Hale V. Bradt PhD '61
Bradt studied neutron-star and black-hole binary systems through their X-ray emission by making use of rockets and satellite missions, including the Rossi X-ray Timing Explorer (RXTE). RXTE enabled the study of compact objects with high statistics so the plasmas in their vicinities can be studied with time resolutions comparable to the dynamical time constants of matter in the deep potential wells. The mission, among other important results, revealed the presence of accreting X-ray pulsars (neutron stars) with spin periods of a few milliseconds. It has also demonstrated a link between accretion and jet formation in (black-hole) “microquasars”. Microquasars are black-hole accretors in the Milky-Way Galaxy which exhibit pronounced radio jets, as do their more massive and distant counterparts, the well-known extragalactic quasars. The mission completed sixteen years of productive observations in January 2012.
Of late, Bradt has been writing on military history and other topics.
Professor Bradt joined the Department of Physics as an Instructor in 1961, was promoted to Assistant Professor in 1963, to Associate Professor in 1968, to Professor in 1972, and became Professor Emeritus in 2001. A music major, he earned his A.B. from Princeton University in 1952 and his Ph.D. in Physics from MIT in 1961. Bradt founded MIT’s sounding rocket program in X-ray astronomy in 1967, was a co-Investigator on the MIT SAS-3 mission (launched in 1975) and a co-Principal Investigator on the High-Energy Astronomy Observatory, HEAO-1 (1977). He was Principal Investigator of the All-Sky-Monitor (ASM) instrument on the Rossi X-ray Timing Explorer (RXTE, 1995) until 2001. Bradt’s work has long been directed toward the determination of X-ray source positions and the follow-up studies of the objects identified.
Bradt served terms as the Secretary/Treasurer and Chairman of the High Energy Astrophysics Division (HEAD) of the American Astronomical Society (AAS) in 1973–5 and 1981 respectively. He was awarded the Buechner Teaching Prize of the MIT Physics Department in 1990 and was a 1999 co-recipient of the Rossi Prize of the HEAD/AAS for his role in bringing about the RXTE mission and the results forthcoming from it.
During retirement, Bradt served as a freshman advisor at MIT for 16 years. He also wrote two textbooks published by Cambridge University Press: Astronomy Methods (2004) and Astrophysics Processes (2008). In 2016 and 2017 he published two versions of Wilber’s War, the story of his family during World War II. Currently (2020), he is completing a history (Chasing Black Holes) of his and MIT’s roles in the RXTE mission.
Awards & Honors
- 2020 // Legacy Fellow of the American Astronomical Society
- 2017 // MIT Lazarus Excellence in Advising Award
- 2015 // Darius and Susan Anderson Distinguished Service Award of the Institute of Governmental Studies
- 2015 // Anderson Award
- 2012 // Karl T. Compton Medal for Leadership in Physics
- 2010 // Chambliss Astronomical Writing Prize (AAS) "For his upper level undergraduate/graduate astronomy textbook, “Astrophysics Processes.”"
- 2004 // Outstanding Freshman Advisor of the Year Award, MIT
- 1999 // AAS Bruno Rossi Prize
- 1990 // Buechner Teaching Award, MIT
- 1987 // Oliver E. Buckley Condensed Matter Prize, American Physical Society
- 1981 // Chairman, High-Energy Div. AAS
- 1978 // NASA Exceptional Scientific Achievement Medal
- 1972 // APS Fellow
X-ray and Optical Observations of the Pulsar NP 0532 in the Crab Nebula, H. Bradt, et al, Nature 222, 728 (1969)
The Optical Counterparts of Compact Galactic X-ray Sources, H. Bradt and J. McClintock, Ann. Rev. Astron. & Astrophys. 21, 13 (1983)
X-ray Astronomy Missions, H. Bradt, T. Ohashi, & K Pounds, Ann. Rev. Astron. & Astrophys. 30, 391 (1992)
The X-ray Timing Explorer, H. Bradt, J. Swank, & R. Rothschild, Astron. & Astrophys. Suppl, Series 97, 355 (1993).