Please use this identifier to cite or link to this item: http://hdl.handle.net/2248/7710
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dc.contributor.authorSreehari, H-
dc.contributor.authorNandi, Anuj-
dc.contributor.authorDas, Santabrata-
dc.contributor.authorAgrawal, V. K-
dc.contributor.authorMandal, Samir-
dc.contributor.authorRamadevi, M. C-
dc.contributor.authorKatoch, Tilak-
dc.date.accessioned2021-06-25T13:32:12Z-
dc.date.available2021-06-25T13:32:12Z-
dc.date.issued2020-12-
dc.identifier.citationMonthly Notices of the Royal Astronomical Society, Vol. 499, No. 4, pp. 5891–5901en_US
dc.identifier.issn1365-2966-
dc.identifier.urihttp://hdl.handle.net/2248/7710-
dc.descriptionRestricted Accessen_US
dc.description.abstractWe report the results of AstroSat observations of GRS 1915+105 obtained using 100 ks Guaranteed Time during the soft state. The colour–colour diagram indicates a variability class of δ with the detection of high-frequency quasi-periodic oscillation (HFQPO) in the power density spectra. The HFQPO is seen to vary in the frequency range of 67.96–70.62 Hz with percentage rms ∼0.83–1.90 per cent and significance varying from 1.63 to 7.75. The energy dependent power spectra show that the HFQPO features are dominant only in 6–25 keV energy band. The broad-band energy spectra (0.7–50 keV) of Soft X-ray Telescope and Large Area X-ray Proportional Counter modelled with nthComp and powerlaw imply that the source has an extended corona in addition to a compact ‘Comptonizing corona’ that produces high-energy emission and exhibits HFQPOs. The broad-band spectral modelling indicates that the source spectra are well described by thermal Comptonization with electron temperature (kTe) of 2.07–2.43 keV and photon index (Γnth) between 1.73 and 2.45 with an additional powerlaw component of photon index (ΓPL) between 2.94 and 3.28. The norm of nthComp component is high (∼8) during the presence of strong HFQPO and low (∼3) during the absence of HFQPO. Further, we model the energy spectra with the kerrbb model to estimate the accretion rate, mass, and spin of the source. Our findings indicate that the source accretes at super-Eddington rate of 1.17−1.31 M˙Edd⁠. Moreover, we find the mass and spin of the source as 12.44–13.09 M⊙ and 0.990–0.997 with 90 per cent confidence suggesting that GRS 1915+105 is a maximally rotating stellar mass X-ray binary black hole source.en_US
dc.language.isoenen_US
dc.publisherOxford University Press on behalf of the Royal Astronomical Societyen_US
dc.relation.urihttps://doi.org/10.1093/mnras/staa3135-
dc.rights© Royal Astronomical Society-
dc.subjectAccretionen_US
dc.subjectAccretion discsen_US
dc.subjectBlack hole physicsen_US
dc.subjectX-rays: binariesen_US
dc.titleAstroSat view of GRS 1915+105 during the soft state: detection of HFQPOs and estimation of mass and spinen_US
dc.typeArticleen_US
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