Two new X-ray pulsars detected in the SMC using archive Chandra data (CXOU J005527.9-721058 and CXOU J005455.6-724510).

ATel #217; W. R.T. Edge, M. J. Coe and V. A. McBride (Southampton University)
on 15 Jan 2004; 13:16 UT
Credential Certification: W R T Edge (wrte@astro.soton.ac.uk)

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Two new X-ray pulsars have been detected in the SMC using archive Chandra data. An examination of Chandra Observation ID 2948, which took place between 2002-07-04 09:47:57 and 2002-07-04 12:45:44 (Zezas et al. astro-ph/0310562, 2003), shows an X-ray source at R.A. = 00h55m27.9s Decl. = -72d10m58s (equinox 2000) with a 90% confidence radial uncertainty of 0.6 arcsec. Timing analysis on this object revealed a period of 34.08 seconds +/- 0.03 seconds with a confidence of 98.5%. The position of this pulsar is within the 13 arcsec 90% confidence error radius of the ROSAT source RX J0055.4-7210. Similarly, an X-ray source at R.A. = 00h54m55.6s Decl. = -72d45m10s (equinox 2000), with a 90% confidence radial uncertainty of 0.6 arcsec, was noted in Chandra Observation ID 2946, which took place between 2002-07-04 06:48:04 and 2002-07-04 09:47:57. This was found to have a period of 503.5 seconds +/- 6.7 seconds at a >99% level of confidence. Selective analysis of the source region makes it unlikely that this period is a harmonic of the 1000s Y dithering frequency, moreover no significant pulse period was found at 1000 seconds. This object is very close to RX J0054.9-7245 = AX J0054.8-7244 which is listed in both Haberl & Pietsch (2003, astro-ph/0311092) and Yokogawa et al (2003, PASJ 55, 161) as a HMXB pulsar candidate.