| Name: Bharathi PK |
| Affiliation: Central University of South Bihar |
| Conference ID: ASI2026_326 |
| Title: A Comprehensive Study of Thermonuclear X-ray Bursts from Neutron Stars with AstroSat: Probing the Underlying Physics |
| Abstract Type: Poster |
| Abstract Category: High Energy Phenomena, Fundamental Physics and Astronomy |
| Author(s) and Co-Author(s) with Affiliation: Bharathi PK(Central University of South Bihar, Gaya - 824236, India), Aromal P(Indian Institute of Technology Indore, Indore - 453552, India), Manoneeta Chakraborty(Indian Institute of Technology Indore, Indore - 453552, India) |
| Abstract: Type-I thermonuclear X-ray bursts are observed from neutron star low-mass X-ray binary (NS-LMXB) systems due to unstable ignition of accreted matter on the stellar surface. These events offer an excellent opportunity to investigate physics under extreme conditions of strong gravity and ultradense matter. This study presents a comprehensive investigation of X-ray bursts observed from the NS-LMXBs using the Large Area X-ray Proportional Counter (LAXPC) instrument onboard the Indian multi-wavelength mission AstroSat. We developed a dedicated pipeline for burst search in the light curve, which has resulted in the detection of 63 bursts from 37 different sources to date. We further conduct a profile modelling of the bursts, particularly focusing on the burst decay behavior, and compare the decay characteristics across a variety of bursts from different sources. In many cases, the decay profile deviated from the canonical exponential behavior, and such characteristics can offer insight into the thermodynamic conditions on the surface of the neutron star as the hotspot created during thermonuclear fusion cools. Furthermore, we performed time-resolved spectroscopy of the detected bursts, which led to the identification of several interesting features, including photospheric radius expansion and peculiarly shaped, peaked bursts. Particularly, we detected several cases where peaked features were present during the decay part of the light curve. Our analysis correlates the occurrence of these peaked features with the corresponding hotspot temperature and radius characteristics to probe the origin mechanism of these features. Moreover, we connect the temperature and radius evolution of the hotspot with the thermodynamic conditions indicated by the decay profile analysis. We further estimate the ignition latitude and examine its influence on the burst properties. Such a comprehensive study using bursts detected by AstroSat will shed light on the thermonuclear ignition conditions, accretion rate dependence, flame propagation and hotspot evolution associated with the type-I bursts. |
