SEARCH FOR PULSED {gamma}-RAY EMISSION FROM GLOBULAR CLUSTER M28

Journal Article · Sun Mar 10 04:00:00 EDT 2013 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/765/2/L47· OSTI ID:22130823

Wu, J. H. K.; Kong, A. K. H.; Huang, R. H. H.; Tam, P. H. T. ^[1]; Hui, C. Y. ^[2]; Wu, E. M. H.; Takata, J.

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1. Institute of Astronomy and Department of Physics, National Tsing Hua University, Hsinchu, Taiwan (China)
2. Department of Astronomy and Space Science, Chungnam National University, Daejeon (Korea, Republic of)

Using the data from the Large Area Telescope on board the Fermi Gamma-ray Space Telescope, we have searched for {gamma}-ray pulsations from the direction of the globular cluster M28 (NGC 6626). We report the discovery of a signal with a frequency consistent with that of the energetic millisecond pulsar (MSP) PSR B1821-24 in M28. A weighted H-test test statistic of 28.8 is attained, which corresponds to a chance probability of {approx}10{sup -5} (4.3{sigma} detection). With a phase-resolved analysis, the pulsed component is found to contribute {approx}25% of the total observed {gamma}-ray emission from the cluster. However, the unpulsed level provides a constraint for the underlying MSP population and the fundamental plane relations for the scenario of inverse Compton scattering. Follow-up timing observations in radio/X-ray are encouraged to further investigate this periodic signal candidate.

• OSTI ID: 22130823
• Journal Information: Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 2 Vol. 765; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
COMPTON EFFECT
COSMIC GAMMA SOURCES
COSMIC X-RAY SOURCES
DETECTION
EMISSION
GAMMA RADIATION
PERIODICITY
PROBABILITY
PULSARS
PULSATIONS
SPACE
STARS
TELESCOPES
X RADIATION