What is LIGO ?

LIGO (the Laser Interferometer Gravitational-Wave Observatory) is a cutting-edge project to detect gravitational waves arriving at the Earth from astronomical sources such as black holes and neutron stars. These waves were predicted by Albert Einstein in 1916 as a consequence of his general theory of relativity (GR), but they remained undetectable for almost a century. LIGO succeeded in making the first direct detection of gravitational waves on September 14, 2015. That plus additional events detected by LIGO, and in some cases also by its European counterpart Virgo, have given us a new vision of binary objects in the universe, including a population of rather heavy (but still "stellar-mass") black holes, and are enabling precise tests of GR. LIGO thus sits at the interface between physics and astronomy, and between experiment and theory.

In August 2017, LIGO and Virgo observed the binary neutron star event GW170817, which was coincident with a gamma-ray burst detected by the Fermi GBM instrument and precipitated a spectacularly successful multi-messenger observing campaign by astronomers worldwide. See, for instance, the UMD press release plus summaries in Nature, Science, APS Physics, and Astrophysical Journal Letters.

University of Maryland physicists, including professors Peter Shawhan (in the Gravitation Experiment group) and Alessandra Buonanno (in the Gravitation Theory group) plus their students, are active members of the LIGO Scientific Collaboration. Our research focus includes conducting searches for compact binary coalescence and "burst" signals, and connecting those events with other astronomical messengers including gamma-rays, X-rays, and radio transients. For instance, astronomers were alerted to the binary neutron star merger GW170817 thanks in part to event candidate selection software developed at Maryland.