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GR: Fachverband Gravitation und Relativitätstheorie

GR 6: Gravitational waves

GR 6.3: Vortrag

Montag, 17. März 2014, 17:10–17:30, SPA SR220

Gravitational wave constraints on the shape of neutron stars — •Nathan K. Johnson-McDaniel — Theoretisch-Physikalisches Institut, Friedrich-Schiller-Universität Jena

The gravitational wave observatories LIGO and Virgo have placed interesting upper bounds (below the limits from electromagnetic observations of the spin-down) on the gravitational radiation emitted by certain known pulsars, notably the Crab and Vela pulsars. We show how to convert these upper bounds into upper bounds on the l = m = 2 deformation of the star’s surface, in full general relativity, to first order in the deformation. This relation only depends on the star’s mass and radius, with reasonable assumptions about the matter at its surface. We then apply this relation to stars that have direct LIGO/Virgo bounds below the spin-down limit and compare with the expected surface deformation due to rotation. In particular, we find that the latest LIGO/Virgo observations have constrained the l = m = 2 deformation to be smaller than the rotational deformation for the Crab pulsar for all equations of state considered and for the Vela pulsar for the equations state with larger radii. These statements could not have been made using only the bounds on the l = m = 2 deformation from electromagnetic observations of the spin-down.