Session T6: Astrophysics of Black Hole Mergers

Gravitational waves from black hole mergers: From waveforms to astronomy

The merger of binary black holes is a key target for measurement by both ground and space-base detectors. Not only are their waves very loud, and hence promising targets for detection, but they are also information rich. Measurement of these waves can teach us a great deal about the system and environment that produced the binary system, making it clear that the measurement of these waves will provide a wealth of astronomically interesting data. In this talk, I will summarize this situation from the standpoint of measurements with the space-based LISA detector. LISA's target waves come from the coalescence of massive black hole systems, in the range $10^4 - 10^7\,M_\odot$; many of these systems will be at relatively high redshift ($z > 3$ or so). Measuring these waves will thus give insight into the cosmological growth and evolution of massive black holes; in particular, we expect to be able to determine the holes' masses and spins with great precision, to determine the luminosity distance to the binary with high precision, and to locate the event on the sky with moderate precision. I will summarize what is known about how well these measurements can be done, and discuss how this information can be used to learn about the cosmological growth of black holes and possibly even help map the large structure of the universe.   

Numerical Relativity and Black Hole Mergers

I shall review recent developments in the simulation of binary black hole systems, focusing on results of relevance to expected astrophysical systems and gravitational wave detection.   

The Astrophysical Context of Black Hole Mergers

Mergers between two black holes are anticipated to be key sources of gravitational waves for ground-based and space-based detectors, depending on the masses of the holes. The fundamental process of merger depends only on the mass ratios and spins of the holes, rather than on their absolute masses. This scale-independence has been exploited in numerous successful numerical simulations over the past few years. However, many aspects of the astrophysical processes affecting these systems do depend on masses. Indeed, detection and characterization of these mergers can yield unique information about stellar evolution, dynamics at many scales, and even the evolution of structure in the universe as a whole. I will give an overview of these processes and discuss future directions to pursue.