Geminga

Article By:

Bignami, Giovanni F. Institute for Advanced Studies, Pavia, Italy, and Italian National Institute for Astrophysics, Institute for Space Astrophysics and Cosmic Physics, Milan Section, Italy.

Last reviewed:January 2020

DOI:https://doi.org/10.1036/1097-8542.757292

A nearby neutron star that emits pulsed x-rays and gamma rays, steady optical radiation, and possibly radio and optical pulsations. Since the 1970s, it has been studied at a level of detail very unusual for a neutron star. As a result, not only are its nature and distance well known, but also a good understanding has been reached of the physical processes responsible for its multiwavelength emission. Since 2008, NASA's Fermi Gamma-ray Space Telescope mission has unveiled a wealth of Geminga-like gamma-ray pulsars, showing that they are as abundant as the radio-selected neutron stars. Moreover, it is now clear that the vast majority of the hitherto mysterious population of unidentified gamma-ray objects (UGOs) in our galaxy consists of objects like Geminga. Thus, Geminga has been revealed to be the prototype of a new galactic population of neutron stars.

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