### Sources and Simulations

**Numerical Relativity and Data Analysis**

The recent developments in numerical relativity are very encouraging for gravitational wave astrophysics. It is now possible to simulate many tens of cycles of black hole inspiral, followed by merger and ringdown of the black holes. Progress in binary black hole simulations holds promise for improving gravitational wave searches and maximizing the amount of astrophysical information that one could extract from a detection of a binary inspiral signal. The picture to the right shows the trajectory of two black holes orbiting each other in a numerical simulation. Over 30 gravitational wave cycles can be extracted from this simulation and used to both improve existing data analysis algorithms and develop new algorithms to search LIGO data for binary black hole inspirals.

The Syracuse group collaborates closely with the Cornell-Caltech numerical relativity group to simulate black hole mergers on supercomputers and extract information about gravitational waves and the physics of strong gravitational fields from these simulations.

**Probing the Spacetime Geometry of Strong Field Objects**

Members of the Syracuse group are studying the inspiral and coalescence of neutron star--intermediate mass black hole binaries detectable by the ground based network of detectors. In recent years, evidence from ultra-luminous X-ray sources and the dynamics of globular clusters suggests that there may exist a population of intermediate mass black holes (IMBHs) with masses in the range 10^{2} to 10^{4} solar masses. The motivation to search for such systems in ground based detectors is that the mass ratio of the binary components may be high enough that the neutron star will act as a probe of the gravitational field of the larger black hole (shown pictorally at left). Rate estimates of neutron star--IMBH capture in globular clusters suggest that the coalescence rate may be as high as 10 per year for the Advanced LIGO detectors. Of particular interest is whether we can measure the multipole structure of the spacetime using LIGO, and develop techniques to map the spacetime geometry of the black hole with sufficient accuracy to test the no-hair theorem.