The correlation timescale of the X-ray flux during the outbursts of soft X-ray transients

Abstract

Recent studies of black hole and neutron star low mass X-ray binaries (LMXBs) show a positive correlation between the X-ray flux at which the low/hard(LH)-to-high/soft(HS) state transition occurs and the peak flux of the following HS state. By analyzing the data from the All Sky Monitor (ASM) onboard the Rossi X-ray Timing Explorer (RXTE), we show that the HS state flux after the source reaches its HS flux peak still correlates with the transition flux during soft X-ray transient (SXT) outbursts. By studying large outbursts or flares of GX 339-4, Aql X-1 and 4U 1705-44, we have found that the correlation holds up to 250, 40, and 50 d after the LH-to-HS state transition, respectively. These time scales correspond to the viscous time scale in a standard accretion disk around a stellar mass black hole or a neutron star at a radius of ~104-5 Rg, indicating that the mass accretion rates in the accretion flow either correlate over a large range of radii at a given time or correlate over a long period of time at a given radius. If the accretion geometry is a two-flow geometry composed of a sub-Keplerian inflow or outflow and a disk flow in the LH state, the disk flow with a radius up to ~105 Rg would have contributed to the nearly instantaneous non-thermal radiation directly or indirectly, and therefore affects the time when the state transition occurs.

arXiv comment7 pages, 3 figures

References in corpus (18)

• Advection-Dominated Accretion and the Spectral States of Black Hole X-Ray Binaries: Application to Nova Muscae 1991
• Correlated X-ray Spectral and Timing Behavior of the Black Hole Candidate XTE J1550-564: A New Interpretation of Black Hole States
• Spectral Properties of Accretion Disks Around Galactic and Extragalactic Black Holes
• The evolution of the timing properties of the black-hole transient GX 339-4 during its 2002/2003 outburst
• A New Model for Black Hole Soft X-ray Transients in Quiescence
• Hysteresis in the Light Curves of Soft X-ray Transients
• Coronal outflow dominated accretion discs: a new possibility for low luminosity black holes?
• Multi-wavelength observations of the 2002 outburst of GX 339-4: two patterns of X-ray-optical/near-infrared behavior
• Two Different Long-term Behaviors in Black-Hole Candidates: Evidence for Two Accretion Flows?
• A Possible Explanation for the "Parallel Tracks" Phenomenon in Low-Mass X-Ray Binaries
• State Transitions in Bright Galactic X-ray Binaries: Luminosities Span by Two Orders of Magnitude
• Correlation between Hard X-ray Peak Flux and Soft X-ray Peak Flux in the Outburst Rise of Low Mass X-ray Binaries
• Mass transfer during low mass X-ray transient decays
• Long-Term X-ray Monitoring of 1E 1740.7-2942 and GRS 1758-258
• INTEGRAL and RXTE monitoring of GRS 1758-258 in 2003 and 2004. A transition from the dim soft state to the hard state
• Peak Luminosities of the Hard States of GX 339-4: Implications for the Accretion Geometry, Disk Mass, and Black Hole Mass
• Hard X-ray Flares Preceding Soft X-ray Outbursts in Aquila X-1: A Link between Neutron Star and Black Hole State Transitions
• A Hard-to-Soft State Transition during A Luminosity Decline of Aquila X-1