P. H. T. Tam, Albert K. H. Kong, C. Y. Hui. Gamma-ray emission from globular clusters


Natural Sciences / Astronomy / Astrophysics

Submitted on: Sep 11, 2012, 16:31:50

Description: Over the last few years, the fruitful data provided by the Large Area Telescope aboard the Fermi Gamma-ray Space Telescope has revolutionized our understanding of high-energy processes in globular clusters, particularly those involving compact objects like millisecond pulsars (MSPs). Gamma-ray emission between 100 MeV to 10 GeV has been detected from more than a dozen globular clusters in our Galaxy, most notably 47 Tucanae and Terzan 5. Based on a sample of known gamma-ray globular clusters, empirical relations between the gamma-ray luminosity and properties of globular clusters such as stellar encounter rate, metallicity, as well as optical and infrared photon energy density in the cluster, have been derived. The gamma-ray spectra are generally described by a power law with a cut-off at a few GeV. Together with the detection of pulsed gamma-rays from a millisecond pulsar in a globular cluster, such spectral signature gives support that gamma-rays from globular clusters are collective curvature emission from magnetospheres of MSPs within the cluster.

The abstract of this article will be published in the September 2012 issue of "Intellectual Archive Bulletin", ISSN 1929-1329.

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P_H_T_Tam__Gamma-ray_emission.pdf



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