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Please use this identifier to cite or link to this item: http://hdl.handle.net/2289/8700
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dc.contributor.authorGhosh, Tanuman-
dc.contributor.authorSethi, Shiv-
dc.contributor.authorDewangan, Gulab Chand-
dc.contributor.authorBachetti, Matteo-
dc.contributor.authorRana, Vikram-
dc.contributor.authorMisra, Ranjeev-
dc.date.accessioned2026-03-25T06:25:29Z-
dc.date.available2026-03-25T06:25:29Z-
dc.date.issued2026-03-16-
dc.identifier.citationThe Astrophysical Journal, 2026, Vol. 1000 (1), AR No. 105en_US
dc.identifier.issn1538-4357-
dc.identifier.urihttp://hdl.handle.net/2289/8700-
dc.descriptionOpen Accessen_US
dc.description.abstractThe origin of the large-amplitude, quasi-periodic X-ray flux variations in several classes of the Galactic microquasar GRS 1915+105 remains unresolved. We address this issue through flux-resolved, broadband (0.8–20 keV) spectral modeling and simultaneous covariance spectral analysis during two κ and two ω class observations using AstroSat/SXT and LAXPC. The lightcurves show strong, quasi-periodic oscillations involving rapid transitions between bright bursts and deep dips on timescales of a few tens of seconds. Flux-resolved spectroscopy indicates that high-flux intervals in both classes are dominated by a hot, optically thick accretion disk with steep Comptonized emission, whereas low-flux intervals correspond to a cooler or partially recessed disk and a harder coronal continuum. These transitions involve a systematic 1–2 keV drop in disk temperature and a pronounced hardening of the Comptonized component, with flux reductions of up to a factor of five. Using covariance spectra across 0.015–5 Hz, we show that the rapid coherent variability arises almost entirely from the disk, which exhibits strong energy-dependent variations, while the Comptonized component contributes minimally. The combined results suggest that radiation-pressure-driven structural changes in the disk, with a slower coronal response, produce the observed oscillations, consistent with cyclic disk evacuation and refilling in the κ and ω classes.en_US
dc.language.isoenen_US
dc.publisherThe Astrophysical Journalen_US
dc.relation.urihttps://doi.org/10.48550/arXiv.2511.10183en_US
dc.relation.urihttp://doi.org/10.3847/1538-4357/ae4343en_US
dc.rights© 2026. National Astronomical Observatories, CAS and IOP Publishing Ltden_US
dc.titleSynchrotron Radiation from NGC 470 HLX1—a Hidden Hyperluminous Accreting Neutron Star?en_US
dc.typeArticleen_US
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