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We have used the SINFONI near-infrared integral field unit on the Very Large Telescope to resolve the optical emission line structure of one of the brightest (LLyα ≈ 1044 erg s-1) and nearest (z ≈ 2.38) of all Lyα blobs (LABs). The target, known in the literature as object "B1", lies at a redshift where the main optical emission lines are accessible in the observed near-infrared.We detect luminous [O III] λλ4959,5007 and Hα emission with a spatial extent of at least 32 × 40 kpc (4" × 5"). The dominant optical emission line component shows relatively broad lines (600-800 km s-1, FWHM) and line ratios consistent with active galactic nucleus (AGN) photoionization. The new evidence for AGN photoionization, combined with previously detected C IV and luminous, warm infrared emission, suggest that B1 is the site of a hidden quasar. This is confirmed by the fact that [O II] is relatively weak compared with [O III] (extinction-corrected [O III]/[O II] of about 3.8), which is indicative of a high, Seyfert-like ionization parameter. From the extinction-corrected [O III] luminosity we infer a bolometric AGN luminosity of ~3×1046 erg s-1, and further conclude that the obscured AGN may be Compton-thick given existing X-ray limits. The large line widths observed are consistent with clouds moving within the narrow-line region of a luminous QSO. The AGN scenario is capable of producing sufficient ionizing photons to power the Lyα, even in the presence of dust. By performing a census of similar objects in the literature, we find that virtually all luminous LABs harbor obscured quasars. Based on simple duty-cycle arguments, we conclude that AGNs are the main drivers of the Lyα in LABs rather than the gravitational heating and subsequent cooling suggested by cold stream models. We also conclude that the empirical relation between LABs and overdense environments at high redshift must be due to a more fundamental correlation between AGNs (or massive galaxies) and environment. [ABSTRACT FROM AUTHOR]

In this Letter we report the serendipitous discovery of a genuine type II quasar at using integral-field data from the Visual Multi-Object Spectrograph (VIMOS) on the Very Large Telescope (VLT). This is the first discovery of a type II quasar at from optical data alone. J094531-242831, hereafter J0945-2428, exhibits strong narrow emission lines, has a resolved host galaxy, and is undetected to a radio flux density limit of . All of these characteristics lead us to believe that J0945-2428 is a bona fide type II quasar. The luminosity of the narrow emission lines in this object suggest that the intrinsic power of the central engine is similar to that found in powerful radio galaxies, indicative of a similarly large supermassive black hole of (assuming that it is accreting at its Eddington limit). However, from near-infrared imaging observations we find that the old stellar population in the host galaxy has a luminosity of ∼ 0.2 L⋆, mildly inconsistent with the correlation between black hole mass and bulge luminosity found locally, although the uncertainty in the black hole mass estimate is large. This discovery highlights the power that integral-field units have in discovering hidden populations of objects, particularly the sought-after type II quasars, which are invoked to explain the hard X-ray background. As such, future large integral-field surveys could open up a new window on the obscured accretion activity in the Universe. [ABSTRACT FROM AUTHOR]

We present VLT-UVES echelle spectroscopy of the H I and C IV absorption in the spatially extended Lyα emission around two high-redshift radio galaxies 0200 + 015 (z = 2.23) and 0943-242 (z = 2.92). The absorbers in 0943-242 exhibit little additional structure compared with previous lowresolution spectroscopy and the main absorber is still consistent with a H I column density of ∼ 10[sup 19] cm[sup -2]. This is consistent with a picture in which the absorbing gas has low density and low metallicity and is distributed in a smooth absorbing shell located beyond the emission-line gas. However, the main absorbers in 0200 + 015 are very different. The previous single-absorber fit of H I column density ...10[sup 19] cm[sup -2] now splits into two ∼4 × 10[sup 14] cm[sup -2] absorbers which extend more than 15 kpc to obscure additional Lyα emission coincident with a radio lobe in these high-resolution observations. Although consistent with the shell-like distribution for the absorption systems, 0200 + 015 requires a much higher metal enrichment than 0943-242. The metallicity, inferred from the C IV absorption, is considerably lower in 0943-242 than in 0200 + 015. We explain these differences with an evolutionary scenario based on the size of the radio source. In both sources the H I absorption gas originates from either a gas-rich merger or pristine cluster gas which cools and collapses towards the centre of the dark matter halo. The higher metallicity in the larger radio source (0200 + 015) may be a result of a starburst-driven superwind (concurrent with the triggering of the radio emission) which has engulfed the outer halo in this older source. We also find a significant blue asymmetry in the He II λ 1640 emission line, suggesting that the line-emitting gas is outflowing from the central regions. Dust obscuration toward the central engine, presumably due to the dusty toms invoked in the unified scheme, prevents us from seeing outflow... [ABSTRACT FROM AUTHOR]

