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S.W.J. Colgan (NASA/Ames Research Center), A.S. Cotera (University of Arizona, Steward Observatory), P.R. Maloney (Center for Astrophysics and Space Astronomy), D.J. Hollenbach (NASA/Ames Research Center)
ISO LWS and SWS observations of the ~solar mass black hole candidates 1E1740.7-2942 and GRS1758-258 are presented. For 1E1740.7-2942, it has been suggested that the luminosity is provided in whole or part by Bondi-Hoyle accretion from a surrounding black hole (Bally & Leventhal 1991, Nat, 353, 234). Maloney etal. (1997, ApJ 482, L41) have predicted that detectable far-infrared line emission from [OI] (63 microns), [CII] (158 microns), [SiII] (35 microns) and other lines will arise from black holes which are embedded in molecular clouds. No strong line emission associated with either 1E1740.7-2942 or GRS1758-258 was detected, implying either that 1) these sources are not embedded in dense molecular clouds, or 2) that their average X-ray luminosity over the past 100 years is significantly lower than its current value. The measured upper limits to the line fluxes are compared with the models of Maloney etal. to constrain the properties of the ISM in the vicinity of these X-ray sources.
Based on observations with ISO, an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, the Netherlands and the United Kingdom) and with the participation of ISAS and NASA.