Category Archives: News

Visualization Lab Construction Started

After months of planning, the construction of our visualization lab started on Monday. Already, I am impressed with the speed of their work in renovating the space that was a classroom.  Hopefully we can have the equipment installed by the end of the month.  Then we’ll start working on setting up the computers that drive the stereoscopic projection wall and monitor wall, ready for science by the end of the semester.  I plan to publish a few posts that outline the build process of the lab.

WREK Interview

A few weeks ago, I was interviewed by Charlie Bennett, who runs the North Avenue Lounge show on Georgia Tech’s student radio station.  I had a great time during the show. We chatted about my homecoming to Georgia Tech, my research, and the construction of the visualization lab for our group.  The show will be streaming until March 5th, so go listen!

“The Birth of a Galaxy” Published

High-z dwarf galaxy
High-redshift disk dwarf galaxy

In late November, our paper, “The Birth of a Galaxy: Primordial Metal Enrichment and Stellar Populations”, was accepted for publication in The Astrophysical Journal. It was recently published in the January 20th issue.

In this paper, we followed the formation of over 300 Population III (metal-free) stars and accurately modeled the radiative feedback from their main sequence and studied the chemical enrichment from their supernovae. Our methods allowed us to follow a natural transition from Population III to Population II star formation, leading to the formation of 38 high-redshift dwarf galaxies with the most massive having M = 109 solar masses. We found that they produce a metallicity floor of 10-3 of solar metallicity in the vicinity (5-10 kpc) of their host halos. At redshift 7, about 14% of the cosmic mass is enriched above 10-6 of solar metallicity. This gives some clues on the origin of an observed metallicity floor of 10-3 in damped Lyman alpha absorbers.

New members and computer update

We have four new members to our group, starting in the Spring semester.  Chao Shi, a second-year graduate student, will be focusing on black hole growth from both stellar-sized and massive seeds.  Three undergraduate students, Erin Caldwell, Vasiliy Demchenko, and Martin Halicek, will be joining the group, obtaining valuable experience in astrophysics research and learning about various topics in high-redshift galaxy formation.

In other news, our cluster arrived in Georgia Tech a couple of weeks ago, and the IT guys are configuring it right now.  It’ll be ready and stress-tested by the new year. Then it’ll get some stress-testing from myself!

Computer Cluster Ordered

Last week, I got word that the 16-core processors were available for order from our supplier.  I placed an order for our dedicated cluster that will be composed of

  • 8 nodes each with 64 cores and 256GB of RAM
  • A total of 512 cores and 2TB of RAM
  • QDR Infiniband interconnect
  • 48TB of long-term storage space.  Scratch space is 250TB.  It is shared among other clusters and connected by Infiniband.
The cluster should arrive in about a month and be tested and ready for science in December or January.  There are plans to expand the cluster to have Tesla GPU systems. It will be a very useful resource for rapid development and science once it become online. I’m very excited about it!

New opening for a postdoctoral researcher

Applications are invited for a postdoctoral position in the field of computational and theoretical cosmology at the Center for Relativistic Astrophysics (CRA) in the Georgia Institute of Technology. The successful candidate will work in conjunction with Dr. John Wise. The position is for 2 years with a possible extension to 3 years, depending on funding availability. The appointment can begin at anytime before September 1, 2012. Continue reading New opening for a postdoctoral researcher

AMD 16-core CPUs now shipping

AMD just announced that their 16-core Opteron “Interlagos” processors are now in production.  First they will be shipped to retailers for testing in their platform, and then later in Q4 they will be available to the public.  This is great news for the group because our new 512-core cluster will be based on the Interlagos chips.   We will be placing our order soon and will be waiting for the arrival of the dedicated cluster sometime in December!

Cover image on Science News

Let’s start out the news feed with something big.  A fantastic rendering of one of our simulations made the July 30th cover of Science News!  The associated article does an excellent job in describing the current state of the field.  This beautiful visualization was created by Ralf Kaehler at SLAC.  The featured simulation shows a Population III star at the end of its 3 Myr life.  Most of the surrounding gas is heated to 30,000 K, shown in red, whereas the dense gas associated with nearby halos shield against the stellar radiation and survive this blast of radiation.  The HII region that is created is over-pressurized and drives a 30 km/s shock from the star.  Because the host dark matter halo is only 1 million solar masses, its escape velocity is 3 km/s.  Over 90% of the gas is expelled from the halo, delaying further star formation and having possible consequences on the first galaxy.  This is clearly seen in the expanding, clumpy shell, centered on the star.