Detection of gamma-ray emission from globular clusters M15, NGC 6397, 5904, 6218 and 6139 with Fermi-LAT
Abstract
In the third Fermi catalogue (3FGL) there are 16 gamma-ray globular clusters. Following an analysis of the recently released Pass 8 data from the Fermi Large Area Telescope (LAT), we report the discovery of significant gamma-ray emission from M15 and NGC 6397, confirm that NGC 5904 is a gamma-ray-emitter and provide evidence of gamma-ray emission from NGC 6218 and 6139. Interestingly, in the globular clusters M15, NGC 6397 and 5904, millisecond pulsars (MSPs) have been found in the radio or X-ray, which strongly support the MSP origin of the gamma-ray emission. Owing to the relatively low luminosity of the gamma-ray emission, however, we do not find any evidence for gamma-ray pulsation or flux variability in these sources.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- June 2016
- DOI:
- 10.1093/mnras/stw567
- arXiv:
- arXiv:1603.02358
- Bibcode:
- 2016MNRAS.459...99Z
- Keywords:
-
- globular clusters: individual: M15;
- globular clusters: individual: NGC 5904;
- globular clusters: individual: NGC 6397;
- globular clusters: individual: NGC 6218;
- globular clusters: individual: NGC 6139;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 17 pages, 4 figures. Accepted for publication in MNRAS