Observations of black hole candidate GRS 1758-258 by the GRATIS balloon-borne telescope and other observatories.

摘要

The Gamma Ray Arcminute Telescope Imaging System (GRATIS) was flown from Alice Springs, Australia on October 17--18, 1995. The experiment consists of 35 individual one-dimensional coded-aperture telescopes with a field of view of 40 arcminutes in the imaging direction.; We review the basic design of GRATIS, concentrating on the electronics critical to data acquisition.; We survey the origins and types of background radiation that contaminate the data of GRATIS. We review previous work attempting to characterize the atmospheric gamma-ray background and combine the most dependable experimental results to model it. We calculate approximate magnitudes for all background components, and give the results of Monte Carlo simulations of the cosmic diffuse and atmospheric components using the COG radiation transport package.; Finally, we combine GRATIS data with previously published and archival data from GRANAT, ROSAT, CGRO, RXTE, BeppoSAX, ASCA, and the VLA to produce a long-term multi-wavelength light curve of Galactic black hole candidate GRS 1758-258. In light of divergent analyses of the 1991--1993 ROSAT observations, we have re-analyzed these data; we find the soft x-rays track the hard x-rays, and that the fits require no black-body component---indicating that GRS 1758-258 did not go to the high state in 1993. We offer two standard corona-disk interpretations of the emission and an interpretation based on the ADAF model for a system with m˙ ≲ m˙crit. We find the 1990--1993 co-eval hard and soft observations support the ADAF predictions. We discuss a new way to constrain black-hole mass with spectral data and the ADAF theory, and apply this technique to GRS 1758-258 to find MBH ≳ 8--9 M⊙ at an assumed distance of 8.5 kpc.; Further investigations of the ADAF model allow us to critically evaluate the model against the data and flux-flux diagram of Barret, McClintock, & Grindlay (1996) and to understand the limits of the latter's "X-ray burster box."