X-ray properties of the microquasar GRS 1915+105 during a variability class transition

Abstract

We present a detailed X-ray study of the microquasar GRS 1915+105 during a variability class transition observed in 2000 June with the PPCs of the Indian X-ray Astronomy Experiment. We supplement this observation with data from the RXTE archives. The source made a transition from a steady low-hard state to a regular oscillatory behaviour in the light curve known as bursts or class `rho' (Belloni et al. 2000) between 2000 May 11 and 17 and reverted back to the low-hard state on 2000 June 27. A gradual change in the burst recurrence time from about 75 s to about 40 s was observed which then increased to about 120 s during the ~ 40 days of class `rho'. The regular bursts disappeared from the X-ray light curves and the class transition was observed to occur within 1.5 hours on 2000 June 27 with the PPCs. A correlation is found between the observed QPO frequency at 5-8 Hz in the quiescent phase and the average X-ray intensity of the source during the class `rho'. We notice a strong similarity between the properties of the source during the class `rho' and those during the oscillatory phase of the observations of class `alpha'. From the timing and spectral analysis, it is found that the observed properties of the source over tens of days during the class `rho' are identical to those over a time scale of a few hundreds of seconds in the class `alpha'. Examining the light curves from the beginning of the RXTE/PCA and RXTE/ASM observations, it is found that the change of state from radio-quiet low-hard state to high state occurs through the X-ray classes `rho' and `alpha' which appear together during the state transition. It is further inferred that the source switches from low-hard state to the class `rho' through the intermediate class `alpha'.

10 pages with 9 figures, LaTex. To be appeared in MNRAS

Cited by in corpus (15)

• GRS 1915+105 and the Disc-Jet Coupling in Accreting Black Hole Systems
• Model for Relaxation Oscillations of Luminous Accretion Disk in GRS1915+105: Variable Inner Edge
• Time delays between the soft and hard X-ray bands in GRS 1915+105
• The peculiar 2011 outburst of the black hole candidate IGR J17091-3624, a GRS 1915+105 like source?
• The complex behaviour of the microquasar GRS 1915+105 in the rho class observed with BeppoSAX. I: Timing analysis
• Unraveling the foretime of GRS 1915+105 using AstroSat observations: Wide-band spectral and temporal characteristics
• Class Transitions and Two Component Accretion Flow in GRS 1915+105
• Connection between accretion disk and superluminal radio jets and the role of radio plateau state in GRS 1915+105
• Fast Transition between High-soft and Low-soft States in GRS 1915+105: Evidence for a Critically Viscous Accretion Flow
• Comptonization efficiencies of the variability classes of GRS 1915+105
• Properties of unique hard X-ray dips observed from GRS 1915+105 and IGR J17091-3624 and their implications
• Interpreting the large amplitude X-ray variation of GRS 1915+105 and IGR J17091-3624 as modulations of an accretion disc
• A statistical analysis of the "heartbeat" behaviour of GRS 1915+105
• Evidence of variation of the accretion flow geometry in GRS 1915+105 from IXAE and RXTE data
• Light curve fingerprints: an automated approach to the extraction of X-ray variability patterns with feature aggregation -- an example application to GRS 1915+105