arXiv subjects

Anish Kalsi

Publications and source records attributed to Anish Kalsi.

3 recordsLinked to original sources

arXiv2026

UX Men: Detached Eclipsing Binary as a Benchmark Candidate

We present ultra-precise fundamental parameters for the detached eclipsing binary UX Men based on 31 TESS sectors ($\sim$882 d) and radial velocities from HARPS, FEROS, CORALIE, and UCLES. The light curves were detrended for spot-induced variability and modelled independently with JKTEBOP and ALLESFITTER, while radial velocities were extracted via TODCOR and fitted with a Keplerian orbit. Spectral disentangling yielded individual component spectra analysed with iSpec to determine $T_{\rm eff}$ and $\mathrm{[M/H]}$. Multi-band photometry was used to determine the fluxes, flux ratios and ultimately to measure photometric $T_{\rm eff}$. We obtain the masses $M_{\rm A}$ = $1.2300 \pm{0.0012}$ M$_{\odot}$, $M_{\rm B}$ = $1.1946\pm{0.0012}$ M$_{\odot}$ and radii $R_{\rm A}$ = $1.3605\pm{0.0031}$ R$_{\odot}$, $R_{\rm B}$ = $1.2801\pm{0.0069}$ R$_{\odot}$ with sub-percent precision. Uncertainties were found to be dominated by systematic effects coming from (weak) stellar activity. $T_{\rm eff,A}$ = $6302\pm{77}$, $T_{\rm eff,B}$ = $6292\pm65$ \& Metallicity estimates are $[M/H]_{\rm A} = 0.02\pm{0.13}$ dex and $[M/H]_{\rm B}= 0.07\pm{0.10}$ dex. Isochrone fitting yields a consistent age of $\tau$ = $2.75\pm{0.13}$ Gyr. The system exhibits a $\sim$ 673-day periodicity in eclipse-timing variations, likely due to stellar activity, with no evidence for a third body. Results are independent of the modelling code used, but without proper treatment of activity-induced systematics the uncertainties would be underestimated. UX Men is a high-precision benchmark binary providing stringent tests of stellar models and a robust calibration source for PLATO. Expanding the sample of well-characterised detached eclipsing binaries will strengthen the empirical foundations for stellar physics and the calibration of future photometric missions

astro-ph.SR↗

arXiv2024

A catalogue of low-mass X-ray binaries in the Galaxy: from the INTEGRAL to the Gaia era

Low-mass X-ray binaries (LMXBs) are high-energy sources that require multi-wavelength follow up campaigns to be fully characterized. New transients associated to LMXBs are regularly discovered, and previously known systems are often revisited by astronomers to constrain their intrinsic parameters. All of this information compiled into a catalogue may build up to a useful tool for subsequent studies on LMXBs and their population. We provide an update on past LMXB catalogues dating back 16 years and propose to the community a database on Galactic LMXBs with the most complete manually curated set of parameters and their original references. On top of a fixed version accessible through Vizier, we propose to host the catalogue independently on our GitHub collaboration, side-by-side with our previous catalogue on high-mass X-ray binaries. The database will be regularly updated based on new publications and community inputs. We build a working base by cross-matching previous LMXB catalogues and supplementing them with lists of hard X-ray sources detected in the past 20 years. We compile information from Simbad on LMXBs as a starting point for a thorough, manual search in the literature to retrieve important parameters that characterize LMXBs. We retrieve newly detected LMXBs and candidates directly from literature searches. Counterparts to these LMXBs are compiled from hard X-rays to infrared and radio domains. Every piece of information presented on the LMXBs is curated and backed by accurate references. We present a catalogue of 339 Galactic LMXBs listing their coordinates, companion star spectral type, systemic radial velocity, component masses and compact object nature, the presence of type I X-ray bursts as well as orbital data. Coordinates and identifiers of counterparts at various wavelengths are given, including 140 LMXBs detected in {\it Gaia} DR3.

astro-ph.HE↗

arXiv2023

GRB Optical and X-ray Plateau Properties Classifier Using Unsupervised Machine Learning

The division of Gamma-ray bursts (GRBs) into different classes, other than the "short" and "long", has been an active field of research. We investigate whether GRBs can be classified based on a broader set of parameters, including prompt and plateau emission ones. Observational evidence suggests the existence of more GRB sub-classes, but results so far are either conflicting or not statistically significant. The novelty here is producing a machine-learning-based classification of GRBs using their observed X-rays and optical properties. We used two data samples: the first, composed of 203 GRBs, is from the Neil Gehrels Swift Observatory (Swift/XRT), and the latter, composed of 134 GRBs, is from the ground-based Telescopes and Swift/UVOT. Both samples possess the plateau emission (a flat part of the light curve happening after the prompt emission, the main GRB event). We have applied the Gaussian Mixture Model (GMM) to explore multiple parameter spaces and sub-class combinations to reveal if there is a match between the current observational sub-classes and the statistical classification. With these samples and the algorithm, we spot a few micro-trends in certain cases, but we cannot conclude that any clear trend exists in classifying GRBs. These microtrends could point towards a deeper understanding of the physical meaning of these classes (e.g., a different environment of the same progenitor or different progenitors). However, a larger sample and different algorithms could achieve such goals. Thus, this methodology can lead to deeper insights in the future.

astro-ph.HE↗