Unified dark energy and dark matter from dynamical spacetime

by David Benisty

at Astrophysics and Cosmology Seminar

Wed, 31 Oct 2018, 11:10
Physics building (#54) room 207

Abstract

Note: talk starts at 11:10 am Abstract: A unification of dark matter and dark energy based on a dynamical space time theory is suggested By introducing a dynamical space time vector field as a Lagrange multiplier a conservation of an energy momentum tensor T is implemented This Lagrangian generalizes the Unified dark energy and dark matter from a scalar field different from quintessence Phys RevD 81 043520 2010 which did not consider a Lagrangian formulation This generalization allows the solutions which were found previously but in addition to that also non singular bouncing solutions that rapidly approach to the CDM model The dynamical time vector field exactly coincides with the cosmic time for the a CDM solution and suffers a slight shift advances slower with respect to the cosmic time in the region close to the bounce for the bouncing non singular solutions In addition we introduced some exponential potential which could enter into the T stress energy tensor or coupled directly to the measure g gives a possible interaction between DE and DM and could explain the coincidence problem A mechanism of inflation from higher dimensions compactification is also studied An Early Universe capable of providing exponential growth for some dimensions and exponential contraction for others giving therefore an explanation for the big size of the observed four dimensional Universe as well as the required smallness of the extra dimensions is obtained For Dynamical time solution: a negative vacuum energy puts an upper bound on the maximum volume and the bounce imposes a lower bound So that in the early universe the volume oscillates but in each oscillation the extra dimensions contract exponentially and the ordinary dimension expand exponentially The dynamical space time theory provides a natural way to exit from the inflation compactification epoch since the scalar field that drives the vacuum energy can smoothly climb into small positive values of vacuum energy which is the end of the inflation compactification

Created on 25-10-2018 by Bar Lev, Yevgeny (ybarlev)
Updaded on 25-10-2018 by Bar Lev, Yevgeny (ybarlev)