated treatment of the propagation of Lyman-series photons. We model three sources of H$α$ emission: star-forming H II regions, collisional excitation and…

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astro-ph.HE

STOKES tables and KY codes

Jakub Podgorný, Michal Dovčiak

The family of KY codes is an XSPEC-compatible package of fully relativistic models for spectro-polarimetric modeling of X-ray binary systems and active galactic nuclei. Within Kerr space-time, they compute accretion disc line profiles, reflection spectra from discs illuminated by Comptonized coronal radiation, and thermal disc emission including disc-corona interaction and disc self-irradiation. Many of these models include polarimetric computations, and more advanced timing variants compute X-r…

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astro-ph.IM

On-sky demonstration of a vector Zernike wavefront sensor in a cascaded adaptive optics system

M. Motte, V. Chambouleyron, R. Fétick, F. Oyarzun, M. A. Alagao, A. Striffling, E. Vinerskas, J. -F. Sauvage et al.

To directly image and characterise Earth-like exoplanets, future high-contrast instruments will require adaptive-optics systems operating at increasingly high loop frequencies to reduce temporal errors. Increasing the loop frequency reduces the signal-to-noise ratio per wavefront-sensor frame, making highly sensitive wavefront sensors, such as the Zernike wavefront sensor (ZWFS), attractive candidates. However, the limited dynamic range of the classical ZWFS makes on-sky operation challenging. W…

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astro-ph.SR

Astrometric modeling of unresolved variable binary systems. II. Application to Gaia epoch astrometry of nearby pulsating and convective red giants

L. Decin, K. Sivkova, P. Kervella, A. Chiavassa, E. Beguin

(Abbreviated) The interpretation of high-precision astrometry for intrinsically variable stars remains challenging, particularly for unresolved binary systems containing asymptotic giant branch (AGB) stars. In such systems, large-amplitude pulsations and evolving convective surface structures induce time-dependent photocentre displacements that perturb the observed orbital motion. At the same time, Gaia DR4 epoch astrometry offers the prospect of deriving accurate orbital solutions and parallaxe…

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astro-ph.HEastro-ph.GA

TeV Gamma Rays and Neutrinos from Winds Driven by Radiatively Inefficient Accretion Flows of Low-Luminosity Active Galactic Nuclei

Nobuyuki Sakai, John F. Beacom, Kohta Murase

Recently, the Large High Altitude Air Shower Observatory (LHAASO) reported the first TeV gamma-ray detection from a low-luminosity active galactic nucleus (LLAGN) lacking a strong jet. This source, NGC 4278, is one of the nearest LLAGNs that can be studied in detail as a template for more distant objects. Most previous studies have focused on the month-scale-variable gamma-ray activities, seeking to explain them with weak jets. We focus instead on NGC 4278's quiet-period emission, proposing a di…

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astro-ph.IM

Learning Radio Astronomical Representations with LeJEPA and Very Small Models

Erica Lastufka, Mariia Drozdova, Vitaliy Kinakh, Taras Holotyak, Miroslava Dessuages-Zavadsky, Daniel Schaerer, Svyatoslav Voloshynovskiy

Representations learned by vision foundation models pretrained on natural images have been shown to be useful for out-of-domain astronomical images. Performance on scientific downstream tasks increases with model size, which both carries higher inference costs and limits scalability, even when considering parameter-efficient adaptation. An alternative is to learn representations directly from astronomical observations rather than natural images, through self-supervised pretraining. We evaluate L…

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nucl-thastro-ph.HEastro-ph.IMhep-ph

NS-UNO: Neutron Star EoS Inference from an Unconstrained Number of Observations

Valéria Carvalho, Márcio Ferreira, Michał Bejger, Constança Providência

Future multimessenger observations of neutron stars (NS) are expected to substantially increase both the number and precision of astrophysical constraints on the equation of state (EoS) of dense matter. This motivates inference frameworks capable of accommodating a variable, non fixed number of observations while preserving the posterior information associated with each measurement. In this work, we introduce NS-UNO, a Neural Posterior Estimation framework for NS EoS inference designed to accomm…

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astro-ph.HEhep-ph

Cascades from ultra-high-energy neutrinos

Gaetano Di Marco, Rhorry Gauld, Rafael Alves Batista, Alfonso García-Soto, Miguel Á. Sánchez-Conde

Neutrinos produced at the highest energies can interact with cosmic neutrino and radiation backgrounds during their propagation to Earth. The many available $νν$, $ν\barν$, and $νγ$ channels can lead to their absorption or energy redistribution, whilst the leptonic and hadronic final states may feed secondary fluxes of neutrinos, protons, and electromagnetic particles through the decay or hadronisation of the heavy leptons, bosons, and quarks produced. We present a framework to characterise thes…

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astro-ph.SRastro-ph.GA

Interferometric Survey of Stellar Parameters: Towards homogeneous FGK stars parameters and surface-brightness color relation in the context of PLATO space mission

Romina V. Ibañez Bustos, Denis Mourard, Nicolas Nardetto, Jeremy Jones, Nayeem Ebrahimkutty, Juraj Jonák, Hugo Nowacki, Mathieu Vrard et al.

