A New Mask for An Old Suspect: Testing the Sensitivity of the Galactic Center Excess to the Point Source Mask

TL;DR

This study examines how the Galactic center gamma-ray excess is affected by different point source masks, finding that the excess persists in template fits but is masked when using wavelet-based point source detection, suggesting most bright sources are accounted for.

Contribution

It introduces an analysis of the Galactic center excess sensitivity to the point source mask using the latest 4FGL catalog and wavelet methods, highlighting the impact of source masking on excess detection.

Findings

Galactic center excess remains in template fits despite new point source catalog.

Wavelet search shows no small-scale bright regions when masking 4FGL sources.

Constraints on luminosity function for unresolved point sources are established.

Abstract

The Fermi-LAT collaboration has recently released a new point source catalog, referred to as 4FGL. For the first time, we perform a template fit using information from this new catalog and find that the Galactic center excess is still present. On the other hand, we find that a wavelet-based search for point sources is highly sensitive to the use of the 4FGL catalog: no excess of bright regions on small angular scales is apparent when we mask out 4FGL point sources. We postulate that the 4FGL catalog contains the large majority of bright point sources that have previously been suggested to account for the excess in gamma rays detected at the Galactic center in Fermi-LAT data. Furthermore, after identifying which bright sources have no known counterpart, we place constraints on the luminosity function necessary for point sources to explain the smooth emission seen in the template fit.