English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Zendy Plus

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Zendy Tools

Zendy Open

Excellent coverage of the entire 16-month 1996-97 outburst cycle of GROJ1655-40 was provided by RXTE. We present a full spectral analysis of thesedata, which includes 52 PCA spectra from 2.5-20 keV and HEXTE spectra above 20keV. We also include a nearly continuous ASM light curve with several intensitymeasurements per day. The data are interpreted in the context of the multicolorblackbody 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 sourceexhibits intense hard flares on time scales of hours to days which arecorrelated with changes in both the fitted temperature and radius of the inneraccretion disk. During the high/soft state, the spectrum is dominated by thesoft thermal emission from the accretion disk with spectral parameters thatsuggest approximately constant inner disk radius and temperature. We find thata tight relationship exists between the observed inner radius of the disk andthe flux in the power-law component. During intense hard flares, the inner diskradius is observed to decrease by as much as a factor of three on a time scaleof days. The apparent decrease of the inner disk radius observed during theflares may be due to the failure of the multicolor disk model caused by asteepening of the radial temperature profile in the disk coupled with increasedspectral hardening and not physical changes of the inner disk radius. Assumingthat our spectral model is valid during periods of weak power-law emission, ourmost likely value for the inner disk radius implies a* < 0.7. Such a low valuefor the black hole angular momentum is inconsistent with the relativistic framedragging and the `diskoseismic' models as interpretations for the 300 Hz X-rayQPO seen during some of these RXTE observations.Comment: 34 pages including 9 figures and 3 tables. Accepted for publication  in the Astrophysical Journal. Our interpretation of the data and the main  conclusions have been significantly revise

RXTESpectral Observations of the 1996–1997 Outburst of the Microquasar GRO J1655−40