| Name: Suraj Chaurasia |
| Affiliation: Banaras Hindu University |
| Conference ID: ASI2026_770 |
| Title: Long-Term AstroSat Spectral Study of Cygnus X-3 |
| Abstract Type: Poster |
| Abstract Category: High Energy Phenomena, Fundamental Physics and Astronomy |
| Author(s) and Co-Author(s) with Affiliation: Suraj Kumar Churasia(Banaras Hindu University, Varansi - 221005, India), Amit Pathak(Banaras Hindu University, Varansi - 221005, India), Ranjeev Misra(Inter-University Centre for Astronomy and Astrophysics, Pune -411007, India-) |
| Abstract: Recent X-ray polarimetric observations have revealed an unusually high polarization degree in the X-ray binary Cygnus X-3, indicating a reflection-dominated spectrum. Motivated by these findings, we present a long-term spectral study of Cygnus X-3 using AstroSat observations obtained between 2016 and 2019. We analyzed seven AstroSat observations using data from the LAXPC and SXT instruments, dividing the good time intervals into time resolved segments, resulting in a total of 57 spectra. Hardness–intensity diagrams constructed using the 3.0–10.0 keV and 10.0–30.0 keV bands were used to classify the source into soft, intermediate, and hard spectral states. All spectra were modeled using a uniform pure reflection framework in XSPEC, isolating the reflected emission component motivated by recent polarization results. We find that the pure reflection model provides statistically acceptable fits across all segments and spectral states. In the hard state, the spectra are dominated by Comptonized emission, characterized by high electron temperatures, low disk normalization, and a larger covering fraction. In contrast, the soft state is dominated by the thermal disk component, with the electron temperature decreasing to ~5 keV and a significantly reduced covering fraction. The inner disk temperature remains nearly constant across different spectral states. Additionally, we observe strong correlations between disk and Comptonization parameters, indicating a coupled disk–corona geometry. |
