The Origin of an Extended X-Ray Emission Apparently Associated with the Globular Cluster 47 Tucanae

Abstract

Using the Suzaku X-ray Imaging Spectrometer, we performed a 130 ks observation of an extended X-ray emission, which was shown by ROSAT and Chandra observations to apparently associate with the globular cluster 47 Tucanae. The obtained 0.5-6 keV spectrum was successfully fitted with a redshifted thin thermal plasma emission model whose temperature and redshift are 2.2^+0.2_-0.3 keV (at the rest frame) and 0.34±0.02, respectively. The derived parameters, including the temperature, redshift, and luminosity, indicate that the extended X-ray source is a background cluster of galaxies, and its projected location falls, by chance, on the direction of the proper motion of 47 Tucanae.