On the Variations of Fundamental Constants and AGN feedback in the QSO host galaxy RXJ0911.4+0551 at z=2.79

TL;DR

This study uses high-quality spectral observations of a high-redshift quasar to test for variations in fundamental constants and investigate AGN feedback effects on molecular gas, finding no significant changes over 11.3 billion years.

Contribution

First sensitive measurement of fundamental constant variations at high redshift using CO and CI lines in a quasar host galaxy.

Findings

No detectable variation in fundamental constants within measurement uncertainties.

Evidence of molecular outflows indicating negative feedback in the galaxy.

High-precision redshift measurements of emission lines at z=2.79.

Abstract

We report on sensitive observations of the CO(7-6) and CI(2-1) transitions in the z=2.79 QSO host galaxy RXJ0911.4+0551 using the IRAM Plateau de Bure interferometer (PdBI). Our extremely high signal to noise spectra combined with the narrow CO line width of this source (FWHM = 120 km/s) allows us to estimate sensitive limits on the space-time variations of the fundamental constants using two emission lines. Our observations show that the CI and CO line shapes are in good agreement with each other but that the CI line profile is of order 10% narrower, presumably due to the lower opacity in the latter line. Both lines show faint wings with velocities up to +/-250 km/s, indicative of a molecular outflow. As such the data provide direct evidence for negative feedback in the molecular gas phase at high redshift. Our observations allow us to determine the observed frequencies of both transitions with so far unmatched accuracy at high redshift. The redshift difference between the CO and CI lines is sensitive to variations of dF/F with F=alpha^2/mu where alpha is the fine structure constant and mu the proton-to-electron mass ratio. We find dF/F=6.9 +/-3.7 x 10^-6 at a lookback time of 11.3 Gyr, which within the uncertainties, is consistent with no variations of the fundamental constants.