| 研究実績の概要 |
Although GR is well established at small scales, GR faces challenges predicting dynamics on large scales, which motivated the hypotheses of dark energy and dark matter. Metric affine gravity (MAG) has been proposed to resolve some of these issues. In this fellowship, we aimed to develop observational tests of a subset of MAG, called symmetric teleparallel (STEGR), specifically f(Q) models, which are a function of nonmetricty (Q), alone. These models are stable and produce the same GW speed observed in the GW170817 event. We have considered three specific forms for f(Q): a power law, a logarithmic, and an exponential in Q.
For each model we have checked the ranges of parameters that produce background evolution consistent with observed cosmic expansion rate. We have checked the effective dark energy equation of state produced by each model. We have checked the parameters in the perturbations: effective gravitational coupling in the Poisson equation, the amplitude damping parameter in the propagation of GW, and performed a chi-squared error analysis to bound the model parameters. We found that the logarithmic, and one of the two branches of the exponential model are excluded by observational data, while we obtained bounds on the parameters of the power law and other branch of the exponential model.
Future observations of gravitational waves will play a crucial role in testing the theory as a probe independent and complementary to electromagnetic observations.
|
