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Research Trends

Latest preprints in space engineering and astrophysics.

astro-ph.HE

Extended gamma-ray emission in the vicinity of the Westerlund 1 massive star cluster and Kes 41 supernova remnant seen by the Fermi Large Area Telescope

L. Tibaldo, R. Bernet, L. Härer, M. Lemoine-Goumard, L. Mohrmann, G. Peron, B. Reville, T. Vieu et al.

There is growing evidence for cosmic-ray acceleration in massive stellar clusters. Furthermore, extended gamma-ray emission suggests that particle transport in the vicinity of their sources is influenced by physical processes markedly different from large-scale diffusion in the Milky Way. We characterize extended gamma-ray emission in the direction of the Westerlund 1 stellar cluster and Kes 41 supernova remnant using > 16 years of data from the Fermi Large Area Telescope (LAT) at energies > 0.8…

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gr-qcastro-ph.IM

A Differentiable Parametric Model of Binary-Black-Hole Initial Data: I. Conformally flat Bowen-York punctures

Frederik De Ceuster, Tjonnie G. -F. Li

Constraint-satisfying initial data for binary black holes require the repeated solution of a nonlinear elliptic boundary-value problem throughout the physical parameter space. We present a para\-metric, differentiable initial-data model that combines sparse-grid spectral interpolation with Newton refinement over a family of binary configurations. Interpolation is used only to provide warm starts for the underlying elliptic solver, rather than to replace it. A small number of Newton iterations re…

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astro-ph.SRastro-ph.EP

Untangling EIT Waves: What a Measured Speed Actually Traces

Olena Podladchikova

Nearly three decades after the first SOHO/EIT observations, reported EUV-wave speeds still range from a few tens to more than 1000 km/s. This Perspective asks what those numbers actually trace. A measured image speed depends on passband and line-of-sight weighting, cadence, difference imaging, the selected crest or leading edge, propagation sector, fitted interval, and projection geometry. Same-event comparisons quantify this observation-operator effect. In events common to the Nitta and Muhr an…

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astro-ph.GA

The internal kinematics and chemistry of 20 Milky Way strings

C. Boeche, A. Vallenari, J. Alonso-Santiago, A. Bragaglia, R. Carrera, E. Dalessandro, E. Carretta, E. Franciosini et al.

Context: the recent discovery of filamentary stellar structures in the Milky Way disk raises the question of their formation in the context of the Galaxy evolution. Aims: in this work, we aim to kinematically and chemically characterize several filamentary stellar structures by looking for clues about their origin and formation mechanism. Methods: recent works using machine-learning techniques and $Gaia$ data have identified many previously unknown Galactic strings. We cross-matched such data wi…

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physics.ins-detastro-ph.IMcond-mat.supr-con

Post-fabrication trimming of a 1024-pixel, single-photon counting, Microwave Kinetic Inductance Detector array with a pixel pitch of 150 micron

Wilbert Ras-Vinke, Hessel Schulte, David J. Thoen, Kevin Kouwenhoven, Steven A. H. de Rooij, Tonny A. H. M. Coppens, Jochem J. A. Baselmans, Pieter J. de Visser et al.

Microwave Kinetic Inductance Detectors are superconducting resonators capable of single-photon counting with energy resolving capability at visible and near-infrared wavelengths. Their zero read noise, extremely low dark counts, and compatibility with frequency-division multiplexing make them well suited for large imaging arrays. The detector yield of these arrays is often limited by the fabrication-induced frequency scatter leading to resonator collisions. We find that the tight packing of the…

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astro-ph.HE

Hadronic origin of gamma rays and neutrinos from blazars: Multi-messenger implications and observational constraints

Rodrigo Sasse, Rita de Cássia dos Anjos

We investigate whether cosmogenic gamma rays and neutrinos from ultra-high-energy cosmic rays (UHECRs) produced in hadronically active blazars can significantly contribute to the observed spectral energy distribution (SED), and examine the potential of the Cherenkov Telescope Array Observatory (CTAO) to detect and discriminate this component. For four nearest neutrino bright blazars modeled by Rodrigues (2024), specifically AP Librae, TXS 1700+685, PKS 2326$-$502, and PKS 2345$-$16, we constrain…

