Constraining spatial variations of the fine structure constant using clusters of galaxies and Planck data

TL;DR

This paper introduces an improved method using galaxy clusters and Planck data to constrain spatial variations of the fine structure constant, finding potential dipole anisotropy aligned with other cosmic anomalies.

Contribution

It presents a novel approach combining Sunyaev-Zeldovich measurements and MCMC analysis to better constrain spatial variations of fundamental constants.

Findings

Improved constraints on the fine structure constant variations.

Best-fit dipole direction aligns with known cosmic anomalies.

Current data cannot confirm a dipole but shows potential for future studies.

Abstract

We propose an improved methodology to constrain spatial variations of the fine structure constant using clusters of galaxies. We use the {\it Planck} 2013 data to measure the thermal Sunyaev-Zeldovich effect at the location of 618 X-ray selected clusters. We then use a Monte Carlo Markov Chain algorithm to obtain the temperature of the Cosmic Microwave Background at the location of each galaxy cluster. When fitting three different phenomenological parameterizations allowing for monopole and dipole amplitudes in the value of the fine structure constant we improve the results of earlier analysis involving clusters and the CMB power spectrum, and we also found that the best-fit direction of a hypothetical dipole is compatible with the direction of other known anomalies. Although the constraining power of our current datasets do not allow us to test the indications of a fine-structure constant dipole obtained though high-resolution optical/UV spectroscopy, our results do highlight that clusters of galaxies will be a very powerful tool to probe fundamental physics at low redshift.