Gravitational-wave astronomy has entered a new era, as an international array of ground-based laser interferometer gravitational-wave detectors recently reached their design sensitivity. In late 2007, the Laser Interferometer Gravitational-wave Observatory (LIGO) completed its 2-year science run, at a design strain sensitivity of 10-21 (rms), over a band width of ~ 100 Hz. At this moment, the data are still being analyzed, and more stringent upper limits are being imposed on possible sources of LIGO, including compact binaries (consisting of neutron stars and/or black holes), pulsars, gamma-ray bursts, and the stochastic background. An improved version of LIGO, called Enhanced LIGO, will operate for one year starting from this Fall. Enhanced LIGO will be a factor of ~ 2 to 3 as sensitive as initial LIGO, which is consistent with a compact-binary merger event-rate of ~ 1/yr according to the most optimistic (yet highly uncertain) astrophysical estimate. In the next several years, LIGO will be upgraded into Advanced LIGO, ~ 10 times as sensitive as initial LIGO. In this talk, I will discuss the physics of LIGO detectors and why they have been able to reach such a dramatic sensitivity, as well as the physics of LIGO sources and statistical techniques employed to extract their signatures from LIGO data. I will also discuss challenges we face in modeling gravitational-wave sources, and in improving future LIGO detectors.

ANL Physics Division Colloquium Schedule