We revisit the well-studied outburst of the low mass X-ray binary (LMXB) system V404 Cygni, and claims of gamma-ray excesses observed with the Fermi-LAT instrument. Upon analysing an 11.5 year dataset with the 8-year LAT point source catalogue and 8-year background models, we find no evidence to suggest that there is high energy gamma-ray emission during the outburst period (or at any other time) from V404 Cygni. This is due to the proximity of V404 Cygni to the gamma-ray emitting blazar B2023+336, a luminous source approximately 0.3 degrees away, which causes source confusion at the position of V404 Cygni, the luminous gamma-ray background, and the use of older background models and catalogues in previous studies.
@article{arxiv.2107.09395,
title = {V404 Cygni with Fermi-LAT},
author = {Max Harvey and Cameron B. Rulten and Paula M. Chadwick},
journal= {arXiv preprint arXiv:2107.09395},
year = {2021}
}
Comments
11 pages, 6 figures. Accepted for publication in Monthly Notices of the Royal Astronomical Society