| Name: | Anirudh Salgundi |
| Affiliation: | Indian Institute of Technology Bombay |
| Conference ID : | ASI2024_686 |
| Title : | Broadband spectral and timing analysis of slow burster 4U 1728-34 using AstroSat |
| Authors : | Anirudh Salgundi 1, Utkarsh Pathak 1, Suman Bala 1,2, Gayathri Raman 3, Varun Bhalerao 1 |
| Authors Affiliation: | 1 Department of Physics, IIT Bombay, Powai, Mumbai - 400076, India
2 Science and Technology Institute, Universities Space Research Association, Huntsville, AL 35805, USA
3 Department of Astronomy and Astrophysics, The Pennsylvania State University, 525 Davey Lab, University Park, PA 16802, USA |
| Mode of Presentation: | Poster |
| Abstract Category : | High Energy Phenomena, Fundamental Physics and Astronomy |
| Abstract : | In Neutron Star Low Mass X-ray Binary (NS-LMXB) systems, active accretion from the companion leads to accumulation of fuel (a mixture of Hydrogen and Helium) which undergoes hydrostatic compression with increased accretion. Eventually, ignition level is reached (timescales ~few hours to days) causing the entire fuel layer on the NS to burn rapidly, leading to type-I thermonuclear bursts (TNBs). During the burst, X-ray intensity rises by an order of magnitude within a few seconds, reaching peak luminosities of 10^39 ergs/s. The flux then exponentially decays at a slower rate (tens to hundreds of seconds). Time-resolved spectral analysis of TNBs can shed light on spin frequency and Photospheric Radius Expansion (PRE) mechanism, which in turn can provide strong upper limits on the radius of the NS, which is important for constraining the Equation of State (EoS). This work encompasses a comprehensive study on the "Slow Burster" (4U 1728-34) utilizing all the archival observations from LAXPC and SXT instruments onboard AstroSat. Time-resolved spectro-temporal analysis of 13 TNBs have been performed where the source was evolving between multiple spectral states. Energy resolved burst lightcurve and spectrum analysis shows presence of hard photons > 20 keV. We see evidence of PRE mechanisms in 6 of the bursts. Fast Fourier Transforms on persistent and burst lightcurves show evidence of Kilohertz QPO (~900 Hz) and Burst Oscillations ~363 Hz. We will present a detailed comparison of the continuums and bursts of the source, spanning over years of observation.
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