Cosmological Simulations of Running Vacuum Models Explored

by Tommy on 21/01/2017

I found this exposition to be moderately interesting.

Pairwise velocities in the “Running FLRW” cosmological model, Antonio Bibiano and Darren J. Croton (16 January 2017)

We present an analysis of the pairwise velocity statistics from a suite of cosmological N-body simulations describing the “Running Friedmann-LemaĆ®tre-Robertson-Walker” (R-FLRW) cosmological model. This model is based on quantum field theory in a curved space-time and extends ΛCDM with a time-evolving vacuum energy density ρΛ. To enforce local conservation of matter a time-evolving gravitational coupling is also included. Our results constitute the first study of velocities in the R-FLRW cosmology, and we also compare with other dark energy simulations suites, repeating the same analysis. We find a strong degeneracy between the pairwise velocity and σ8 at z = 0 for almost all scenarios considered, which remains even when we look back to epochs as early as z = 2. We also investigate various Coupled Dark Energy models, some of which show minimal degeneracy, and reveal interesting deviations from ΛCDM which could be readily exploited by future cosmological observations to test and further constrain our understanding of dark energy.

And for a bigger picture of the so called ‘multiverse’, there is this.

A Single Big Bang and Innumerable Similar Finite Observable Universe, Nilton Penha Silva, Accepted by Progress in Physics, Progress in Physics, 13, 2 (4 January 2017)

Gravity dominated Universe until it was 3.214 Gyr old and, after that, dark energy dominates leading to an eternal expansion, no matter if the Universe is closed, flat or open. That is the prediction of the expansion factor recently proposed by Silva. It is also shown that there is an upper limit for the size of the Observable Universe relative radial comoving coordinate, beyond which nothing is observed by our fundamental observer, on Earth. Our Observable Universe may be only a tiny portion of a much bigger Universe most of it unobservable to us. This leads to the idea that an endless number of other fundamental observers may live on equal number of Observable Universes similar to ours. An unique Big Bang originated an unique Universe, only part of it observable to us.

So take that, string theorists!

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