The Ultraviolet-Optical-Infrared Energy Distribution of LMC X-3: Observation of an Accretion Disk around a Black Hole
Maraschi, L.; Tanzi, E. G.; Chiappetti, L.; Bouchet, P.; Belloni, T.; Falomo, R.; Treves, A.
Italy, Chile
Abstract
LMC X-3 was observed quasi-simultaneously at UV (IUE), optical, and IR (ESO, La Silla) frequencies in 1987 January. The overall energy distribution exhibits a broad peak around 10^15^ Hz. The UV flux appears well in excess of that measured by us in 1986 March, which can be attributed to the noncollapsed star in the system. The excess emission can be interpreted in terms of an accretion disk surrounding the collapsed component. A good spectral fit to the excess is obtained with a blackbody distribution with T ~ 14,000 K and a projected area A cos i ~ 3.7 x 10^23^ cm^2^. Supposing that the disk radius equals the Roche lobe of the compact object, an inclination i ~ 55^deg^ is found. The results are discussed within the model of the system.