Kyle S. Dawson

Associate Professor, Physics and Astronomy

328 INSCC • 801-581-4785 • kdawson@astro

 

Current Research

New observations are required to better understand if cosmic acceleration is caused by deviations from General Relativity (GR) on large scales or by a new form of energy. It is possible to distinguish scenarios of acceleration that require dark energy from those that require modifications to GR by independently probing both cosmic expansion history and the structure growth rate. Of equal importance to dark energy, the fundamental properties of neutrinos and General Relativity (GR) are recorded in cosmic history, yet poorly explored by current surveys. Wide-field optical spectroscopy figures prominently in the effort to constrain fundamental physics; the three dimensional maps of galaxies and quasars obtained by such surveys provide an atlas of large-scale structure in which the physics of the expansion history, neutrino masses, and GR are embedded.

In 2014, we completed a spectroscopic survey of 10,000 square degrees using a 1000-fiber spectrograph mounted to the 2.5-meter telescope at Apache Point Observatory in New Mexico. Designed to study Baryon Acoustic Oscillations (BAO), we observed more than one million galaxies and 200,000 distant quasars over a period of five years. The data were used to constrain the cosmic expansion history to 1-2% precision in three distinct periods of cosmic time, the most distant of which dates back more than 10 billion years. This project, known as the Baryon Oscillation Spectroscopic Survey (BOSS), placed tighter constraints on cosmic expansion history than any other spectroscopic survey. Please see the list of my BOSS publications for more details on the scientific results from this project.

I am the Instrument Scientist on the Extended Baryon Oscillation Spectroscopic Survey (eBOSS). eBOSS will constrain cosmology through spectroscopic observations of an entirely new sample of galaxies and quasars from that used in BOSS. eBOSS began in 2014 using the same spectrograph and telescope as that used in BOSS and will use more than 500,000 galaxy spectra and more than 500,000 quasar spectra to explore cosmology in epochs never studied from the perspective of spectroscopic clustering. I am largely interested in characterizing the large sample of faint spectra to improve the sample for clustering measurements and to better understand the astrophysical processes behind the distant galaxies and quasars we observe. Please see the list of my eBOSS publications for updates and recent results from this project.

Finally, I am deeply involved with the planning for the Dark Energy Spectroscopic Instrument (DESI). DESI is planned to begin in 2019 and will be the largest spectroscopic survey ever conducted.

Prior Research

As a graduate student, I used the Berkeley-Illinois-Maryland Array (BIMA) and the Owens Valley Radio Observatory (OVRO) to perform radio/microwave observations of the sky at 30 GHz. We used these interferometers to study small-scale anisotropy in the Cosmic Microwave Background (CMB) induced by galaxy clusters through a process known as the Sunyaev-Zel'dovich (SZ) effect. A blind survey for arcminute-scale anisotropy in 18 independent fields constituted my thesis project. With these data, I placed the best limits at the time on secondary CMB anisotropy at angular scales optimized for the SZ signature. We also used these instruments to conduct a survey of known galaxy clusters. These data were used in combination with archival X-ray data to place new constraints on the cosmic distance scale using projections of the cluster gas profile as a distance indicator and to measure the gas mass fraction in galaxy clusters. Please see the list of my CMB publications for more details on my work with CMB observations.

As a postdoctoral researcher, I used the Hubble Space Telescope to study Type Ia supernovae (SNe Ia) and galaxy clusters. I continued this work in my first five years at Utah and expanded it to include studies of SNe in the ultraviolet with the Swift satellite and in the optical from the Sloan Digital Sky Supernova Survey. The results of my work in the field of SN cosmology can be found in the list of SN Publications. The results from our studies of galaxy clusters can be found in the list of Cluster Publications.

As a postdoctoral researcher, I also developed new charge-coupled devices (CCDs) for a proposed space-based telescope. These CCDs were designed for significantly improved quantum efficiency up to 1000 nm and for more resilience against the harsh environment of space radiation. I conducted table-top experiments by exploring the damage incurred by 12.5 MeV protons from the LBNL 88-Inch Cyclotron onto these detectors. We then modelled the degradation in weak lensing signal expected from radiation damage. This experience led to other work in calibration and instrumentation that can be found in my list of Instrument Publications.

I still maintain a good relationship with my former research group (or at least I think I do). The most recent collaboration with my graduate group occurred during the Snowmass process. This was in 2013 where we explored the various techniques that can be used to constrain cosmology. The papers describing the wide range of possible cosmology programs are a great introduction to the field of cosmology; they are found in my list of Snowmass publications.

Publications

Publications from Utah (Led by Dawson group member or with myself as 1st, 2nd, or 3rd author)

All publications

eBOSS

BOSS

Instrument and Technical

Supernovae

Galaxy Clusters

SZ and Cosmic Microwave Background

Snowmass and Overview of Observational Cosmology