I am a Director's Postdoctoral Fellow in the Theoretical Astrophysics and Cosmology group at Los Alamos National Laboratory (LANL). My research primarily concerns the formation of the first stars, black holes and galaxies. I am especially interested in the prospects for observing these objects with future facilities such as the James Webb Space Telescope (JWST), the European Extremely Large Telescope (E-ELT), and the Energetic X-ray Imaging Survey Telescope (EXIST).
Email: jlj@lanl.gov
Telephone: 505-665-8739
Find me on Linkedin and ResearchGate
In April 2012 our work on the critical metallicity for planet formation was reviewed in Astrobiology magazine. It was also recently featured in a LANL news release.
In May 2012 I will be presenting our work on the formation of supermassive stars and black holes at the First Stars IV conference in Kyoto, Japan.
Our group at LANL is currently planning a workshop on the first black holes for spring 2013. Details can be found here soon.
In January 2012 I presented our research on supermassive star formation at the 219th AAS meeting in Austin, TX.
I am contributing a chapter on the theory of the formation of the first galaxies to an upcoming book in the Springer/Astrophysics and Space Science Library series. A preprint of the chapter is available here.
In June 2011 I participated in the First Galaxies workshop organized by our research group at the Max Planck Institute for Extraterrestrial Physics (MPE). See all of the participants here.
In July 2010 I presented our work on early black holes at the workshop What drives the growth of black holes? at Durham University in England.
In March 2010 I presented at the The First Stars and Galaxies conference at the University of Texas at Austin. See my contribution to the proceedings, Observational Signatures of the First Galaxies, here.
Since the fall of 2009 I have been collaborating with other members of the Theoretical Modeling of Cosmic Structures group at MPE to study the effects of radiation emitted by the first generations of stars in the First Billion Years project.
In May 2009 I completed my Ph.D. in Astronomy at UT Austin, where I was a member of the new Texas Cosmology Center.
In August 2008 our simulation of radiation from the first stars appeared in the New York Times.
In December 2007 our work on Population III star formation in the assembly of the first galaxies was reported by the New Scientist.
Click on the images at left to read more on each topic in a scientific journal article.
In the First Billion Years (FiBY) project, we have performed some of the most sophisticated and complete cosmological simulations of the earliest epochs of galaxy formation. We have found that the radiation emitted from both primordial and metal-enriched stars alters the chemical evolution of the early universe in rich and complex ways.
The first planets formed only when a sufficient amount of dust was generated in the interstellar medium by the first generations of stars. The first Earth-like planets probably formed only once the abundance of heavy elements reached 10 percent of that in our Sun. The growing collection of observational data so far support the prevailing theory of planet formation at low metallicity.
The most massive stars ever formed may have collapsed to become the protogalactic seeds of supermassive black holes. While the radiation they emit limits the growth of some of these stars, the most massive grow until they collapse. Click here to watch a movie showing the formation of, and accretion of primordial gas onto, a black hole formed from a supermassive star.
Stars are usually discussed as the source of the photons that reionized the Universe. Supernovae may also be responsible for a substantial fraction of reionization, due to the hard spectrum of the radiation they emit. This is especially true for very powerful supernovae, which may have been more common during the epoch of reionization than they are today.
Publication search - See all of my scientific publications through the ADS.
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Printable publication list - Download my publication list as a pdf.
Citation breakdown - See my author profile in Google scholar.
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Below is a brief summary of my education and past experience. View my complete CV as a pdf here.
Ph.D., Astronomy
The University of Texas at Austin
Advisor: Dr. Volker Bromm
Dissertation: "Star Formation in the Assembly of the First Galaxies"
B.S., Physics, minors in Mathematics and Spanish
Truman State University (2000-2004)
Summa cum laude, with Departmental Honors
Director's Postdoctoral Fellow (August 2011-present), Los Alamos National Laboratory
Postdoctoral Research Fellow (2009-2011), Max Planck Institute for Extraterrestrial Physics
Wendell Gordon Fellow (2008-2009), The University of Texas at Austin
Graduate Teaching Assistant (2004-2008), The University of Texas at Austin