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

ABSTRACTeXTP is a science mission designed to study the state of matter under extreme conditions of density, gravity and magnetism. Primary goals are the determination of the equation of state of matter at supra-nuclear density, the measurement of QED effects in highly magnetized star, and the study of accretion in the strong-field regime of gravity. Primary targets include isolated and binary neutron stars, strong magnetic field systems like magnetars, and stellar-mass and supermassive black holes. The mission carries a unique and unprecedented suite of state-of-the-art scientific instruments enabling for the first time ever the simultaneous spectral-timing-polarimetry studies of cosmic sources in the energy range from 0.5-30 keV (and beyond). Key elements of the payload are: the Spectroscopic Focusing Array (SFA) -a set of 11 X-ray optics for a total effective area of ∼0.9 m 2 and 0.6 m 2 at 2 keV and 6 keV respectively, equipped with Silicon Drift Detectors offering <180 eV spectral resolution; the Large Area Detector (LAD) -a deployable set of 640 Silicon Drift Detectors, for a total effective area of ∼3.4 m 2 , between 6 and 10 keV, and spectral resolution better than 250 eV; the Polarimetry Focusing Array (PFA) -a set of 2 X-ray telescope, for a total effective area of 250 cm 2 at 2 keV, equipped with imaging gas pixel photoelectric polarimeters; the Wide Field Monitor (WFM) -a set of 3 coded mask wide field units, equipped with position-sensitive Silicon Drift Detectors, each covering a 90 degrees x 90 degrees field of view. The eXTP international consortium includes major institutions of the Chinese Academy of Sciences and Universities in China, as well as major institutions in several European countries and the United States. The predecessor of eXTP, the XTP mission concept, has been selected and funded as one of the so-called background missions in the Strategic Priority Space Science Program of the Chinese Academy of Sciences since 2011. The strong European participation has significantly enhanced the scientific capabilities of eXTP. The planned launch date of the mission is earlier than 2025.

We present the results of X-ray spectroscopic observations with XMM-Newton for four highredshift radio-loud quasars at z > 4. Among these, three objects, namely GB B1508+5714, PMN J0324−2918 and PKS B1251−407, do not show soft X-ray spectral flattening; the derived upper limits on assumed intrinsic absorption are (3.3-17.3) × 10 21 cm −2 , the least of which is among the most stringent limits for z > 4 quasars. There is a tentative indication for soft X-ray spectral flattening in PMN J1451-1512 at z = 4.76, though the significance is not high. These observations more than double the number of z > 4 radio-loud quasars that have X-ray spectroscopic data to seven, which compose a significant subset of a flux-limited sample of z > 4 radio-loud quasars. Based on this subset, we show, in the second part of this paper, some preliminary results on the overall X-ray spectral properties of the sample. Soft X-ray spectral flattening, which is thought to arise from intrinsic X-ray absorption, was found in about half of the sample (3/7 or 4/7). We give a preliminary distribution of the absorption column density N H . For those with detected X-ray absorption, the derived N H values fall into a very narrow range (around a few times 10 22 cm −2 for 'cold' absorption), suggesting a possible common origin of the absorber. This N H distribution is consistent with that in the redshift range of 2-4, though the data are sparse. Those that do not show X-ray absorption are constrained to have upper limits on the N H broadly consistent in general with the lower end of the distribution of the detected N H . Compared to lower redshift samples at z < 2, there is an extension, or a systematic shift, towards higher values in the intrinsic N H distribution at z > 4, and an increase of the fraction of radio-loud quasars showing X-ray absorption towards high redshifts. These results indicate a cosmic evolution effect, which seems to be the strongest at redshifts around 2. There is a tentative tendency that objects showing X-ray absorption have X-ray fluxes systematically higher than those showing apparently no absorption. After the spectral flattening is accounted for, the rest frame 1-50 keV continua have photon indices with a mean of 1.64 and a standard deviation of 0.11 (or a mean of 1.67 and a standard deviation of 0.14 for a Gaussian fit). Variability appears to be common on time-scales from a few months to years in the quasar rest frame, sometimes in both fluxes and spectral slopes.

We report the discovery of an unambiguous, substantial low-energy cutoff in the broad band X-ray spectrum of the radio quasar RX J1028.6-0844 at a redshift of 4.276 obtained with the ASCA satellite, which we preferably explained as indication of excess X-ray absorption. The equivalent hydrogen column density of the absorbing matter, depending on the redshift and metallicity, ranges from 2.5 10 21 cm −2 for local absorption up to 2.1 10 23 cm −2 (solar metallicity) or 1.6 10 24 cm −2 (10% solar metallicity) for absorption at the quasar redshift. Such a value is among the largest found for high-redshift radio quasars. The absorption, if interpreted as being produced close to the quasar, may indicate the presence of a remarkably large amount of obscuring matter in the quasar environment in the early universe. Implications of the result for the possible origins of the absorbing matter are discussed, concerning especially galactic intervening matter, cool intracluster gas, and ambient medium around the quasar jet. The quasar itself has an enormous apparent luminosity of at least about 2.6 10 47 erg s −1 (H 0 = 50 km s −1 Mpc −1 , q 0 = 0.5) and a power law photon index of 1.67( +0.07 −0.04 ) in the 2-50 keV band in the source rest frame. 5 H 0 = 50 km s −1 Mpc −1 and q 0 = 0.5 are assumed throughout the paper.