E. S. Bartlett, M. J. Coe, F. Haberl, V. A. McBride, R. H. D. Corbet
We report on the first X-ray images of the Phoenix dwarf galaxy, taken with
\emph{XMM-Newton} in July 2009. This local group dwarf galaxy shares
similarities with the Small Magellanic Cloud (SMC) including a burst of star
formation $\sim$50 Myr ago. The SMC has an abundance of High Mass X-ray
Binaries (HMXBs) and so we have investigated the possibility of an HMXB
population in Phoenix with the intention of furthering the understanding of the
HMXB-star formation rate relation. The data from the combined European Photon
Imaging Cameras (EPIC) were used to distinguish between different source
classes (foreground stars, background galaxies, AGN and supernova remnants)
using EPIC hardness ratios and correlations with optical and radio catalogues.
Of the 81 X-ray sources in the field of view, six are foreground stars, four
are galaxies and one is an AGN. The remaining sources with optical counterparts
have log($\frac{f_X}{f_{opt}}$) consistent with AGN in the local universe.
Further investigation of five sources in the field of view suggests they are
all background AGN. Their position behind the gas cloud associated with Phoenix
makes them a possible tool for further probing the metallicity of this region.
We find no evidence for any HMXBs in Phoenix at this time. This rules out the
existence of the X-ray persistent supergiant X-ray binary systems. However the
transient nature of the Be/X-ray binaries means we cannot rule out a population
of these sources but can conclude that it is not extensive.
View original:
http://arxiv.org/abs/1202.4728
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