About me




I am a Professor in the Department of Physics & Astronomy and the Associate Dean for Undergraduate & International Programs in the College of Science at Texas A&M University. I am also a member of the George P. and Cynthia W. Mitchell Institute for Fundamental Physics and Astronomy.

Before joining Texas A&M, I was a Hubble Fellow and Goldberg Fellow at the National Optical Astronomy Observatory. I received my PhD in Astronomy from Harvard University and my BS in Physics from MIT.

If you would like to get in touch with me, my contact information can be found here.


My research interests include the extragalactic distance scale, massive time-series photometry and "near-field" cosmology:

• My main area of research involves optical and near-infrared photometry of Cepheid and Mira variables in galaxies near and far with the Hubble Space Telescope and various ground-based telescopes. The aim of these projects is to better measure the expansion rate of the Universe (the Hubble constant) with better accuracy and precision. This ultimately allows a better constraint of the properties of dark energy, which is the largest component of the Universe and is responsible for the acceleration of its expansion. I am also interested in characterizing changes in the observed optical and near-infrared properties of Cepheids as a function of metal abundance. More information on these projects can be found here.

• I am also involved in a long-term program to obtain redshifts for an all-sky, flux limited sample of about 45,000 galaxies selected from the 2 Micron All-Sky Survey (2MASS). The aim of this project is to produce the most detailed map of large-scale structure in our region of the Universe, free from the biases and incompleteness present in previous optical-based studies. This project is coupled with a peculiar-velocity survey that uses the Tully-Fisher relation (2MTF) to characterize large-scale flows in the local Supercluster and study the distribution of dark matter. More information on this project can be found here.

I am fortunate to work with several colleagues who are helping me with these projects. A list of current and past members of my group can be found here.


One of my priorities is to reach out to the community to keep them up to date on our latest discoveries and thank them for their taxpayer support. I participate in the Department's annual Physics Festival and give public talks. If you would like me to visit your institution, please do not hesistate to contact me.