Observing Cosmological Processes in Real Time with Repeating Fast Radio Bursts

TL;DR

Repeating strongly lensed fast radio bursts can enable real-time observation of cosmological processes such as cosmic expansion and mass accretion across different redshifts.

Contribution

This paper proposes using repeating lensed FRBs as a novel method to observe cosmological evolution in real time.

Findings

Potential to observe cosmic expansion directly

Ability to measure transverse proper motion of cosmic structures

Feasibility of detecting growth of density perturbations

Abstract

It is noted that the duration of a fast radio burst (FRB), about $10^{-3}$ s, is a smaller fraction of the time delay between multiple images of a source gravitationally lensed by a galaxy or galaxy cluster than the human lifetime is to the age of the universe. Thus repeating, strongly lensed FRBs may offer an unprecedented opportunity for observing cosmological evolution in "real time". The possibility is discussed of observing cosmic expansion, transverse proper motion, mass accretion and perhaps growth of density perturbations, as a function of redshift.