The WiggleZ Dark Energy Survey: measuring the cosmic expansion history using the Alcock-Paczynski test and distant supernovae

TL;DR

This paper combines supernovae data and galaxy clustering analysis from the WiggleZ survey to measure the universe's expansion history, providing evidence for acceleration and consistency with a cosmological constant.

Contribution

It presents a new, non-parametric measurement of the cosmic expansion rate over redshifts 0.1 to 0.9 using the Alcock-Paczynski test and supernovae data, independent of cosmological models.

Findings

Confirmed the universe's acceleration in expansion.

Measured the Hubble rate with 10-15% precision in four redshift bins.

Results are consistent with a cosmological-constant dark energy.

Abstract

Astronomical observations suggest that today's Universe is dominated by a dark energy of unknown physical origin. One of the most notable consequences in many models is that dark energy should cause the expansion of the Universe to accelerate: but the expansion rate as a function of time has proven very difficult to measure directly. We present a new determination of the cosmic expansion history by combining distant supernovae observations with a geometrical analysis of large-scale galaxy clustering within the WiggleZ Dark Energy Survey, using the Alcock-Paczynski test to measure the distortion of standard spheres. Our result constitutes a robust and non-parametric measurement of the Hubble expansion rate as a function of time, which we measure with 10-15% precision in four bins within the redshift range 0.1 < z < 0.9. We demonstrate that the cosmic expansion is accelerating, in a manner independent of the parameterization of the cosmological model (although assuming cosmic homogeneity in our data analysis). Furthermore, we find that this expansion history is consistent with a cosmological-constant dark energy.