X-ray Nova XTE J1550-564: RXTE Spectral Observations
Abstract
Excellent coverage of the 1998 outburst of the X-ray Nova XTE J1550-564 was provided by the Rossi X-ray Timing Explorer. XTE J1550-564 exhibited an intense (6.8 Crab) flare on 1998 September 19 (UT), making it the brightest new X-ray nova observed with RXTE. We present a spectral analysis utilizing over 100 Proportional Counter Array spectra from 2.5-20 keV spanning more than 150 days, and a nearly continuous All Sky Monitor light curve. The spectra were fit to a model including multicolor blackbody disk and power-law components. XTE J1550-564 is observed in the very high, high/soft, and intermediate canonical outburst states of black hole X-ray novae. We also present correlations between the variable, low frequency (2-13 Hz) QPOs and the spectral parameters for XTE J1550-564 and compare these to similar correlations for the microquasar GRO J1655-40. The correlations are generally in the opposite sense for the two sources except that both sources exhibit a linear increase in the QPO frequency as the disk flux increases. This correlation implies that the QPO frequency is governed by the mass accretion rate in the disk.
- Publication:
-
AAS/High Energy Astrophysics Division #4
- Pub Date:
- April 1999
- Bibcode:
- 1999HEAD....4.1509S