Eur. Phys. J. Plus (2020) 135: 207
https://doi.org/10.1140/epjp/s13360-020-00243-9

Regular Article

Space-time waves from a collapse with a time-dependent cosmological parameter

¹ Departamento de Física, Centro Universitario de Ciencias Exactas e Ingenierías, Universidad de Guadalajara, Av. Revolución 1500, Colonia Olímpica, C.P. 44430, Guadalajara, Jalisco, Mexico
² Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Funes 3350, C.P. 7600, Mar del Plata, Argentina
³ Instituto de Investigaciones Físicas de Mar del Plata (IFIMAR), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Mar del Plata, Argentina

^* e-mail: mbellini@mdp.edu.ar

Received: 29 December 2019
Accepted: 20 January 2020
Published online: 3 February 2020

Abstract

We study the emission of space-time waves produced by back-reaction effects during a collapse of a spherically symmetric universe with a time-dependent cosmological parameter, which is driven by a scalar field. As in a previous work, the final state avoids the final singularity due to the fact the co-moving relativistic observer never reaches the center, because the physical time evolution , decelerates for a co-moving observer which falls with the collapse. The equation of state of the system depends on the rate of the collapse, but always is positive: .