The microphysical properties of Dark Matter (DM), such as its mass and coupling strength, are typically assumed to retain their vacuum values when considering DM behaviour at a range of scales. However, DM interactions in different astrophysical and cosmological environments may be impacted by the properties of the background which in turn can substantially affect both DM production and the...
Big Bang Nucleosynthesis (BBN) describes the very first nucleosynthesis in the universe. The nuclear network of BBN produces the lightest elements and explains their cosmic abundances. With precision abundance observations, BBN can probe the physics of the early universe and place limits on key cosmological parameters. These key parameters also leave their imprint in the cosmic microwave...
When two galaxies collide, the supermassive black holes located at their centers can form a binary pair. These extreme gravitational situation causes ripples in spacetime (called gravitational waves) that carry away significant energy and angular momentum so that the two black holes themselves eventually collide. During the in-spiral phase, the gravitational waves are measurable by current...
The Tolman–Ehrenfest criterion of thermal equilibrium for a static fluid in a static spacetime is generalized to stationary heat conduction with negligible backreaction, and then applied to Hawking radiation in the Schwarzschild–de Sitter geometry. The two horizons acting as thermostats remain in thermal equilibrium. The temperature of the radiation fluid interpolates between those of the two...
Gavitational instantons are complete, Ricci-flat Riemannian manifolds (M,g) characterized by their asymptotic behaviour. We will cosnider asymptotically locally Euclidean (ALE) (a quotient of Euclidean space) with quartic volume growth, and asymptotically locally flat (ALF) spaces with cubic volume growth (e.g. a circle bundle over R^3). Explicit examples can be constructed from known black...
