COUNTS-IN-CYLINDERS IN THE SLOAN DIGITAL SKY SURVEY WITH COMPARISONS TO N-BODY SIMULATIONS
- Center for Cosmology, Department of Physics and Astronomy, University of California at Irvine, Irvine, CA 92697 (United States)
- Department of Physics, University of Arkansas, 825 West Dickson Street, Fayetteville, AR 72701 (United States)
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260 (United States)
- Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics, and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States)
Environmental statistics provide a necessary means of comparing the properties of galaxies in different environments, and a vital test of models of galaxy formation within the prevailing hierarchical cosmological model. We explore counts-in-cylinders, a common statistic defined as the number of companions of a particular galaxy found within a given projected radius and redshift interval. Galaxy distributions with the same two-point correlation functions do not necessarily have the same companion count distributions. We use this statistic to examine the environments of galaxies in the Sloan Digital Sky Survey Data Release 4 (SDSS DR4). We also make preliminary comparisons to four models for the spatial distributions of galaxies, based on N-body simulations and data from SDSS DR4, to study the utility of the counts-in-cylinders statistic. There is a very large scatter between the number of companions a galaxy has and the mass of its parent dark matter halo and the halo occupation, limiting the utility of this statistic for certain kinds of environmental studies. We also show that prevalent empirical models of galaxy clustering, that match observed two- and three-point clustering statistics well, fail to reproduce some aspects of the observed distribution of counts-in-cylinders on 1, 3, and 6 h{sup -1} Mpc scales. All models that we explore underpredict the fraction of galaxies with few or no companions in 3 and 6 h{sup -1} Mpc cylinders. Roughly 7% of galaxies in the real universe are significantly more isolated within a 6 h{sup -1} Mpc cylinder than the galaxies in any of the models we use. Simple phenomenological models that map galaxies to dark matter halos fail to reproduce high-order clustering statistics in low-density environments.
- OSTI ID:
- 21567728
- Journal Information:
- Astrophysical Journal, Vol. 726, Issue 1; Other Information: DOI: 10.1088/0004-637X/726/1/1; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
Similar Records
Extensions to models of the galaxy–halo connection
Cosmological Constraints from the Clustering of the Sloan Digital Sky Survey DR7 Luminous Red Galaxies