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Gamma ray observations of black hole candidates nova Ophiuchus 1993 and nova Velorum 1993

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Title: Gamma ray observations of black hole candidates nova Ophiuchus 1993 and nova Velorum 1993
Author: Moss, Michael Jamieson
Advisor: Haymes, Robert C.
Degree: Doctor of Philosophy thesis
Abstract: Results of spectral analysis and time series analysis of the transient source x-ray nova Velorum 1993 (GRS 1009-45) and x-ray nova Ophicuhus 1993 (GRS 1716-249) are presented. These data were accumulated using the OSSE (Oriented Scintillation Spectrometer Experiment) low-energy gamma ray telescope on the Compton Gamma Ray Observatory. Spectral observations of the two x-ray novae showed the presence of gamma ray emission to greater than 100 keV, which is thought to be a signature of a binary system with an accreting black hole. Observations of GRS 1009-45 shows that it was in a gamma-ray soft state during the one-day OSSE observation, which occurred during the exponential decay phase of the outburst. The spectrum of GRS 2716-249 acquired during the plateau stage of outburst indicated a hard state, while spectra acquired during the sawtooth outbursts suggest that a hard to soft transition occurs as the decay progresses. The 40-200 keV pre-outburst luminosity of GRS 1716-249 is shown to be two orders of magnitude less than that estimated during the plateau-stage observation. The only significant power density spectrum was that acquired for GRS 1716-249 during the plateau stage of outburst. It is consistent with the sum of two QPO peaks at 0.128 and 0.32 Hz and a red noise ($\nu\sp{-1}$) component. This power spectrum is consistent with other black hole candidate power spectra for which the source is in the low state. Power spectra for GRS 1009-45 and GRS 1716-249 during the peak of a sawtooth outburst are also presented. They are consistent with band-limited white noise. Corresponding autocorrelations are shown for all observations.
Citation: Moss, Michael Jamieson. (1997) "Gamma ray observations of black hole candidates nova Ophiuchus 1993 and nova Velorum 1993." Doctoral Thesis, Rice University. http://hdl.handle.net/1911/19190.
URI: http://hdl.handle.net/1911/19190
Date: 1997

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