Clustering of quasars.

Faint stars with ultraviolet excess are often found to be quasi-stellar objects (QSOs). We have formed a complete sample of such stars at the South Galactic Pole using machine measurements of UK Schmidt photographs. Statistical analysis of the stars' sky distribution shows evidence both that they are clustered amongst themselves and that they are anti-clustered with respect to faint galaxies

A brief mental health outcome scale: relationships between scale scores and diagnostic/sociodemographic variables in the long-term mentally ill.

A brief mental health outcomes scale: relationships between scale scores and diagnostic/sociodemographic variables in the long-term mentally ill The Global Assessment of Functioning (GAF) scale is a quick and simple measure of overall psychological disturbance. A recent study by our group reported the reliability and validity of the scale in a population of severely mentally ill people. The current study extends the analysis of this population to consider a number of questions, i.e. what are the associations for this group between variations in GAF scores and sociodemographic variables? Are lower scores associated with particular diagnoses for the group assessed? What are the characteristics of those patients whose scores were most variable? What were the completion rates for use of the scale? No associations were observed between GAF score and the sociodemographic variables used in this study. Lower GAF scores were associated with psychotic diagnoses. Those with most varying scores were, in the main, white European nonimmigrant males with a diagnosis of schizophrenia. Completion rates for the study were reasonable at 73.8%. This study involved the repeated assessment of a large number of clients by a changing multidisciplinary team. Inspite of the extended nature of the study, completion rates remained reasonable, suggesting that the scale was acceptable for routine clinical use. The GAF in itself, however, appears to be unsuitable for making individual treatment decisions but could be used as a first step before using more sophisticated scales

The evolution of host mass and black hole mass in quasi-stellar objects from the 2dF QSO Redshift Survey

We investigate the relation between the mass of super-massive black holes (Mbh) in QSOs and the mass of the dark matter halos hosting them (Mdh). We measure the widths of broad emission lines (Mgii lambda 2798, Civ lambda 1549) from QSO composite spectra as a function of redshift. These widths are then used to determine virial black hole mass estimates. We compare our virial black hole mass estimates to dark matter halo masses for QSO hosts derived by Croom et al. (2005) based on measurements of QSO clustering. This enables us to trace the Mbh-Mdh relation over the redshift range z=0.5 to 2.5. We calculate the mean zero-point of the Mbh-Mdh relation to be Mbh=10^(8.4+/-0.2)Msun for an Mdh=10^(12.5)Msun. These data are then compared with several models connecting Mbh and Mdh as well as recent hydrodynamical simulations of galaxy evolution. We note that the flux limited nature of QSO samples can cause a Malmquist-type bias in the measured zero-point of the Mbh-Mdh relation. The magnitude of this bias depends on the scatter in the Mbh-Mdh relation, and we reevaluate the zero-point assuming three published values for this scatter. (abridged)Comment: 11 pages, 4 figures, accepted for publication in MNRA

The 2dF-SDSS LRG and QSO survey: the QSO luminosity function at 0.4 \lt z \lt 2.6

We present the QSO luminosity function of the completed 2dF-SDSS LRG and QSO (2SLAQ) survey, based on QSOs photometrically selected from Sloan Digital Sky Survey imaging data and then observed spectroscopically using the 2dF instrument on the Anglo-Australian Telescope. We analyse 10637 QSOs in the redshift range 0.4<z<2.6 to a g-band flux limit of 21.85 (extinction corrected) and an absolute continuum magnitude of Mg(z=2)<-21.5. This sample covers an area of 191.9 deg^2. The binned QSO luminosity function agrees with that of the brighter SDSS main QSO sample, but extends ~2.5 mags fainter, clearly showing the flattening of the luminosity function towards faint absolute magnitudes. 2SLAQ finds an excess of QSOs compared to the 2dF QSO Redshift Survey at g>20.0, as found previously by Richards et al. (2005). The luminosity function is consistent with other previous, much smaller, samples produced to the depth of 2SLAQ. By combining the 2SLAQ and SDSS QSO samples we produce a QSO luminosity function with an unprecedented combination of precision and dynamic range. With this we are able to accurately constrain both the bright and faint ends of the QSO LF. While the overall trends seen in the evolution of the QSO LF appear similar to pure luminosity evolution, the data show very significant departures from such a model. Most notably we see clear evidence that the number density of faint QSOs peaks at lower redshift than bright QSOs: QSOs with Mg>-23 have space densities which peak at z2. By fitting simple luminosity function models in narrow Mg intervals we find that this downsizing is significant at the 99.98 per cent level (abridged).Comment: 20 pages, 18 figures. Accepted for publication in MNRAS. The data on which this paper is based can be accessed at http://www.2slaq.info

Digital Sky Surveys from the ground: Status and Perspectives

I first review the status of Digital Sky Surveys. The focus will be on extragalactic surveys with an area of more than 100 deg2. The Sloan Digital Sky Survey is the archetype of such imaging surveys and it is its great success that has prompted great activity in this field. The latest surveys explore wider, fainter and higher resolution and also a longer wavelength range than SDSS. Many of these surveys overlap particularly in the S Hemisphere where we now have Pan-STARRS, DES and the ESO VST surveys, and our aim here is to compare their properties. Since there is no dedicated article on the VST ATLAS in this symposium, we shall especially review the properties of this particular survey. This easily fits onto our other main focus which is to compare overlapping Southern Surveys and see how they best fit with the available NIR imaging data. We conclude that the Southern Hemisphere will soon overtake the North in terms of multiwavelength imaging. However we note that the South has more limited opportunities for spectroscopic follow-up and this weakness will persist during the LSST era. Some new perspectives are offered on this and other aspects of survey astronomy

The VLT Survey Telescope ATLAS

The VLT Survey Telescope ATLAS survey is an optical ugriz survey aiming to cover ≈4700 deg2 of the southern sky to similar depths as the Sloan Digital Sky Survey (SDSS). From reduced images and object catalogues provided by the Cambridge Astronomical Surveys Unit, we first find that the median seeing ranges from 0.8 arcsec FWHM (full width at half-maximum) in i to 1.0 arcsec in u, significantly better than the 1.2–1.5 arcsec seeing for SDSS. The 5σ mag limit for stellar sources is rAB = 22.7 and in all bands these limits are at least as faint as SDSS. SDSS and ATLAS are more equivalent for galaxy photometry except in the z band where ATLAS has significantly higher throughput. We have improved the original ESO magnitude zero-points by comparing m < 16 star magnitudes with the AAVSO Photometric All-Sky Survey in gri, also extrapolating into u and z, resulting in zero-points accurate to ≈ ± 0.02 mag. We finally compare star and galaxy number counts in a 250 deg2 area with SDSS and other count data and find good agreement. ATLAS data products can be retrieved from the ESO Science Archive, while support for survey science analyses is provided by the OmegaCAM Science Archive, operated by the Wide-Field Astronomy Unit in Edinburgh