X‐ray bright sources in the Chandra Small Magellanic Cloud Wing Survey – detection of two new pulsars

ABSTRACT We investigate the X-ray and optical properties of a sample of X-ray bright sourcesfrom the Small Magellanic Cloud (SMC) Wing Survey. We have detected two newpulsars with pulse periods of 65.8 s (CXOU J010712.6-723533) and 700 s (CXOUJ010206.6-714115), and present observations of two previously known pulsars RXJ0057.3-7325 (SXP101) and SAX J0103.2-7209 (SXP348). Our analysis has led tothree new optical identifications for the detected pulsars. We find long-term opticalperiods for two of the pulsars, CXOU J010206.6-714115 and SXP101, of 267 and 21.9d, respectively. Spectral analysis of a sub-set of the sample shows that the pulsarshave harder spectra than the other sources detected. By employing a quantile-basedcolour-colour analysis we are able to separate the detected pulsars from the rest ofthe sample. Using archival catalogues we have been able to identify counterparts forthe majority of the sources in our sample. Combining this with our results from thetemporal analysis of the Chandra data and archival optical data, the X-ray spectralanalysis, and by determining the X-ray to optical flux ratios we present preliminaryclassifications for the sources. In addition to the four detected pulsars, our sampleincludes two candidate foreground stars, 12 probable active galactic nuclei, and fiveunclassified sources.Keywords: X-rays:binaries– stars:emission-line,Be – (galaxies:)MagellanicClouds