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SUMMARY:ASP Online Seminars: Covariant density and velocity perturbations
of the quasi-Newtonian cosmological model in f(T) gravity
DTSTART;VALUE=DATE-TIME:20210921T133000Z
DTEND;VALUE=DATE-TIME:20210921T150000Z
DTSTAMP;VALUE=DATE-TIME:20210927T203800Z
UID:indico-event-1016176@indico.cern.ch
CONTACT:ASP-IOC@cern.ch\;hebasami181@gmail.com
DESCRIPTION:Speakers: Heba Sami Abdulrahman (Northwest University\, South
Africa)\nAbstract:\n\nIn this work\, we investigate classes of shear-free
cosmological dust models with irrotational fluid flows within the framewor
k of f(T) gravity. In particular\, we use the 1 + 3 covariant formalism an
d we present the covariant linearised evolution and constraint equations.
We then derive the integrability conditions describing a consistent evolut
ion of the linearised field equations of quasi-Newtonian universes in the
f(T) gravitational theory. Finally\, we derive the evolution equations for
the density and velocity perturbations of the quasi-Newtonian universe. W
e explore the behaviour of the matter density contrast for two models of t
he f(T) theories of gravity\, namely the power-law f(T) model where f(T) =
µT_0(T=T_0)^n and the more generalized model where f(T) = T + µT_0(T=T_
0)^n with and without the application of the so-called quasistatic approxi
mations. Our numerical solutions show that these f(T) models can be suitab
le alternatives to study the growth of energy density fluctuations\, while
applying the so-called quasi-static approximation but the results show th
at this approximation is not applicable here. Moreover\, any small deviati
on from general relativity and any small change in the initial conditions
of the perturbations causes huge orders-of-magnitude deviations from limit
ing general relativistic results\, potentially putting constraints on the
modified theory.\n\n \n\n \nhttps://indico.cern.ch/event/1016176/
URL:https://indico.cern.ch/event/1016176/
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