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Naef

Fakultäten » Mathematisch-naturwissenschaftliche Fakultät » Physik-Institut » Prof. Dr. Philippe Jetzer » Naef

Completed research project

Title / Titel Gravitational radiation in f(R) gravity
PDF Abstract (PDF, 14 KB)
Summary / Zusammenfassung Since the discovery of the PSR 1913+16 system by Hulse and Taylor in 1974, binary
pulsars have become an important laboratory for testing gravity theories. Among such
theories we consider so–called f(R) theories, for which the Einstein–Hilbert action of GR
is replaced by a nonlinear function f of the Ricci scalar R. For such theories, still an open
problem is the calculation of the energy loss of a binary pulsar system by radiation of
gravitational waves in the linearised theory. We investigated the gravitational radiation
emitted by an isolated system for gravity theories with Lagrange density f(R) = R+aR2.
As a formal result we obtained leading order corrections to the quadrupole formula
in General Relativity. We made use of the analogy of f(R) theories with scalar-tensor
theories, which in contrast to General Relativity feature an additional scalar degree of
freedom. Unlike General Relativity, where the leading order gravitational radiation is
produced by quadrupole moments, the additional degree of freedom predicts gravitational
radiation of all multipoles, in particular monopoles and dipoles, as this is the case for the
most alternative gravity theories known today. An application to a hypothetical binary
pulsar moving in a circular orbit yields a limit by constraining
the dipole power to account at most for 1% of the quadrupole power as predicted by
General Relativity.
Publications / Publikationen Phys. Rev. D., Volume 84, (2011), 024027
Project leadership and contacts /
Projektleitung und Kontakte
Dr. Joachim Naef (Project Leader)  
Prof. Philippe Jetzer jetzer@physik.uzh.ch
Funding source(s) /
Unterstützt durch
SNF (Personen- und Projektförderung)
 
Duration of Project / Projektdauer Jul 2010 to Jun 2011