V404 Cygni with Fermi-LAT

We revisit the well-studied outburst of the low-mass X-ray binary (LMXB) system V404Cygni, and claims of gamma-ray excesses observed with the Fermi-LAT instrument. Upon analysing an 11.5 yr data set with the 8-yr LAT point source catalogue and 8-yr 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 V404Cygni. This is due to the proximity of V404Cygni to the gamma-ray emitting blazar B2023+336, a luminous source approximately 0.3(circle) away, which causes source confusion at the position of V404Cygni, the luminous gamma-ray background, and the use of older background models and catalogues in previous studies.

Automated summary

Through analysis of data and background models, this study found no evidence of high energy gamma-ray emission from V404Cygni at any time, possibly due to confusion caused by its proximity to other emitting sources.