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Context.The infrared wide-field camera (WFCAM) is now in operation on the 3.8 m UK Infrared Telescope on Mauna Kea. WFCAM currently has the fastest survey speed of any infrared camera in the world, and combined with generous allocations of telescope time, will produce deep maps of the sky from Zto Kband. The data from a set of public surveys, known as UKIDSS, will be initially available to astronomers in ESO member states, and later to the world.

The IRAM Plateau de Bure mm interferometer and deep K-band imaging have been used to identify the brightest submm source detected in the Lockman field of the UK 8 mJy SCUBA survey. The near infrared counterpart is an extended (20-30 kpc), clumpy, and extremely red object. The spectral energy distribution suggests it to be a dusty star forming object at a redshift of about 3 (2-4). Its star formation rate and near-infrared properties are consistent with Lockman 850.1 being a massive elliptical in formation.

The high redshift sub-mm sources discovered by SCUBA are widely believed to represent the dust-enshrouded formation of massive elliptical galaxies. Given the strong evidence for a link between the formation of the spheroid and the growth of the central black hole, one might expect to see a luminous quasar at the nucleus of every SCUBA source. Somewhat surprisingly, however, only a very small fraction (~ 5%) are detected in X-rays. In this paper I discuss some of the implications of these results and discuss the accumulating evidence that sub-mm sources and quasars may represent different stages in the evolutionary sequence of a massive proto-spheroid.

We present additional optical spectroscopic identifications of sources identified in three deep ASCA GIS fields which also form part of a deep ROSAT survey. In total, 26 ASCA sources have been detected down to a 2–10 keV flux limit of S2−10 = 5 × 10⁻¹⁴ erg cm⁻² s⁻¹. Low Dispersion Survey Spectrograph observations have increased the spectroscopic completeness of the survey to between 65 and 85 per cent, with identifications for up to 13 QSOs with broad emission lines and six objects with narrow emission lines. Combining these objects with the AGN identified in the HEAO A-1 sample by Grossan, we find evidence for significant cosmological evolution in the 2–10 keV band (〈Ve/Va〉 = 0.63 ± 0.03), fitted by a pure luminosity evolution model: L ∝ (1 + z)^k, k = 2.04^+0.18−0.22. The present-epoch 2–10 keV AGN X-ray luminosity function, Φ(LX), is best represented by a two-power-law function: Φ(LX) ∝ L^−3.0, L^* > 10^44.1 erg s⁻¹; Φ(LX ∝ L^−1.9, L^* < 10^44.1 erg s⁻¹. Depending on the extent to which we extrapolate the z = 0 AGN luminosity function, we predict a total contribution to the 2–10 keV X-ray background from QSOs and narrow-emission-line galaxies which ranges from 48 per cent (for AGN with LX > 10⁴² erg s⁻¹) to 80 per cent (LX > 10³⁹ erg s⁻¹).

We report on the discovery of a narrow‐emission‐line object at z= 0.672 detected in a deep ASCAsurvey. The object, AXJ 0341.4–4453, has a flux in the 2–10 keV band of 1.1 ± 0.27 × 10−13erg s−1cm−2, corresponding to a luminosity of 1.8 × 1044erg s−1(q0= 0.5, H0= 50 km s−1Mpc−1). It is also marginally detected in the ROSAT0.5–2 keV band with a flux 5.8 × 10−15erg s−1cm−2. Both the ASCAdata alone and the combined ROSAT/ASCAdata show a very hard X‐ray spectrum, consistent with either a flat power law (α < 0.1) or photoelectric absorption with a column of nH> 4 × 1022cm−2(α = 1). The optical spectrum shows the high‐ionization, narrow emission lines typical of a Seyfert 2 galaxy. We suggest that this object may be typical of the hard sources required to explain the remainder of the X‐ray background at hard energies.