Gamma-Ray Emission from Globular Clusters 2Ms-Gc01, Ic 1257, Fsr 1735, Ngc 5904 and 6656

Globular clusters (GCs) are the oldest stellar systems in the Galaxy, in which millisecond pulsars are widely believed to be the only steady gamma-ray emitters. So far, nine gamma-ray GCs have been identified and a few candidates, such as 2MS-GC01 and IC 1257, have been suggested. In this work, after analysing the publicly available Fermi Large Area Telescope data, we confirm the significant gamma-ray emission from 2MS-GC01 and IC 1257 and report the discovery of gamma-ray emission from NGC 5904 and 6656 within their tidal radii. Also, strong evidence of significant gamma-ray emission is found from FSR 1735. From the observed gamma-ray luminosities, we estimate the numbers of millisecond pulsars that are expected to be present in these GCs.