Gamma-ray emission from globular clusters
| Autor: | Albert K. H. Kong, Pak-Hin Thomas Tam, Chung Y. Hui |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2012 |
| Předmět: |
010504 meteorology & atmospheric sciences
lcsh:Astronomy Astrophysics::High Energy Astrophysical Phenomena FOS: Physical sciences General Physics and Astronomy Astrophysics 01 natural sciences Pulsar wind nebula Luminosity lcsh:QB1-991 Spitzer Space Telescope Millisecond pulsar 0103 physical sciences Astrophysics::Solar and Stellar Astrophysics 010303 astronomy & astrophysics Astrophysics::Galaxy Astrophysics 0105 earth and related environmental sciences High Energy Astrophysical Phenomena (astro-ph.HE) gamma-ray observations Physics Astrophysics::Instrumentation and Methods for Astrophysics clusters: globular Astrophysics - Astrophysics of Galaxies Galaxy Neutron star Astrophysics of Galaxies (astro-ph.GA) Globular cluster General Earth and Planetary Sciences Astrophysics - High Energy Astrophysical Phenomena Fermi Gamma-ray Space Telescope |
| Zdroj: | Journal of Astronomy and Space Sciences, Vol 33, Iss 1, Pp 1-11 (2016) |
| Popis: | Over the last few years, the data obtained using the Large Area Telescope (LAT) aboard the Fermi Gamma-ray Space Telescope has provided new insights on high-energy processes in globular clusters, particularly those involving compact objects such as Millisecond Pulsars (MSPs). Gamma-ray emission in the 100 MeV to 10 GeV range has been detected from more than a dozen globular clusters in our galaxy, including 47 Tucanae and Terzan 5. Based on a sample of known gamma-ray globular clusters, the empirical relations between gamma-ray luminosity and properties of globular clusters such as their stellar encounter rate, metallicity, and possible optical and infrared photon energy densities, have been derived. The measured gamma-ray spectra are generally described by a power law with a cut-off at a few gigaelectronvolts. Together with the detection of pulsed gamma-rays from two MSPs in two different globular clusters, such spectral signature lends support to the hypothesis that gamma-rays from globular clusters represent collective curvature emission from magnetospheres of MSPs in the clusters. Alternative models, involving Inverse-Compton (IC) emission of relativistic electrons that are accelerated close to MSPs or pulsar wind nebula shocks, have also been suggested. Observations at >100 GeV by using Fermi/LAT and atmospheric Cherenkov telescopes such as H.E.S.S.-II, MAGIC-II, VERITAS, and CTA will help to settle some questions unanswered by current data. 11 pages, 7 figures, 2 tables, J. Astron. Space Sci., in press |
| Databáze: | OpenAIRE |
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