Seminario
"Gravitational waves and nonaxisymmetric oscillation modes in mergers of compact object binaries "
Relatore: Professor. Nikolaos Stergioulas
Sala Feynman
24 Novembre 2011 ore 16.30
Abstract

We study the excitation of nonaxisymmetric modes in the postmerger phase of binary compact object mergers and the associated gravitational wave emission. Our analysis is based on generalrelativistic simulations, in the spatial conformal flatness approximation, using smoothedparticlehydrodynamics for the evolution of matter, and we use a set of equal and unequal mass models, described by two nonzerotemperature hadronic equations of state and by one strange star equation of state. Through Fourier transforms of the evolution of matter variables, we can identify a number of oscillation modes, as well as several nonlinear components (combination frequencies). We focus on the dominant m=2 mode, which forms a triplet with two nonlinear components that are the result of coupling to the quasiradial mode. A corresponding triplet of frequencies is identified in the gravitational wave spectrum, when the individual masses of the compact objects are in the most likely range of 1.2 to 1.35 $M_\odot$. We can thus associate, through direct analysis of the dynamics of the fluid, a specific frequency peak in the gravitational wave spectrum with the nonlinear component resulting from the difference between the m=2 mode and the quasiradial mode. Once such observations become available, both the m=2 and quasiradial mode frequencies could be extracted, allowing for the application of gravitationalwave asteroseismology to the postmerger remnant and leading to tight constraints on the equation of state of highdensity matter.


