The Hubble constant and dark energy from cosmological distance measures

Abstract

We study how the determination of the Hubble constant from cosmological distancemeasures is affected by models of dark energy and vice versa. For this purpose, constraintson the Hubble constant and dark energy are investigated using the cosmologicalobservations of cosmic microwave background, baryon acoustic oscillations and type Iasupernovae. When one investigates dark energy, the Hubble constant is often a nuisanceparameter; thus it is usually marginalized over. On the other hand, when one focuses onthe Hubble constant, simple dark energy models such as a cosmological constant and aconstant equation of state are usually assumed. Since we do not know the nature ofdark energy yet, it is interesting to investigate the Hubble constant assumingsome types of dark energy and see to what extent the constraint on the Hubbleconstant is affected by the assumption concerning dark energy. We show thatthe constraint on the Hubble constant is not affected much by the assumptionfor dark energy. We furthermore show that this holds true even if we removethe assumption that the universe is flat. We also discuss how the prior on theHubble constant affects the constraints on dark energy and/or the curvature of theuniverse.