6 papers · 1 filter
Bessel-Hagen currents for linearised Weyl-squared gravity
Michael Hobson, Will Barker, Anthony Lasenby
For the Fierz-Pauli action the Bessel-Hagen construction does not produce a preferred local gauge-invariant energy-momentum tensor; it identifies only a gauge-invariant equivalence…
How black hole mimickers and Shapiro-free lenses signal effective dark matter
Lirui Yang, Will Barker, Tobias Mistele +1
We report the existence of two exotic compact objects in the leading relativistic model of modified Newtonian dynamics, namely aether-scalar-tensor theory. This model is consistent…
The radial metric function does not identify null surfaces
Yi-Hsiung Hsu, Will Barker, Michael Hobson +1
We investigate the conditions under which a hypersurface becomes null through the use of coordinate transformations. We demonstrate that, in static spacetimes, the correct criterio…
Buchdahl bound, photon ring, ISCO and radial acceleration in Einstein-æther theory
Yi-Hsiung Hsu, Anthony Lasenby, Will Barker +2
Spherically symmetric Einstein-æther (EÆ) theory with a Maxwell-like kinetic term is revisited. We consider a general choice of the metric and the æther field, finding that:~(i) th…
Gravitomagnetism and galaxy rotation curves: a cautionary tale
A. N. Lasenby, M. P. Hobson, W. E. V. Barker
We investigate recent claims that gravitomagnetic effects in linearised general relativity can explain flat and rising rotation curves, such as those observed in galaxies, without…
Static energetics in gravity
William E V Barker, Anthony N Lasenby, Michael P Hobson +1
A stress-energy tensor for linear gravity adapted to the harmonic gauge was recently proposed by Butcher, Hobson and Lasenby. By removing gauge constraints and imposing full metric…