Testing Einstein's Equivalence Principle and its Cosmological Evolution from Quasar Gravitational Redshifts

Abstract

We propose and apply a new test of Einstein's Equivalence Principle (EEP) based on the gravitational redshift induced by the central super massive black hole of quasars in the surrounding accretion disk. Specifically, we compare the observed gravitational redshift of the Fe III$\lambda \lambda$2039-2113 emission line blend in quasars with the predicted values in a wide, uncharted, cosmic territory ($0\lesssim z_{cosm}\lesssim 3$). For the first time we measure, with statistical uncertainties comparable or better than those of other classical methods outside the Solar System, the ratio between the observed gravitational redshifts and the theoretical predictions in 10 independent cosmological redshift bins in the $1\lesssim z_{cosm}\lesssim 3$ range. The average of the measured over predicted gravitational redshifts ratio in this cosmological redshift interval is $⟨z_g^m/z_g^p⟩=1.05\pm 0.06$ with scatter $0.13\pm 0.05$ showing no cosmological evolution of EEP within these limits. This method can benefit from larger samples of measurements with better S/N ratios, paving the way for high precision tests (below 1\%) of EEP on cosmological scales.

References in corpus (13)

• The Confrontation between General Relativity and Experiment
• Confirmation of general relativity on large scales from weak lensing and galaxy velocities
• The black hole mass - stellar velocity dispersion relation of narrow-line Seyfert 1 galaxies
• The Black Hole Mass Scale of Classical and Pseudo Bulges in Active Galaxies
• The effect of nuclear gas distribution on the mass determination of supermassive black holes
• Active galactic nuclei at z ~ 1.5: I. Spectral energy distribution and accretion discs
• Gravitational Redshift of Galaxies in Clusters from the Sloan Digital Sky Survey and the Baryon Oscillation Spectroscopic Survey
• The MarkI helioseismic experiment.I. Measurements of the solar gravitational redshift (1976-2013)
• Comparing gravitational redshifts of SDSS galaxy clusters with the magnification redshift enhancement of background BOSS galaxies
• Fe III emission in quasars: evidence for a dense turbulent medium
• The supermassive black hole masses of reverberation-mapped active galactic nuclei
• Relativistic Effects on Galaxy Redshift Samples due to Target Selection
• Individual Estimates of the Virial Factor in 10 Quasars: Implications on the Kinematics of the Broad Line Region

Cited by in corpus (2)

• Measuring the Virial Factor in SDSS DR5 Quasars with Redshifted H$\beta$ and Fe ii Broad Emission Lines
• Detection of Gravitational Redshift in Open Cluster non-degenerate stars