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EGRET upper limits to the high-energy gamma-ray emission from the millisecond pulsars in nearby globular clustersWe report upper limits to the high-energy gamma-ray emission from the millisecond pulsars (MSPs) in a number of globular clusters. The observations were done as part of an all-sky survey by the energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory (CGRO) during Phase I of the CGRO mission (1991 June to 1992 November). Several theoretical models suggest that MSPs may be sources of high-energy gamma radiation emitted either as primary radiation from the pulsar magnetosphere or as secondary radiation generated by conversion into photons of a substantial part of the relativistic e(+/-) pair wind expected to flow from the pulsar. To date, no high-energy emission has been detected from an individual MSP. However, a large number of MSPs are expected in globular cluster cores where the formation rate of accreting binary systems is high. Model predictions of the total number of pulsars range in the hundreds for some clusters. These expectations have been reinforced by recent discoveries of a substantial number of radio MSPs in several clusters; for example, 11 have been found in 47 Tucanae (Manchester et al.). The EGRET observations have been used to obtain upper limits for the efficiency eta of conversion of MSP spin-down power into hard gamma rays. The upper limits are also compared with the gamma-ray fluxes predicted from theoretical models of pulsar wind emission (Tavani). The EGRET limits put significant constraints on either the emission models or the number of pulsars in the globular clusters.
Document ID
19950036455
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Michelson, P. F.
(Stanford Univ. Stanford, CA, United States)
Bertsch, D. L.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Brazier, K.
(Max-Planck-Institut fuer Extraterrestrische Physik Garching, Germany)
Chiang, J.
(Stanford Univ. Stanford, CA, United States)
Dingus, B. L.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Fichtel, C. E.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Fierro, J.
(Stanford Univ. Stanford, CA, United States)
Hartman, R. C.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Hunter, S. D.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Kanbach, G.
(Max-Planck-Institut fuer Extraterrestrische Physik Garching, Germany)
Date Acquired
August 16, 2013
Publication Date
November 1, 1994
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 435
Issue: 1
ISSN: 0004-637X
Subject Category
Astronomy
Accession Number
95A68054
Funding Number(s)
CONTRACT_GRANT: NAG5-1472
CONTRACT_GRANT: NAG5-1605
Distribution Limits
Public
Copyright
Other

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