Richard Ellis's Homepage

Richard Ellis

Astronomy 249-17, Caltech

Pasadena CA 91125

Position: Steele Professor of Astronomy
Office: (626)-395-2598
Cell: (626)-676-5530
Secretary: (626)-395-4970
Fax: (626)-568-9352
Email: rse@astro.caltech.edu

Overview of Research:

I am working primarily in observational cosmology addressing issues related to the nature of the world model, the origin and evolution of galaxies, the growth of large scale structure and the nature and distribution of dark matter. I am enthusiastic about the use of new instruments and observational opportunities when they further the progress that can be made in these areas. In particular I am deeply involved in promoting and managing the science partnership for the Thirty Meter Telescope.

Recent Press Releases and Interviews:

Watch the promotional video about the excitement of the Thirty Meter Telescope

Watch an interview about 90 years of gravitational lensing produced for the Royal Society

Listen to an interview on BBC Radio Wales on how I became an astronomer (light entertainment only!)

My most recent press release: Keck Telescope and Cosmic Lens Resolve Nature and Fate of Early Star-Forming Galaxy

Read the associated Nature scientific article

Research Programs:

My current interests at Caltech fall under 3 main headings:

Gravitational lensing: I have been interested in the role that gravitational lensing can play in cosmology and galaxy formation studies since the late 1980's. I am working with others in defining the weak lensing case and survey parameters for the Joint Dark Energy Mission (JDEM). On small scales I am using strong lensing to separate dark and baryonic matter distributions in clusters. On larger scales I am using weak lensing to map the distribution in panoramic survey fields. I have participated in a number of comparative studies to understand the prospects for precision measures of weak lensing using ground- and space-based facilities.

Distant Supernovae: I took part in one of the earliest successful studies to locate and characterize cosmologically-distant Type Ia supernovae and later joined the Supernova Cosmology Project . The resulting "accelerating Universe" is a bewildering result which has motivated a number of more ambitious ongoing and future supernovae surveys. I am putting most of my effort into examining the validity of using Type Ia SNe for future studies. My research includes examining the environmental dependence of supernova properties as well as the question of possible spectral evolution such as might arise from changes in the progenitor composition. This work is of a long term nature and is being undertaken with spectrographs on Keck and HST.

Galaxy Formation and Evolution: I have been interested in studying the properties of distant galaxies since I was a postdoc in the late 1970's. The facilities we have access to now make those early studies look so primitive! I use the combination of HST images, Spitzer photometry, ground-based K-band imaging and, most of all, Keck spectroscopy to better understand the origin of the wide diversity of galaxy morphologies. Key questions I am working on include the mass-dependent assembly of galaxies over the redshift range 0 to 6, the contribution of low luminosity galaxies to cosmic reionization, and the onset of ordered rotation and high velocity dispersions in spiral and elliptical galaxies respectively..I am a recent convert to the phenomenal advances being made in these areas through the use of adaptive optics.