The Clustering Characteristics of H I-selected Galaxies from the 40% ALFALFA Survey
Abstract
The 40% Arecibo Legacy Fast ALFA survey catalog (α.40) of ~10,150 H I-selected galaxies is used to analyze the clustering properties of gas-rich galaxies. By employing the Landy-Szalay estimator and a full covariance analysis for the two-point galaxy-galaxy correlation function, we obtain the real-space correlation function and model it as a power law, ξ(r) = (r/r 0)-γ, on scales <10 h -1 Mpc. As the largest sample of blindly H I-selected galaxies to date, α.40 provides detailed understanding of the clustering of this population. We find γ = 1.51 ± 0.09 and r 0 = 3.3 + 0.3, -0.2 h -1 Mpc, reinforcing the understanding that gas-rich galaxies represent the most weakly clustered galaxy population known; we also observe a departure from a pure power-law shape at intermediate scales, as predicted in ΛCDM halo occupation distribution models. Furthermore, we measure the bias parameter for the α.40 galaxy sample and find that H I galaxies are severely antibiased on small scales, but only weakly antibiased on large scales. The robust measurement of the correlation function for gas-rich galaxies obtained via the α.40 sample constrains models of the distribution of H I in simulated galaxies, and will be employed to better understand the role of gas in environmentally dependent galaxy evolution.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- May 2012
- DOI:
- 10.1088/0004-637X/750/1/38
- arXiv:
- arXiv:1202.6005
- Bibcode:
- 2012ApJ...750...38M
- Keywords:
-
- galaxies: clusters: general;
- galaxies: distances and redshifts;
- large-scale structure of universe;
- radio lines: galaxies;
- surveys;
- Astrophysics - Cosmology and Extragalactic Astrophysics
- E-Print:
- 30 pages, 10 figures, accepted by ApJ