Changing Redshifts caused by a Changing Expansion Velocity of the Universe

TL;DR

This paper discusses the potential to measure real-time changes in the universe's expansion rate through redshift drift observations with next-generation telescopes, providing a direct test of cosmological models.

Contribution

It explains the concept of redshift drift and its relation to cosmic expansion, illustrating its significance within the Lambda-CDM model framework.

Findings

Redshift drift can be measured over a decade with future telescopes.

Redshift drift directly relates to changes in cosmic expansion rate.

The phenomenon offers a new way to test cosmological models.

Abstract

With the next generation of big telescopes such as the ELT and SKA it might become possible to measure changes in the expansion rate of the Universe in real time by measuring the change of the redshifts of a large number of galaxies over a period of the order of 10 years. This phenomenon, known as 'redshift drift,' will provide a crucial direct test of cosmological models. The change in redshift is readily explained using the concept of conformal time which is the comoving distance of a galaxy in lightyears. We emphasize that the redshift drift is directly proportional to the average change in the cosmic expansion rate between the time of a galaxy's light emission and its absorption. This phenomenon is illustrated within the framework of the concordance model, the Lambda-CDM model of the universe.