Environmental densities around galaxies
The figure below shows environmental densities from the
Sloan Digital Sky Survey (SDSS) at z<0.1.
Each point represents a galaxy or galaxies with a redshift measurement from
SDSS DR7. The color represents the projected density of galaxies surrounding
a galaxy: red corresponds to about 10 luminous galaxies per Mpc^2; blue to 1
per Mpc^2; green to 0.1 per Mpc^2. The color scale is shown at the bottom of
the figure. The yellow circles correspond to a 5 Mpc diameter around some
x-ray detected clusters from
Bohringer et al. 2000.
The animated gif steps through redshift slices with
the scale bar corresponding to 50 comoving Mpc.
The description of the environmental densities is given by
Baldry et al. 2006.
Ivan Baldry, written 2006 May 10th, updated 2008 November 20;
animated gif created using gifsicle.
