Analysis of Thermonuclear X-ray bursts in 4U 1728-34 using AstroSat/LAXPC

We present the X-ray spectral and temporal analysis of neutron star low mass X-ray binary 4U 1728-34 observed by AstroSat/LAXPC.A total of 12 thermonuclear X-ray bursts were detected during the observational period, with significant variations in burst intensity and wait times, ranging from 6 minutes to 22.5 hours. The highest-intensity burst was observed in Data6. Energy-resolved burst profiles reveal that the bursts are detected up to the 24–27 keV energy band, with the burst decay time inversely related to the energy range. Analysis of the Color-Color Diagram (CCD) and Hardness-Intensity Diagram (HID) indicates that 4U 1728-34 underwent frequent transitions between hard and soft spectral states. Pre-burst spectral analysis shows variations in spectral states, with high electron temperatures kTe indicating hard states and low kTe indicating soft states. These transitions, consistent with findings from the Color-Color Diagram, reveal a dynamic shift in accretion properties. Comparisons of burst spectra show a decrease in electron temperature while photon indices remain consistent.