I am a theoretical cosmologist, and I am interested in the three major unknown actors on the cosmic stage: dark matter, dark energy, and the inflaton field.

In the standard cosmological model, each of these three substances control the dynamics of the Universe during one stage of its evolution, but despite their importance, their nature is still mysterious. Since the explanations for dark matter, dark energy, and inflation must involve new physics, I analyze how they behave in the most highly energetic environment ever realized: the early Universe.

Below, I briefly describe some of my recent and ongoing projects, with links to articles and to the more detailed descriptions provided on my Research page. For those looking for a comprehensive publication list, here is a link to my publications on the arXiv, INSPIRE and ADS .

UNC-CH students: I encourage you to contact me if you are interested in any of these topics. I have projects available for both graduate and undergraduate students.

Inflation and the Origins of Cosmic Structure

In the first moments after the Big Bang, there is strong evidence that a period of extremely rapid expansion called inflation smoothed the Universe while simultaneously seeding the inhomogeneities that would eventually become galaxies. The engine driving that expansion, dubbed the inflaton, is unknown. My projects pertaining to inflation:


Image: NASA/WMAP science team

Dark Matter

About fifteen percent of the matter in the Universe is made of known particles. The composition of the remaining "dark matter" is a mystery. My projects pertaining to dark matter:

  • Simulating the formation of dark matter microhalos to learn how their properties depend on the physics of the early Universe.
  • Using observational constraints on emission from dark matter annihilation to constrain the microhalo population and to probe the evolution of the early Universe and the origins of dark matter.
  • Investigating the astrometric microlensing signatures of dark matter subhalos and microhalos.

Image: ESA/Planck

Dark Energy and Modified Gravity

Currently, most of the Universe's energy is "dark energy." This energy is unlike any other energy that we know of because it is causing the Universe's expansion to accelerate, even though gravity should be slowing the expansion down. I have focused on an alternative explanation for cosmic acceleration: that general relativity is not the ultimate theory of gravity. My projects pertaining to modifed gravity:
Image: ESA/Planck

Content last updated on October 14, 2013: new website coming soon!