The XMM-LSS mosaic:
A unique deep view of the X-ray sky on large scales
(An alternative presentation of the mosaic without contours and no sources highlighted is available here).
The left picture shows the current XMM-LSS mosaic, which is the largest view of the deep X-ray sky obtained to date.
The XMM-LSS field is located on the celestial equator, at high galactic latitude. The X-ray coverage extends to some 11 deg2 and is made of 99 adjacent XMM pointings (91 from the XMM-LSS programme ranging from 10 to 27 ks, 8 from the Subaru Deep Survey, ranging from 40 to 80 ks).
The picture is a composite of three bands: red[0.3-0.5], green[0.5-2.0] and blue[2.0-4.5] keV.
More than 7.000 sources have been detected down to a flux of 1E-15 erg/s/cm2 in the soft band. They show a wealth of X-ray spectral properties. About 97% of the sources are Active Galactic Nuclei or stars (point-like sources). The others are mainly clusters of galaxies as well as a few very nearby galaxies (extended sources).
One of the main goals of the XMM-LSS survey is to study the cosmic network underlined by clusters of galaxies: the number density of clusters and their spatial distribution as a function of cosmic time provide constraints on the cosmological models that are complementary to those from supernovae and the cosmic microwave background.
Clusters of galaxies are strong X-ray emitters: the tenuous gas filling the space between galaxies is settled in the cluster dark matter potential and heated up to temperatures of several tens of millions degrees. Since cluster X-ray emission can be deduced ab initio from cosmological models, special care has been devoted to the cluster detection and characterisation procedures in the XMM-LSS survey. It is thus possible to define various samples of X-ray selected clusters.
The white circles indicate the C1 population i.e. clusters whose X-ray emission has been unambiguously flagged as extended. The C1 clusters constitute a purely X-ray selected sample and are thus of prime interest for cosmology. The number of collected photons varies from about 200 to several thousands.
The images on the right provide deeper insights into the X-ray mosaic, in order to enlighten the X-ray properties of some representative sources. Positions of the zoomed areas are indicated by red squares on the mosaic. The objects are described in the “detailed caption” below.
Investigator(s): Marguerite Pierre
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