Radio measurements of constant variation, and perspectives with ALMA

TL;DR

This paper reviews current radio-based constraints on fundamental constant variations and discusses how ALMA's enhanced sensitivity will improve future measurements, highlighting advantages over optical methods.

Contribution

It provides a comprehensive review of radio measurements of fundamental constants and quantifies the expected improvements with ALMA's capabilities.

Findings

Radio constraints on nd rom quasar absorption lines

ALMA's increased sensitivity will significantly enhance detection of radio sources

Radio domain offers advantages over optical in measuring constant variations

Abstract

The present constraints on fundamental constant variation (\alpha and \mu) obtained in the radio range are reviewed, coming essentially from absorption lines in front of quasars of intermediate to high-z galaxies, through CO, HI, OH, HCO+, HCN .. lines up to NH3 and CII. With ALMA, the sensitivity to detect radio continuum sources in narrow bands will increase by an order of magnitude, and the expected progress is quantified. The relative advantage of the radio domain with respect to the optical one is emphasized.