Eclipse Dynamics and X-ray Burst Characteristics in the Low-Mass X-ray Binary EXO 0748-676

This study investigates the timing and spectral characteristics of X-ray bursts from the neutron star system EXO 0748-676 using the NuSTAR observatory’s FPMA and FPMB instruments in the 3-79 keV range. We identify Type I X-ray bursts driven by thermonuclear explosions on the neutron star’s surface, notably a significant burst at $X=18,479.97$, indicating rapid energy release, followed by a recoil burst at $X=19,463.97$, reflecting stabilization. The correlation between burst timing and the neutron star’s optical period suggests modulation by its rotation and periodic accretion dynamics. Spectral modeling reveals a photon index of $\mathrm{\Gamma }=1.24\pm 0.014$ and a cutoff energy of $E_C=36.20\pm 1.04\text{keV}$, indicating a hot corona around the neutron star. The measured flux of approximately $(381.17\pm 0.014)\times {10}^{-12}{\text{erg cm}}^{-2}{\text{s}}^{-1}$ underscores the dynamic nature of accretion-driven systems. Calculated luminosities derived from distance estimates range from $(3.86\pm 0.239)\times {10}^{36}\text{erg/s}$ to $(2.3\pm 0.177)\times {10}^{36}\text{erg/s}$. Comparative analysis with prior observations from the IBIS/ISGRI instrument on the INTEGRAL satellite shows variability in emission characteristics, including softer photon indices and higher cutoff energies in 2003 and 2004. Our examination of smaller energy gaps (3-7 keV, 7-12 keV, etc.) reveals energy-dependent behavior in burst characteristics, enhancing our understanding of nuclear burning phases. Overall, these findings validate models describing Type I X-ray bursts and lay the groundwork for future investigations into similar astrophysical systems and stellar evolution processes in extreme environments.