Fermi-LAT Observations of Sagittarius A*: Imaging Analysis

Abstract

Sagittarius A* (Sgr A*)-the supermassive black hole (SMBH) in the center of our galaxy-has been observed in most of the electromagnetic spectrum, from radio to X-rays. Diffuse gamma-ray emission has been observed around Sgr A* and a gamma-ray point source has been detected coinciding with the SMBH's position, although there is no definitive association between the two. In this work, we have used similar to 11 yr of Fermi Large Area Telescope observations of the point source 4FGL J1745.6-2859 and performed a detailed imaging analysis across four energy bands. Our goal is to elucidate the nature of the gamma-ray emission at the Galactic Center (GC) and whether it is associated with the SMBH. We find that the centroid of the emission approaches Sgr A*'s location as the energy increases. Assuming that the gamma-ray point source is located at the GC, we estimate a luminosity of 2.61 x 10(36) erg s(-1) in the 100 MeV to 500 GeV energy range. This is consistent with Sgr A*'s bolometric luminosity. Based on the point source properties, we ruled out several potential candidates for its nature and favor a cosmic-ray origin either from protons, electrons, or both, accelerated by-or in the vicinity of-the SMBH. Our results indicate that the point source at the GC is indeed the gamma-ray counterpart of Sgr A* in the GeV range.