P. H. T. Tam, Albert K. H. Kong, C. Y. Hui. Gamma-ray emission from globular clusters
Submitted on: Sep 11, 2012, 16:31:50
Natural Sciences / Astronomy / Astrophysics
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 Library of Congress (USA) reference page : http://lccn.loc.gov/cn2013300046.
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