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quant-phastro-ph.IMphysics.optics

Multiparameter quantum bounds for entanglement-assisted aperture synthesis

Kalaga Madhav, Pieter Kok, Nic Scott

Entanglement-assisted optical interferometry promises diffraction-limited imaging over baselines where light cannot be physically combined, but existing theory treats only a single visibility on one two-station baseline. This work formulates the multiparameter estimation problem for an M-station array imaging an extended scene. A reduction lemma shows that the multimode quantum Fisher information (QFI) equals the mean photon number times the QFI of a single delocalized photon, collapsing the pro…

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astro-ph.IMastro-ph.GA

Enabling New Discoveries with Machine Learning

Michelle Lochner

The next generation of telescopes such as the Square Kilometre Array and the Vera C. Rubin Observatory will produce enormous quantities of data, too large for traditional analysis techniques. Machine learning has proven invaluable in handling massive data volumes and automating tasks traditionally done by human scientists. The question is, can machine learning also automate scientific discovery? Recent advances in the field have made this feasible but only when combined with expert human input t…

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astro-ph.GA

The JWST Emission Line Survey (JELS): Multi-wavelength properties of Paschen line-emitters at Cosmic Noon

Malte Brinch, Edo Ibar, Luis Ossa-Fuentes, Corey Pirie, Philip Best, R. K. Cochrane, Kenneth Duncan, James Dunlop et al.

Context: Narrowband JWST/NIRCam selection isolates star-forming galaxies in well-defined redshift slices, while ALMA and archival far-IR/submm data reveal obscured growth. We combine these to measure Paschen-line SFRs, infer nebular extinction from EAZY Av, and probe FIR-to-submm emission via weighted-median stacking, to constrain galaxy growth at cosmic noon. Aims: We characterize stellar, nebular, and FIR properties of Paschen-selected galaxies in COSMOS, in two ensembles at z~1.50 (Pa-alpha)…

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astro-ph.HEastro-ph.GA

Search for refractive substructure in active galactic nuclei using ground-based VLBI observations

Tatiana A. Koryukova, Alexander V. Plavin, Alexander B. Pushkarev, Yuri Y. Kovalev

We present the results of the first systematic search for refractive scattering substructure in active galactic nuclei (AGN) using ground-based very long baseline interferometry (VLBI) data. We selected 1074 AGNs showing a steep frequency dependence of their angular sizes and compared the observed long-baseline visibility amplitudes with the predictions of the refractive substructure model for scatter-broadened images. Nine sources showed consistency with the expected level of refractive noise,…

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astro-ph.EPcs.LG

Physics-Informed Multi-Task Surrogate Model for the Martian Nightside Thermosphere

Sergey Nikiforov

Modeling the Martian nightside thermosphere remains challenging due to sparse in situ sampling and strong coupling among transport, magnetic, and seasonal processes. Purely data-driven models can produce non-physical artifacts, such as density inversions, in poorly sampled altitude regimes. We present a multi-task physics-informed neural network that simultaneously predicts the base-10 logarithmic densities of four neutral species (O, CO$_2$, N$_2$, and Ar) using more than a decade of MAVEN/NGIM…

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astro-ph.HE

Orthogonal polarization modes of nonbirefringent origin in a geometric radio pulsar signal model

J. Dyks, L. Saha, A. Frankowski

Motion of plasma in pulsar magnetospheres essentially follows bent magnetic field lines which may result in radiation beams sweeping past the observer's sightline. We show that under certain conditions such a passing beamlet can produce two orthogonal polarization modes (OPMs) solely from averaging of radiative contributions, without involving birefringence. This requires that radiation from different stages of the passage is contributed incoherently, hence that the timescale for the coherence i…

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astro-ph.IM

Modelling Fourier filtering wavefront sensors for PSD-based methods: the AOPERA tool

Romain Fétick, Vincent Chambouleyron, Lisa-Marie Mazzolo, Christophe Vérinaud, Arnaud Striffling, Cédric Héritier-Salama, Benoit Neichel, Jean-Francois Sauvage et al.