We present VLT-UVES echelle spectroscopy of the H I and C IV absorption in the spatially extended Lyα emission around two high-redshift radio galaxies 0200 + 015 (z = 2.23) and 0943-242 (z = 2.92). The absorbers in 0943-242 exhibit little additional structure compared with previous lowresolution spectroscopy and the main absorber is still consistent with a H I column density of ∼ 10[sup 19] cm[sup -2]. This is consistent with a picture in which the absorbing gas has low density and low metallicity and is distributed in a smooth absorbing shell located beyond the emission-line gas. However, the main absorbers in 0200 + 015 are very different. The previous single-absorber fit of H I column density ...10[sup 19] cm[sup -2] now splits into two ∼4 × 10[sup 14] cm[sup -2] absorbers which extend more than 15 kpc to obscure additional Lyα emission coincident with a radio lobe in these high-resolution observations. Although consistent with the shell-like distribution for the absorption systems, 0200 + 015 requires a much higher metal enrichment than 0943-242. The metallicity, inferred from the C IV absorption, is considerably lower in 0943-242 than in 0200 + 015. We explain these differences with an evolutionary scenario based on the size of the radio source. In both sources the H I absorption gas originates from either a gas-rich merger or pristine cluster gas which cools and collapses towards the centre of the dark matter halo. The higher metallicity in the larger radio source (0200 + 015) may be a result of a starburst-driven superwind (concurrent with the triggering of the radio emission) which has engulfed the outer halo in this older source. We also find a significant blue asymmetry in the He II λ 1640 emission line, suggesting that the line-emitting gas is outflowing from the central regions. Dust obscuration toward the central engine, presumably due to the dusty toms invoked in the unified scheme, prevents us from seeing outflow... [ABSTRACT FROM AUTHOR]

We present optical spectra and near-infrared imaging of a sample of 31 serendipitous X-ray sources detected in the field of Chandra observations of the A 2390 cluster of galaxies. The sources have 0.5–7 keV fluxes of (0.6–8)×10[sup -14] erg cm[sup -2] s[sup -1] and lie around the break in the 2–10 keV source counts. They are therefore typical of sources dominating the X-ray Background in that band. 12 of the 15 targets for which we have optical spectra show emission lines at a range of line luminosities, and half of these show broad lines. These active galaxies and quasars have soft X-ray spectra. Including photometric redshifts and published spectra, we have redshifts for 17 of the sources, ranging from z∼0.2 up to z∼3 , with a peak between z=1–2 . 10 of our sources have hard X-ray spectra indicating a spectral slope flatter than that of a typical unabsorbed quasar. Two hard sources that are gravitationally lensed by the foreground cluster are obscured quasars, with intrinsic 2–10 keV luminosities of (0.2–3)×10[sup 45] erg s[sup -1] , and absorbing columns of N[sub H]>10[sup 23] cm[sup -2] . Both of these sources were detected in the mid-infrared by ISOCAM on the Infrared Space Observatory, which when combined with radiative transfer modelling leads to the prediction that the bulk of the reprocessed flux emerges at ∼100 μm. [ABSTRACT FROM AUTHOR]