The clustering of galaxies in the SDSS-III DR10 Baryon Oscillation Spectroscopic Survey: no detectable colour dependence of distance scale or growth rate measurements

Citation:

Ross AJ, Samushia L, Burden A, Percival WJ, Tojeiro R, Manera M, Beutler F, Brinkmann J, Brownstein JR, Carnero A, et al. The clustering of galaxies in the SDSS-III DR10 Baryon Oscillation Spectroscopic Survey: no detectable colour dependence of distance scale or growth rate measurements. Monthly Notices of the Royal Astronomical Society. 2014;437 :1109-1126.

Date Published:

January 1, 2014

Abstract:

We study the clustering of galaxies, as a function of their colour, fromData Release Ten (DR10) of the Sloan Digital Sky Survey III (SDSS-III)Baryon Oscillation Spectroscopic Survey. DR10 contains 540 505 galaxieswith 0.43 < z < 0.7; from these we select 122 967 for a `Blue'sample and 131 969 for a `Red' sample based on k + e corrected (to z =0.55) r - i colours and i-band magnitudes. The samples are chosen suchthat both contain more than 100 000 galaxies, have similar redshiftdistributions and maximize the difference in clustering amplitude. TheRed sample has a 40 per cent larger bias than the Blue(bRed/bBlue = 1.39 ± 0.04), implying thatthe Red galaxies occupy dark matter haloes with an average mass that is0.5 log10 M greater. Spherically averagedmeasurements of the correlation function, ξ0, and thepower spectrum are used to locate the position of the baryon acousticoscillation (BAO) feature of both samples. Using ξ0, weobtain distance scales, relative to the distance of our referenceΛ cold dark matter cosmology, of 1.010 ± 0.027 for the Redsample and 1.005 ± 0.031 for the Blue. After applyingreconstruction, these measurements improve to 1.013 ± 0.020 forthe Red sample and 1.008 ± 0.026 for the Blue. For each sample,measurements of ξ0 and the second multipole moment,ξ2, of the anisotropic correlation function are used todetermine the rate of structure growth, parametrized byfσ8. We find fσ8, Red = 0.511 ±0.083, fσ8, Blue = 0.509 ± 0.085 andfσ8, Cross = 0.423 ± 0.061 (from thecross-correlation between the Red and Blue samples). We use thecovariance between the bias and growth measurements obtained from eachsample and their cross-correlation to produce an optimally combinedmeasurement of fσ8, comb = 0.443 ± 0.055. Thisresult compares favourably to that of the full 0.43 < z < 0.7sample (fσ8, full = 0.422 ± 0.051) despite thefact that, in total, we use less than half of the number of galaxiesanalysed in the full sample measurement. In no instance do we detectsignificant differences in distance scale or structure growthmeasurements obtained from the Blue and Red samples. Our results areconsistent with theoretical predictions and our tests on mock samples,which predict that any colour-dependent systematic uncertainty on themeasured BAO position is less than 0.5 per cent.

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