Hi, I'm a graduate student at Harvard University working on a PhD thesis in theoretical astrophysics and cosmology. I spend most of my time thinking about structures in the Universe that are much much larger than the solar system and usually even the Milky Way. My advisers are Harvard professors Matias Zaldarriaga and Lars Hernquist. I also have collaborated with Suvendra Dutta, Claude-Andre Faucher-Giguere, Steve Furlanetto, Adam Lidz and Oliver Zahn.
Much of my research has focused on understand the morphology of the reionization epoch and how upcoming observations can be used to understand the reionization process. Reionization is the time when the first stars in the universe turn on and the photons from these stars ionize all of the hydrogen (most of the atoms in the Universe are hydrogen). We think that reionization happened when the universe was several hundred million years old, but exactly when and how it happened is something that astronomers are attempting to answer. Suvendra Dutta has made 3-D movies of the neutral hydrogen during reionization and the neutral hydrogen plus ionizing sources from a 100 comoving Mpc simulation. Also, click here for a simple 2-D slice through the Universe as it is being reionized. For additional discussion of our scientific results click here.
The most exciting of upcoming observation of reionization involves imaging the 21cm line of high redshift neutral hydrogen as it becomes ionized. I have been involved with predicting what this signal will look like as well as with optimizing the design of a radio telescope to constrain this signal. These predictions provide support for the radio astronomers at Harvard/CFA, MIT and Australia who are designing one of these radio telescopes, the Mileura Widefield Array.
Another exciting probe is to discern the properties of reionization by studying high-redshift galaxies. If the galaxies are selected by their Lyman-alpha emission, then the distribution of ionized bubbles will modulate the observed distribution of these galaxies. Detecting this modulation will allow us to understand reionization. Click here for further discussion.
In addition to studying hydrogen reionization, I have recently been focusing on simulating HeII reionization (which we think occurs at z~3 from quasars). HeII reionization affects the properties of the z=3 intergalactic medium. It heats the intergalactic medium by more than 10,0000 degrees, and this heating is very inhomogeneous. This process also affects the statistics of the HI and HeII Ly-alpha forest absorption and high redshift metal lines. Click here for a movie of a 2-D slice through a 430 Mpc simulation of HeII reionization. The left panels show the ionized fraction and the right show the temperature (blue = 10,000 K, red = 25,0000 K, and white signifies even larger temperatures).I have also worked on research projects involving Gamma Ray Bursts -- the largest and brightest explosions in the universe -- (both trying to understand the prompt spectra of these objects with Vahe' Petrosian at Stanford and as probes of the epoch of reionization), secondary CMB anisotropies, the structure of dark matter halos, and the observational consequences of a weakly interacting dark matter. I currently am trying to understand why the violent relaxation of gravitationally interacting particles typically leads to a standard profile. This profile is similar to the dark matter halo profiles seen in cosmological simulations.
Click here for my scientific publications.A bit of background... I grew up in Northern Virginia before moving to Kerrville, TX, (a town 60 miles outside of San Antonio) for my junior and senior years of high school. I received my undergraduate education at Stanford University, receiving a B.S. in physics and in math in 2004. At Stanford, I met my fiance, Jennifer Yeh, and we plan to get married next summer (July 2008). My number of hobbies seems to be decreasing as a function of time. Recently, my (and Jennifer's) biggest hobby has been finding tasty restaurants in the Boston area. If you think that this does not count at a hobby, I am an avid golfer. I have not played as much as I would like these past couple of years (partly because of the New England weather and partly because I don't own a car), and as a result my handicap has suffered. In place of golf, I have been substituting tennis, a hobby which is aided by there being four tennis courts one minute walk from our office.
Soon I hope to have a link to some pictures.