Modeling the Energy-dependent Broadband Variability in the Black Hole Transient GX 339–4 Using AstroSat and NICER
We present a spectro-timing analysis of the black hole X-ray transient GX 339–4 using simultaneous observations from AstroSat and the Neutron Star Interior Composition Explorer (NICER) during the 2021 outburst period. The combined spectrum obtained from NICER, Large Area X-ray Proportional Counter a...
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IOP Publishing
2024-01-01
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| Series: | The Astrophysical Journal |
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| Online Access: | https://doi.org/10.3847/1538-4357/ad7d8b |
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| author | Hitesh Tanenia Akash Garg Ranjeev Misra Somasri Sen |
| author_facet | Hitesh Tanenia Akash Garg Ranjeev Misra Somasri Sen |
| author_sort | Hitesh Tanenia |
| collection | DOAJ |
| description | We present a spectro-timing analysis of the black hole X-ray transient GX 339–4 using simultaneous observations from AstroSat and the Neutron Star Interior Composition Explorer (NICER) during the 2021 outburst period. The combined spectrum obtained from NICER, Large Area X-ray Proportional Counter and SXT data is effectively described by a model comprising a thermal disk component, hard Comptonization component, and reflection component with an edge . Our analysis of the AstroSat and NICER spectra indicates the source to be in a low/hard state, with a photon index of ∼1.64. The power density spectra obtained from both AstroSat and NICER observations exhibit two prominent broad features at 0.22 Hz and 2.94 Hz. We generated energy-dependent time lag and fractional root mean square (frms) at both frequencies in a broad energy range of 0.5–30 keV and found the presence of hard lags along with a decrease in variability at higher energy levels. Additionally, we discovered that the correlated variations in accretion rate, inner disk radius, coronal heating rate, and the scattering fraction, along with a delay between them, can explain the observed frms and lag spectra for both features. |
| format | Article |
| id | doaj-art-b6e211f35a8b46d0bcda68a56e38132e |
| institution | OA Journals |
| issn | 1538-4357 |
| language | English |
| publishDate | 2024-01-01 |
| publisher | IOP Publishing |
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| series | The Astrophysical Journal |
| spelling | doaj-art-b6e211f35a8b46d0bcda68a56e38132e2025-08-20T02:17:59ZengIOP PublishingThe Astrophysical Journal1538-43572024-01-01975219010.3847/1538-4357/ad7d8bModeling the Energy-dependent Broadband Variability in the Black Hole Transient GX 339–4 Using AstroSat and NICERHitesh Tanenia0Akash Garg1https://orcid.org/0000-0002-7567-3475Ranjeev Misra2https://orcid.org/0000-0002-7609-2779Somasri Sen3Department of Physics , Jamia Millia Islamia, Jamia Nagar, New Delhi-110025, India ; tanenia.hitesh@gmail.comInter-University Centre for Astronomy and Astrophysics , Ganeshkhind, Pune-411007, IndiaInter-University Centre for Astronomy and Astrophysics , Ganeshkhind, Pune-411007, IndiaDepartment of Physics , Jamia Millia Islamia, Jamia Nagar, New Delhi-110025, India ; tanenia.hitesh@gmail.comWe present a spectro-timing analysis of the black hole X-ray transient GX 339–4 using simultaneous observations from AstroSat and the Neutron Star Interior Composition Explorer (NICER) during the 2021 outburst period. The combined spectrum obtained from NICER, Large Area X-ray Proportional Counter and SXT data is effectively described by a model comprising a thermal disk component, hard Comptonization component, and reflection component with an edge . Our analysis of the AstroSat and NICER spectra indicates the source to be in a low/hard state, with a photon index of ∼1.64. The power density spectra obtained from both AstroSat and NICER observations exhibit two prominent broad features at 0.22 Hz and 2.94 Hz. We generated energy-dependent time lag and fractional root mean square (frms) at both frequencies in a broad energy range of 0.5–30 keV and found the presence of hard lags along with a decrease in variability at higher energy levels. Additionally, we discovered that the correlated variations in accretion rate, inner disk radius, coronal heating rate, and the scattering fraction, along with a delay between them, can explain the observed frms and lag spectra for both features.https://doi.org/10.3847/1538-4357/ad7d8bAccretionBlack hole physicsHigh energy astrophysicsLow-mass x-ray binary starsStellar accretion disksX-ray astronomy |
| spellingShingle | Hitesh Tanenia Akash Garg Ranjeev Misra Somasri Sen Modeling the Energy-dependent Broadband Variability in the Black Hole Transient GX 339–4 Using AstroSat and NICER The Astrophysical Journal Accretion Black hole physics High energy astrophysics Low-mass x-ray binary stars Stellar accretion disks X-ray astronomy |
| title | Modeling the Energy-dependent Broadband Variability in the Black Hole Transient GX 339–4 Using AstroSat and NICER |
| title_full | Modeling the Energy-dependent Broadband Variability in the Black Hole Transient GX 339–4 Using AstroSat and NICER |
| title_fullStr | Modeling the Energy-dependent Broadband Variability in the Black Hole Transient GX 339–4 Using AstroSat and NICER |
| title_full_unstemmed | Modeling the Energy-dependent Broadband Variability in the Black Hole Transient GX 339–4 Using AstroSat and NICER |
| title_short | Modeling the Energy-dependent Broadband Variability in the Black Hole Transient GX 339–4 Using AstroSat and NICER |
| title_sort | modeling the energy dependent broadband variability in the black hole transient gx 339 4 using astrosat and nicer |
| topic | Accretion Black hole physics High energy astrophysics Low-mass x-ray binary stars Stellar accretion disks X-ray astronomy |
| url | https://doi.org/10.3847/1538-4357/ad7d8b |
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