John R. Peterson
Asst. Professor of Physics
Purdue University
Teaching:
Spring
2007: Physics 360, Quantum Mechanics
Fall
2007: Physics 172, Modern Mechanics
Spring
2008: Physics 360, Quantum Mechanics
Research:
Current
Research Focus: X-ray &
Optical Astrophysics, Particle Astrophysics, & Cosmology / Clusters of
Galaxies, Dark Energy, & Large Scale Structure
My
research focuses on astrophysics and cosmology using data from X-ray and
optical telescopes. Some work we
have done on the X-ray spectra of clusters of galaxies (above left)
demonstrates a discrepancy in a model how the gas in clusters of galaxies
cools. The X-ray spectrum contains
a number of atomic emission lines, which act as a thermostat for gas of
specific temperatures. The light
blue model is the standard model for complete cooling, but is clearly
inconsistent with the observed data (dark blue). Instead a model where the colder plasma is missing (red)
matches the data well. The interpretation
of this is still unclear, since it would seem to indicate an enormous heating
source inside the largest structures in the Universe.
By
simply counting the number of clusters of galaxies in the Universe and
measuring where they are, we have an extremely sensitive indicator of how much
dark matter and dark energy there is in the Universe. The above middle image shows a collection of new clusters of
galaxies we have found by using the most sensitive X-ray telescopes. The number and location of the clusters
of galaxies in the Universe follows a theory for how fast matter can form
structures as the Universe begins to expand. Thus, this can be used to measure properties of dark matter
and dark energy.
Finally,
galaxies can be studied in optical images (above right) to map the distribution
of matter in the Universe. In
addition, gravitational forces that alter the path of light before it reaches
us can distort the shapes of distant galaxies. This is a new technique that can map the dark matter in the
Universe. The Large Synoptic
Survey Telescope (LSST) is a new telescope that is being designed to be the
worlds largest survey telescope, which will map the dark matter across almost
the entire sky. The above right
image is a simulation of stars and galaxies that we have performed to plan the
design of LSST.
Graduate
Students:
Collaborative
Software Projects (Protected):
X-ray
Imaging and Spectroscopy:
Optical
Imaging:
Optical
Simulation
Telescopes:
XMM-Newton Observatory (http://xmm.vilspa.esa.es)
Chandra X-ray Observatory (http://chandra.harvard.edu)
LSST (Large Synoptic Survey Telescope)
(http://www.lsst.org)
Suzaku (http://www.astro.isas.ac.jp/suzaku)
Sloan (http://www.sdss.org)
Hubble (http://hubble.nasa.gov)
Biographical
Information:
Education:
PhD,
Physics, Columbia University, 2003
M
Phil, Physics, Columbia University, 2000
MA,
Physics, Columbia University, 1999
BA
Honors, Physics, University of Chicago, 1997
Professional
History:
2006- Assistant
Professor of Physics, Purdue University
2003-2006 Postdoctoral Research Associate,
Stanford University and SLAC
1997-2003 Graduate Research Assistant,
Columbia University
1994-1997 Undergraduate Research Assistant,
University of Chicago and Fermilab