Albert Einstein Institute | Max Planck Institute for Gravitational Physics | 2017 Oct 24
Combining gravitational-wave observations and pulsar timing to study alternatives to the theory of general relativity
Einstein's theory of general relativity has withstood 100 years of experimental scrutiny. However, these tests do not constrain how well the very strong gravitational fields produced by merging neutron stars obey this theory. New, more sophisticated techniques can now search for deviations from general relativity with unprecedented sensitivity. Scientists at the Max Planck Institutes for Gravitational Physics and for Radio Astronomy studied two foremost tools for testing the strong-field regime of gravity – pulsar timing and gravitational-wave observations – and demonstrated how combining these methods can put alternative theories of general relativity to the test.
Only recently, neutron stars have been observed through gravitational waves. On August 17, 2017, the LIGO-Virgo detector network measured gravitational waves from the merger of two neutron stars. These exotic objects are made up of incredibly dense matter; a typical neutron star weighs up to twice as much our Sun but has a diameter of only 20 kilometers. This year marks the 50th-year anniversary for the first observation of neutron stars, as pulsars. The precise nature of such extremely dense matter has remained a mystery for decades.
The authors investigated theories of gravity in which the strong gravitational fields within neutron stars differ from those predicted by general relativity. This strong-field deviation causes binary systems to radiate energy and merge more quickly than in general relativity – a behaviour that should be seen in neutron star observations. ...
Constraining Nonperturbative Strong-Field Effects in Scalar-Tensor Gravity by Combining
Pulsar Timing and Laser-Interferometer Gravitational-Wave Detectors - Lijing Shao et al
- arXiv.org > gr-qc > arXiv:1704.07561 > 25 Apr 2017 (v1), 18 Sep 2017 (v2)