TUESDAY, June 9

LIGO/TAPIR Seminar, 1:00 PM - 2:00 PM, SCR 351 W Bridge
"Gravitational Wave Bursts from Vortex Avalanches in Pulsar Glitches," Lila Warszawski, University of Melbourne.

Abstract:

We estimate the burst gravitational wave signal from a glitching pulsar. The glitches are modelled as a nonaxisymmetric rearrangement of pinned superfluid vortices in the inner crust of the star, resulting in the reorganization of the superfluid velocity field, a time-varying current quadrupole moment, and hence a gravitational wave signal. We present two alternative models for the collective motion of vortices during a glitch: an avalanche process, in which stress reservoirs relax via a domino effect (like tectonic plates), and a coherent noise process, in which vortices respond stochastically to a global stimulus. We calculate the amplitude, polarization, and frequency content of the burst signal from a single glitch, and cross-correlate the waveform with standard templates in burst pipelines. We also set out the conditions for the signal to be detectable by Advanced LIGO. For both the avalanche and coherent noise processes the glitch sizes are observed to follow a power law with an index that varies between pulsars, and the waiting times between successive glitches have a Poissonian distribution, as observed in radio timing data. Based on these statistical distributions, we estimate the combined stochastic gravitational wave signal emanating from a realistically distributed pulsar population in a Milky-Way-type galaxy.