Astrophysical implications of the Asymptotic Safety Scenario in Quantum Gravity

Abstract

In recent years it has emerged that the high energy behavior of gravity could be governed by an ultraviolet non-Gaussian fixed point of the (dimensionless) Newton's constant, whose behavior at high energy is thus antiscreened. This phenomenon has several astrophysical implications. In particular in this article recent works on renormalization group improved cosmologies based upon a renormalization group trajectory of Quantum Einstein Gravity with realistic parameter values will be reviewed. It will be argued that quantum effects can account for the entire entropy of the present Universe in the massless sector and give rise to a phase of inflationary expansion. Moreover, the prediction for the final state of the black hole evaporation, is a Planck size remnant which is formed in an infinite time. Workshop on Continuum and Lattice Approaches to Quantum Gravity

Asymptotic safety of quantum gravity beyond Ricci scalars

“…Provided that asymptotic safety is realised in nature, it is conceivable that the characteristic quantum gravitational modifications have impacted during the very early universe, including its phase of inflationary expansion and the phase of late time acceleration. A number of studies have explored these possibilities by exploiting characteristics of an asymptotically safe fixed point using renormalisation group improvements of the effective action or of the gravitational equations of motion including those of Friedmann-Robertson-Walker universes [48,[108][109][110][111][112][113][114][115][116][117][118][119][120][121][122][123][124][125][126].…”

Asymptotic Safety and Black Holes

“…We build on results found in four dimensions [27,31,24] and in higher dimensions [156,63]. It is the central assumption of this approach that the leading quantum gravity corrections to black hole metrics are accounted for through replacing Newton's coupling constant by a 'running' coupling which evolves under the renormalisation group equations for gravity.…”

Asymptotically safe cosmology – A status report

“…The prospect that Asymptotic Safety could be capable of describing gravitational force at all length scales makes the theory quite attractive for cosmological model building [9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,35,36,37,38]. On the one hand some or all of the free parameters appearing in the Asymptotic Safety construction (including the value of the cosmological constant and Newton's constant complemented by a low number of higher-derivative couplings) may be determined from cosmological data.…”