arXiv subjects

R. Seeburger

Publications and source records attributed to R. Seeburger.

3 recordsLinked to original sources

arXiv2026

Multiplicity of Massive Stars at Low Metallicity: Early Results from the BLOeM Campaign

Massive stars at low metallicity (Z) play a central role in shaping the high-redshift Universe, yet their multiplicity remains poorly constrained. The Binarity at Low Metallicity (BLOeM) campaign is a two-year survey of 929 stars in the Small Magellanic Cloud with the Fibre Large Array Multi Element Spectrograph (FLAMES) instrument at ESO's Very Large Telescope, providing the first large-scale spectroscopic monitoring of massive stars at low Z (1/5 solar). Analysis of the initial nine epochs reveals high intrinsic binary fractions (>70%) on the main sequence and a steep decline in evolved objects. Analysis of the full dataset will yield orbital solutions, identify black-hole companions, and allow a derivation of the initial mass function for single and binary stars at low Z.

physics.gen-ph↗

arXiv2024

What excites the optical emission in X-ray-selected galaxies?

We present a study of $1347$ galaxies at $z<0.35$ with detected nuclear X-ray emission and optical emission line diagnostics in the Baldwin-Phillips-Terlevich (BPT) diagram. This sample was obtained by cross-matching the X-ray Multi-Mirror Mission Observatory - Newton (XMM-Newton) DR10 catalogue with Sloan Digital Sky Survey (SDSS) DR17 galaxies with well-measured line ratios. The distribution of these sources in the BPT diagram covers all three excitation regimes: Ionized Hydrogen (HII) regions (23\%), `composites' (30\%), and Seyfert galaxies with the low ionization nuclear emission line regions (LINERs) (47\%). In contrast, the fraction of objects classified as active galactic nuclei (AGN) in the SDSS subsample selected for cross-match with XMM-Newton is only 13\%. This fact illustrates that X-ray emission from galaxies commonly points towards the presence of AGN. Our data show, for the first time, a clear dependence of the BPT position on the ratio of the X-ray to $H\alpha$ fluxes. Sources dominated by X-ray emission lie in the Seyfert and LINER regimes of the BPT diagram. Most sources with a low X-ray-to-$H\alpha$-luminosity ratio, $log_{10}(L_X/L_{H\alpha}) < 1.0$, lie in the HII regime. In our sample, there are even 45 galaxies that have $L^{Star}_{XR}/L^{Total}_{Xray}>0.5$. In contrast, the positions of the sample members in the BPT diagram exhibit {no} dependence on the X-ray hardness ratio. Our finding suggests that the X-ray-to-$H\alpha$ ratio can help us to differentiate galaxies whose X-ray flux is dominated by an AGN {from galaxies with} central X-ray binaries and other stellar X-ray sources.

astro-ph.GA↗

arXiv2022

X-ray galaxies selected from HyperLEDA database

We cross-matched the 4XMM-DR10 catalog with the HyperLEDA database and obtained the new sample of galaxies that contain X-ray sources. Excluding duplicate observations and false matches, we present a total of 7759 galaxies with X-ray sources. In the current work, we present general properties of the sample: namely the distribution in equatorial coordinates, radial velocity distribution, morphological type, and X-ray fluxes. The sample includes morphological classification for 5241 galaxies with X-ray emission, almost half of which, 42\%, are elliptical (E, E-S0). Most galaxies in the sample have nuclear X-ray emission (6313 or 81\%), and the remaining 1443 (19\%) present X-ray emission from the host galaxy. This sample can be used for future deep studies of multi wavelengths properties of the galaxies with X-ray emission.

astro-ph.GA↗