"The dynamic response of merging neutron stars", department colloquium February 1, 2012

Jocelyn Read, University of Mississippi

Neutron stars give us a unique glimpse of physics at extreme scales: the matter in their cores is compressed to densities up to ten times that of an atomic nucleus, in a state fundamentally described by quantum chromodynamics. There is substantial uncertainty about how matter behaves at this density, and astrophysical observations of neutron stars help pin it down.

We should soon be able to observe the gravitational waves radiated by a neutron star is orbiting a black hole or another neutron star. The two objects will spiral towards each other and, eventually, collide. Such events make up a large portion of gravitational-wave sources that Advanced LIGO is expected to observe, and the results of the collision may also explain short gamma-ray bursts that current satellites see.

Details of these signals can tell us about the dense matter that makes up neutron stars, as the matter's properties determine how the neutron star responds to its companion. There are two observational signatures that this talk will cover: First, some gamma-ray flares could be explained by the behaviour of dense matter in the neutron-star crust, as a result of the crust shattering from a resonance with the sweep of tides. Second, contributions to the gravitational-wave signal itself can be seen in from strong tidal deformations as the stars approach each other.