We search for γ-ray emission from 114 Galactic high mass X-ray binaries, including 4 well studied catalogued sources, in 12.5 years of Fermi-LAT data in conjunction with the 10-year point source catalogue. Where a γ-ray excess appears to be spatially coincident with an X-ray binary, further investigation is performed to ascertain whether this excess is the product of physical processes within the binary system itself. We identify γ-ray excesses coincident with 20 high mass X-ray binaries where there is little or no prior evidence for γ-ray emission. However, we find that many of these are false positives caused by source confusion or the γ-ray background. Nonetheless, tentative but promising indicators of γ-ray emission are identified for several new systems, notably including 1A 0535+262, RX J2030.5+4751 and SAX J1324.4-6200.

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We revisit the well-studied outburst of the low mass X-ray binary (LMXB) system V404 Cygni, and claims of γ-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 γ-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 γ-ray emitting blazar B2023+336, a luminous source approximately 0.3○ away, which causes source confusion at the position of V404 Cygni, the luminous γ-ray background, and the use of older background models and catalogues in previous studies.

Radio galaxies are uncommon γ-ray emitters, and only low-redshift radio galaxies are detected with the Fermi Large Area Telescope (Fermi-LAT). However, they offer potential insights into the emission mechanisms of active galaxies, particularly as the alignment of their jets with respect to the Earth means that, unlike blazars, their emission is not necessarily jet dominated. We use the Fermi-LAT data to perform an unbiased survey of 78 radio galaxies from the Bologna complete sample in order to search for new γ-ray-emitting radio galaxies. We observe statistically significant γ-ray emission from four of the six known Fermi-LAT-detected radio galaxies included in this sample, and find some evidence for γ-ray emission spatially coincident with four previously undetected radio galaxies. As a large parameter space is searched, we calculate a probability distribution to compute the look-elsewhere effect. We find that these four spatially coincident sub-threshold γ-ray excesses are most likely a chance association, and are unlikely to be emission from the radio galaxies. Upper limits on flux are calculated for the radio galaxies from which no γ-ray emission is observed.

Binary star systems represent a significant proportion of the Galactic stellar population, with X-ray binaries being an important subset of these for high energy astrophysics. Although hundreds of X-ray binaries are detected in the Milky Way and beyond, only 12 of these systems are listed in the 4FGL-DR2, the latest Fermi-LAT point source catalogue. With such a small number detectable by Fermi-LAT, much is still unknown about the mechanisms by which these systems emit -rays. We present the method and current status of our large-scale survey of the X-ray binary population using over 12 years of Fermi-LAT data, and current catalogues and background models.