https://doi.org/10.1140/epjc/s10052-019-6606-x
Regular Article - Theoretical Physics
Non-comoving baryons and cold dark matter in cosmic voids
1
Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, A.P. 48–3, 62251, Cuernavaca, Morelos, México
2
Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, A. P. 70–543, 04510, Ciudad de México, México
* e-mail: ismaeldg@icf.unam.mx
Received:
8
November
2018
Accepted:
17
January
2019
Published online:
1
February
2019
We examine the fully relativistic evolution of cosmic voids constituted by baryons and cold dark matter (CDM), represented by two non-comoving dust sources in a 
CDM background. For this purpose, we consider numerical solutions of Einstein’s field equations in a fluid-flow representation adapted to spherical symmetry and multiple components. We present a simple example that explores the frame-dependence of the local expansion and the Hubble flow for this mixture of two dusts, revealing that the relative velocity between the sources yields a significantly different evolution in comparison with that of the two sources in a common 4-velocity (which reduces to a Lemaître–Tolman–Bondi model). In particular, significant modifications arise for the density contrast depth and void size, as well as in the amplitude of the surrounding over-densities. We show that an adequate model of a frame-dependent evolution that incorporates initial conditions from peculiar velocities and large-scale density contrast observations may contribute to understand the discrepancy between the local value of 
and that inferred from the CMB.
© The Author(s), 2019
