Alignment between galaxies and large-scale structure
Alignment between galaxies and large-scale structure作者机构：Max-Planck-Institute for Astrophysics Karl-Schwarzschild-Str. 1 D-85741 Garching Germany MPA/SHAO Joint Center for Astrophysical Cosmology at Shanghai Astronomical Observatory Shanghai 200030 China Jodrell Bank Centre for Astrophysl＇cs Alan Turing Building The University of Manchester Manchester M13 9PL UK Department of Physics Institute of Computational Cosmology University of Durham Science Laboratories South Road Durham DH1 3LE UK
出 版 物：《Chinese Journal of Astronomy and Astrophysics》 (中国天文和天体物理学报（英文版）)
年 卷 期：2009年第9卷第1期
页 面：41-58页
核心收录：
学科分类：07[理学] 070401[理学-天体物理] 0704[理学-天文学]
基 金：supported by NSFC (Nos. 10533030, 10821302,10878001) the Knowledge Innovation Program of CAS (No. KJCX2-YW-T05) by 973 Program(No. 2007CB815402)
主 题：dark matter halos clustering-galaxies large-scale structure of Universe- cosmology theory -dark matter
摘 要：Based on the Sloan Digital Sky Survey DR6 （SDSS） and the ＇Millennium Simulation （MS）, we investigate the alignment between galaxies and large-scale structure. For this purpose, we develop two new statistical tools, namely the alignment correlation function and the cos（20）-statistic. The former is a two-dimensional extension of the traditional two-point correlation function and the latter is related to the ellipticity correlation function used for cosmic shear measurements. Both are based on the cross correlation between a sample of galaxies with orientations and a reference sample which represents the large-scale structure. We apply the new statistics to the SDSS galaxy catalog. The alignment correlation function reveals an overabundance of reference galaxies along the major axes of red, luminous （L 〉 ～L＊） galaxies out to projected separations of 60 h-lMpc. The signal increases with central galaxy luminosity. No alignment signal is detected for blue galaxies. The cos（2θ）-statistic yields very similar results. Starting from a MS semi-analytic galaxy catalog, we assign an orientation to each red, luminous and central galaxy, based on that of the central region of the host halo （with size similar to that of the stellar galaxy）. As an alternative, we use the orientation of the host halo itself. We find a mean projected misalignment between a halo and its central region of -25°. The misalignment decreases slightly with increasing luminosity of the central galaxy. Using the orientations and luminosities of the semi-analytic galaxies, we repeat our alignment analysis on mock surveys of the MS. Agreement with the SDSS results is good if the central orientations are used. Predictions using the halo orientations as proxies for cen- tral galaxy orientations overestimate the observed alignment by more than a factor of 2. Finally, the large volume of the MS allows us to generate a two-dimensional map of the alignment correlation function, which shows the reference galaxy distrib
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