Buchdahl type inequalities in $d$-dimensions

Abstract

Spherically symmetric anisotropic static compact solutions to the Einstein equations in dimension $d\geq4$ are considered. Various matter models are examined and upper bounds on the ratio of the gravitational mass to the radius in these different models are obtained. Bounds are also generalised in the presence of a non-zero charge and a positive cosmological constant. These bounds are then used to find the maximum of the gravitational redshift at the surface of the object.

23 pages. To appear in Classical and Quantum Gravity. Matches published version. Typos fixed, section added discussing saturation of bounds