Compensation of the atmospheric turbulence thanks to adaptive optics (AO) has now become commonly used for VLT or ELT class telescopes in order to retrieve a resolution close to their diffraction limit. Following the increasing trend of AO system, there is also a stronger necessity for simulations in order to understand and predict their performance facing different observing conditions, that are the evolution of the atmospheric turbulence or the diversity of AO guide source. The so-called PSD b…

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astro-ph.HE

Evidence of a Low-Energy Cutoff in the Injected Spectrum of a Pulsar Wind Nebula

Zhihong Shi, C. -Y. Ng, Niccol`o Bucciantini, B. M. Gaensler, Zhen Yan, David J. Wilner, Douglas C. -J. Bock, Hua-bai Li et al.

Bow-shock pulsar wind nebulae (PWNe) are synchrotron sources formed when the outflow of supersonic pulsars is confined by the surrounding interstellar medium. These sources are dominated by freshly injected particles, thus providing a unique laboratory for studying particle acceleration in relativistic outflows. The Mouse is a prototypical bow-shock PWN and is bright in the radio and X-ray bands, enabling detailed multi-wavelength spectral modeling. Using data from 17 telescopes, the Mouse is de…

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astro-ph.EP

Magnetically Driven Obliquity in Circumplanetary Disks and Twisted Bipolar-jet Formation

Raúl O. Chametla, Martin E. Pessah, F. Javier Sánchez-Salcedo, David Vokrouhlický, Mauricio Reyes-Ruiz, Ondrej Chrenko, Alessandro Morbidelli

Circumplanetary disks (CPDs) regulate gas accretion onto forming giant planets and provide the environment in which their satellites may form. We use high-resolution, global three-dimensional simulations to investigate the early formation, orientation, and outflows of a CPD around a Jupiter-mass planet embedded in a turbulent magnetized protoplanetary disk. Within a locally isothermal, ideal-MHD framework, we evolve disks threaded by net vertical magnetic fields, corresponding to initial plasma…

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astro-ph.EPastro-ph.SR

Can the Long-Term Impact of Stellar M-Dwarf Flares Alter the Spectral Features of a Giant Gaseous Exoplanet?

Amy Louca, Shang-Min Tsai, Yamila Miguel

In this work, we model the long-term impact of recurrent stellar flares on the atmospheres of metal-rich gaseous exoplanets. Using synthetic flare spectra from a fiducial flare model integrated with a photochemical kinetics code, we track the changes in atmospheric composition with time. We further analyze the spectral variability by feeding these abundance profiles into a radiative transfer code at various time steps. Our simulations showed variability and persistent changes in key atmospheric…

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astro-ph.GAastro-ph.IMgr-qc

Milky Way Structure from Double White Dwarf Gravitational-Wave Sources

Shao-Dong Zhao, Xue-Hao Zhang, Qun-Ying Xie, Yu-Xiao Liu, Soumya D. Mohanty

The millihertz gravitational-wave sky will be dominated by $\sim10^{4}$--$10^{7}$ resolved double white dwarf binaries in the Milky Way, whose three-dimensional spatial distribution traces the Galaxy's structural parameters. We present \textsc{Galena}, a hierarchical Bayesian pipeline that recovers these parameters from a double white dwarf catalogue through an inhomogeneous Poisson-process likelihood. Each source's $3\times3$ Galactic position covariance is computed from the waveform Fisher inf…

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astro-ph.GAastro-ph.IMgr-qc

Milky Way Structure from Double White Dwarf Gravitational-Wave Sources

Shao-Dong Zhao, Xue-Hao Zhang, Qun-Ying Xie, Yu-Xiao Liu, Soumya D. Mohanty

The millihertz gravitational-wave sky will be dominated by $\sim10^{8}$ double white dwarfs while $\sim10^{4}$ be resolvable in the Milky Way, whose three-dimensional spatial distribution traces the Galaxy's structural parameters. We present \textsc{Galena}, a hierarchical Bayesian pipeline that recovers these parameters from a double white dwarf catalogue through an inhomogeneous Poisson-process likelihood. Each source's $3\times3$ Galactic position covariance is computed from the waveform Fish…