The estimation of stellar angular diameters can be performed from the surface brightness - color relation (SBCR) and photometry. The SBCR have been considered by the PLATO space mission as an independent empirical alternative for estimating stellar radii of FGK stars. In this context, we have implemented an homogeneous approach not only for calibrating the SBCR for FGK-IV/V stars but, also for determining their fundamental parameters in order to place the stars reliably on the HR diagram and to…

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astro-ph.SRastro-ph.EP

Joint Observations of PTPS Targets (JOTA). Combined spectroscopic and photometric analysis of 16 SB1 systems

Robert Jaros, Andrzje Niedzielski, Sohaib Ali, Divyansh Srivastava, Julia Sierzputowska, Monika Adamów, Jorge Lillo-Box, Dmytro Orikhovskyi et al.

Context. The Pennsylvania-Toruń Planet Search, which operates on a sample of $\sim$1000 northern-hemisphere stars, has been underway since 2004. Stars with radial velocity (RV) amplitudes exceeding 2 km s$^{-1}$ represent a backup subprogram sample dedicated to monitoring binary stars with multiple instruments. Aims. We used almost 21 years of combined RV measurements to search for Doppler signals consistent with stellar or brown dwarf companions and to produce a catalog of both known and previo…

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astro-ph.SR

Equilibrium \(\mathrm{H}_2^+/\mathrm{H}^-\) Abundance Ratios in MARCS Atmosphere Models

Aiganym Sarsembayeva, Hernando Quevedo

We investigate the equilibrium abundance ratio of the molecular hydrogen ion \(\mathrm{H}_2^+\) and the negative hydrogen ion \(\mathrm{H}^-\) in stellar atmospheres using compact Saha-type equilibrium expressions and layer-by-layer partial pressures from MARCS model atmospheres. The analysis distinguishes the temperature-dependent coefficient ratio \(K_{\mathrm{H}_2^+}(T)/K_{\mathrm{H}^-}(T)\) from the full abundance ratio, which also depends on the local ionisation factor \(N_{\mathrm{H}^+}/N_…

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astro-ph.IM

DINOspec: Efficient Multimodal Alignment of Vision and Spectral Foundation Models for Astronomy

Erica Lastufka, Mariia Drozdova, Daniel Schaerer, Svyatoslav Voloshynovskiy

Astronomical observations provide multimodal views of physical systems, with images and spectra capturing complementary properties of celestial objects. Scientific foundation models can learn powerful representations from these observations, but representations learned by separate models remain difficult to combine. We investigate whether physical representations learned by separate vision and spectral models can be aligned without retraining their encoders. We introduce DINOspec, a multimodal f…

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astro-ph.GA

Photometric redshifts for active galactic nuclei with LePHARE for the Vera C. Rubin Observatory

R. Shirley, M. Salvato, J. Cohen-Tanugi, O. Ilbert, S. Arnouts, R. Ansari, R. Assef, M. Banerji et al.

Active Galactic Nuclei (AGN) play a crucial role in galaxy evolution, but they are a minority of extragalactic sources with diverse Spectral Energy Distributions (SEDs), which depend on their means of selection. Upcoming large-scale surveys such as LSST will identify many AGN, but analysis tools are not optimized for them. The limited number of photometric bands in these surveys impacts the calculation of photometric redshifts for AGN, which are essential for scientific advancement. We use LePHA…

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astro-ph.GA

Photometric redshifts for active galactic nuclei with LePHARE for the Vera C. Rubin Observatory

R. Shirley, M. Salvato, J. Cohen-Tanugi, O. Ilbert, S. Arnouts, R. Ansari, R. Assef, M. Banerji et al.

Active Galactic Nuclei (AGN) play a crucial role in galaxy evolution, but they are a minority of extragalactic sources with diverse Spectral Energy Distributions (SEDs), which depend on their means of selection. Upcoming large-scale surveys such as LSST will identify many AGN, but analysis tools are not optimized for them. The limited number of photometric bands in these surveys impacts the calculation of photometric redshifts for AGN, which are essential for scientific advancement. We use LePHA…

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astro-ph.HEastro-ph.GA

ALMA Observations of DEM L241/LMC P3 in the Large Magellanic Cloud: Evidence for the Formation of Cool Molecular Jets Driven by a Microquasar

Yasuo Fukui, Bhuvana G. R., Hidetoshi Sano, Kisetsu Tsuge, Rami Z. E. Alsaberi, Rin Yamada, Yuya Asano, Aya Bamba et al.

