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 γ-ray emission has been observed around Sgr A* and a γ-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 ~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 γ-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 γ-ray point source is located at the GC, we estimate a luminosity of 2.61 × 1036 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 γ-ray counterpart of Sgr A* in the GeV range.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- September 2021
- DOI:
- 10.3847/1538-4357/ac0efe
- arXiv:
- arXiv:2107.00756
- Bibcode:
- 2021ApJ...918...30C
- Keywords:
-
- Galactic center;
- Gamma-ray astronomy;
- Supermassive black holes;
- Gamma-ray sources;
- 565;
- 628;
- 1663;
- 633;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- Accepted for publication in The Astrophysical Journal. 21 pages, 9 figures, 4 tables