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arXiv · 2103.06278

UV and X-ray observations of the neutron star LMXB EXO 0748-676 in its quiescent state

A. S. Parikh·N. Degenaar·J. V. Hernandez Santisteban·R. Wijnands·I. Psaradaki·E. Costantini·D. Modiano·J. M. Miller
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Abstract

The accretion behaviour in low-mass X-ray binaries (LMXBs) at low luminosities, especially at 3500 km/s), which could indicate that it results from an outflow such as a pulsar wind. By studying several epochs of X-ray and near-UV data obtained with XMM-Newton, we find no clear indication that the emission in the two wavebands is connected. Moreover, the luminosity ratio of Lx/Luv >100 is much higher than that observed from neutron star LMXBs that exhibit low-level accretion in quiescence. Taken together, this suggests that the UV and X-ray emission of EXO 0748-676 may have different origins, and that thermal emission from crust-cooling of the neutron star, rather than ongoing low-level accretion, may be dominating the observed quiescent X-ray flux evolution of this LMXB.

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A. S. Parikh, N. Degenaar, J. V. Hernandez Santisteban, R. Wijnands, I. Psaradaki, E. Costantini, D. Modiano, J. M. Miller. 2021-03-10. UV and X-ray observations of the neutron star LMXB EXO 0748-676 in its quiescent state. https://doi.org/10.1093/mnras/staa3734, 10.1093/mnras/stab188

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