We present ALMA observations of DEML 241/LMC P3, the most luminous $γ$-ray binary consisting of a compact object and an O star, in CO emission. We have found an one-sided jet-like CO feature of 8 pc length and 1 pc width, which accompanies another weaker CO jet candidate with slightly different orientation. The one-sided CO jet exhibits striking alignment with LMC P3, suggesting that the jet was driven by LMC P3. We have determined kinetic temperature of the CO jet to be significantly high at 33…

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astro-ph.SRastro-ph.GA

Phosphorus abundances and multi-element co-enrichment in nearby FGK stars

Dario Esposito, Giovanni Covone, Donato Giovannelli, Paola Manini, Christian Magliano, Laura Inno, Luca Cacciapuoti, Víctor M. Rivilla et al.

The distribution of bio-essential elements is key to assessing the chemical fertility of galactic environments. We analyse phosphorus abundances for 233 nearby FGK stars from the Hypatia Catalog, separating thin- and thick-disk populations. We study [P/Fe] as a function of [Fe/H] and other elemental abundances using non-parametric tests and bootstrap resampling, and we examine residual correlations at fixed [Fe/H] together with molar ratios involving P. We find a [P/Fe]-[Fe/H] trend broadly simi…

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astro-ph.HEastro-ph.IM

SNAD: enabling discovery in the era of big data

Maria Pruzhinskaya, Emille E. O. Ishida, Konstantin Malanchev, Anastasia Lavrukhina, Etienne Russeil, Timofey Semenikhin, Sreevarsha Sreejith, Emmanuel Gangler et al.

In the era of wide-field surveys and big data in astronomy, the SNAD team is exploiting the potential of modern datasets for discovering new, unforeseen, or rare astrophysical objects and phenomena with machine learning (ML). The SNAD pipeline was built under the hypothesis that, although automatic ML algorithms have a crucial role to play in this task, the scientific discovery is only completely realized when such systems are designed to boost the impact of domain knowledge experts. Our key con…

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astro-ph.GAastro-ph.IM

Broad-band host measurements of little red dots and similar compact nuclei require source-conditioned polychromatic PSFs

Sergio Bonaque-González

Characterizing compact sources in the early Universe is difficult because light from physically distinct components can overlap within the same diffraction-limited image. A common method uses field stars to model how a single point of light appears and from this estimates the intrinsic structure and contributions of the physical components of the distant object under study. Many important properties inferred for high-redshift objects depend on the accuracy of this method. Using the little red do…

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astro-ph.EPastro-ph.GAnlin.CDphysics.class-ph

Planar Three-Body Problem: theoretical predictions and simulation results

Yogesh Dandekar, Ethan Springer, Shoval Zard, Alessandro Alberto Trani, Barak Kol, Ofek Birnholtz

We investigate the statistical properties of the non-hierarchical planar three-body problem, relevant to astrophysical systems with nearly planar dynamics, including protoplanetary disks and AGN disks. Using the Flux-based statistical theory of the three-body problem, previously studied in three dimensions, we derive theoretical predictions for several statistical observables in the planar case. Focusing on ergodic disintegration outcomes, we compare these predictions directly with numerical sim…

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astro-ph.HEastro-ph.GA

Hunting the nature of the Seyfert 1 galaxy GRS 1734-292: can it be a gamma-ray emitter?

Luigi Foschini

It has been proposed that the radio-weak Seyfert galaxy GRS 1734-292 is the counterpart of 3EG J1736-2908 and of the nearby Fermi/LAT source. I examine this identification, considering that the radio weakness could result from free-free absorption of a relativistic jet. An association with the EGRET detections is plausible, whereas the latest Fermi/LAT localization no longer favors GRS 1734-292. New observations, especially at radio frequencies of tens of GHz, would help to settle the issue.

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astro-ph.GA

Testing SALT Approximations with Numerical Radiative Transfer Code. II. Thermal and Microturbulent Line Broadening

Cody Carr, Renyue Cen, Leo Michel-Dansac, Claudia Scarlata, Alaina Henry

Forward models that connect galactic winds to their predicted spectral-line profiles have proved effective for inferring wind properties in controlled settings, but important limitations remain. In particular, many models rely on the Sobolev approximation to solve the radiative transfer equation and neglect line broadening caused by thermal and turbulent motions within the wind. In the first paper of this series, we demonstrated that neglecting this broadening in Semi-Analytical Line Transfer (S…

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astro-ph.HEastro-ph.SR

SN 2019cqc: A Hydrogen-rich Superluminous Supernova Showing Electron-Scattering Signatures

Dinesh Hebbar, Rupak Roy, Matt Nicholl, Jesper Sollerman, Joseph P Anderson, Mariusz Gromadzki, D. Andrew Howell, Tuomas Kangas et al.

