Study of timing evolution from non-variable to structured large-amplitude variability transition in GRS 1915+105 using AstroSat

Abstract

In this work, we present a $\sim$90 ks continuous monitoring of the Galactic micro-quasar GRS 1915+105 with AstroSat when the source undergoes a major transition from a non-variable, $\chi$ class (similar to radio-quiet $\chi$ class) to a structured, large amplitude, periodic heartbeat state (similar to $\rho$ class). We show that such transition takes place via an intermediate state when the large-amplitude, irregular variability of the order of hundreds of seconds in the soft X-ray band turned into a 100-150 sec regular, structured, nearly periodic flares. The properties of a strong low-frequency quasi-periodic oscillations (LF QPO) in the frequency range 3-5 Hz also evolve marginally during these variability transitions. We also study time-lag and rms spectra at the QPO and harmonic component and the dynamic power spectra. We note few important differences between the heartbeat state and the $\rho$ class. Interestingly, the time-averaged LF QPO properties in the hard X-ray band is relatively stable in three states when compared to the significant evolution observed in the slow variability properties at mHz frequencies. Such relative stability of LF QPOs implies the inner disk-corona coupled accretion flow which determines the LF QPO properties, may be uninterrupted by the launch of long, large-amplitude flares.

arXiv comment17 pages, 41 figures, Accepted for publication in ApJ

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Cited by in corpus (11)

• The comptonizing medium of the black-hole X-ray binary MAXI~J1535$-$571 through type-C quasi-periodic oscillations
• Identification of QPO frequency of GRS 1915+105 as the relativistic dynamic frequency of a truncated accretion disk
• Unraveling the foretime of GRS 1915+105 using AstroSat observations: Wide-band spectral and temporal characteristics
• Broadband Spectral and Timing Properties of MAXI J1348-630 using AstroSat and NICER Observations
• AstroSat view of the newly discovered X-ray transient MAXI~J1803--298 in the Hard-intermediate state
• AstroSat view of IGR J17091-3624 and GRS 1915+105: decoding the 'pulse' in the 'Heartbeat State'
• Identifying the radiative components responsible for Quasi-Periodic Oscillations of black hole systems
• Correlations between QPO frequencies and spectral parameters of GRS 1915+105 using AstroSat observations
• Time-resolved spectroscopy on the heartbeat state of GRS 1915+105 using AstroSat
• LAXPC instrument onboard AstroSat: Five exciting years of new scientific results specially on X-ray Binaries
• Probing heartbeat oscillations from the black hole X-ray binary GRS 1915+105 using spectral-timing analysis