# Prospects of strongly lensed repeating fast radio bursts: complementary constraints on dark energy evolution

## TL;DR

This paper explores the potential of strongly lensed repeating fast radio bursts as a new tool for constraining dark energy properties, demonstrating significant improvements when combined with existing cosmological probes.

## Contribution

It introduces the novel idea of using strongly lensed repeating FRBs for precision cosmology and quantifies their impact on dark energy constraints.

## Key findings

- Adding lensed FRB time delays doubles the dark energy figure of merit.
- Strongly lensed FRBs can independently constrain cosmic curvature.
- Combining FRBs with CMB and supernovae enhances dark energy understanding.

## Abstract

Fast radio bursts (FRBs) are highly dispersed and probably extragalactic radio flashes with millisecond-duration. Recently, the Canadian Hydrogen Intensity Mapping Experiment (using the CHIME/FRB instrument) has reported detections of 13 FRBs during a pre-commissioning phase. It is more exciting that one of the 13 FRBs is a second source of repeaters which suggests that CHIME/FRB and other wide-field sensitive radio telescopes will find a substantial population of repeating FRBs. We have proposed strongly lensed repeating FRBs as a precision cosmological probe, e.g. constraining the Hubble constant and model-independently estimating the cosmic curvature. Here, we study complementary constraints on the equation of state of dark energy from strongly lensed FRBs to currently available popular probes. It is found that, in the framework of Chevalier-Polarski-Linder parametrization, adding time delay measurement of 30 strongly lensed FRB systems to cosmic microwave background radiation and type Ia supernovae can improve the dark energy figure of merit by a factor 2. In the precision cosmology era, this improvement is of great significance for studying the nature of dark energy.