The 2dF Galaxy Redshift Survey: luminosity dependence of galaxy clustering

We investigate the dependence of the strength of galaxy clustering on intri nsic luminosity using the Anglo-Australian two degree field galaxy redshift survey (2dFGRS). The 2dFGRS is over an order of magnitude larger than prev ious redshift surveys used to address this issue. We measure the projected two-point correlation function of galaxies in a series of volume-limited sa mples. The projected correlation function is free from any distortion of th e clustering pattern induced by peculiar motions and is well described by a power law in pair separation over the range 0.1 < (r/h(-1) Mpc) < 10. The clustering of L*(M-bj - 5 log(10) h = -19.7) galaxies in real space is well -fitted by a correlation length r(0) = 4.9 +/- 0.3h(-1) Mpc and power-law s lope gamma = 1.71 +/- 0.06. The clustering amplitude increases slowly with absolute magnitude for galaxies fainter than M*, but rises more strongly at higher luminosities. At low luminosities, our results agree with measureme nts from the Southern Sky Redshift Survey 2 by Benoist et al. However, we f ind a weaker dependence of clustering strength on luminosity at the highest luminosities. The correlation function amplitude increases by a factor of 4.0 between M-bj - 5 log(10) h = -18 and -22.5, and the most luminous galax ies are 3.0 times more strongly clustered than L* galaxies. The power-law s lope of the correlation function shows remarkably little variation for samp les spanning a factor of 20 in luminosity. Our measurements are in very goo d agreement with the predictions of the hierarchical galaxy formation model s of Benson et al.