English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Tools annual

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

We propose and apply a new test of Einstein's Equivalence Principle (EEP)based on the gravitational redshift induced by the central super massive blackhole of quasars in the surrounding accretion disk. Specifically, we compare theobserved gravitational redshift of the Fe III$\lambda\lambda$2039-2113 emissionline blend in quasars with the predicted values in a wide, uncharted, cosmicterritory ($0 \lesssim z_{cosm}\lesssim3$). For the first time we measure, withstatistical uncertainties comparable or better than those of other classicalmethods outside the Solar System, the ratio between the observed gravitationalredshifts and the theoretical predictions in 10 independent cosmologicalredshift bins in the $1 \lesssim z_{cosm}\lesssim3$ range. The average of themeasured over predicted gravitational redshifts ratio in this cosmologicalredshift interval is $\langle z^m_g/z_g^p\rangle=1.05\pm 0.06$ 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/Nratios, paving the way for high precision tests (below 1\%) of EEP oncosmological scales.

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