Modified gravity as a diagravitational medium

The Interstellar Medium as a Gravity Wave Detector

An observer, situated several thousand light-years away from a radio pulsar, finds himself embedded in the diffraction pattern resulting from the propagation of the radio waves through the irregular interstellar medium. The observer’s movement relative to the pattern causes an apparent scintillation of the pulsar. A binary star, situated close to the pulsar’s line-of-sight, is generating relati...

Cluster density profiles as a test of modified gravity

Lucas Lombriser, Fabian Schmidt, Tobias Baldauf, Rachel Mandelbaum, Uroš Seljak, and Robert E. Smith Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth, PO1 3FX, UK Institute for Theoretical Physics, University of Zurich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland Theoretical Astrophysics, California Institute of Technology M/C 350-17, Pasadena, California 91...

Nonderivative modified gravity: a classification

We analyze the theories of gravity modified by a generic nonderivative potential built from the metric, under the minimal requirement of unbroken spatial rotations. Using the canonical analysis, we classify the potentials V according to the number of degrees of freedom (DoF) that propagate at the nonperturbative level. We then compare the nonperturbative results with the perturbative DoF propag...

Gravity from a Modified Commutator

We show that a suitably chosen position-momentum commutator can elegantly describe many features of gravity, including the IR/UV correspondence and dimensional reduction (‘holography’). Using the most simplistic example based on dimensional analysis of black holes, we construct a commutator which qualitatively exhibits these novel properties of gravity. Dimensional reduction occurs because the ...

Modified gravity and cosmology