Speaker
Description
IGR J17285−2922 is a very faint transient low-mass X-ray binary whose compact object has not yet been securely identified. Its consistently hard X-ray spectra during detected outbursts and its multiwavelength behaviour favour a black hole interpretation, although a neutron star primary has not been excluded. We investigate the nature of the compact object using two archival NICER observations obtained during the 2019 outburst that were not included in previous studies, providing a total cleaned exposure of approximately 3 ks. Our analysis combines X-ray spectroscopy with high-time-resolution variability diagnostics. The NICER energy spectra are compared with quasi-simultaneous Swift/XRT measurements to characterize the X-ray flux and spectral state of the source. Energy-resolved power-density spectra, broad-band fractional variability, and searches for coherent pulsations and quasi-periodic oscillations are used to investigate compact-object-sensitive timing signatures. Particular attention is given to high-frequency variability and possible thermal emission consistent with a neutron-star surface or boundary layer. Together, these independent spectral and timing diagnostics provide a new test of the black hole and neutron star interpretations of IGR J17285−2922 and help refine the classification of this very faint X-ray binary.
