Are Galaxy Clusters Suggesting an Accelerating Universe Independent of SNe Ia and Gravity Metric Theory?

TL;DR

This paper presents a kinematic method using Sunyaev-Zel'dovich effect and X-ray data from galaxy clusters to independently confirm the universe's acceleration, without relying on gravity theories or supernova data.

Contribution

It introduces a new, model-independent technique to measure cosmic acceleration using galaxy cluster data, providing results consistent with an accelerating universe.

Findings

Universe is currently accelerating.

Transition from deceleration to acceleration occurred recently.

Future Planck data could improve constraints on cosmic expansion.

Abstract

A kinematic method to access cosmic acceleration based exclusively on the Sunyaev-Zel'dovich effect (SZE) and X-ray surface brightness data from galaxy clusters is proposed. By using the SZE/X-ray data from 38 galaxy clusters [Bonament et al., Astrop. J. 647, 25 (2006)], we find that the present Universe is accelerating and that the transition from an earlier decelerating to a late time accelerating regime occurred relatively recent. Such results are fully independent on the validity of any metric gravity theory, the possible matter-energy contents filling the Universe, as well as on the SNe type Ia Hubble diagram from which the present acceleration was inferred. The ability of the ongoing Planck satellite mission to obtain tighter constraints on the expansion history through SZE/X-ray angular diameters is also discussed. Two simple simulations of future Planck data suggest that such technique will be competitive with supernova data besides being complementary to it.