Abstract. The XMM-OM instrument extends the spectral coverage of the XMM-Newton observatory into the ultraviolet and optical range. It provides imaging and time-resolved data on targets simultaneously with observations in the EPIC and RGS. It also has the ability to track stars in its field of view, thus providing an improved post-facto aspect solution for the spacecraft. An overview of the XMM-OM and its operation is given, together with current information on the performance of the instrument.

Abstract. The initial results from XMM-Newton observations of the rich cluster of galaxies Abell 1795 are presented. The spatially-resolved X-ray spectra taken by the European Photon Imaging Cameras (EPIC) show a temperature drop at a radius of ∼200 kpc from the cluster center, indicating that the ICM is cooling. Both the EPIC and the Reflection Grating Spectrometers (RGS) spectra extracted from the cluster center can be described by an isothermal model with a temperature of ∼4 keV. The volume emission measure of any cool component (< 1 keV) is less than a few % of the hot component at the cluster center. A strong O viii Lyman α line was detected with the RGS from the cluster core. The O abundance and its ratio to Fe at the cluster center is 0.2-0.5 and 0.5-1.5 times the solar value, respectively.

We present an analysis of the submillimetre/X‐ray properties of 19 X‐ray absorbed, Compton‐thin quasi‐stellar objects (QSOs) selected to have luminosities and redshifts that represent the peak of cosmic QSO activity, i.e. ∼ L* objects at 1 < z < 3. Of these, we present new data for 11 objects not previously observed at submillimetre wavelengths and additional data for a further three. The detection rate is 42 per cent, much higher than typically reported for samples of QSOs. Detection statistics show (at the 3–4σ level) that this sample of absorbed QSOs has a higher submillimetre output than a matched sample of unabsorbed QSOs. We argue that the far‐infrared luminosity is produced by massive star formation. In this case, the correlation found between far‐infrared luminosity and redshift can be interpreted as cosmological evolution of the star formation rate in the QSO host galaxies. Because the submillimetre luminous phase is confined to z > 1.5, the high star formation rates are consistent with a scenario in which the QSOs evolve to become local luminous elliptical galaxies. Combining these results with previously published data for X‐ray unabsorbed QSOs and submillimetre‐selected galaxies, we propose the following evolutionary sequence: the forming galaxy is initially far‐infrared luminous but X‐ray weak similar to the sources discovered by the Submillimetre Common‐User Bolometer Array (SCUBA); as the black hole and spheroid grow with time, a point is reached when the central QSO becomes powerful enough to terminate the star formation and eject the bulk of the fuel supply (the Compton‐thin absorbed QSO phase); this transition is followed by a period of unobscured QSO activity, which subsequently declines to leave a quiescent spheroidal galaxy.

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The correlation, found in nearby galaxies, between black hole mass and stellar bulge mass implies that the formation of these two components must be related. Here we report submillimeter photometry of eight x-ray absorbed active galactic nuclei which have luminosities and redshifts characteristic of the sources that produce the bulk of the accretion luminosity in the universe. The four sources with the highest redshifts are detected at 850 microns, with flux densities between 5.9 and 10.1 milliJanskies, and hence are ultraluminous infrared galaxies. Interpreting the submillimeter flux as emission from dust heated by starbursts, these results suggest that the majority of stars in spheroids were formed at the same time as their central black holes built up most of their mass by accretion, accounting for the observed demography of massive black holes in the local universe. The skewed rate of submillimeter detection with redshift is consistent with a high redshift epoch of star formation in radio quiet active galactic nuclei, similar to that seen in radio galaxies.In the local universe, central black holes are found in most galaxy spheroids (a collective term for elliptical galaxies and the bulges of spiral galaxies) with mass roughly proportional to that of the spheroid (0.13% ±0.4 dex) (1). The simplest explanation for this proportionality is that the black hole mass is built up in active galactic nuclei (AGN) by accretion of the same gas that is rapidly forming the stars which make up the spheroid, i.e. the formation of the spheroid and the growth of the massive black hole are coeval. Assuming that 10% of the spheroid mass M is converted from hydrogen to helium in stars (2) at an efficiency of 0.007 and radiated, and that 0.13% of the spheroid mass M is accreted by the central black hole (1) at 10% efficiency, the ratio of radiation emitted by the starburst (E SB ) to that emitted by the AGN (E AGN )is:

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We present measurements of the optical and X-ray continua of 108 AGN (Seyfert 1s and quasars) from the Rosat International X-ray/Optical Survey (RIXOS). The sample covers a wide range in redshift (0 < z < 3.3), in X-ray spectral slope (-1.5<α x <2.6) and in optical-to-X-ray ratio (0.4<α ox <1.5). A correlation is found between α x and α ox ; similar correlations have recently been reported in other X-ray and optical samples. We also identify previously unreported relationships between the optical slope (α opt ) and α x (particularly at high redshifts) and between α opt and α ox . These trends show that the overall optical-to-X-ray continuum changes from convex to concave as α x hardens, demonstrating a strong behavioural link between the optical/UV big blue bump (BBB) and the soft X-ray excess, which is consistent with them being part of the same spectral component.By constructing models of the optical-to-X-ray continuum, we demonstrate that the observed correlations are consistent with an intrinsic spectrum which is absorbed through different amounts of cold gas and dust. The intrinsic spectrum is the sum of an optical-to-soft X-ray 'big bump' component and an α x =1 power law; the column density of the cold gas ranges from 0 to ∼ 4 × 10 21 cm −2 and the dust-to-gas ratio is assumed to be Galactic. The 'big bump' may be represented by a T brem ∼ 10 6 K thermal bremsstrahlung or an accretion disk with a surrounding hot corona. The scatter in the data can accommodate a wide range in big bump temperature (or black hole mass) and strength. A source for the absorbing gas may be the dusty, molecular torus which lies beyond the broad line-emitting regions, although with a much lower column density than observed in Seyfert 2 galaxies. Alternatively, it may be the bulge of a spiral host galaxy or an elliptical host galaxy.

A B S T R A C TA total of 235 active galactic nuclei (AGN) from two different soft X-ray surveys [the ROSAT Deep Survey (DRS) and the ROSAT International X-ray Optical Survey (RIXOS)] with redshifts between 0 and 3.5 are used to study the clustering of X-ray selected AGN and its evolution. A 2j significant detection of clustering of such objects is found on scales < 40-80 h ¹1 Mpc in the RIXOS sample, while no clustering is detected on any scales in the DRS sample. Assuming a single power-law model for the spatial correlation function (SCF), quantitative limits on the AGN clustering have been obtained: a comoving correlation length 1:5 Շ r 0 Շ 3:3 h ¹1 Mpc is implied for comoving evolution, while 1:9 Շ r 0 Շ 4:8 for stable clustering and 2:2 Շ r 0 Շ 5:5 for linear evolution. These values are consistent with the correlation lengths and evolutions obtained for galaxy samples, but imply smaller amplitude or faster evolution than recent ultraviolet and optically selected AGN samples. We also constrain the ratio of bias parameters between X-ray selected AGN and IRAS galaxies to be Շ1:7 on scales Շ10 h ¹1 Mpc, a somewhat smaller value than is inferred from local large-scale dynamical studies.