ASCA Discovery of a Be X-Ray Pulsar
in the SMC: AX J0051-733
Kensuke Imanishi1,
Jun Yokogawa1,
Masahiro Tsujimoto1, and
Katsuji Koyama1,2
1
Department of Physics, Graduate School of Science,
Kyoto University, Sakyo-ku, Kyoto, 606-8502
2
CREST, Japan Science and Technology Corporation
(JST),
4-1-8 Honmachi, Kawaguchi, Saitama 332-0012
ASCA
observed the central region of the
Small Magellanic Cloud,
and found a hard X-ray source, AX J0051-733, at the position
of the
ROSAT
source RX J0050.8-7316,
which has an optical counterpart of a Be star.
Coherent X-ray pulsations of
323.1 ± 0.3 s were discovered from AX J0051-733.
The pulse profile shows several sub-peaks in
the soft (0.7-2.0 keV) X-ray band, but becomes nearly sinusoidal
in the harder (2.0-7.0 keV) X-ray band.
The X-ray spectrum was found to be hard, and is
well fitted by a power-law model with a photon index of
1.0 ± 0.4.
The long-term flux history was examined with the archival data of
Einstein
observatory and ROSAT; a flux variability with a
factor  10 was found.
1999, PASJ, 511, 151
|