RAPID COOLING OF THE NEUTRON STAR IN THE QUIESCENT SUPER-EDDINGTON TRANSIENT XTE J1701–462
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Author(s)
Homan, Jeroen
Wijnands, Rudy
Mendez, Mariano
Altamirano, Diego
Cackett, E. M.
Brown, Edward F.
Belloni, Tomaso M.
Degenaar, N.
Lewin, Walter H. G.
Fridriksson, Joel Karl
Date Issued
May 2010
Journal
Astrophysical Journal
Publisher
Institute of Physics/American Astronomical Society
Citation
Fridriksson, Joel K., Jeroen Homan, Rudy Wijnands, Mariano Méndez, Diego Altamirano, Edward M. Cackett, Edward F. Brown, Tomaso M. Belloni, Nathalie Degenaar, and Walter H. G. Lewin. “RAPID COOLING OF THE NEUTRON STAR IN THE QUIESCENT SUPER-EDDINGTON TRANSIENT XTE J1701–462.” The Astrophysical Journal 714, no. 1 (April 8, 2010): 270–286. © 2010 American Astronomical Society.
Version
Final published version
Abstract
We present Rossi X-Ray Timing Explorer and Swift observations made during the final three weeks of the 2006-2007 outburst of the super-Eddington neutron star (NS) transient XTE J1701-462, as well as Chandra and XMM-Newton observations covering the first sime800 days of the subsequent quiescent phase. The source transitioned quickly from active accretion to quiescence, with the luminosity dropping by over 3 orders of magnitude in sime13 days. The spectra obtained during quiescence exhibit both a thermal component, presumed to originate in emission from the NS surface, and a non-thermal component of uncertain origin, which has shown large and irregular variability. We interpret the observed decay of the inferred effective surface temperature of the NS in quiescence as the cooling of the NS crust after having been heated and brought out of thermal equilibrium with the core during the outburst. The interpretation of the data is complicated by an apparent temporary increase in temperature sime220 days into quiescence, possibly due to an additional spurt of accretion. We derive an exponential decay timescale of sime120[superscript +30][subscript –20] days for the inferred temperature (excluding observations affected by the temporary increase). This short timescale indicates a highly conductive NS crust. Further observations are needed to confirm whether the crust is still slowly cooling or has already reached thermal equilibrium with the core at a surface temperature of sime125 eV. The latter would imply a high equilibrium bolometric thermal luminosity of sime5 × 10[superscript 33]ergs[superscript –1] for an assumed distance of 8.8 kpc.
MIT Department
Massachusetts Institute of Technology. Department of Physics
MIT Kavli Institute for Astrophysics and Space Research
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DOI of Published Version
https://doi.org/10.1088/0004-637x/714/1/270
