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MNRAS-2009-Croom-19-44.pdf (3.74 MB)

The 2dF-SDSS LRG and QSO Survey: the spectroscopic QSO catalogue

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posted on 2023-06-07, 21:24 authored by Scott M. Croom, Gordon T. Richards, Shanks Tom, Jonathan LovedayJonathan Loveday, et al
We present the final spectroscopic QSO catalogue from the 2dF-SDSS LRG (luminous red galaxy) and QSO (2SLAQ) survey. This is a deep, 18 < g < 21.85 (extinction corrected), sample aimed at probing in detail the faint end of the broad line active galactic nuclei luminosity distribution at z less than or similar to 2.6. The candidate QSOs were selected from SDSS photometry and observed spectroscopically with the 2dF spectrograph on the Anglo-Australian Telescope. This sample covers an area of 191.9 deg(2) and contains new spectra of 16 326 objects, of which 8764 are QSOs and 7623 are newly discovered [the remainder were previously identified by the 2dF QSO Redshift Survey (2QZ) and SDSS]. The full QSO sample (including objects previously observed in the SDSS and 2QZ surveys) contains 12 702 QSOs. The new 2SLAQ spectroscopic data set also contains 2343 Galactic stars, including 362 white dwarfs, and 2924 narrow emission-line galaxies with a median redshift of z = 0.22. We present detailed completeness estimates for the survey, based on modelling of QSO colours, including host-galaxy contributions. This calculation shows that at g less than or similar to 21.85 QSO colours are significantly affected by the presence of a host galaxy up to redshift z similar to 1 in the SDSS ugriz bands. In particular, we see a significant reddening of the objects in g - i towards the fainter g-band magnitudes. This reddening is consistent with the QSO host galaxies being dominated by a stellar population of age at least 2-3 Gyr. The full catalogue, including completeness estimates, is available on-line at


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