Abstract
We present the first measurements of clustering in the Sloan Digital Sky Survey (SDSS) galaxy redshift survey. Our sample consists of 29,300 galaxies with redshifts 5700 km s-1 ≤ cz ≤ 39,000 km s-1, distributed in several long but narrow (25-5°) segments, covering 690 deg2. For the full, flux-limited sample, the redshift-space correlation length is approximately 8 h-1 Mpc. The two-dimensional correlation function ξ(rp,π) shows clear signatures of both the small-scale, fingers-of-God distortion caused by velocity dispersions in collapsed objects and the large-scale compression caused by coherent flows, though the latter cannot be measured with high precision in the present sample. The inferred real-space correlation function is well described by a power law, ξ(r) = (r/6.1 ± 0.2 h-1 Mpc)-1.75±0.03, for 0.1 h-1 Mpc ≤ r ≤ 16 h-1 Mpc. The galaxy pairwise velocity dispersion is σ12 ≈ 600 ± 100 km s-1 for projected separations 0.15 h-1 Mpc ≤ rp ≤ 5 h-1 Mpc. When we divide the sample by color, the red galaxies exhibit a stronger and steeper real-space correlation function and a higher pairwise velocity dispersion than do the blue galaxies. The relative behavior of subsamples defined by high/low profile concentration or high/low surface brightness is qualitatively similar to that of the red/blue subsamples. Our most striking result is a clear measurement of scale-independent luminosity bias at r 10 h-1 Mpc: subsamples with absolute magnitude ranges centered on M* - 1.5, M*, and M* + 1.5 have real-space correlation functions that are parallel power laws of slope ≈-1.8 with correlation lengths of approximately 7.4, 6.3, and 4.7 h-1 Mpc, respectively.
Highlights
The primary observational goals of the Sloan Digital Sky Survey (SDSS) are to image 10,000 deg2 of the north Galactic cap in five passbands, with an r-band limiting magnitude of 22.5, to obtain spectroscopic redshifts of 106 galaxies and 105 quasars, and to obtain similar data for three $200 deg2 stripes in the south Galactic cap, with repeated imaging to enable co-addition and variability studies in one of these stripes (York et al 2000)
This paper presents the first measurements of galaxy clustering from the SDSS redshift survey, based on a sample of $30,000 galaxies observed during commissioning operations and during the first few months of the survey proper
We have presented the first measurements of galaxy clustering from early SDSS spectroscopic data, based on a sample of 29,300 galaxies
Summary
The primary observational goals of the Sloan Digital Sky Survey (SDSS) are to image 10,000 deg of the north Galactic cap in five passbands, with an r-band limiting magnitude of 22.5, to obtain spectroscopic redshifts of 106 galaxies and 105 quasars, and to obtain similar data for three $200 deg stripes in the south Galactic cap, with repeated imaging to enable co-addition and variability studies in one of these stripes (York et al 2000). One of the principal scientific objectives is to map the large-scale structure traced by optical galaxies with unprecedented precision over a wide range of scales These measurements of large-scale structure will allow critical tests of cosmological models and theories of galaxy formation. The redshift-space clustering of galaxies has been a central concern of observational cosmology since the early studies of Gregory & Thompson (1978) and Joeveer & Einasto (1978). Two factors that complicate and enrich the interpretation of galaxy clustering in redshift surveys are the distortions of structure induced by peculiar velocities and the possibility that galaxies are ‘‘ biased ’’ tracers of the underlying matter distribution. A discussion of our jackknife error estimation procedure, and comparison of this procedure to results from mock redshift catalogs, appears in the Appendix
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