Cover Image

Saved in:
Bibliographic Details
Main Authors: Marino, A., Yang, H., Zelati, F. Coti, Rea, N., Guillot, S., Jaisawal, G. K., Maitra, C., Ness, J. -U., Haberl, F., Kuulkers, E., Yuan, W., Feng, H., Tao, L., Jin, C., Sun, H., Zhang, W., Chen, W., Heuvel, E. P. J. van den, Soria, R., Zhang, B., Weng, S. -S., Ji, L., Zhang, G. B., Pan, X., Lv, Z., Zhang, C., Ling, Z., Chen, Y., Jia, S., Liu, Y., Cheng, H. Q., Li, D. Y., Gendreau, K. C., Ng, M., Strohmayer, T. E.
Format: Preprint
Published: 2024
Subjects:
High Energy Astrophysical Phenomena
Online Access:https://arxiv.org/abs/2407.21371
Tags: Add Tag
No Tags, Be the first to tag this record!
Table of Contents:
  • On May 27 2024, the Wide-field X-ray Telescope onboard the Einstein Probe (EP) mission detected enhanced X-ray emission from a new transient source in the Small Magellanic Cloud (SMC) during its commissioning phase. Prompt follow-up with the EP Follow-up X-ray Telescope, the Swift X-ray Telescope and NICER have revealed a very soft, thermally emitting source (kT$\sim$0.1 keV at the outburst peak) with an X-ray luminosity of $L\sim4\times10^{38}$ erg s$^{-1}$, labelled EP J005245.1-722843. This super-soft outburst faded very quickly in a week time. Several emission lines and absorption edges were present in the X-ray spectrum, including deep Nitrogen (0.67 keV) and Oxygen (0.87 keV) absorption edges. The X-ray emission resembles the SSS phase of typical nova outbursts from an accreting white dwarf (WD) in a binary system, despite the X-ray source being historically associated with an O9-B0e massive star exhibiting a 17.55 days periodicity in the optical band. The discovery of this super-soft outburst suggests that EP J005245.1-722843 is a BeWD X-ray binary: an elusive evolutionary stage where two main-sequence massive stars have undergone a common envelope phase and experienced at least two episodes of mass transfer. In addition, the very short duration of the outburst and the presence of Ne features hint at a rather massive, i.e., close to the Chandrasekhar limit, Ne-O WD in the system.

Similar Items