Astronomy and Astrophysics – Astrophysics
Scientific paper
1998-09-15
Astronomy and Astrophysics
Astrophysics
34 pages including 9 figures and 3 tables. Accepted for publication in the Astrophysical Journal. Our interpretation of the da
Scientific paper
10.1086/307474
Excellent coverage of the entire 16-month 1996-97 outburst cycle of GRO J1655-40 was provided by RXTE. We present a full spectral analysis of these data, which includes 52 PCA spectra from 2.5-20 keV and HEXTE spectra above 20 keV. We also include a nearly continuous ASM light curve with several intensity measurements per day. The data are interpreted in the context of the multicolor blackbody disk/power-law model. The source is observed in the very high, high/soft, and low/hard outburst states. During the very high state, the source exhibits intense hard flares on time scales of hours to days which are correlated with changes in both the fitted temperature and radius of the inner accretion disk. During the high/soft state, the spectrum is dominated by the soft thermal emission from the accretion disk with spectral parameters that suggest approximately constant inner disk radius and temperature. We find that a tight relationship exists between the observed inner radius of the disk and the flux in the power-law component. During intense hard flares, the inner disk radius is observed to decrease by as much as a factor of three on a time scale of days. The apparent decrease of the inner disk radius observed during the flares may be due to the failure of the multicolor disk model caused by a steepening of the radial temperature profile in the disk coupled with increased spectral hardening and not physical changes of the inner disk radius. Assuming that our spectral model is valid during periods of weak power-law emission, our most likely value for the inner disk radius implies a* < 0.7. Such a low value for the black hole angular momentum is inconsistent with the relativistic frame dragging and the `diskoseismic' models as interpretations for the 300 Hz X-ray QPO seen during some of these RXTE observations.
Bailyn Charles D.
McClintock Jeffrey E.
Orosz Jerome A.
Remillard Ronald A.
Sobczak Gregory John
No associations
LandOfFree
RXTE Spectral Observations of the 1996-97 Outburst of the Microquasar GRO J1655-40 does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with RXTE Spectral Observations of the 1996-97 Outburst of the Microquasar GRO J1655-40, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and RXTE Spectral Observations of the 1996-97 Outburst of the Microquasar GRO J1655-40 will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-260262