XMM-Newton observations of the peculiar Be X-ray binary A0538-66

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Main Authors: Rigoselli, Michela, Tresoldi, Caterina, Ducci, Lorenzo, Mereghetti, Sandro
Format: Preprint
Published: 2024
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author Rigoselli, Michela
Tresoldi, Caterina
Ducci, Lorenzo
Mereghetti, Sandro
author_facet Rigoselli, Michela
Tresoldi, Caterina
Ducci, Lorenzo
Mereghetti, Sandro
contents A0538-66 is a neutron star/Be X-ray binary located in the Large Magellanic Cloud and, since its discovery in the seventies, it showed a peculiar behavior which makes it a unique object in the high-mass X-ray binaries scene: the extremely eccentric orbit (e=0.72), the short spin period of the neutron star (P=69 ms), the episodes of super-Eddington accretion. These characteristics contribute to a remarkable bursting activity that lasts from minutes to hours and increases the flux by a factor 10^3-10^4. In 2018, A0538-66 was observed by XMM-Newton in a particularly active state, characterized by a forest of short bursts lasting 0.7-50 seconds each. In this contribution we present a reanalysis of these observations. The timing analysis allowed us to distinguish between the epochs of direct accretion and propeller state, that do not correlate with the orbital position of the neutron star. The spectral analysis revealed that during the accretion regime three components (a soft one, a hard one, and a ~6.4-keV emission line) equally contribute to the overall emission, while the propeller regime is characterized by a single soft component. We discuss these findings in the context of spherical and disk accretion regimes, highlighting the similarities and the differences with other X-ray binary systems.
format Preprint
id arxiv_https___arxiv_org_abs_2410_18606
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle XMM-Newton observations of the peculiar Be X-ray binary A0538-66
Rigoselli, Michela
Tresoldi, Caterina
Ducci, Lorenzo
Mereghetti, Sandro
High Energy Astrophysical Phenomena
A0538-66 is a neutron star/Be X-ray binary located in the Large Magellanic Cloud and, since its discovery in the seventies, it showed a peculiar behavior which makes it a unique object in the high-mass X-ray binaries scene: the extremely eccentric orbit (e=0.72), the short spin period of the neutron star (P=69 ms), the episodes of super-Eddington accretion. These characteristics contribute to a remarkable bursting activity that lasts from minutes to hours and increases the flux by a factor 10^3-10^4. In 2018, A0538-66 was observed by XMM-Newton in a particularly active state, characterized by a forest of short bursts lasting 0.7-50 seconds each. In this contribution we present a reanalysis of these observations. The timing analysis allowed us to distinguish between the epochs of direct accretion and propeller state, that do not correlate with the orbital position of the neutron star. The spectral analysis revealed that during the accretion regime three components (a soft one, a hard one, and a ~6.4-keV emission line) equally contribute to the overall emission, while the propeller regime is characterized by a single soft component. We discuss these findings in the context of spherical and disk accretion regimes, highlighting the similarities and the differences with other X-ray binary systems.
title XMM-Newton observations of the peculiar Be X-ray binary A0538-66
topic High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2410.18606