Scintillation in scalar-tensor theories of gravity
C. Bracco 1 and
P. Teyssandier 2
Received 23 July 1998 / Accepted 9 September 1998
We study the scintillation produced by time-varying gravitational fields within scalar-tensor theories of gravity. The problem is treated in the geometrical optics approximation for a very distant light source emitting quasi plane monochromatic electromagnetic waves. We obtain a general formula giving the time dependence of the photon flux received by a freely falling observer. In the weak-field approximation, we show that the contribution to the scintillation effect due to the focusing of the light beam by a gravitational wave is of first order in the amplitude of the scalar perturbation. Thus scalar-tensor theories contrast with general relativity, which predicts that the only first-order effect is due to the spectral shift. Moreover, we find that the scintillation effects caused by the scalar field have a local character: they depend only on the value of the perturbation at the observer. This effect provides in principle a mean to detect the presence of a long range scalar field in the Universe, but its smallness constitutes a tremendous challenge for detection.
Key words: gravitation relativity
This article contains no SIMBAD objects.
© European Southern Observatory (ESO) 1998
Online publication: October 22, 1998