A deep XMM-Newton serendipitous survey of a middle-latitude area

Abstract

<i>Context. <i/>The radio-quiet neutron star 1E1207.4-5209 has been the target of several <i>XMM-Newton<i/> observations, with a total exposure of ~350 ks. The source is located at intermediate galactic latitude (), i.e. in a sky region with an extremely interesting mix of both galactic and extra-galactic X-ray sources.<i>Aims. <i/>The aim of our work is to investigate the properties of both the intermediate-latitude galactic and extra-galactic X-ray source populations in the 1E1207.4-5209 field.<i>Methods. <i/>We performed a coherent analysis of the whole <i>XMM-Newton<i/> observation data set to build a catalogue of serendipitous X-ray sources detected with high confidence and to derive information on the source flux, spectra, and time variability. In addition, we performed a complete multi-band (<i>UBVRI<i/>) optical coverage of the field with the <i>Wide Field Imager<i/> (<i>WFI<i/>) of the ESO/MPG 2.2 m telescope (La Silla) to search for candidate optical counterparts to the X-ray sources, down to a <i>V<i/>-band limiting magnitude of ~24.5.<i>Results. <i/>From the combined observation data set we detected a total of 144 serendipitous X-ray sources. We find evidence that the source distribution may be different from those computed either in the Galactic plane or at high galactic latitudes. Thanks to the refined X-ray positions and to the <i>WFI<i/> observations, we found candidate optical counterparts for most of the X-ray sources in our compilation. For most of the brightest ones we proposed a likely classification based on both the X-ray spectra and the optical colours.<i>Conclusions. <i/>Our results indicate that at intermediate galactic latitude the X-ray source population is dominated by the extra-galactic component, but with a significant contribution from the galactic component in the soft energy band, below 2 keV.