Jim Condon (NRAO, Charlottesville, USA)

Dark Energy and the Hubble Constant - Jim Condon Colloquium

ATNF Marsfield Lecture Theatre

Abstract

Dark energy (DE) dominates the energy density and future expansion of
the universe, and its nature is a major unsolved problem for theoretical physics. The equation-of-state and energy density of DE
can be constrained observationally by comparing an accurate (< 3% rms)
value of the Hubble constant with the known distance to the
last-scattering surface of the cosmic microwave background. The
Megamaser Cosmology Project (MCP) is now measuring geometric distances
to water masers in the nuclei of distant Seyfert galaxies in order to
obtain an accurate value of H0 free from the systematic errors
associated with "standard candles." I will review the effect of DE on
the Hubble constant and present the latest MCP results.