Research Interests
I work mostly on topics concerning the evolution of
galaxies
and quasars, and observational cosmology-- the origin, contents and
evolution
of the universe. Much of my recent work concerns clusters of
galaxies--
giant structures of hundreds or thousands of galaxies and clouds of hot
gas,
held together by the gravity of invisible dark matter. Some of the
questions
I work on include: how much dark matter is in clusters, how do clusters
grow
and evolve over time within the expanding universe, and how does the
environment
of the galaxy cluster affect the unfortunate galaxies which fall into
it.
I am also part of a consortium to discovery new very distant clusters
(the
RCS Survey),
with the aim of exploring how dark matter and dark energy together form
and
shape these giant structures over billions of years.
I love looking at the universe, and use a variety of
different
types of telescope for research: large and small ground-based
telescopes
from around the world, the Hubble Space Telescope, the Spitzer Infrared
Telescope,
and the Chandra and XMM-Newton X-Ray space telescopes.
Caption:
1) an optical
light photograph (in black/white reverse color) of the core of a rich
galaxy
cluster, with cluster galaxies marked with identification
numbers.
This image comes from a survey measuring the speeds of galaxies in
clusters
as gravity puls them through space. These results indicate that
clusters
contain 10 times more mass in the form of invisible dark matter as they
do
in luminous star-filled galaxies.
2) A Hubble Space
Telescope image of one of the RCS distant clusters (z=0.77). The blue
and
red arcs around the central region are much more distant galaxies (up
to
z=4.78). Their appearance has been magnified and stretched to this
extreme
shape via gravitational lensing from the warping of space by the
cluster's
great mass, and we can use these images to constrain the cluster's dark
matter
mass distribution.
3) Hot X-ray
emitting gas confined by the gravity of a galaxy cluster, observed by
the Chandra
X-Ray Observatory. The temperatures and shapes of these cluster gas
clouds
provide yet another way of measuring the dark matter in clusters.
Teaching
Courses I've taught at CU include ASTR 3510 and ASTR 3520 Astronomical Observations and Instrumentation, ASTR 5750 graduate-level Astronomical Observations, ASTR 5720 graduate level course on Galaxies, ASTR 1120 Stars and Galaxies, and similar introductory survey courses on the Universe outside of the Solar System, and ASTR 2010, Modern Cosmology for non-scientists.Other Stuff
I'm married to APS professor Nick Schneider, have two
kids (ages 8 and 11), and enjoy hiking and skiing, travel, music,
reading, dancing,
gardening...
Dr. Erica Ellingson
CASA CB 389
U. Colorado
Boulder, CO 80309
303-492-6610
email: elling@casa.colorado.edu
Visiting Professorship, New Mexico State University
(1994-1995)
Professor, Astrophysics and Planetary Sciences, U. Colorado (1995-
present)
Director, Sommers-Bausch Observatory, 2000-2002
Selected publications:
Ellingson, E., 2005, "The properties of galaxies on
the
outskirts of clusters," invited review in "The Outskirts of Galaxy
Clusters:
Intense Life in the Suburbs," Edited by Antonaldo Diaferio, IAU
Colloquium
#195
Ellingson, E., et al. 2001, "The Evolution of
Population
Gradients in Galaxy Clusters: The Butcher-Oemler Effect and Cluster
Infall,"
ApJ, 547, 609
Yee, H.K.C., & Ellingson, E., 2003,
"Correlations
of Richness and Global Properties in Galaxy Clusters," ApJ, 585,
215
Gladders, M, Yee, H.K.C. & Ellingson, E., 2002,
"
Discovery of a z =0.77 Galaxy Cluster with Multiple, Bright,
Strong-Lensing
Arcs," AJ, 123,1
Lewis, A., Ellingson, E. & Stocke, J., 2002,
"New
X-Ray Clusters in the Einstein Extended Medium Sensitivity Survey,"
ApJ,
566, 771
Selected Current Research Projects:
HST: On the Road to Coma: A longitudinal study of
cluster
galaxy evolution
Spitzer: IRAC Observations of High redshift RCS
Clusters
Chandra: X-ray observations of z=1 clusters
from
the Red-Sequence Cluster survey
Chandra: The AGN Content of Intermediate Redshift
Clusters
Apache Point Observatory: K-Band Luminosities and
Stellar
Masses of High Redshift Clusters
Magellan, CFHT and HST Observatories:
Masses of RCS Clusters