Open AccessThe 2dF Galaxy Redshift Survey: the amplitudes of fluctuations in the 2dFGRS and the CMB, and implications for galaxy biasing
Author(s) -
Lahav Ofer,
Bridle Sarah L.,
Percival Will J.,
Peacock John A.,
Efstathiou George,
Baugh Carlton M.,
BlandHawthorn Joss,
Bridges Terry,
Can Russell,
Cole Shaun,
Colless Matthew,
Collins Chris,
Couch Warrick,
Dalton Gavin,
Propris Roberto De,
Driver Simon P.,
Ellis Richard S.,
Frenk Carlos S.,
Glazebrook Karl,
Jackson Carole,
Lewis Ian,
Lumsden Stuart,
Maddox Steve,
Madgwick Darren S.,
Moody Stephen,
Norberg Peder,
Peterson Bruce A.,
Sutherland Will,
Taylor Keith
Publication year - 2002
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2002.05485.x
Subject(s) - physics , astrophysics , cosmic microwave background , reionization , galaxy , cmb cold spot , omega , redshift , hubble's law , galaxy cluster , amplitude , planck , cosmic background radiation , astronomy , anisotropy , quantum mechanics
We compare the amplitudes of fluctuations probed by the 2dF Galaxy Redshift Survey (2dFGRS) and by the latest measurements of the cosmic microwave background (CMB) anisotropies. By combining the 2dFGRS and CMB data, we find the linear‐theory rms mass fluctuations in 8 h −1 Mpc spheres to be σ 8m =0.73±0.05 (after marginalization over the matter density parameter Ω m and three other free parameters). This normalization is lower than the COBE normalization and previous estimates from cluster abundance, but it is in agreement with some revised cluster abundance determinations. We also estimate the scale‐independent bias parameter of present‐epoch L s =1.9 L ∗ APM‐selected galaxies to be b ( L s , z =0)=1.10±0.08 on comoving scales of 0.02< k <0.15 h Mpc ‐1 . If luminosity segregation operates on these scales, L ∗ galaxies would be almost unbiased, b ( L * , z =0)≈0.96 . These results are derived by assuming a flat ΛCDM Universe, and by marginalizing over other free parameters and fixing the spectral index n =1 and the optical depth due to reionization τ =0 . We also study the best‐fitting pair (Ω m , b ), and the robustness of the results to varying n and τ . Various modelling corrections can each change the resulting b by 5–15 per cent. The results are compared with other independent measurements from the 2dFGRS itself, and from the Sloan Digital Sky Survey (SDSS), cluster abundance and cosmic shear.