Gamma-ray emission from globular clusters 2MS-GC01, IC 1257, NGC5904, NGC6656 and FSR1735

Globular clusters (GCs) are the oldest stellar system in the Galaxy, in which the millisecond pulsars are widely believed to be the only steady γ-ray emitters. So far 9 γ-ray GCs have been identified and a few candidates such as 2MS-GC01 and IC 1257 have been suggested. In this work, after analyzing the publicly-available Fermi-LAT data we confirm the significant γ-ray emission from 2MS-GC01 and IC 1257 and report the discovery for γ-ray emission from NGC 5904 and NGC 6656 within their tidal radii. Also a strong evidence of significant γ-ray emission is found from FSR 1735. From the observed γ-ray luminosities, the numbers of MSPs that are expected to be present in these GCs are estimated.