Discovery of a New Flaring Class in GRS 1915+105 Using AstroSat

The highly variable black hole X-ray binary GRS 1915+105 has shown many flaring classes when the source oscillates between the high soft state (HS) and the hard intermediate state with a transition time of less than 10 s. The X-ray flux is anticorrelated with the hardness ratio (HR2) during these X-...

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Main Authors: Ruchika Dhaka, J. S. Yadav, Ranjeev Misra, Pankaj Jain
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:The Astrophysical Journal
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Online Access:https://doi.org/10.3847/1538-4357/adc381
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author Ruchika Dhaka
J. S. Yadav
Ranjeev Misra
Pankaj Jain
author_facet Ruchika Dhaka
J. S. Yadav
Ranjeev Misra
Pankaj Jain
author_sort Ruchika Dhaka
collection DOAJ
description The highly variable black hole X-ray binary GRS 1915+105 has shown many flaring classes when the source oscillates between the high soft state (HS) and the hard intermediate state with a transition time of less than 10 s. The X-ray flux is anticorrelated with the hardness ratio (HR2) during these X-ray flaring classes. We have analyzed Astrosat/Large Area X-ray Proportional Counter and Soft X-ray Telescope data and report here a new X-ray flaring class named η class when the source oscillates between two HS states (the power-law index is always greater than 4) with transition time around 50 s. The X-ray flux is correlated with the hardness ratio. This class is quasi-regular, and we have detected high-frequency quasiperiodic oscillations around 70 Hz during this new flaring class. The accretion rate changes by a factor of 3 over the burst cycle. We report here the results of our extensive study of spectral and timing characteristics of this new class.
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spelling doaj-art-bfc8f825bd5344b4ae9568edbb325b5c2025-08-20T01:47:37ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-01984211810.3847/1538-4357/adc381Discovery of a New Flaring Class in GRS 1915+105 Using AstroSatRuchika Dhaka0https://orcid.org/0000-0002-1404-8924J. S. Yadav1Ranjeev Misra2https://orcid.org/0000-0002-7609-2779Pankaj Jain3Department of Physics, IIT Kanpur , Kanpur, Uttar Pradesh 208016, IndiaTata Institute of Fundamental Research , Homi Bhabha Road, 400005, Mumbai, India; Space, Planetary & Astronomical Sciences & Engineering, IIT Kanpur , Kanpur, Uttar Pradesh 208016, IndiaInter-University Center for Astronomy and Astrophysics , Ganeshkhind, Pune 411007, IndiaSpace, Planetary & Astronomical Sciences & Engineering, IIT Kanpur , Kanpur, Uttar Pradesh 208016, IndiaThe highly variable black hole X-ray binary GRS 1915+105 has shown many flaring classes when the source oscillates between the high soft state (HS) and the hard intermediate state with a transition time of less than 10 s. The X-ray flux is anticorrelated with the hardness ratio (HR2) during these X-ray flaring classes. We have analyzed Astrosat/Large Area X-ray Proportional Counter and Soft X-ray Telescope data and report here a new X-ray flaring class named η class when the source oscillates between two HS states (the power-law index is always greater than 4) with transition time around 50 s. The X-ray flux is correlated with the hardness ratio. This class is quasi-regular, and we have detected high-frequency quasiperiodic oscillations around 70 Hz during this new flaring class. The accretion rate changes by a factor of 3 over the burst cycle. We report here the results of our extensive study of spectral and timing characteristics of this new class.https://doi.org/10.3847/1538-4357/adc381High energy astrophysicsBlack hole physicsX-ray observatoriesX-ray astronomy
spellingShingle Ruchika Dhaka
J. S. Yadav
Ranjeev Misra
Pankaj Jain
Discovery of a New Flaring Class in GRS 1915+105 Using AstroSat
The Astrophysical Journal
High energy astrophysics
Black hole physics
X-ray observatories
X-ray astronomy
title Discovery of a New Flaring Class in GRS 1915+105 Using AstroSat
title_full Discovery of a New Flaring Class in GRS 1915+105 Using AstroSat
title_fullStr Discovery of a New Flaring Class in GRS 1915+105 Using AstroSat
title_full_unstemmed Discovery of a New Flaring Class in GRS 1915+105 Using AstroSat
title_short Discovery of a New Flaring Class in GRS 1915+105 Using AstroSat
title_sort discovery of a new flaring class in grs 1915 105 using astrosat
topic High energy astrophysics
Black hole physics
X-ray observatories
X-ray astronomy
url https://doi.org/10.3847/1538-4357/adc381
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AT jsyadav discoveryofanewflaringclassingrs1915105usingastrosat
AT ranjeevmisra discoveryofanewflaringclassingrs1915105usingastrosat
AT pankajjain discoveryofanewflaringclassingrs1915105usingastrosat