Aims. Pointed observations with XMM-Newton provide the basis for creating catalogues of X-ray sources detected serendipitously in each field. This paper describes the creation and characteristics of the 2XMM catalogue. Methods. The 2XMM catalogue has been compiled from a new processing of the XMM-Newton EPIC camera data. The main features of the processing pipeline are described in detail. Results. The catalogue, the largest ever made at X-ray wavelengths, contains 246 897 detections drawn from 3491 public XMM-Newton observations over a 7-year interval, which relate to 191 870 unique sources. The catalogue fields cover a sky area of more than 500 deg 2 . The non-overlapping sky area is ∼360 deg 2 (∼1% of the sky) as many regions of the sky are observed more than once by XMM-Newton. The catalogue probes a large sky area at the flux limit where the bulk of the objects that contribute to the X-ray background lie and provides a major resource for generating large, well-defined X-ray selected source samples, studying the X-ray source population and identifying rare object types. The main characteristics of the catalogue are presented, including its photometric and astrometric properties

Most ultraluminous X-ray sources 1 (ULXs) display a typical set of properties not seen in Galactic stellar-mass black holes (BHs): higher luminosity (L x > 3 × 10 39 erg s −1 ), unusually soft X-ray components (kT 0.3 keV) and a characteristic downturn 2,3 in their spectra above ≈ 5 keV. Such puzzling properties have been interpreted either as evidence of intermediate-mass BHs 4,5 , or as emission from stellar-mass BHs accreting above their Eddington limit 6,7 , analogous to some Galactic BHs at peak luminosity 8,9 . Recently, a very soft X-ray spectrum has been observed in a rare and transient stellar-mass BH 10 .Here we show that the X-ray source P13 in the galaxy NGC 7793 11 is in a ≈ 64 day period binary and exhibits all three canonical properties of ULXs. By modelling the strong optical and UV modulations due to X-ray heating of the B9Ia donor star, we constrain the BH mass to less than 15 solar masses. Our results demonstrate that in P13, soft thermal emission and spectral curvature are indeed signatures of supercritical accretion. By analogy, ULXs with similar X-ray spectra and luminosities of up to a few 10 40 erg s −1 can be explained by supercritical accretion onto massive stellar BHs.We organised an X-ray, UV and optical spectrophotometric monitoring programme Stacking Swift low state data reveals the source at L X (0.3-10 keV) = 5 ± 1 × 10 37 erg s −1 (90% confidence level), a factor 100 less than in the previously seen bright X-ray state. Scheduled and serendipitous Chandra and XMM-Newton observations carried out in 2011 and 2012 detected the source at the same low X-ray luminosity and will be reported elsewhere.Optical spectra point at a B9I spectral type (Fig. 1). In addition to high-order Balmer absorption lines, the spectrum exhibits Balmer emission up to at least Hγ as well as and V (λ central = 5500Å; ∆ V = 0.5 mag) light-curves and the behaviour of the V -I colour index point at a strong X-ray heating effect of the supergiant star hemisphere facing the compact companion. An X-ray source with a tenth of the nominal X-ray luminosity would brighten the star by only ≈ 0.1 magnitude in V at maximum light and would have basically no effect in the faint X-ray state. Therefore, we conclude that in 2011 part of the companion star photosphere continues to be illuminated by a luminous X-ray source which is however shielded from our view. The Galactic X-ray binary Her X-1 exhibits similar bright/faint X-ray states 18 as well as periodic phase shifts of photometric maxima 19 . By analogy, we suggest that a tilted precessing accretion disk is at the origin of both the X-ray bright & faint states and of the phase jitter of optical maximum light.In order to constrain the geometry and dynamics of the system we simultaneously fitted the V and UVOT u light-curves using the Eclipsing Light Curve code 20 (ELC). We tested four X-ray luminosity levels ranging from 0.7 up to 2 times a nominal value of 4.2 × 10 39 erg s −1 (derived from the diskbb + comptt fit to the Chandra spectrum extrapolated to the 0.3-20 keV r...