Strong Gravity

The long-awaited detection of gravitational waves has provided us with another source of information about the Universe. In this talk I will give an overview of how we extract information from gravitational wave signals with a focus on signals for which we do not have a definitive and reliable model for what the signal looks like. In particular I will describe how we can analyze the signal emitted after two neutron stars have merged. I will describe how the information extracted from such a signal can be used to place constrains on the equation of state of dense matter.

The era of gravitational wave detection is upon us.  Advanced LIGO (aLIGO) is now in full operation.  It has successfully detected the gravitational waves emitted from distant pairs of black holes (BHs) as they spiral together and merge.  And we have many more detections to look forward to.  But where are these BH-BH mergers happening, in the vast wilderness of the cosmos?  

One of the preferred candidates are globular clusters, massive systems of very old stars densely packed together and bound together by gravity.  Globular clusters are factories for black hole binary mergers. But we are only able to observe these factories in operation now. In order to understand how they were built and the treasures they should be expected to produce at present, we must somehow rewind their evolution over billions of years to say something about the initial conditions. Only then will we be able to understand how these beasts birth BH binaries, and are contributing to the gravitational waves currently being observed by aLIGO. After a brief overview of the concept of chaos, I will discuss recent progress in advancing our understanding of the origins of BH-BH mergers.