Gravitational theories differing from general relativity may explain the accelerated expansion of the Universe without a cosmological constant. However, to pass local gravitational tests, a "screening mechanism"is needed to suppress, on small scales, the fifth force driving the cosmological acceleration. We consider the simplest of these theories, i.e., a scalar-tensor theory with first-order derivative self-interactions, and study isolated (static and spherically symmetric) nonrelativistic and relativistic stars. We produce screened solutions and use them as initial data for nonlinear numerical evolutions in spherical symmetry. We find that these solutions are stable under large initial perturbations, as long as they do not cause gravitational collapse. When gravitational collapse is triggered, the characteristic speeds of the scalar evolution equation diverge, even before apparent black-hole or sound horizons form. This casts doubts on whether the dynamical evolution of screened stars may be predicted in these effective field theories.

Dynamics of Screening in Modified Gravity / ter Haar, Lotte; Bezares, Miguel; Crisostomi, Marco; Barausse, Enrico; Palenzuela, Carlos. - In: PHYSICAL REVIEW LETTERS. - ISSN 0031-9007. - 126:9(2021), pp. 1-6. [10.1103/PhysRevLett.126.091102]

Dynamics of Screening in Modified Gravity

Bezares, Miguel;Crisostomi, Marco;Barausse, Enrico;
2021-01-01

Abstract

Gravitational theories differing from general relativity may explain the accelerated expansion of the Universe without a cosmological constant. However, to pass local gravitational tests, a "screening mechanism"is needed to suppress, on small scales, the fifth force driving the cosmological acceleration. We consider the simplest of these theories, i.e., a scalar-tensor theory with first-order derivative self-interactions, and study isolated (static and spherically symmetric) nonrelativistic and relativistic stars. We produce screened solutions and use them as initial data for nonlinear numerical evolutions in spherical symmetry. We find that these solutions are stable under large initial perturbations, as long as they do not cause gravitational collapse. When gravitational collapse is triggered, the characteristic speeds of the scalar evolution equation diverge, even before apparent black-hole or sound horizons form. This casts doubts on whether the dynamical evolution of screened stars may be predicted in these effective field theories.
2021
126
9
1
6
091102
https://arxiv.org/abs/2009.03354
ter Haar, Lotte; Bezares, Miguel; Crisostomi, Marco; Barausse, Enrico; Palenzuela, Carlos
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.11767/118594
Citazioni
  • ???jsp.display-item.citation.pmc??? 0
  • Scopus 22
  • ???jsp.display-item.citation.isi??? 21
social impact