HEAD 2000, November 2000
Session 31. Galactic Black Holes
Display, Thursday, November 9, 2000, 8:00am-6:00pm, Bora Bora Ballroom

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[31.08] Shot Noise in USA lightcurves of Black Hole Transient XTE~J1118+480

W.B. Focke (Stanford Linear Accelerator Center, Stanford University), J. Scargle (NASA/ Ames Research Center), E. Bloom, B. Giebels, G. Godfrey, K.T. Reilly, P. Saz Parkinson, G. Shabad (Stanford Linear Accelerator Center, Stanford University), K.S. Wood, P.S. Ray, R.M. Bandyopadhyay, M.T. Wolff, G. Fritz, P. Hertz, M.P. Kowalski, M.N. Lovellette, D. Yentis (E. O. Hulburt Center for Space Research, Naval Research Laboratory), USA Experiment Science Working Group

We investigate the behavior of the new transient black hole candidate XTE~J1118+480 using shot noise models in the time domain.

Using light curves from the Unconventional Stellar Aspect experiment (USA) and RXTE, we model the emission as a superposition of shots. Individual structures in the light curve are fit to template functions. The results are compared to a similar analysis performed on light curves from Cygnus~X-1. In both sources, the preferred shape is one with an exponential rise and decay (not necessarily symmetric.) Preliminary results indicate that the characteristic timescale for XTE~J1118+480 is around 10 times as long as for Cygnus~X-1. Templates are fit both to large, isolated events using light curves integrated into constant-width time bins and to overlapping events using Bayesian blocks.

This work was supported by Department of Energy contract DE-AC03-768SF00515, the Office of Naval research, and the NASA Applied Information Systems Research Program.

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