Previous abstract Next abstract
We have collected data from published literature of the past two decades as well as from the public archives of the Vela-5 X-ray all-sky-monitor experiment with the goal of conducting a comprehensive study of the long-term x-ray and optical light curves of X-ray novae. X-ray novae are a subclass of the low-mass X-ray binaries that spend the vast majority of their lifetimes in a quiescent state during which they are extremely faint or undetectable. The outbursts in x-rays and optical occasionally observed from these systems are widely believed to be due to episodic accretion events onto the compact primary, at widely varying recurrence intervals. The quiescent systems allow for dynamical studies of far greater detail than is generally possible for steady LMXBs, and a large fraction of x-ray nova systems are known to contain black holes. During outburst the observed soft x-ray flux traces the accretion rate through the inner edge of the accretion disk while the optical flux reflects the physical conditions at the outer edge of the disk in its high state. The x-ray/optical light curves thus contain important information on the time dependent behavior of the accretion disk during the outburst and decay phases. We describe our efforts to carry out for the first time a systematic, statistical study of x-ray nova light curves. Our study includes recent events as documented by Ginga, GRO and GRANAT. We will attempt to classify the light curves according to properties, such as rise and decay time profiles, plateaus and secondary maxima. We then consider possible correlations between these light- curve characteristics and other system parameters, such as the binary period, the companion mass, brightness during quiescence, and the nature of the compact object. Results of this study have the potential providing the necessary empirical ingredients for subsequent detailed theoretical modelling efforts.
Thursday program listing