Institut für Astronomie & Astrophysik

Asteroseismology of rapidly rotating neutron stars: An alternative approach

July 2015

Daniela D. Doneva, Kostas D. Kokkotas

One of the major challenges following the detection of gravitational waves from oscillating neutron stars is to infer its characteristic parameters like mass, radius and rotation rate via the observed data. For this purpose we should be equipped with a set of relations that connect the frequencies and the damping times of the oscillation modes to the stellar parameters. As a matter of fact this is the essence of the gravitational wave asteroseismology.

In our studies we focus on the fundamental f-modes of rapidly rotating neutron stars that are one of the promising sources of gravitational waves. An approach, different than the previous studies, is employed. First, the moment of inertia is used instead of the stellar radius and, second, the normalization of the oscillation frequencies and damping times is different. It is shown that in the nonrotating case this can lead to a much stronger equation of state independence. Our goal was to generalize the static relations to the rapidly rotating case and values of the spherical mode number l greater than 2. It turns out that this new set of asteroseismology relations we can be used to infer the stellar parameters from the observed gravitational wave signal with very good accuracy. The relations are also particularly useful for the massive rapidly rotating models that are subject to secular instabilities and thus can lead to copious emission of gravitational radiation.

Phys. Rev. D 92, 124004 (2015), arXiv:1507.06606 [astro-ph.SR]