Time resolved spectroscopy of a GRS 1915+105 flare during its unusual low state using AstroSat

Abstract

Since its discovery in 1992, GRS 1915+105 has been among the brightest sources in the X-ray sky. However, in early 2018, it dimmed significantly and has stayed in this faint state ever since. We report on AstroSat and NuSTAR observation of GRS 1915+105 in its unusual low/hard state during 2019 May. We performed time-resolved spectroscopy of the X-ray flares observed in this state and found that the spectra can be fitted well using highly ionised absorption models. We further show that the spectra can also be fitted using a highly relativistic reflection dominated model, where for the lamp post geometry, the X-ray emitting source is always very close to the central black hole. For both interpretations, the flare can be attributed to a change in the intrinsic flux, rather than dramatic variation in the absorption or geometry. These reflection dominated spectra are very similar to the reflection dominated spectra reported for Active Galactic Nuclei in their low flux states.

arXiv comment12 pages, 11 figures, Accepted for publication in MNRAS

References in corpus (33)

• On the Absorption of X-rays in the Interstellar Medium
• X-ray Properties of Black-Hole Binaries
• The Nuclear Spectroscopic Telescope Array (NuSTAR) Mission
• Improved Reflection Models of Black-Hole Accretion Disks: Treating the Angular Distribution of X-rays
• The Spin of the Near-Extreme Kerr Black Hole GRS 1915+105
• A light bending model for the X-ray temporal and spectral properties of accreting black holes
• BlackCAT: A catalogue of stellar-mass black holes in X-ray transients
• The role of the reflection fraction in constraining black hole spin
• A catalogue of low-mass X-ray binaries in the Galaxy, LMC, and SMC (Fourth edition)
• WATCHDOG: A Comprehensive All-Sky Database of Galactic Black Hole X-ray Binaries
• A Parallax Distance to the Microquasar GRS 1915+105 and a Revised Estimate of its Black Hole Mass
• Calibration of the Large Area X-ray Proportional Counter (LAXPC) instrument on-board AstroSat
• On why the Iron K-shell absorption in AGN is not a signature of the local Warm/Hot Intergalactic Medium
• Transient Black Hole Binaries
• The iron line in MCG-6-30-15 from XMM-Newton: evidence for gravitational light-bending?
• X-ray reflection in the NLS1 1H 0707-495
• Spectral and temporal properties of Compton scattering by mildly relativistic thermal electrons
• The not-so-massive black hole in the microquasar GRS1915+105
• AstroSat/LAXPC reveals the high energy variability of GRS 1915+105 in the chi class
• X-ray reflection in the Seyfert galaxy 1H0419-577 revealing strong relativistic effects in the vicinity of a Kerr black hole
• Large Area X-ray Proportional Counter (LAXPC) in Orbit Performance : Calibration, background, analysis software
• The obscured X-ray binaries V404 Cyg, Cyg X-3, V4641 Sgr, and GRS 1915+105
• Iron-line and continuum flux variations in the RXTE spectra of the black-hole candidate XTE J1650-500
• An Obscured, Seyfert-2-like State of the Stellar-mass Black Hole GRS 1915+105 Caused by Failed Disk Winds
• Observations of a radio-bright, X-ray obscured GRS 1915+105
• A Long Look At MCG-5-23-16 With NuSTAR: I- Relativistic Reflection And Coronal Properties
• A NICER View of a Highly-Absorbed Flare in GRS 1915+105
• Evidence of Light-Bending Effects and its implication for spectral state transitions
• The Novel Obscured State of Stellar-mass Black Hole GRS 1915+105
• Multi-epoch X-ray spectral analysis of the narrow-line Seyfert 1 galaxy Mrk 478
• Insight-HXMT observations of a possible fast transition from jet to wind dominated state during a huge flare of GRS~1915+105
• A variable magnetic disc wind in the black hole X-ray binary GRS 1915+105?
• Correlated variability of the reflection fraction with the X-ray flux and spectral index for Mkn 478