Gravity seminar - Uli Sperhake Seminar

Abstract: While Einstein's theory of general relativity has passed numerous tests
with flying colours, there remain important open questions in
observational astrophysics, cosmology and theoretical considerations that
may ultimately require an extension of general relativity. Scalar tensor
theory of Bergmann-Wagoner type is a rare example of a non-trivial
extension of general relativity that (i) is known to be mathematically
well-posed, (ii) is compatible with existing tests and (iii) predicts
potentially observable new phenomena. Whereas massless scalar-tensor
gravity is already severely constrained observationally, theories with a
massive scalar field remain largely uncharted and untested territory. In
this talk we model stellar core collapse in massive scalar-tensor gravity
and show how galactic events can lead to gravitational "breathing mode"
radiation of large amplitude potentially observable with existing
pipelines in LIGO-Virgo. For a wide range of parameters, this radiation is
nearly monochromatic and may even be observed years or centuries after
observation of a related supernova explosion in the electromagnetic
spectrum.