 (Photo of me in 2006!) |
Peter
S. Shawhan
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I am working on a major project
called LIGO (short for
Laser Interferometer Gravitational-wave
Observatory) which is designed to detect gravitational waves coming
from distant astrophysical objects such as black holes, neutron stars,
cosmic strings, or the core of a massive star when it collapses and
creates a supernova. Gravitational waves are distortions in the
geometry of space-time which are predicted, by Einstein's general
theory of relativity, to be emitted when massive bodies change their
shape or orientation rapidly. Direct searches for gravitational
waves began with Joe Weber here at the University of Maryland in the
1960s and have continued with increasingly sensitive detectors.
In particular, the Advanced
LIGO upgrade, completed in 2015, finally enabled the direct
detection of gravitational waves! The first detection, a
remarkably clear signal from the merger of two black holes into a
single, more massive black hole, was recorded by the LIGO detectors
on September 14, 2015, and announced to the world on February 11,
2016. I have set up a
GW150914 Resource Page with links to
find out more information about the discovery and its meaning.
We expect to detect and announce an increasing number of
gravitational wave signals over the next several years. One of
the main research goals of my group at Maryland is to do
"multi-messenger astronomy" by working with astronomers to find other
signatures of gravitational-wave events. We already got a good
start on that with GW150914
(preprint of our paper).
Whereas the construction and
operation of the LIGO observatories are co-led by Caltech (where I
spent 7 years as a postdoctoral fellow and staff scientist) and MIT,
the scientific mission of LIGO is carried out by the LIGO Scientific Collaboration, which
includes scientists at the University of Maryland along with a few
dozen other institutions. You can get an overview of many of the
scientific activities by visiting the LIGO Science Links web page I maintain (though some of the links are restricted to collaboration members). I
served for several years as Co-Chair of the LSC
Burst Analysis
Working Group. I have also been a member of the LSC Executive
Committee, served on the LIGO Program Advisory Committee (PAC), and
co-chaired the LIGO Academic Affairs Council (LAAC).
I am grateful to the National Science Foundation for financial support of my research through grants PHY-0653421, PHY-0738032, PHY-0757957, PHY-1068549 and PHY-1404121, as well as for the overall funding of the LIGO program.
As a graduate student at the
University of Chicago, I worked on a particle
physics experiment called KTeV which
studied the decays of neutral K mesons produced in a fixed-target beam
at Fermilab. The neutral K
meson system is remarkable in that two
neutral K meson states are
observed, one of which lives (on average) about 580 times longer than
the other before it decays. This is the result of mixing of
the quantum eigenstates due to particle interactions, and it turns out
that
there is a small particle-antiparticle asymmetry in the mixing,
referred to as "CP violation". One of the main goals of KTeV was
to measure an even more subtle effect, direct CP violation in the decay
process itself, by comparing
the decays of the short- and long-lived K mesons. My thesis
research was the measurement of direct CP violation using the first
part of the data collected by KTeV; we found a clear nonzero effect,
and published the results in Phys. Rev. Lett.
83, 22 (1999). (For anyone who may be
interested, my Ph.D. thesis is available in PostScript
or PDF format.)