Hydrogen-rich superluminous supernovae without narrow emission lines (SLSNe-II) are rare transients whose powering mechanisms remain debated, particularly the role of circumstellar medium (CSM) interaction. We present photometric and spectroscopic observations of SN 2019cqc to investigate its power source and progenitor mass loss. We model the lightcurve using MOSFiT with the csm and csmni models to constrain the explosion and CSM parameters. SN 2019cqc peaked at $M_g = -20.21 \pm 0.07$ and emit…

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astro-ph.SRastro-ph.EP

Systematic and Statistical Properties of Prominence Eruptions on the M-dwarf YZ CMi

Yuto Kajikiya, Kosuke Namekata, Yuta Notsu, Kai Ikuta, Hiroyuki Maehara, Bunei Sato, Daisaku Nogami

M-dwarfs produce frequent flares, and their associated mass ejections are expected to significantly affect the habitability of close-in exoplanets. Recent spectroscopic observations have revealed several prominence eruptions-indicative of stellar mass ejections-on M-dwarfs through Doppler shifts of the H$α$ line. However, systematic and statistical studies, particularly regarding their association with white-light flares, have been limited due to the lack of intensive and continuous simultaneous…

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astro-ph.SRastro-ph.EP

Systematic and Statistical Properties of Prominence Eruptions on the M-dwarf YZ CMi

Yuto Kajikiya, Kosuke Namekata, Yuta Notsu, Kai Ikuta, Hiroyuki Maehara, Bunei Sato, Daisaku Nogami

M-dwarfs produce frequent flares, and their associated mass ejections are expected to significantly affect the habitability of close-in exoplanets. Recent spectroscopic observations have revealed several prominence eruptions-indicative of stellar mass ejections-on M-dwarfs through Doppler shifts of the H$α$ line. However, systematic and statistical studies, particularly regarding their association with white-light flares, have been limited due to the lack of intensive and continuous simultaneous…

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astro-ph.SRastro-ph.GA

OB stars identified in LAMOST Data Release 10

Guang Yang, Zhicun Liu, Xiao-Long Wang, Yanjun Guo, Wenyuan Cui

A large sample of OB stars plays an important role in studying the stellar parameters of massive stars, as well as the formation and evolution of the Milky Way. With the help of the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) Data Release 10 (DR10), we are able to construct a large sample of OB stars with spectroscopic data. In this study, we identify 48,463 spectra of 34,550 OB stars from LAMOST DR10, based on the Hertzsprung-Russell (H-R) diagram constructed with Gaia DR…

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

Empirical Constraints on the CO Snowline Transition in HD 163296: The Local CO Column and $^{13}$C$^{18}$O Optical Depth

Chunhua Qi, Takahiro Ueda, David J. Wilner, Catherine C. Espaillat

CO isotopologue emission is widely used to infer gas masses and volatile carbon abundances in protoplanetary disks, but converting line emission into a CO column depends on optical depth, temperature structure, linewidth, and isotope ratios. Inferring CO/H$_2$ additionally requires an independent constraint on the local hydrogen column. We use high-resolution $^{13}$C$^{18}$O $2$-$1$ observations of HD 163296 to derive a spatially localized empirical constraint on the CO column at the resolved C…

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astro-ph.SRphysics.flu-dyn

Moment-based formulas for the transport coefficients

J. -F. Wang, G. Qin

The coefficients of the transport equations, describing the propagation features, are particularly important in astrophysics, interplanetary physics, and experimental plasma physics. In this paper, the variable-dependent diffusion coefficients are investigated. For the momentum transport equations, we find that the coefficients are related to statistical quantities, some of which are new. In addition, these coefficients take logarithmic forms, which are different from the results derived in prev…

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astro-ph.EP

Atmospheric escape fractionates secondary but not primary atmospheres

Mara Attia, Tim Lichtenberg

A planet's atmosphere, heated by starlight, can flow off as a wind, taking some gases and leaving others in unknown proportions. Yet this selection wrote the noble-gas records of the terrestrial planets, and decides which gases hot exoplanets keep. We solve this fractionated escape problem for arbitrary composition: a wind sorts gases only for secondary, hydrogen-poor atmospheres, and removes primary, hydrogen-rich atmospheres wholesale. The algebraic solution recovers every published formula as…

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astro-ph.IM

CRUX: A topology-aware load balancer for mesh-based fluid dynamics codes on GPU clusters

M. T. P. Liska, C. Crozier

The rapid growth of computational power has revolutionized numerical simulations, profoundly enhancing our understanding of fluids and plasmas. Computational fluid dynamics (CFD) simulations, which solve partial differential equations governing fluid or plasma motion on discretized grids, have been central to this progress. Recent advances have pushed the resolution and runtime of legacy numerical models to unprecedented levels while enabling newer codes to incorporate increasingly sophisticated…

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