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R. E. Rutledge (Caltech), L. Bildsten (ITP/UCSB), E. F. Brown (U. Chicago), G. G. Pavlov (Penn State), V. E. Zavlin (MPE)
The theory of Deep Crustal Heating predicts a rock-bottom luminosity for transiently accreting neutron stars in quiescence (qNSs), set by by the temperature of the NS core which is heated by crustal reactions during outbursts. Chandra observations of two such objects -- Cen X-4 and Aql X-1 -- confirm previous work that qNSs emit such a luminosity. The H atmosphere spectra imply an emission area radius consistent with that of a neutron star; however, large systematic uncertainties in the NS distance (D) produce a large systematic uncertainty in the NS radius (r) since what is measured is the angular size (r/D). Future work will be directed toward discovery and spectroscopy of qNSs in globular clusters, whose distances are relatively precisely known. I will present observational results from the Chandra Summer 2000 observation of Cen X-4 and the Spring 2001 observation of Aql X-1. This work is funded by the NASA/Chandra Guest Observer Program.
The author(s) of this abstract have provided an email address for comments about the abstract: rutledge@srl.caltech.edu