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

Abstract

[EN]We propose an improved methodology to constrain spatial variations of the fine structure constant using clusters of galaxies. We use the 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 parametrizations 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 cosmic microwave background power spectrum, and we also find 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 data sets 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.