2005/02/23 by S. J. Sturner, C. R. Shrader
Physics and Astronomy · #Astrophysical Phenomena and Observations #Pulsars and Gravitational Waves Research #astro-ph
paper · pdf · doi:10.1086/429815
published as Astrophys.J. 625 (2005) 923-930 · 22 pages, 8 figures, to be published in The Astrophysical Journal
arxiv created 2005/02/23 · openalex publication_date 2005/05/27 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31
The well-known black hole X-ray binary transient XTE J1550-564 underwent an outburst during the spring of 2003, which was substantially underluminous in comparison to previous periods of peak activity in that source. In addition, our analysis shows that it apparently remained in the hard spectral state over the duration of that outburst. This is again in sharp contrast to major outbursts of that source in 1998/1999, during which it exhibited an irregular light curve, multiple state changes, and collimated outflows. This leads us to classify it as a "failed outburst." We present the results of our study of the spring 2003 event, including light curves based on observations from both INTEGRAL and RXTE . In addition, we studied the evolution of the high-energy 3-300 keV continuum spectrum using data obtained with three main instruments on INTEGRAL . These spectra are consistent with typical low-hard-state thermal Comptonization emission. We also consider the 2003 event in the context of a multisource, multievent period-peak luminosity diagram, in which it is a clear outlier. We then consider the possibility that the 2003 event was due to a discrete accretion event rather than limit-cycle instability. In that context, we apply model fitting to derive the timescale for viscous propagation in the disk and infer some physical characteristics.