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astro-ph.SRastro-ph.GA

Long-slit spectroscopy of the bipolar planetary nebula ESO\,428$-$05

Alexei Kniazev

The results of detailed long-slit spectroscopy of the bipolar planetary nebula \ESO\ are presented. The observations were obtained with the facility spectrograph RSS of the SALT telescope. The total measured extent of the nebula reaches $\approx$55$^{\prime\prime}$, and the kinematics along the slit directly confirms its bipolar structure. The inclination of the nebula to the line of sight is estimated as $i\approx 45^{\circ}$, and the kinematic ages of two morphological structures are measured:…

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gr-qcastro-ph.HE

Prospects of electromagnetic follow-up of neutron star-black hole mergers in the LIGO-India era

Yogita Kumari, Kanchan Soni, Sanjit Mitra

Neutron star-black hole (NSBH) mergers are promising multimessenger sources, but only a subset is expected to produce detectable electromagnetic (EM) counterparts, depending on the binary mass ratio, black hole (BH) spin, and neutron star (NS) equation of state (EoS). We investigate the prospects for detecting kilonova counterparts to NSBH mergers in the LIGO-India era using the Vera C. Rubin Observatory (Rubin). We simulate GW230529-motivated NSBH populations with two effective tidal deformabil…

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astro-ph.HE

Time-Correlated Profile Variability in the MeerKAT Pulsar Timing Array

Bhavnesh Bhat, Michael J. Keith, E. Carli, R. M. Shannon, Benjamin W. Stappers

Long-term pulse-profile variability has emerged as a potentially important source of uncertainty for high-precision pulsar timing, as changes in the integrated pulse shape can bias pulse times of arrival and affect the sensitivity of pulsar timing arrays to nanohertz gravitational waves. We present a systematic search for long-term pulse-profile variability in the six-year MeerKAT Pulsar Timing Array data, analysing observations of 84 millisecond pulsars using a two-dimensional Gaussian-process…

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astro-ph.GA

The magnetic field in M16: new results from the JCMT BISTRO survey

R. M. R. Tulloh, D. Ward-Thompson, J. Karoly, J. M. Kirk, K. Pattle

We present a study of the magnetic field (B-field) in the Eagle Nebula (M16) using data from the James Clerk Maxwell Telescope (JCMT) B-fields In STar-forming Region Observations (BISTRO) survey. We extend our previous study of the well-known `Pillars of Creation' region of the nebula to study two other structures in the region, the `Spire' and the bright-rimmed cloud (BRC) known as `SFO30'. These structures show similar B-field morphologies to the Pillars. We calculate B-field strengths using t…

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astro-ph.GA

The Dense Gas Structures Around MMS 2/OMC-3 Traced by C$^{18}$O Emission

Yuhua Liu, Satoko Takahashi, Masahiro N. Machida

We report the Atacama Large Millimeter/submillimeter Array observations of 1.3 mm continuum, C$^{18}$O ($J=2$$-$$1$), and N$_{2}$D$^{+}$ ($J=3$$-$$2$) toward the millimeter multi-system MMS 2 in the Orion Molecular Cloud-3 region, at an angular resolution of 1.59" ($\sim$620 au). MMS 2 is in the flat-spectrum phase, with its protostars in the late stage of the main accretion phase. We detect the centrally condensed structures traced by C$^{18}$O emission associated with the 1.3 mm continuum sour…

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astro-ph.EP

JWST-SUPER I: New insights into irradiated warm Neptunes atmospheres from MIRI observations of HD 106315 c

A. Dyrek, R. Waters, S. -M. Tsai, M. Holmberg, B. Edwards, J. Pye, M. Güdel, N. Crouzet et al.

Sulphur-bearing molecules have recently emerged as powerful tracers of atmospheric photochemistry in exoplanets observed with JWST. In several warm giant planets, SO$_2$ has been detected as a product of UV-driven chemical processing, suggesting a close connection between stellar irradiation, atmospheric metallicity, and sulphur chemistry. Whether these trends extend to Neptune-mass planets orbiting hotter stars remains largely unexplored. We investigate the atmospheric composition of the warm N…

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astro-ph.IM

First Very Long Baseline Interferometry Fringe Detection at 690GHz

Ming-Tang Chen, Geoffrey B. Crew, Dan Bintley, Alan Roy, Keiichi Asada, Johnson Han, Kuan-Yu Liu, Chin-Shin Chang et al.

