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The 2dF Galaxy Redshift Survey: stochastic relative biasing between galaxy populations

Wild, Vivienne and Peacock, John A. and Lahav, Ofer and Conway, Edward and Maddox, Steve and Baldry, Ivan K. and Baugh, Carlton M. and Bland-Hawthorn, Joss and Bridges, Terry and Cannon, Russell and Cole, Shaun and Colless, Matthew and Collins, Chris and Couch, Warrick and Dalton, Gavin and De Propris, Roberto and Driver, Simon P. and Efstathiou, George and Ellis, Richard S. and Frenk, Carlos S. and Glazebrook, Karl and Jackson, Carole and Lewis, Ian and Lumsden, Stuart and Madgwick, Darren and Norberg, Peder and Peterson, Bruce A. and Sutherland, Will and Taylor, Keith (2005) The 2dF Galaxy Redshift Survey: stochastic relative biasing between galaxy populations. Monthly Notices of the Royal Astronomical Society, 356 (1). pp. 247-269. ISSN 0035-8711. doi:10.1111/j.1365-2966.2004.08447.x.

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It is well known that the clustering of galaxies depends on galaxy type. Such relative bias complicates the inference of cosmological parameters from galaxy redshift surveys, and is a challenge to theories of galaxy formation and evolution. In this paper we perform a joint counts-in-cells analysis on galaxies in the 2dF Galaxy Redshift Survey, classified by both colour and spectral type, η, as early- or late-type galaxies. We fit three different models of relative bias to the joint probability distribution of the cell counts, assuming Poisson sampling of the galaxy density field. We investigate the non-linearity and stochasticity of the relative bias, with cubic cells of side 10 ⩽ L ⩽ 45 Mpc (h = 0.7). Exact linear bias is ruled out with high significance on all scales. Power-law bias gives a better fit, but likelihood ratios prefer a bivariate lognormal distribution, with a non-zero ‘stochasticity’, i.e. scatter that may result from physical effects on galaxy formation other than those from the local density field. Using this model, we measure a correlation coefficient in log-density space (r_(LN)) of 0.958 for cells of length L = 10 Mpc, increasing to 0.970 by L = 45 Mpc. This corresponds to a stochasticity σ_b/bˆ of 0.44 ± 0.02 and 0.27 ± 0.05, respectively. For smaller cells, the Poisson-sampled lognormal distribution presents an increasingly poor fit to the data, especially with regard to the fraction of completely empty cells. We compare these trends with the predictions of semi-analytic galaxy formation models: these match the data well in terms of the overall level of stochasticity, variation with scale and the fraction of empty cells.

Item Type:Article
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URLURL TypeDescription Paper
Baugh, Carlton M.0000-0002-9935-9755
Bland-Hawthorn, Joss0000-0001-7516-4016
Colless, Matthew0000-0001-9552-8075
Ellis, Richard S.0000-0001-7782-7071
Norberg, Peder0000-0002-5875-0440
Additional Information:© 2004 RAS. Accepted 2004 August 23. Received 2004 July 22; in original form 2004 March 16. The 2dF Galaxy Redshift Survey was made possible through the dedicated efforts of the staff of the Anglo-Australian Observatory, both in creating the 2dF instrument and in supporting it on the telescope. JAP and OL thank PPARC for their Senior Research Fellowships. Many thanks go to Paul Hewett, Yehuda Hoffman, Mike Irwin and Dan Mortlock for helpful discussions on galaxy evolution and statistics.
Funding AgencyGrant Number
Particle Physics and Astronomy Research Council (PPARC) UNSPECIFIED
Subject Keywords:methods: statistical, surveys, galaxies: distances and redshifts, galaxies: statistics, large-scale structure of Universe
Issue or Number:1
Record Number:CaltechAUTHORS:20200710-171317876
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Official Citation:Vivienne Wild, John A. Peacock, Ofer Lahav, Edward Conway, Steve Maddox, Ivan K. Baldry, Carlton M. Baugh, Joss Bland-Hawthorn, Terry Bridges, Russell Cannon, Shaun Cole, Matthew Colless, Chris Collins, Warrick Couch, Gavin Dalton, Roberto De Propris, Simon P. Driver, George Efstathiou, Richard S. Ellis, Carlos S. Frenk, Karl Glazebrook, Carole Jackson, Ian Lewis, Stuart Lumsden, Darren Madgwick, Peder Norberg, Bruce A. Peterson, Will Sutherland, Keith Taylor, The 2dF Galaxy Redshift Survey: stochastic relative biasing between galaxy populations, Monthly Notices of the Royal Astronomical Society, Volume 356, Issue 1, January 2005, Pages 247–269,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:104345
Deposited By: Rebecca Minjarez
Deposited On:15 Jul 2020 15:00
Last Modified:16 Nov 2021 18:30

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