The 2dF-SDSS LRG and QSO survey: evolution of the clustering of luminous red galaxies since z = 0.6 - AstrophysicsReportar como inadecuado

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Abstract: We present an analysis of the small-to-intermediate scale clustering ofsamples of Luminous Red Galaxies LRGs from the Sloan Digital Sky Survey andthe 2dF-SDSS LRG and QSO 2SLAQ survey carefully matched to have the samerest-frame colours and luminosity. We study the spatial two-pointauto-correlation function in both redshift-space and real-space of a combinedsample of over 10,000 LRGs, which represent the most massive galaxies in theuniverse with stellar masses > 10^11 h^-1 M sun and space densities 10^-4 h^-3Mpc^-3. We find no significant evolution in the amplitude r 0 of thecorrelation function with redshift, but do see a slight decrease in the slopewith increasing redshift over 0.19 < z < 0.55 and scales of 0.32 < r < 32 h^-1Mpc. We compare our measurements with the predicted evolution of dark matterclustering and use the halo model to interpret our results. We find that ourclustering measurements are inconsistent >99.9% significance with a passivemodel whereby the LRGs do not merge with one another; a model with a mergerrate of 7.5 +- 2.3% from z = 0.55 to z = 0.19 i.e. an average rate of 2.4%Gyr^-1 provides a better fit to our observations. Our clustering and numberdensity measurements are consistent with the hypothesis that the merged LRGswere originally central galaxies in different haloes which, following themerger of these haloes, merged to create a single Brightest Cluster Galaxy. Inaddition, we show that the small-scale clustering signal constrains the scatterin halo merger histories. When combined with measurements of the luminosityfunction, our results suggest that this scatter is sub-Poisson. While this is ageneric prediction of hierarchical models, it has not been tested before.

Autor: David A. Wake, Ravi K. Sheth, Robert C. Nichol, Carlton M. Baugh, Joss Bland-Hawthorn, Russell Cannon, Matthew Colless, Warrick J


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