James Rhoads is an astrophysicist whose research spans gamma-ray burst afterglows and the detection of some of the earliest galaxies in the observable universe. He earned his undergraduate degree from Harvard College in 1991 and his doctorate from Princeton University in 1997, and has held research positions at the Space Telescope Science Institute, Arizona State University, and NASA Goddard Space Flight Center. Among the numbers that mark his career, the Large Area Lyman Alpha survey he co-founded assembled samples of several hundred Lyman-alpha emitting galaxies at redshift z=4.5, placing those galaxies among the most distant objects systematically catalogued at the time.
Key facts
- Occupation: astrophysicist
- Education: Princeton University
Education and training
Rhoads completed his undergraduate degree in Astronomy and Astrophysics at Harvard College in 1991. He then spent one year at Emmanuel College, Cambridge University, in the Department of Applied Mathematics and Theoretical Physics, earning a Certificate of Advanced Study in Mathematics by completing Part III of the Mathematical Tripos in 1992.
His doctorate in Astrophysical Sciences came from Princeton University in 1997, under the supervision of David Spergel. During his time at Princeton he also worked on papers with J. Richard Gott, Ed Turner, and Bohdan Paczynski.
Gamma-ray burst afterglows
Rhoads began studying gamma-ray burst afterglows four years before they were observationally discovered. Working with Bohdan Paczynski, he developed an early model for radio afterglows of gamma-ray bursts.
He went on to develop two tests for gamma-ray burst jet collimation: one based on the statistics of orphan afterglows, and one based on afterglow light curves. His 1999 paper on beamed afterglows was written while he was affiliated with Kitt Peak National Observatory, located at 950 North Cherry Avenue, Tucson, Arizona.
Lyman-alpha galaxies and the LALA survey
Rhoads has been a pioneer in the study of high-redshift galaxies selected by strong emission in the Lyman-alpha line, which is the n=2 to 1 transition of atomic hydrogen. The use of this line as a signpost of young galaxies in formation was originally proposed by Partridge and Peebles in 1967.
In 2000, Rhoads and collaborators including Sangeeta Malhotra, Arjun Dey, Daniel Stern, Hyron Spinrad, and Buell Jannuzi published the first results from the Large Area Lyman Alpha (LALA) survey in The Astrophysical Journal Letters, volume 545, L85. The LALA survey assembled samples of several hundred Lyman-alpha emitting galaxies at redshift z=4.5, tens of galaxies at z=5.7, and one galaxy at z=6.5.
Rhoads and Sangeeta Malhotra continue to lead a NASA-funded science investigation team exploring Lyman-alpha galaxies, in collaboration with roughly a dozen scientists working in Arizona, Texas, Sweden, and the Netherlands.
Career positions
From November 1999 to December 2005, Rhoads served as an Institute Fellow and then as Assistant Astronomer on a tenure track at the Space Telescope Science Institute in Baltimore, Maryland. He moved to Arizona State University in January 2006, where he served as Associate Professor and then Professor of Astronomy in the School of Earth and Space Exploration until December 2016.
In January 2017, Rhoads joined NASA Goddard Space Flight Center in Greenbelt, Maryland, as a Research Astrophysicist. He is housed in the Exoplanets and Stellar Astrophysics Laboratory, Org Code 667.
ULTRASAT mission
Since mid-2021, Rhoads has served as NASA Project Scientist for the ULTRASAT mission, a near-ultraviolet imaging satellite with a 200 square-degree field of view. ULTRASAT was developed by the Israel Space Agency and the Weizmann Institute of Science and is an international partnership led by Israel, with participation from the United States through NASA and from Germany through DESY.
NASA’s role in the mission includes providing the launch as a secondary payload on a commercial geostationary orbit launch, funding eight U.S. participating scientists, and establishing a U.S.-based science archive. As of a 2024 NASA Technical Reports Server entry, ULTRASAT had an anticipated launch in late 2027.
Did you know
- The LALA survey that Rhoads co-founded in 1998 identified a galaxy at redshift z=6.535, one of the most distant galaxies confirmed at the time of its discovery. Characterizing it required data from both ground-based Kitt Peak telescopes and the Hubble Space Telescope. (rhoads.asu.edu)
Data sources
- Wikidata
- science.gsfc.nasa.gov
- iopscience.iop.org
- scholar.google.com
- rhoads.asu.edu
- spacenews.com
- ntrs.nasa.gov
Data updated: 2026-10-31