| Name: Ramanshu P. Singh |
| Affiliation: Veer Bahadur Singh Purvanchal University |
| Conference ID: ASI2026_595 |
| Title: Broadband Spectral-Timing Evolution of GX 339-4 During Its 2023-2024 Outburst Using Multi-Mission Observations |
| Abstract Type: Oral |
| Abstract Category: High Energy Phenomena, Fundamental Physics and Astronomy |
| Author(s) and Co-Author(s) with Affiliation: Ramanshu P. Singh(Veer Bahadur Singh Purvanchal University, Jaunpur - 222003, India), Akash Garg(Inter-University Centre for Astronomy and Astrophysics (IUCAA), Pune - 411007, India), Ranjeev Misra(Inter-University Centre for Astronomy and Astrophysics (IUCAA), Pune - 411007, India) |
| Abstract: We present a broadband spectral–timing study of the black hole X-ray binary GX 339-4 during its 2023-2024 outburst using coordinated observations from AstroSat, NICER, NuSTAR, and INTEGRAL. The source evolution is investigated across the hard–intermediate, soft–intermediate, and soft spectral states. The near-peak soft–intermediate state benefits from simultaneous broadband coverage spanning 0.7–200 keV, enabling robust spectral constraints. The spectra are well described by a model consisting of thermal disk emission, thermal Comptonization, and relativistic reflection, expressed as const * TBabs * (thcomp * diskbb + relxillCp), with the inclusion of a low-energy absorption edge to account for residual calibration features in the soft X-ray band. The fits are statistically acceptable across all epochs.. Low frequency quasi-periodic oscillations (LFQPOs) are detected during the intermediate states, with centroid frequencies evolving alongside spectral parameters. The combined spectral-timing behaviour indicates systematic changes in the relative contributions of the accretion disk and corona during state transitions. While geometric parameters remain subject to model degeneracies, the broadband multi-mission coverage provides a coherent view of the accretion flow evolution throughout the outburst. |
