Fast optical variability in Supergiant X-ray binaries

Fuente: arXiv
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Main Authors: Di Filippantonio, D., Reig, P., Fabregat, J.
Format: Preprint
Published: 2024
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author Di Filippantonio, D.
Reig, P.
Fabregat, J.
author_facet Di Filippantonio, D.
Reig, P.
Fabregat, J.
contents The main goal of this work is to investigate the fast photometric variability of the optical counterparts to supergiant X-ray binaries and to compare the general patterns of such variability with the Galactic population of other early-type stars. We analyzed a sample of 14 high-mass X-ray binaries with supergiant companions observed by the Transiting Exoplanet Survey Satellite (TESS) and 4 Be/X-ray binaries with persistent X-ray emission for comparison. All sources exhibit fast aperiodic light variations. The shape of the periodogram is well described by a red noise component at intermediate frequencies ($\sim 1-10$ d$^{-1}$). At lower frequencies the noise level flattens while at higher frequencies the periodogram is dominated by white noise. We find that the patterns of variability of the massive companions in supergiant X-ray binaries agree with that of single early-type evolved stars in terms of the general shape of the periodograms. However, they exhibit higher amplitude at low frequencies and lower characteristic frequencies than Be/X-ray binaries. Unlike Be/X-ray binaries, supergiant X-ray binaries exhibit a total lack of coherent signals at high frequencies. Most sources have been analyzed over multiple TESS sectors, spanning a duration of 4 years. We do not find any significant variation over time in the low-frequency variability characteristics. This study reveals that stochastic low-frequency variability is a very common, if not ubiquitous, feature intrinsic to supergiant optical companions in X-ray binaries.
format Preprint
id arxiv_https___arxiv_org_abs_2412_06457
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Fast optical variability in Supergiant X-ray binaries
Di Filippantonio, D.
Reig, P.
Fabregat, J.
Solar and Stellar Astrophysics
High Energy Astrophysical Phenomena
The main goal of this work is to investigate the fast photometric variability of the optical counterparts to supergiant X-ray binaries and to compare the general patterns of such variability with the Galactic population of other early-type stars. We analyzed a sample of 14 high-mass X-ray binaries with supergiant companions observed by the Transiting Exoplanet Survey Satellite (TESS) and 4 Be/X-ray binaries with persistent X-ray emission for comparison. All sources exhibit fast aperiodic light variations. The shape of the periodogram is well described by a red noise component at intermediate frequencies ($\sim 1-10$ d$^{-1}$). At lower frequencies the noise level flattens while at higher frequencies the periodogram is dominated by white noise. We find that the patterns of variability of the massive companions in supergiant X-ray binaries agree with that of single early-type evolved stars in terms of the general shape of the periodograms. However, they exhibit higher amplitude at low frequencies and lower characteristic frequencies than Be/X-ray binaries. Unlike Be/X-ray binaries, supergiant X-ray binaries exhibit a total lack of coherent signals at high frequencies. Most sources have been analyzed over multiple TESS sectors, spanning a duration of 4 years. We do not find any significant variation over time in the low-frequency variability characteristics. This study reveals that stochastic low-frequency variability is a very common, if not ubiquitous, feature intrinsic to supergiant optical companions in X-ray binaries.
title Fast optical variability in Supergiant X-ray binaries
topic Solar and Stellar Astrophysics
High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2412.06457