Braneworld extra dimensions in light of GW170817
Abstract
The search for extra dimensions is a challenging endeavor to probe physics beyond the Standard Model. The joint detection of gravitational waves (GW) and electromagnetic (EM) signals from the merging of a binary system of compact objects like neutron stars can help constrain the geometry of extra dimensions beyond our 3 +1 spacetime ones. A theoretically wellmotivated possibility is that our observable Universe is a 3 +1 dimensional hypersurface, or brane, embedded in a higher 4 +1 dimensional antide Sitter (AdS_{5} ) spacetime, in which gravity is the only force which propagates through the infinite bulk space, while other forces are confined to the brane. In these types of braneworld models, GW and EM signals between two points on the brane would, in general, travel different paths. This would result in a time lag between the detection of GW and EM signals emitted simultaneously from the same source. We consider the recent nearsimultaneous detection of the GW event GW170817 from the LIGO/Virgo collaboration, and its EM counterpart, the short gammaray burst GRB170817A detected by the Fermi Gammaray Burst Monitor and the International GammaRay Astrophysics Laboratory AntiCoincidence Shield spectrometer. Assuming the standard Λ cold dark matter scenario and performing a likelihood analysis which takes into account astrophysical uncertainties associated to the measured time lag, we set an upper limit of ℓ≲0.535 Mpc at 68% confidence level on the AdS_{5} radius of curvature ℓ. Although the bound is not competitive with current Solar System constraints, it is the first time that data from a multimessenger GWEM measurement is used to constrain extradimensional models. Thus, our work provides a proof of principle for the possibility of using multimessenger astronomy for probing the geometry of our spacetime.
 Publication:

Physical Review D
 Pub Date:
 March 2018
 DOI:
 10.1103/PhysRevD.97.064039
 arXiv:
 arXiv:1711.06628
 Bibcode:
 2018PhRvD..97f4039V
 Keywords:

 General Relativity and Quantum Cosmology;
 Astrophysics  Cosmology and Nongalactic Astrophysics;
 High Energy Physics  Phenomenology;
 High Energy Physics  Theory
 EPrint:
 9 pages, 3 figures, version accepted by PRD. The MCMC code, chains, and scripts to reproduce our results and plots can be found at http://github.com/sunnyvagnozzi/Braneworldextradimensions