Direct test of the FLRW metric from strongly lensed gravitational wave observations.

The assumptions of large-scale homogeneity and isotropy underly the familiar Friedmann-Lemaître-Robertson-Walker (FLRW) metric that appears to be an accurate description of our Universe. In this paper, we propose a new strategy of testing the validity of the FLRW metric, based on the galactic-scale lensing systems where strongly lensed gravitational waves and their electromagnetic counterparts can be simultaneously detected. Each strong lensing system creates opportunity to infer the curvature parameter of the Universe.

Publisher Correction: Precision cosmology from future lensed gravitational wave and electromagnetic signals.

The original PDF version of this Article inadvertently highlighted the author surnames and omitted the publication date. These have now been corrected in the PDF version of the Article. The HTML version was correct from the time of publication.

Precision cosmology from future lensed gravitational wave and electromagnetic signals.

The standard siren approach of gravitational wave cosmology appeals to the direct luminosity distance estimation through the waveform signals from inspiralling double compact binaries, especially those with electromagnetic counterparts providing redshifts. It is limited by the calibration uncertainties in strain amplitude and relies on the fine details of the waveform. The Einstein telescope is expected to produce 10-10 gravitational wave detections per year, 50-100 of which will be lensed.

Speed of Gravitational Waves from Strongly Lensed Gravitational Waves and Electromagnetic Signals.

We propose a new model-independent measurement strategy for the propagation speed of gravitational waves (GWs) based on strongly lensed GWs and their electromagnetic (EM) counterparts. This can be done in two ways: by comparing arrival times of GWs and their EM counterparts and by comparing the time delays between images seen in GWs and their EM counterparts. The lensed GW-EM event is perhaps the best way to identify an EM counterpart.