X-Rays from V723 Mon are due to Optical Loading in Swift XRT
Abstract
V723 Mon was recently reported to be hosting the nearest (d = 460 pc) candidate black hole by Jayasinghe et al. An X-ray detection was claimed based on deep Swift XRT observations with a luminosity of LX ≈ 8 × 1029 erg s-1 or LX/LEdd ≈ 10-9. Here we show that the X-ray photons detected by Swift XRT are due to optical loading from the bright (V = 8.3 mag) star. Using events in the 2-10 keV energy band, where optical loading does not strongly contribute, we find a 3σ upper-limit on the unabsorbed 2-10 keV X-ray flux of FX < 2.8 × 10-14 erg cm-2 s-1, corresponding to a luminosity LX < 7.2 × 1029 erg s-1 at a distance of 460 pc or LX/LEdd ≲ 2 × 10-9 for a M ≈ 3M⊙ black hole.
- Publication:
-
Research Notes of the American Astronomical Society
- Pub Date:
- November 2021
- DOI:
- 10.3847/2515-5172/ac35e5
- Bibcode:
- 2021RNAAS...5..259H
- Keywords:
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- Black holes;
- Spectroscopic binary stars;
- 162;
- 1557