An X-ray Baldwin effect for the narrow Fe Kα lines observed in active galactic nuclei

The majority of active galactic nuclei (AGN) observed by XMM–Newton reveal narrow Fe Kα lines at ∼6.4 keV, due to emission from cold (neutral) material. There is an X-ray Baldwin effect in type I AGN, in that the equivalent width (EW) of the line decreases with increasing luminosity, with weighted linear regression giving EW∝ L[superscript −0.17±0.08] (Spearman Rank probability of >99.9 per cent).With current instrumental capabilities it is not possible to determine the precise origin for the narrow line, with both the broad-line region and putative molecular torus being possibilities. A possible explanation for the X-ray Baldwin effect is a decrease in the covering factor of the material forming the fluorescence line

XMM–Newton observations of seven soft X-ray excess quasi-stellar objects

XMM–Newton observations of seven quasi-stellar objects (QSOs) are presented and the EPIC spectra analysed. Five of the active galactic nuclei (AGN) show evidence for Fe Kα emission, with three being slightly better fitted by lines of finite width; at the 99 per cent level they are consistent with being intrinsically narrow, though. The broad-band spectra can be well modelled by a combination of different temperature blackbodies (BBs) with a power law, with temperatures between kT ∼ 100 and 300 eV. On the whole, these temperatures are too high to be direct thermal emission from the accretion disc, so a Comptonization model was used as a more physical parametrization. The Comptonizing electron population forms the soft excess emission, with an electron temperature of ∼120–680 eV. Power-law, thermal plasma and disc BB models were also fitted to the soft X-ray excess. Of the sample, four of the active galactic nuclei are radio quiet and three radio loud. The radio-quiet QSOs may have slightly stronger soft excesses, although the electron temperatures cover the same range for both groups

XMM-Newton spectroscopy of high-redshift quasars

XMM–Newton observations of 29 high-redshift (z > 2) quasars, including seven radio-quiet, 16 radio-loud and six broad absorption line (BAL) objects, are presented; due to the high redshifts, the rest-frame energy bands extend up to ∼30–70 keV. Over 2–10 keV, the quasars can be well fitted in each case by a simple power law, with no strong evidence for iron emission lines. The lack of iron lines is in agreement both with dilution by the radio jet emission (for the radio-loud quasars) and the X-ray Baldwin effect. No Compton reflection humps at higher energies (i.e. above 10 keV in the rest frame) are detected either. Over the broad-band (0.3–10 keV), approximately half (nine out of 16) of the radio-loud quasars are intrinsically absorbed, with the values of N[subscript H] generally being 1 × 10²² to 2 × 10²² cm[superscript -]² in the rest frames of the objects. None of the seven radio-quiet objects shows excess absorption, while four of the six BAL quasars are absorbed. The radio-loud quasars have flatter continuum slopes than their radio-quiet counterparts (Γ[subscript RL] ∼ 1.55; Γ[subscript RQ] ∼ 1.98 over 2–10 keV), while, after modelling the absorption, the underlying photon index for the six BAL quasars is formally consistent with the non-BAL radio-quiet objects

Serendipitous active galactic nuclei in the XMM–Newton fields of Markarian 205 and QSO 0130−403

The X-ray spectra of serendipitously observed active galactic nuclei (AGN) in the XMM–Newton fields of Mrk 205 and QSO 0130−403 are analysed. The sample consists of 23 objects, none of which is detected at radio frequencies, with a median X-ray luminosity of ∼4 × 10[superscript 44] erg s[superscript −1] and redshifts ranging from ∼0.1 to just over 3. The mean photon index was found to be 1.89 ± 0.04. In contrast with past ASCA and ROSAT observations of high-redshift radio-loud quasars, we find little evidence for excess intrinsic absorption in these radio-quiet objects, with only three sources requiring a column density in excess of the Galactic value. Comparing the measured spectral indices over the redshift range, we also find there is no X-ray spectral evolution of quasi-stellar objects (QSOs) with time, up to redshift of 3. Within the sample there is no evidence for evolution of the optical to X-ray spectral index, α[subscript ox], with redshift, the mean value being −1.66 ± 0.04. However, upon comparing the values from the Bright Quasar Survey at low redshift (z 4), a slight steepening of αox is noted for the more distant objects. In most of the sources there is no significant requirement for a soft excess, although a weak thermal component (⩽ 10 per cent of L[subscript X]) cannot be excluded. There is an indication of spectral flattening (by ΔΓ = 0.2) at higher energies (>3 keV, QSO rest frame) for the sample as a whole. This is consistent with the presence of a Compton reflection component in these radio-quiet AGN, with the scattering medium (such as an accretion disc or molecular torus) occupying a solid angle of 2π sr to the X-ray source

A high-velocity ionized outflow and XUV photosphere in the narrow emission line quasar PG1211+143

We report on the analysis of a 60-ks XMM–Newton observation of the bright, narrow emission line quasar PG1211+143. Absorption lines are seen in both European Photon Imaging Camera and Reflection Grating Spectrometer spectra corresponding to H- and He-like ions of Fe, S, Mg, Ne, O, N and C. The observed line energies indicate an ionized outflow velocity of 24 000 km s1. The highest energy lines require a column density of NH 5 × 1023 cm2, at an ionization parameter of log ξ 3.4. If the origin of this high-velocity outflow lies in matter being driven from the inner disc, then the flow is likely to be optically thick within a radius of 130 Schwarzschild radii, providing a natural explanation for the big blue bump (and strong soft X-ray) emission in PG1211+143

The signature of supernova ejecta in the X-ray afterglow of the gamma-ray burst 011211

Now that γ-ray bursts (GRBs) have been determined to lie at cosmological distances, their isotropic burst energies are estimated to be as high as 10[superscript 54] erg (ref. 2), making them the most energetic phenomena in the Universe. The nature of the progenitors responsible for the bursts remains, however, elusive. The favoured models range from the merger of two neutron stars in a binary system[superscript 3-5] to the collapse of a massive star[superscript 6-8]. Spectroscopic studies of the afterglow emission could reveal details of the environment of the burst, by indicating the elements present, the speed of the outflow and an estimate of the temperature. Here we report an X-ray spectrum of the afterglow of GRB011211, which shows emission lines of magnesium, silicon, sulphur, argon, calcium and possibly nickel, arising in metal-enriched material with an outflow velocity of the order of one-tenth the speed of light. These observations strongly favour models[superscript 30] where a supernova explosion from a massive stellar progenitor precedes the burst event and is responsible for the outflowing matter

The European Photon Imaging Camera on XMM-Newton: The pn-CCD camera

The European Photon Imaging Camera (EPIC) consortium has provided the focal plane instruments for the three X-ray mirror systems on XMM-Newton. Two cameras with a reflecting grating spectrometer in the optical path are equipped with MOS type CCDs as focal plane detectors (Turner 2001), the telescope with the full photon flux operates the novel pn-CCD as an imaging X-ray spectrometer. The pn-CCD camera system was developed under the leadership of the Max-Planck-Institut für extraterrestrische Physik (MPE), Garching. The concept of the pn-CCD is described as well as the different operational modes of the camera system. The electrical, mechanical and thermal design of the focal plane and camera is briefly treated. The in-orbit performance is described in terms of energy resolution, quantum efficiency, time resolution, long term stability and charged particle background. Special emphasis is given to the radiation hardening of the devices and the measured and expected degradation due to radiation damage of ionizing particles in the first 9 months of in orbit operation