PAUL C. JOSS, Professor
of Physics
Research Interests
The focus of Prof. Joss's research is the theory of neutron stars,
supernovae, and binary systems. At present, he is investigating
a promising new model for the origin of cosmic gamma-ray bursts,
a mysterious phenomenon that has puzzled astrophysicists for the
past thirty years. In this new model, two massive stars in a binary
system merge to form a single, rapidly rotating star. The newly
formed star later explodes to form an extraordinary type of supernova,
which has been dubbed a "hypernova." During the hypernova explosion,
the core of the star collapses to form a central black hole, while
the rapidly rotating matter just outside the core forms a massive
torus surrounding the black hole. It then takes anywhere from a
fraction of a second to a few minutes for the matter in the torus
to fall into the black hole, releasing huge amounts of energy as
it does so. This object can be called a microquasar, since it is
a miniature version of the quasars that form in the nuclei of active
galaxies. In both quasars and microquasars, the energy released
by the infalling matter is emitted in beams that are directed along
the rotation axis of the infalling matter. In the case of a microquasar
produced in a hypernova event, we see a gamma-ray burst if one of
these beams is directed toward the earth. In order to determine
the viability of this model, Prof. Joss is presently carrying out
the world's first realistic calculations of the processes leading
up to the formation of a microquasar, from the evolution of the
original binary system to the hypernova explosion itself.
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Biographical Sketch
Professor Joss joined the faculty in the MIT Department of Physics
in 1973. He received his B.A. in Physics from Cornell University
(1966) and his Ph.D. in Astronomy and Space Sciences from Cornell
in 1971.
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Selected Publications
"Limits on energy storage in the crusts of accreting neutron
stars," Mock PC, Joss PC, ASTROPHYSICAL JOURNAL 500 (1): 374-387
Part 1 JUN 10 1998.
"The nature and evolutionary history of GRO J1744-28,"
Rappaport S, Joss PC, ASTROPHYSICAL JOURNAL 486 (1): 435-444 Part
1 SEP 1 1997.
"The relation between white-dwarf mass and orbital period
in wide binary radio pulsars," Rappaport S, Podsiadlowski P,
Joss PC, DiStefano R, Han Z, MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL
SOCIETY 273 (3): 731-741 APR 1 1995.
"The progenitor of supernova-1993J - a stripped supergiant
in a binary-system," Podsiadlowski P, Hsu JJL, Joss PC, Ross
RR, NATURE 364 (6437): 509-511 AUG 5 1993.
"Presupernova evolution in massive interacting binaries,"
Podsiadlowski P, Joss PC, Hsu JJL, ASTROPHYSICAL JOURNAL 391 (1):
246-264 Part 1 MAY 20 1992.
"The detectability of brown dwarfs - predictions and uncertainties,"
Nelson LA, Rappaport S, Joss PC, ASTROPHYSICAL JOURNAL 404 (2):
723-733 Part 1 FEB 20 1993.
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