The tidal signatures of gravitational wave standard sirens

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• Chris Messenger (University of Cardiff)
• Wednesday 09 November 2011, 14:00-15:00
• Physics Library, Physics West Building.

If you have a question about this talk, please contact Alastair Sanderson.

Our knowledge about the the dynamics of the Universe (the rate of its expansion) and what it is made up of (namely, dark matter and dark energy) comes from deducing the distances and redshifts of distant galaxies. So far, this knowledge has come from a very careful calibration of distances to so-called standard candles – sources whose intrinsic luminosity can be inferred from their observed properties such as the spectral content, time-variability of the flux of radiation, etc. astronomers build the distance scale by using several steps, each of which works only over a limited range of the distance. Cosmologists have long sought for standard candles that can work on large distance scales without being dependent on the lower rungs of cosmic distance ladder. In 1986 Schutz recognised that gravitational waves from the coalescence of binary neutron stars and/or black holes are standard candles that can be used to accurately measure distances to their host galaxies. It has so far been thought that gravitational wave observations cannot measure the red-shift due to an inherent degeneracy between the source mass and its red-shift. Here we show that binary neutron stars, in contrast, produce waveforms modified by matter effects which depend on their unredshifted masses. Our results demonstrate that future ground-based gravitational-wave detectors can measure the cosmological redshift-distance relation, independently of associated electromagnetic observations and of the current cosmological distance ladder.

This talk is part of the Astrophysics Seminars series.

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