The Quiescent X-Ray Spectrum of the Neutron Star in Cen X-4 Observed with Chandra/ACIS-S

摘要: We report on spectral and intensity variability analysis from a Chandra/ACIS-S observation of the transient, type-I X-ray bursting low-mass binary Cen X-4. The quiescent spectrum during this is statistically identical to one observed previously with Beppo/SAX, close, but not identical, ASCA. best described as pure Hydrogen atmosphere thermal plus power-law component that dominates above 2 keV. best-fit radius neutron star r=12.9+/-2.6 (d/1.2 kpc) km if interstellar absorption fixed at value implied by optical reddening. Allowing be free parameter yields r=19+45-10 (90% confidence). surface inconsistent solar metallicity. find 3sigma upper-limit root-mean-square <18% (0.2-2.0 keV; 0.0001-1 Hz) observation. On other hand, 0.5-10.0 keV luminosity decreased 40+/-8% in 4.9 years between Asca Chandra observations. This can attributed component. Moreover, we limit variation temperature <10% over these years. stability emission area supports interpretation due hot core.