A Discovery of a Peculiar Pulsar in the Small Magellanic Cloud

Abstract

We report on a peculiar X-ray binary pulsar IKT1 = RXJ0047.3-7312 observed with XMM-Newton in Oct. 2000. The X-ray spectrum is described by a two-component spectrum. The hard component has a broken power-law with respective photon indices of 0.2 and 1.8, below and above the break energy at 5.8 keV. The soft component can be modeled by a blackbody of kT = 0.6 keV. The X-ray flux shows a gradual decrease and periodic variations of about 4000 s. The averaged flux in 0.7-10.0 keV is 2.9x10^-12 ergs/cm^2/s, which is ~10 times brighter than that in a ROSAT observation in Nov. 1999. In addition to the 4000-s variation, we found coherent pulsations of 263 +/- 1 s. These discoveries strengthen the Be/X-ray binary scenario proposed by the ROSAT and ASCA observations on this source, and confirm that most of the hard sources in the Small Magellanic Cloud are X-ray binary pulsars. A peculiar property of this XBP is that the coherent pulsations are found only in the soft component, and the folded light curve shows a flat top shape with a sharp dip. We discuss the nature of this XBP focusing on the peculiar soft component.

5 pages, 5figures, Accepted for publication in PASJ

References in corpus (4)

• Ten eclipsing binaries in the Small Magellanic Cloud: fundamental parameters and SMC distance
• Review of Discrete X-Ray Sources in the Small Magellanic Cloud: Summary of the ASCA Results and Implication on the Recent Star Forming Activity
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Cited by in corpus (6)

• A Long Look at the Be/X-Ray Binaries of the Small Magellanic Cloud
• Very Long-term Optical Variability of High Mass X-ray Binaries in the SMC
• XMM-Newton observation of the Be/neutron star system RX J0146.9+6121: a soft X-ray excess in a low luminosity accreting pulsar
• XMM-Newton observation of the persistent Be/NS X-ray binary pulsar RX J1037.5-5647 in a low luminosity state
• XMM-Newton observation of the persistent Be/NS X-ray binary pulsar RX J0440.9+4431
• Photometric Periodicities of Be/X-ray Pulsars in the Small Magellanic Cloud