The Stromlo-APM Redshift Survey. II. Variation of Galaxy Clustering with Morphology and Luminosity
Abstract
We present clustering measurements for samples of galaxies selected by morphological type and luminosity from the recently completed Stromlo-APM redshift survey. We find very different results between real and redshift-space estimates of the correlation function. The real space correlation function for the all-galaxies sample is well fitted on scales 0.2-20h^-1^ Mpc by a power law with slope γ_r_ = 1.71 and correlation length r_0_ = 5.1h^-1^ Mpc. In redshift space the slope is shallower, γ_S_ = 1.47 and the correlation length is slightly higher, s_0_ = 59h^-1^ Mpc. Early-type galaxies are clustered more strongly by a factor 3.5-S.5, than late-type galaxies. In real space the slope of the correlation function for early-type galaxies is γ_r_ = 1.85, slightly steeper than for late types, γ_r_ = 1.64. In redshift space, however, early-type galaxies have a very shallow correlation function slope, γ_S_ = 1.25. This implies that these early-type galaxies suffer from enhanced redshift-space distortions compared to late-type galaxies. Low-luminosity galaxies are clustered more weakly by a factor of ~2 than L^*^ and brighter galaxies on scales ~> 1h^-1^ Mpc. Also the slope of the correlation function is steeper for low-luminosity galaxies, so that the amplitude is a factor 4 lower at 10h^-1^ Mpc. No difference, however, is seen between the clustering of L^*^ and more luminous galaxies, an observation which may be hard to reconcile with some theories of biased galaxy formation. Both redshift-space and real-space clustering estimates show a similar dependence on luminosity. Our results hint that luminosity segregation may be a purely primordial effect, due to a lower bias factor for low-luminosity galaxies, whereas morphological segregation, being most apparent on scales <~ 1h^-1^ Mpc, may be enhanced by environmental factors.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- April 1995
- DOI:
- 10.1086/175453
- arXiv:
- arXiv:astro-ph/9410018
- Bibcode:
- 1995ApJ...442..457L
- Keywords:
-
- Galactic Clusters;
- Galactic Structure;
- Luminosity;
- Red Shift;
- Sky Surveys (Astronomy);
- Statistical Correlation;
- Astronomical Models;
- Cosmology;
- Data Reduction;
- Data Sampling;
- Mathematical Models;
- Astronomy;
- COSMOLOGY: LARGE-SCALE STRUCTURE OF UNIVERSE;
- GALAXIES: CLUSTERING;
- GALAXIES: DISTANCES AND REDSHIFTS;
- GALAXIES: FUNDAMENTAL PARAMETERS;
- SURVEYS;
- Astrophysics
- E-Print:
- accepted by The Astrophysical Journal, 26 September 1994