English

Does nonlocal gravity yield divergent gravitational energy-momentum fluxes?

General Relativity and Quantum Cosmology 2019-03-06 v3 Cosmology and Nongalactic Astrophysics

Abstract

Energy-momentum conservation requires the associated gravitational fluxes on an asymptotically flat spacetime to scale as 1/r21/r^2, as rr \to \infty, where rr is the distance between the observer and the source of the gravitational waves. We expand the equations-of-motion for the Deser-Woodard nonlocal gravity model up to quadratic order in metric perturbations, to compute its gravitational energy-momentum flux due to an isolated system. The contributions from the nonlocal sector contains 1/r1/r terms proportional to the acceleration of the Newtonian energy of the system, indicating such nonlocal gravity models may not yield well-defined energy fluxes at infinity. In the case of the Deser-Woodard model, this divergent flux can be avoided by requiring the first and second derivatives of the nonlocal distortion function f[X]f[X] at X=0X=0 to be zero, i.e., f[0]=0=f[0]f'[0] = 0 = f''[0]. It would be interesting to investigate whether other classes of nonlocal models not involving such an arbitrary function can avoid divergent fluxes.

Keywords

Cite

@article{arxiv.1811.04647,
  title  = {Does nonlocal gravity yield divergent gravitational energy-momentum fluxes?},
  author = {Yi-Zen Chu and Sohyun Park},
  journal= {arXiv preprint arXiv:1811.04647},
  year   = {2019}
}

Comments

21 pages, no figures, comments welcome; v2: references added; v3: corrected typos and added more references