We report the first very long baseline interferometry (VLBI) experiment conducted in the 690 GHz atmospheric window. On 2024 November 21, observations with the Atacama Large Millimeter/submillimeter Array, the Atacama Pathfinder EXperiment (APEX), and the James Clerk Maxwell Telescope (JCMT) were carried out using ALMA's newly developed Band 9 phasing capability. Fringes were detected on the ALMA-APEX baseline during a scan of the quasar J0423-0120, with a signal-to-noise ratio of ~12 and useful…

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astro-ph.GAastro-ph.SR

A Theoretical Study of the Stellar Parameters and Surface Nucleosynthesis of the Extremely Metal-Poor RGB Giant BD$-18^{\circ}$5550 - Part I: Effects of $α$-enhancement and Internal Mixing

Mrinmay Medhi, Upakul Mahanta, Swapnajyoti Sarma, Apurba Talukdar

We present a detailed stellar evolution study of BD$-18^{\circ}$5550, an extremely metal-poor red giant star in the Galactic halo. Such stars are among the oldest known objects and preserve chemical signatures of the earliest stages of Galactic history. BD$-18^{\circ}$5550 exhibits $α$-enhancement, $\rm[α/Fe]=+0.4$, typical of Population II halo stars, with enhanced abundances of oxygen, magnesium, and other $α$-elements relative to iron. Using the \texttt{MESA} stellar evolution code, we perfor…

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astro-ph.SR

Studies of Two Post Common Envelope Binary Stars

Chris Koen, Alexei Kniazev

New time series photometry of the short period ($P<0.2$~d) binary stars ZTF~J032906.36+070408.3 (ZTF~0329) and ATO~J090.7238+00.5996 (ATL~0602) is presented. The primary (hotter) stars in both systems are white dwarfs, while the cooler stars are M dwarfs. Archival photometry and new and archival spectra are used to derive the temperatures of the components in the two binaries. Both are single-lined binaries. Velocity curves are fitted to radial velocity measurements of the red dwarfs and used to…

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physics.ins-detastro-ph.IMhep-ex

Operation of a negative ion gas time projection chamber without electronegative fill gases

Lachlan J. McKie, Lindsey J. Bignell, Nicholas Adams, Victoria U. Bashu, Ferdos Dastgiri, Gregory J. Lane

The high fidelity reconstruction of particle tracks in micropatterned gaseous time projection chambers renders this technology ideal for future rare-event searches, including direction-sensitive dark matter experiments. Large drift distances are typically required for such experiments, so that the overall spatial resolution is limited by diffusion. Negative ion drift exhibits lower diffusion than electron drift and is thus an attractive option for realising a large-scale detector. The use of ele…

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astro-ph.SRphysics.atom-phphysics.comp-ph

Validity of the CRD limit for modeling scattering polarization in the photospheric Sr I 4607 Å line

Simone Riva, Gioele Janett, Franziska Zeuner, Luca Belluzzi, Fabio Riva, Pietro Benedusi

Context. Scattering polarization in the Sr I 4607 Å line is a key diagnostic for small-scale, unresolved magnetic fields in the quiet solar photosphere, inaccessible to Zeeman-based techniques. The complete frequency redistribution (CRD) limit is commonly used to model this line, but its validity and impact on magnetic sensitivity have not been systematically investigated. This is timely given new facilities observing this line with unprecedented accuracy, and future synoptic programs targeting…

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gr-qcastro-ph.IM

Clock-noise propagation and calibration for phase-locking configurations in space-based gravitational-wave detectors

Pan-Pan Wang, Cheng-Gang Shao

In space-based gravitational-wave detectors, laser phase locking transfers the phase of weak received light to a local laser and maintains the interspacecraft heterodyne frequencies within the phasemeter bandwidth. Fluctuations of the onboard ultrastable oscillators introduce clock noise into these heterodyne phase measurements, requiring additional calibration in time-delay interferometry (TDI). Existing formulations based on six independently formed one-way measurements do not explicitly descr…

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