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Astrophysics: Theoretical
Overview
Faculty in this area of research:
Astrophysics Areas of Research
Overview
MIT theoretical astrophysicists pursue research
in cosmology, gravitation, binary evolution, and a variety of problems
in dynamical astrophysics.
Theoretical cosmology research at MIT spans
the full range of the universe in both time -- from the big bang
to the present day -- and in space, from galaxy scales up to and
beyond the size of the presently observable universe. Alan
Guth developed the inflationary universe model to resolve open
questions of the big bang model, such as why the universe is so
old, so big, and so uniform in space. Later Guth and others realized
that the inflationary model predicted a spectrum of primordial density
perturbations that could account for the observed structure in the
universe. The predictions have been spectacularly confirmed in the
last several years by the measurement of fluctuations in the cosmic
microwave background radiation. Edmund
Bertschinger has developed analytical and numerical methods
for calculating the predicted fluctuations in the microwave background
temperature as well as the dark matter and other constituents of
our universe.
Gravitational astrophysics includes a range
of applications of Newtonian gravity and general relativity. Scott
Hughes studies both the generation of gravitational waves and
their potential use as probes of the distant universe. The two-body
problem in general relativity is a difficult, unsolved problem when
the separation between the two masses becomes comparable to the
Schwarzschild radius. However, approximate solution techniques apply
when the ratio of masses is large, as in the case of stars falling
into the supermassive black holes in the centers of galaxies. Saul
Rappaport studies the effects of stellar evolution on the dynamics
of globular clusters containing hundreds of thousands of stars.
Dense clusters are nurseries for compact binaries and perhaps even
for massive black holes. Edmund
Bertschinger studies the dynamics of dark matter in galaxies
and large-scale structure using large computer simulations and analytic
models.
To study these problems of gravitationl dynamics
with improved dynamic range, MIT theorists are constructing a 24-node
Beowulf cluster with 2.4GHz dual Xeon processors, 2GB of ram per
processor, and gigabit ethernet switching. This supercomputer is
available for use by MIT astrophysicists.
The formation and evolution of X-ray binaries
involves the evolution of stars in binary systems. Paul
Joss and Saul
Rappaport pursue many research problems in binary stellar evolution.
Transfer of mass from one star in the binary system, typically a
normal star burning nuclear fuel in the core, to its collapsed companion
(a white dwarf, neutron star, or black hole) leads to a variety
of very interesting phenomena, including cataclysmic variable stars,
X-ray pulsars, X-ray burst sources, and dead radio pulsars spun
up and brought back to life.
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Astrophysics
Areas of Research
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