Invited review in "The New Cosmology", eds. R. E. Allen,
D. V. Nanopoulos, and C. N. Pope, in press.
astro-ph/0411244
For a PDF version of the article, click
here.
CONSTRAINTS ON FIELD GALAXY HALOS FROM
WEAK LENSING AND SATELLITE DYNAMICS
Tereasa G. Brainerd
Boston University,
Institute for
Astrophysical Research, 725 Commonwealth Ave., Boston, MA 02215
Abstract. Here I summarize constraints on the nature of the dark
matter halos of field galaxies that have been obtained from the most
recent investigations of (i) weak galaxy-galaxy lensing and (ii) the
dynamics of satellite galaxies in orbit about large host
galaxies. Both of these techniques
are statistical in their nature (i.e., large samples of
galaxies are required to obtain a "signal"), but since they have
inherently different selection biases and systematic errors,
they are quite complementary to each other. Results of work over
the last several years on weak lensing and satellite dynamics
is revealing a remarkably consistent picture regarding
the dark matter halos of bright field galaxies (L
L*). The halos extend to large physical radii
( 150
h-1 kpc) and are flattened in
projection on the sky, there is a marked difference in
the depths of the potential wells of early-type galaxies and
late-type galaxies, and the velocity dispersion profiles of
the halos, 
v(rp), decrease at large
projected radii. All of these are expected to hold true in
a cold dark matter universe and, while neither
technique can address the possible small-scale
(
5
h-1 kpc)
conflicts between cold dark matter and observed galaxies, on scales
50
h-1 kpc both techniques yield results that are
consistent with each other, and with the predictions of cold dark matter.
Table of Contents
