📝 SummarXiv

Abstract

Swift J174610.4-290018, a peculiar transient X-ray source originally discovered by the Swift satellite in February 2024 at the onset of its outburst, recently attracted intentional or coincident follow-up X-ray observations using Swift, NuSTAR and Chandra. We have performed a comprehensive analysis of the relevant X-ray data to investigate the spectral and temporal properties of this source between October 2000 and July 2024. Archival Chandra data reveal a plausible additional outburst in 2005, followed by a quiescent state in the next $\sim$19 years. The X-ray spectra in both the quiescent and outburst phases are consistent with a thermal plasma spectrum with relatively high temperatures ($\sim$10 keV) and prominent emission lines from both neutral and highly-ionized iron. A previously proposed low-mass X-ray binary/accretion disk corona scenario for Swift J174610, based on XRISM observations near the peak of the 2024 outburst, is examined against the newly derived X-ray properties and is disfavored, in particular due to its difficulty in explaining the quiescent state spectrum. Instead, we suggest a symbiotic binary/recurrent nova scenario, which gains support from many of the observed X-ray properties of Swift J174610 and a close comparison with the famous Galactic recurrent nova RS Oph. If confirmed, Swift J174610 would represent the first nova detected in the Galactic center, offering new insights into the otherwise elusive population of massive white dwarfs as well as wide binaries in the close vicinity of Sgr A*. Our findings call for multi-wavelength follow-up observations for this highly unusual X-ray source.