The clustering and evolution of massive galaxies

Abstract

In this thesis we investigate the clustering and evolutionary properties of massive galaxies. We present new measurements of galaxy clustering over a range of redshifts using data from the 2SLAQ Survey and the AAOmega LRG Pilot Survey. The clustering properties of Luminous Red Galaxies (LRGs) are measured using nearly 9 000 2SLAQ LRGs at a mean redshift of z = 0.55. We find that the real-space 2-point correlation function is well described by a single power-law of the form ع(r) = (r/ro)(^- ٦), where ٦ = 1.72 ± 0.06 and the correlation length ro = 7.45 ± 0.35 h (^-1) Мрc. Then we study the redshift-space distortions that are present in the clustering signal. From these dynamical and geometric distortions, we derive a value of Ω(_m) = 0.30 ± 0.15 and ß{z = 0.55) = 0.45 ± 0.05, where Ω(_m) is the present day matter density parameter and β = Ω(_m) /b where b is the linear bias parameter. We find for 2SLAQ LRGs, b(z = 0.55) = 1.66 ± 0.35. If one then assumes a "high-peaks" bias model, this value of b is consistent with the measured clustering strengths for low-redshift, massive early-type galaxies, under the assumption that gravitational growth leaves the comoving space density of early-types independent of redshift. We then use the new AAOmega instrument to perform a study of redshift z ~ 0.7 LRGs selected using riz-band photometry. We find a redshift-space correlation length of So = 9.9 ± 0.5 h-l Мрc and show that using LRGs as tracers would be a very competitive strategy for baryon acoustic oscillation studies in future galaxy redshift surveys. We also confirm that this population again has a clustering strength consistent with the above "high-peaks" bias model. Finally, we use data from the Spitzer and Hubble Space Telescopes taken in the COSMOS field and find tentative evidence for dust emission possibly coming from obscured star formation. We also show that z ~ 0.7 LRGs are predominantly early-type galaxies. [brace not closed]