The Low Quiescent X-Ray Luminosity of the Neutron Star Transient XTE J2123–058

• Published in: The Astrophysical journal 2004-08, Vol.610 (2), p.933-940
• Main Authors: Tomsick, John A, Gelino, Dawn M, Halpern, Jules P, Kaaret, Philip
• Format: Article
• Language: English
• Subjects: Astronomy; Binary and multiple stars; Earth, ocean, space; Exact sciences and technology; Late stages of stellar evolution (including black holes); Neutron stars; Stars; X-ray binaries
• ISSN: 0004-637X; 1538-4357
• DOI: 10.1086/421865

We report on the first X-ray observations of the neutron star soft X-ray transient (SXT) XTE J2123-058 in quiescence made by the Chandra X-Ray Observatory and BeppoSAX, as well as contemporaneous optical observations. In 2002, the Chandra spectrum of XTE J2123-058 is consistent with a power- law model or the combination of a blackbody plus a power law, but it is not well described by a pure blackbody. Using the interstellar value of N sub(H), the power-law fit gives gamma = 3.1[image] and indicates an 0.3-8 keV unabsorbed luminosity of 9[image] x 10 super(31)(d/8.5 kpc) super(2) ergs s super(-1) (90% confidence errors). Fits with models consisting of thermal plus power-law components indicate that the upper limit on the temperature of a 1.4 M sub(o), 10 km radius neutron star with a hydrogen atmosphere is kT sub(eff) < 66 eV, and the upper limit on the unabsorbed, bolometric luminosity is L sub([infinity]) < 1.4 x 10 super(32) ergs s super(-1), assuming d = 8.5 kpc. Of the neutron star SXTs that exhibit short ( ~70 yr.