ASCA Discovery of a Be X - Ray Pulsar in the SMC : AX J 0051 − 733
نویسندگان
چکیده
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.
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