Exploring the broadband spectral and timing characteristics of GRS 1915+105 with AstroSat and NICER observations

Fuente: arXiv
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Autores principales: Dhaka, Ruchika, Misra, Ranjeev, Yadav, JS, Jain, Pankaj
Formato: Preprint
Publicado: 2024
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author Dhaka, Ruchika
Misra, Ranjeev
Yadav, JS
Jain, Pankaj
author_facet Dhaka, Ruchika
Misra, Ranjeev
Yadav, JS
Jain, Pankaj
contents In this study, we undertake a spectral-timing analysis of the black hole X-ray binary source GRS 1915+105 using simultaneous observations carried out by AstroSat (LAXPC and SXT) and NICER in 2017. The source showed two flux levels (high and low), whose energy spectra can be described by the thermal comptonization of disk photons. The spectral parameters obtained by the joint fitting of SXT/LAXPC and NICER/LAXPC were consistent. The power density spectra from LAXPC and NICER revealed a broad, prominent feature at approximately 2 Hz. The energy dependence of the fractional R.M.S. and time lag of this feature cannot be explained by only variations of coronal spectral parameters. Instead, a model where the coronal heating rate varies first and induces a change in the disk temperature and inner radius can explain the variation. Our results underline the importance of simultaneous observations by AstroSat and NICER and highlight the need for more sophisticated models to explain the spectral-temporal behavior of black hole systems.
format Preprint
id arxiv_https___arxiv_org_abs_2408_02875
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Exploring the broadband spectral and timing characteristics of GRS 1915+105 with AstroSat and NICER observations
Dhaka, Ruchika
Misra, Ranjeev
Yadav, JS
Jain, Pankaj
High Energy Astrophysical Phenomena
In this study, we undertake a spectral-timing analysis of the black hole X-ray binary source GRS 1915+105 using simultaneous observations carried out by AstroSat (LAXPC and SXT) and NICER in 2017. The source showed two flux levels (high and low), whose energy spectra can be described by the thermal comptonization of disk photons. The spectral parameters obtained by the joint fitting of SXT/LAXPC and NICER/LAXPC were consistent. The power density spectra from LAXPC and NICER revealed a broad, prominent feature at approximately 2 Hz. The energy dependence of the fractional R.M.S. and time lag of this feature cannot be explained by only variations of coronal spectral parameters. Instead, a model where the coronal heating rate varies first and induces a change in the disk temperature and inner radius can explain the variation. Our results underline the importance of simultaneous observations by AstroSat and NICER and highlight the need for more sophisticated models to explain the spectral-temporal behavior of black hole systems.
title Exploring the broadband spectral and timing characteristics of GRS 1915+105 with AstroSat and NICER observations
topic High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2408.02875