Chandra and Swift observations of the quasi-persistent neutron star transient EXO 0748-676 back to quiescence

Authors

N. Degenaar, Astronomical Institute "Anton Pannekoek," University of Amsterdam
R. Wijnands, Astronomical Institute "Anton Pannekoek," University of Amsterdam
M. T. Wolff, Naval Research Laboratory
P. S. Ray, Naval Research Laboratory
K. S. Wood, Naval Research Laboratory
J. Homan, MIT Kavli Institute for Astrophysics and Space Research
W. H. G. Lewin, MIT Kavli Institute for Astrophysics and Space Research
P. G. Jonker, SRON, Netherlands Institute for Space Research
E. M. Cackett, University of MichiganFollow
J. M. Miller, University of Michigan
E. F. Brown, Michigan State University

Document Type

Article

Abstract

The quasi-persistent neutron star X-ray transient and eclipsing binary EXO 0748-676 recently started the transition to quiescence following an accretion outburst that lasted more than 24 years. We report on two Chandra and 12 Swift observations performed within five months after the end of the outburst. The Chandra spectrum is composed of a soft, thermal component that fits to a neutron star atmosphere model with kT^∞ ~ 0.12keV, joined by a hard power-law tail that contributes ~20 per cent of the total 0.5-10 keV unabsorbed flux. The combined Chandra/Swift data set reveals a relatively hot and luminous quiescent system with a temperature of kT^∞ ~ 0.11-0.13keV and a bolometric thermal luminosity of ~8.1 × 10³³-1.6 × 10³⁴(d/7.4kpc)²ergs ^-1. We discuss our results in the context of cooling neutron star models.

Disciplines

Cosmology, Relativity, and Gravity | Stars, Interstellar Medium and the Galaxy

Comments

NOTICE IN COMPLIANCE WITH PUBLISHER POLICY: This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©2009 The Authors. Published by Oxford University Press on behalf of The Royal Astronomical Society. All rights reserved. Available at doi:10.1111/j.1745-3933.2009.00655.x

Recommended Citation

Degenaar, N., Wijnands, R., Wolff, M. T., Ray, P. S., Wood, K. S., Homan, J., Lewin, W. H. G., Jonker, P. G., Cackett, E. M., Miller, J. M., Brown, E. F. 2009. Chandra and Swift observations of the quasi-persistent neutron star transient EXO 0748-676 back to quiescence. MNRAS 396(1), L26-L30.