The 2dF Galaxy Redshift Survey: luminosity functions by density environment and galaxy type |
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| Authors: | Darren J Croton Glennys R Farrar Peder Norberg Matthew Colless John A Peacock I K Baldry C M Baugh J Bland-Hawthorn T Bridges R Cannon S Cole C Collins W Couch G Dalton R De Propris S P Driver G Efstathiou R S Ellis C S Frenk K Glazebrook C Jackson O Lahav I Lewis S Lumsden S Maddox D Madgwick B A Peterson W Sutherland K Taylor |
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| Institution: | Max-Planck-Institut für Astrophysik, D-85740 Garching, Germany;Centre for Cosmology and Particle Physics, Department of Physics, New York University, New York, NY 10003, USA;ETHZ Institut für Astronomie, HPF G3.1, ETH Hönggerberg, CH-8093 Zürich, Switzerland;Anglo-Australian Observatory, PO Box 296, Epping, NSW 2111, Australia;Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ;Department of Physics &Astronomy, Johns Hopkins University, Baltimore, MD 21118-2686, USA;Department of Physics, University of Durham, South Road, Durham DH1 3LE;Department of Physics, Queen's University, Kingston, Ontario, K7L 3N6, Canada;Astrophysics Research Institute, Liverpool John Moores University, Twelve Quays House, Birkenhead L14 1LD;Department of Astrophysics, University of New South Wales, Sydney, NSW 2052, Australia;Department of Physics, University of Oxford, Keble Road, Oxford OX1 3RH;Space Science &Technology Division, Rutherford Appleton Laboratory, Chilton OX11 0QX;Research School of Astronomy &Astrophysics, The Australian National University, Weston Creek, ACT 2611, Australia;Astrophysics Group, Department of Physics, Bristol University, Tyndall Avenue, Bristol BS8 1TL;Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA;Department of Astronomy, California Institute of Technology, Pasadena, CA 91025, USA;CSIRO Australia Telescope National Facility, PO Box 76, Epping, NSW 1710, Australia;Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT;Department of Physics, University of Leeds, Woodhouse Lane, Leeds LS2 9JT;School of Physics &Astronomy, University of Nottingham, Nottingham NG7 2RD;Department of Astronomy, University of California, Berkeley, CA 94720, USA |
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| Abstract: | We use the 2dF Galaxy Redshift Survey to measure the dependence of the b J-band galaxy luminosity function on large-scale environment, defined by density contrast in spheres of radius 8 h ?1 Mpc , and on spectral type, determined from principal component analysis. We find that the galaxy populations at both extremes of density differ significantly from that at the mean density. The population in voids is dominated by late types and shows, relative to the mean, a deficit of galaxies that becomes increasingly pronounced at magnitudes brighter than M b J?5log10 h ??18.5 . In contrast, cluster regions have a relative excess of very bright early-type galaxies with M b J?5log10 h ??21 . Differences in the mid- to faint-end population between environments are significant: at M b J?5log10 h =?18 early- and late-type cluster galaxies show comparable abundances, whereas in voids the late types dominate by almost an order of magnitude. We find that the luminosity functions measured in all density environments, from voids to clusters, can be approximated by Schechter functions with parameters that vary smoothly with local density, but in a fashion that differs strikingly for early- and late-type galaxies. These observed variations, combined with our finding that the faint-end slope of the overall luminosity function depends at most weakly on density environment, may prove to be a significant challenge for models of galaxy formation. |
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| Keywords: | galaxies: luminosity function mass function galaxies: statistics large-scale structure of Universe |
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