XRISM Resolve Spectroscopy of GX 5-1: Constraints on Iron Spectral Features in a Luminous Neutron-Star Binary
Researchers used XRISM Resolve spectroscopy to study GX 5–1, a bright neutron-star binary, looking for narrow iron spectral features. The study found no statistically significant narrow absorption or emission lines in either time-averaged or phase-resolved spectra. This suggests that classical iron diagnostics are weak, strongly ionized, diluted by continuum variability, or suppressed in this extreme source.