Search

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 report the detection of X-ray emission from the hyperluminous infrared galaxy IRAS at and its properties obtained from XMM–Newton observations. Although the X-ray emission is very faint and the data are noisy, a prominent line-like feature in the observed 3–4 keV range is inferred from both photometric and spectroscopic techniques. It indicates an X-ray spectrum dominated by 6.4-keV Fe Kα emission and the presence of a Compton-thick active galactic nucleus. Our estimate of the luminosity of the illuminating source , required to produce the observed Fe Kα emission in reflection from cold matter, means that the hidden quasar nucleus accounts for a significant fraction of the large bolometric luminosity. The soft X-ray emission below 2 keV is found to be spatially extended and probably of a separate origin. The temperature and bolometric luminosity ( and ) obtained from a thermal spectrum place this X-ray source on the relation of galaxy clusters. The possible association with a galaxy cluster can be added to the list of remarkable similarities between IRAS and another hyperluminous infrared galaxy IRAS , both of which have bolometric luminosities dominated by hidden quasar nuclei. Our result on IRAS illustrates how difficult it is to detect Compton-thick Type II quasars at , particularly if their bolometric outputs do not rival the hyperluminous population. [ABSTRACT FROM AUTHOR]