TY - JOUR
T1 - Chandra X-ray observatory observations of the globular cluster M28 and its millisecond pulsar PSR B1821-24
AU - Weisskopf, Martin C.
AU - Becker, Werner
AU - Swartz, Douglas A.
AU - Pavlov, George G.
AU - Elsner, Ronald F.
AU - Grindlay, Jonathan
AU - Mignani, Roberto
AU - Tennant, Allyn F.
AU - Backer, Don
AU - Pulone, Luigi
AU - Testa, Vincenzo
PY - 2004/6
Y1 - 2004/6
N2 - We discuss the results of the first Chandra X-Ray Observatory observations of the globular cluster M28 (NGC 6626). We detect 46 X-ray sources of which 12 lie within one core radius of the center. We measure the radial distribution of the X-ray sources and fit it to a, King profile finding a core radius of r c,x ≈ 11″. We measure for the first time the unconfused phase-averaged X-ray spectrum of the 3.05-ms pulsar B1821-24 and find it is best described by a, power law with photon index Γ ≃ 1.2. We find marginal evidence of an emission line centered at 3.3 keV in the pulsar spectrum, which could be interpreted as cyclotron emission from a corona above the pulsar's polar cap if the magnetic field is strongly different from a centered dipole. We present a spectral analyses of the brightest unidentified source and suggest that it is a transiently accreting neutron star in a low-mass X-ray binary, in quiescence. In addition to the resolved sources, we detect fainter, unresolved X-ray emission from the central core.
AB - We discuss the results of the first Chandra X-Ray Observatory observations of the globular cluster M28 (NGC 6626). We detect 46 X-ray sources of which 12 lie within one core radius of the center. We measure the radial distribution of the X-ray sources and fit it to a, King profile finding a core radius of r c,x ≈ 11″. We measure for the first time the unconfused phase-averaged X-ray spectrum of the 3.05-ms pulsar B1821-24 and find it is best described by a, power law with photon index Γ ≃ 1.2. We find marginal evidence of an emission line centered at 3.3 keV in the pulsar spectrum, which could be interpreted as cyclotron emission from a corona above the pulsar's polar cap if the magnetic field is strongly different from a centered dipole. We present a spectral analyses of the brightest unidentified source and suggest that it is a transiently accreting neutron star in a low-mass X-ray binary, in quiescence. In addition to the resolved sources, we detect fainter, unresolved X-ray emission from the central core.
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U2 - 10.1016/j.nuclphysbps.2004.04.095
DO - 10.1016/j.nuclphysbps.2004.04.095
M3 - Article
AN - SCOPUS:23744435650
SN - 0920-5632
VL - 132
SP - 566
EP - 571
JO - Nuclear Physics B - Proceedings Supplements
JF - Nuclear Physics B - Proceedings Supplements
ER -