Parametric Instability in Scalar Gravitational Fields

Abstract

We present a brief review on a new dynamical mechanism for a strong field effect in scalar tensor theory. Starting with a summary of the essential features of the theory and subsequent work by several authors, we analytically investigate the parametric excitation of a scalar gravitational field in a spherically symmetric radially pulsating neutron star.

Dynamical trapping and relaxation of scalar gravitational fields

“…However, in view of the stringent experimental constraints [3] within the solar system on the linearly coupled ST theory due to Brans and Dicke [4,5], recent works have focused on nonlinear theories under extreme gravity. These include inflation in the early Universe [6,7] and strong field effects in neutron stars, pulsars and core-collapse supernovae (SNe) [8][9][10][11][12][13][14].…”

“…Motivated by the recent interest in the quadratically coupled scalar gravity in neutron stars and core-collapse SNe [8][9][10][11][12][13][14], we shall consider the second order coupling specified by:…”

“…We shall now apply the above framework to cosmology with a view to scalar gravity induced inflation using parameters relevant for energetic astrophysical events in the present epoch. Motivated by the recent interest in the quadratically coupled scalar gravity in neutron stars and core-collapse SNe [8][9][10][11][12][13][14], we shall consider the second order coupling specified by: Ω(φ) = e 1 2 βφ 2 i.e. α(φ) = βφ for some constant β.…”