USA Observation of Spectral and Timing Evolution During the 2000 Outburst of XTE J1550-564

Abstract

We report on timing and spectral observations of the 2000 outburst of XTE J1550-564 made by the Unconventional Stellar Aspect (USA) Experiment on board the Advanced Research and Global Observation Satellite (ARGOS). We observe a low-frequency quasi-periodic oscillation (LFQPO) with a centroid frequency that tends to increase with increasing flux and a fractional rms amplitude which is correlated with the hardness ratio. The evolution of the hardness ratio (4--16 keV/1--4 keV) with time and source flux is examined. The hardness-intensity diagram (HID) shows a cyclical movement in the clockwise direction and possibly indicates the presence of two independent accretion flows. We observe a relationship between the USA 4--16 keV count rate and radio observations and discuss this in the context of previously observed correlations between X-ray, radio, optical and IR data. We examine our results in the context of models invoking two accretion flows: a thin disk and a hot sub-Keplerian flow.

11 pages, 2 figures

References in corpus (4)

• A Black Hole in the Superluminal source SAX J1819.3-2525 (V4641 Sgr)
• X-ray states and radio emission in the black hole candidate XTE J1550-564
• A Transition to the Soft State in GRS 1758-258
• Multiwavelength Observations of the Black Hole Candidate XTE J1550-564 during the 2000 Outburst

Cited by in corpus (6)

• Evidence for a compact jet dominating the broadband spectrum of the black hole accretor XTE J1550-564
• Spectral evolution of the microquasar XTE J1550-564 over its entire 2000 outburst
• "Soft X-ray transient" outbursts which aren't soft
• Accretion flow behaviour during the evolution of the Quasi Periodic Oscillation Frequency of XTE J1550-564 in 1998 outburst
• An X-ray Timing Study of XTE J1550--564: Evolution of the Low Frequency QPO for the Complete 2000 Outburst
• Quasi-periodic Oscillations in XTE J1550-564: The rms-flux relation