Prof. Erica Ellingson

Department of Astrophysical and Planetary Sciences at the University of Colorado

Fellow of the Center for Astrophysics and Space Astronomy.




Research Interests

I work on topics concerning the evolution of galaxies and quasars,, large scale structures and  observational cosmology-- the origin, contents and evolution of the universe.  Much of my recent work concerns measurements of dark matter distributions and galaxies in 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. I use a variety of different types of telescopes for my 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.







1) 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.

2) Hot X-ray emitting gas confined by the gravity of an RCS 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.

3) Image of an RCS cluster at z=0.38, showing the galaxy colors in the cluster core. Blue galaxies are actively forming stars whereas red galaxies have ceased their star formation in the cluster environment. The “cirrus” and contours show the projected galaxy density in the cluster as measured from photometric redshifts.


Current Research Projects:

On the Road to Coma: A longitudinal study of cluster galaxy evolution (APO, HST, Chandra)

The RCS Cluster surveys (20,000 red-sequence-selected clusters to z=1): APO, CFHT, HST, Gemini, Chandra, Spitzer

            Cosmological constraints from large sample of galaxy clusters

             Star formation in and near clusters and superclusters of galaxies

             Comparing cluster-finding efficiencies and cluster dark matter mass estimates from multi-wavelength measures

Multi-wavelength Observations z=1 clusters from the Sparcs/GCLASS Cluster Surveys (Spitzer, Gemini, Chandra, XMM)

Mapping the Infall regions of Clusters;  Galaxy Evolution in Large scale structures  (CFHT, CTIO, Magellan, SALT)




 Courses I've taught at CU include undergraduate Astronomical Observations and Instrumentation (ASTR 3510 and 3520), graduate-level Astronomical Observations (ASTR 5750), a graduate level course on Galaxies, (ASTR 5720), introductory-level  Stars and Galaxies (ASTR 1200) , Modern Cosmology (ASTR 2010) and Ancient Astronomies of the World (ASTR 2000). Honors courses include “Cosmology, Galileo and God” and “Sky Watching.” I am the director of CU-STARS, a program which works towards recruiting and retaining students from diverse backgrounds in STEM majors at CU.

Outreach and Public Speaking

I've written, produced and presented several planetarium shows at CU's Fiske Planetarium covering forefront research on topics such as dark matter, dark energy and galaxy evolution, and regularly present public lectures on these topics for groups in Colorado and elsewhere. and have been a featured speaker for astronomy tours in the Mediterranean,  Caribbean and Asia. I’ve given plenary presentations on observational cosmology for the American Astronomical Society and the Astronomical Society of the Pacific.

Other Stuff

I'm married to APS professor Nick Schneider. We have two kids, and we all enjoy backpacking, skiing, and travel. 


Dr. Erica Ellingson


U. Colorado

Boulder, CO 80309


email:   Erica.Ellingson –at-