Abstract Details
| Name: Sayantan Bhattacharya Affiliation: Tata Institute of Fundamental Research Conference ID: ASI2025_370 Title : High-Resolution XMM-Newton Spectroscopy of EXO 0748-676’s Latest Outburst after Prolonged Quiescence Authors and Co-Authors : Sayantan Bhattacharya 1, Sudip Bhattacharyya 1, Gargi Shaw 1 Abstract Type : Poster Abstract Category : High Energy Phenomena, Fundamental Physics and Astronomy Abstract : EXO 0748–676, a well-studied neutron star low-mass X-ray binary, has re-entered its outburst following 16 years of quiescence. We present the findings from 55.5 ks of XMM-Newton observations, using high-resolution spectroscopy with the Reflection Grating Spectrometer (RGS), which also provided impactful results about the source during the previous outburst. The XMM-Newton European Photon Imaging Camera (EPIC) light curve captures a type I X-ray burst, which leads to an optical burst by three seconds. To investigate the burst’s impact on ionization structure, we categorize spectra into burstless, pre-, and post-burst phases, with additional analysis of dip and non-dip intervals. Across all phases, a broad O VII recombination line dominates the spectrum, accompanied by velocity-broadened O VIII, N VII, and Ne IX features. Particularly, the Ne IX line shows variation in ionization states between pre-burst (11.65 A) and post-burst (13.56 A) spectra, while dips also significantly influence the line profiles. Similarities with the previous outburst are observed, including a similar spectral state, ionization structure, and same elemental lines, indicating stable, long-term accretion characteristics across these two outbursts. This work highlights the consistency in EXO 0748–676's spectral properties, providing insights into its accretion and ionization properties even after prolonged quiescent periods.(https://arxiv.org/abs/2408.02715) |