Discovery of two radio pulsars in the globular cluster M15

WE report the discovery of two radio pulsars, 2127 + 11B and 2127-11C, in the globular cluster M15 (NGC7078), which also contains the 110-ms pulsar 2127 + 11A (ref. 1). Although only twenty globular cluster pulsars are known at present, the detection of three pulsars in a single cluster suggests that there might be a large total population of these objects, which would make them powerful probes of the dynamics and evolution of globular clusters. One of the new pulsars, 2127 +11C, is in a highly eccentric binary system with an 8-hour period. It is thus similar to the famous PSR1913 + 16 system², and study of the pulse arrival times can be expected to provide tests of general relativity, including gravitational wave emission. The companion of PSR2127 + 11C is probably either another neutron star or a massive white dwarf, suggesting that the core of M15 contains a high density of massive stellar remnants.