Eric and other bodies in free fall: does their acceleration depend on their internal structure?

• Clifford Will

Room: 113

Chasing Eric’s elegance for 3 decades

• Scott Hughes (Massachusetts Institute of Technology)

Room: 113 I began graduate studies in Fall 1993, arriving at Caltech vaguely interested in work being done in Kip Thorne’s group, but without a clear sense of what I really wanted to do. Kip’s advice to me was “talk to Eric.” Eric not only got me started thinking about subjects that continue to influence the calculations my group and I do today, but provided the standard that I have attempted to meet in almost all of the work I have done ever since. In this brief talk, I’ll describe the role Eric played in setting the initial data for my scientific career, and how he has continued to be the standard that I aspire to reach in the work that I enjoy the most.

Self-force now and then

• Leor Barack

Room: 113

Black holes: From the inside, out

• Patrick Brady

Room: 113

The masses and radii of the neutron stars observed by NICER

• Sharon Morsink (University of Alberta)

Room: 113 Neutron stars are the densest known gravitationally-stable objects in the Universe. Their strong gravitational fields, rapid rotation rates, and supra-nuclear central densities allow for a fascinating interplay between general relativistic effects and nuclear physics theory. Pulse-profile modeling is a technique that uses the gravitationally-lensed X-ray flux emitted from hot spots on the neutron star's surface to infer its mass and radius. General relativity is a crucial ingredient in this analysis. The Neutron Star Interior Composition ExploreR (NICER) is a NASA X-ray telescope mounted on the International Space Station. NICER is a timing instrument designed to make the measurements required to implement pulse-profile modelling. In this talk, I will give an overview of how NICER data is used to infer a neutron star's radius (and its mass), along with the latest results and future observations of other pulsars.

Following Eric's footsteps down the rabbit hole of the two body problem

• Eanna Flanagan

Room: 113 I highlight some of Eric's seminal contributions to our understanding of the two body problem in general relativity, from the 1990s at Caltech until today, and use them as a springboard for a discussion of two recent research directions. The first is the development of general methods to define and derive coarse-grained variables to describe the motion of macroscopic bodies, valid in contexts with nonlinear self-interactions. These methods are complementary to the methods of effective field theory, and build off earlier formalisms in the linear context by Detweiler and Whiting and by Harte. The second is an effort to understand in what regimes the dynamics of a two body system can be uniquely and/or usefully split into a conservative, Hamiltonian sector and a dissipative sector.

Neutron stars: Promises and challenges from gravitational-wave astronomy

• Jocelyn Read

Room: 113 Ground-based gravitational-wave observatories have detected more than three hundred gravitational-wave signals over the past decade. Most have been from binary black hole mergers, but the catalog of events also includes a handful of black-hole/neutron-star binaries and two or three double neutron star mergers. Observing these mergers is testing our understanding of gravity, revealing dense matter dynamics inside neutron-star cores, and tracing the endpoints of stellar evolution across cosmic time. They also tell us about the engines of transient astronomy and the sites where heavy elements are formed in our universe. As observatory upgrades improve our sensitivity, and as new facilities come online, we expect both increased detection rates and higher-fidelity measurements of the loudest signals. The challenge of gravitational-wave astronomy is moving from detection to interpretation: understanding future observations will place stringent requirements on our modelling of the source systems and how well we understand the physics that describes them. In this talk, I’ll outline gravitational-wave measurements of neutron star properties, in particular the nuclear equation of state, and their implications. I'll show how simplifying assumptions used to analyze the first signals will break down with future observations, and how bringing in information from nuclear science can improve our interpretations. Finally, I’ll discuss how we can quantify and account for uncertainty in signal models in our analyses, reducing systematic biases and allowing unmodeled physics to be inferred from observational data.

Testing the nature of Kerr black holes and Hawking’s area theorem with gravitational waves

• Katerina Chatziioannou

Room: 113

Insights into the rotating black hole interior from numerical solutions

• Frans Pretorius

Room: 113

Closing Remarks Room: 113