The Variable Quiescent X-Ray Emission of the Neutron Star Transient XTE J1701-462

Joel K. Fridriksson, J. Homan, R. Wijnands, E. M. Cackett, N. Degenaar, M. Mendez, D. Altamirano, E. F. Brown, T. M. Belloni, W. H. G. Lewin

Research output: Chapter in Book/Report/Conference proceedingConference contributionAcademic

Abstract

We have monitored the cooling of the neutron star in the transient low-mass X-ray binary XTE J1701-462 with Chandra and XMM-Newton since the source entered quiescence in 2007 after an exceptionally luminous 19-month outburst. A recent Chandra observation made almost 1200 days into quiescence indicates that the neutron star crust is likely still slowly cooling toward thermal equilibrium with the core. The current surface temperature is high compared to other quiescent neutron star transients, with an implied bolometric thermal flux of 5×1033 erg/s. The overall cooling curve seems to have followed a broken power-law shape as predicted by theoretical models, although the observed break is considerably earlier than what is expected from theory. After rapid cooling during the first 200 days of quiescence---strongly indicating a highly conductive neutron star crust---the source unexpectedly showed a large temporary increase in both thermal and non-thermal flux. Prompted by this we conducted a Swift monitoring program of the source during April-October 2010, with short observations taking place once every two weeks. During the program we detected short-term flares up to at least 1×1035 erg/s, a factor of 20 higher than the normal quiescent level. We compare this flaring---presumably arising from episodic low-level accretion---with the behavior observed from faint Galactic transients, and discuss whether flaring in XTE J1701-462 can significantly affect the cooling of the source and whether it can to some extent explain the high temperature of the neutron star core implied by our Chandra observations.
Original languageEnglish
Title of host publicationAmerican Astronomical Society Meeting Abstracts
Pages432.12
Volume43
Publication statusPublished - Jan-2011
EventAmerican Astronomical Society, AAS Meeting #217, #432.12 - Seattle, United States
Duration: 9-Jan-201113-Jan-2011

Conference

ConferenceAmerican Astronomical Society, AAS Meeting #217, #432.12
Country/TerritoryUnited States
CitySeattle
Period09/01/201113/01/2011

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