THE VARIABLE QUIESCENT X-RAY EMISSION OF THE TRANSIENT NEUTRON STAR XTE J1701-462

Journal Article · Mon Aug 01 04:00:00 EDT 2011 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/736/2/162· OSTI ID:21578201

Fridriksson, Joel K ^[1]; Homan, Jeroen ^[2]; Wijnands, Rudy; Altamirano, Diego; Degenaar, Nathalie ^[3]; Cackett, Edward M ^[4]; Brown, Edward F ^[5]; Mendez, Mariano ^[6]

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1. Department of Physics, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States)
2. MIT Kavli Institute for Astrophysics and Space Research, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States)
3. Astronomical Institute 'Anton Pannekoek', University of Amsterdam, Science Park 904, 1098 XH Amsterdam (Netherlands)
4. Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom)
5. Department of Physics and Astronomy, Michigan State University, 3250 Biomedical and Physical Sciences Building, East Lansing, MI 48824 (United States)
6. Kapteyn Astronomical Institute, University of Groningen, P.O. Box 800, 9700 AV Groningen (Netherlands)

We present the results of continued monitoring of the quiescent neutron star low-mass X-ray binary XTE J1701-462 with Chandra and Swift. A new Chandra observation from 2010 October extends our tracking of the neutron star surface temperature from {approx_equal}800 days to {approx_equal}1160 days since the end of an exceptionally luminous 19 month outburst. This observation indicates that the neutron star crust may still be slowly cooling toward thermal equilibrium with the core; another observation further into quiescence is needed to verify this. The shape of the overall cooling curve is consistent with that of a broken power law, although an exponential decay to a constant level cannot be excluded with the present data. To investigate possible low-level activity, we conducted a monitoring campaign of XTE J1701-462 with Swift during 2010 April-October. Short-term flares-presumably arising from episodic low-level accretion-were observed up to a luminosity of {approx}1 x 10{sup 35} erg s{sup -1}, {approx}20 times higher than the normal quiescent level. We conclude that flares of this magnitude are not likely to have significantly affected the equilibrium temperature of the neutron star and are probably not able to have a measurable impact on the cooling curve. However, it is possible that brighter and longer periods of low-level activity have had an appreciable effect on the equilibrium temperature.

• OSTI ID: 21578201
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 736; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ACCRETION DISKS
COOLING
ELECTROMAGNETIC RADIATION
EMISSION
EQUILIBRIUM
IONIZING RADIATIONS
MONITORING
NEUTRON STARS
RADIATIONS
STARS
THERMAL EQUILIBRIUM
TRANSIENTS
X RADIATION