Fermi Gamma-ray Space Telescope

On the population of Milky Way globular clusters in gamma-rays

Raniere de Menezes
(Fabio Cafardo, Rodrigo Nemmen)


Globular clusters (GCs) are evolved stellar systems containing entire populations of millisecond pulsars (MSPs), which are effective gamma-ray emitters. Observations of this emission can be used as a powerful tool to explore the dynamical processes leading to binary system formation in GCs. In this work, 9 years of Fermi Large Area Telescope data were used to investigate the gamma-ray emission from all GCs in the Milky Way. 23 clusters were found as gamma-bright, where 2 of them had never been reported before. It was also found that magnetic braking probably has a smaller impact on the formation rate of binary systems in metal-rich GCs than previously suggested, while large values for stellar encounter rate seem to be a necessary condition. No extended emission was found even for clusters larger than 0.5 degrees on the optical sky.