Probing Gravitational Slip with Strongly Lensed Fast Radio Bursts

Abstract

The rapid accumulation of observed Fast Radio Bursts (FRBs) originating from cosmological distances makes it likely that some will be strongly lensed by intervening matter along the line of sight. Detection of lensed FRB repeaters, which account for a noteworthy fraction of the total population, will allow not only an accurate measurement of the lensing time delay, but also follow-up high-resolution observations to pinpoint the location of the lensed images. Recent works proposed to use such strongly-lensed FRBs to derive constraints on the current expansion rate H0 as well as on cosmic curvature. Here we study the prospects for placing constraints on departures from general relativity via such systems. Using an ensemble of simulated events, we focus on the gravitational slip parameter γPN in screened modified gravity models and show that FRB time-delay measurements can yield constraints as tight as |γPN − 1| 0.04×(Λ/100kpc)×[N/10] −1/2 at 1σ with 10 detections.

Constraining Primordial Black Hole Dark Matter with CHIME Fast Radio Bursts

“…Finally, we showed that for low masses (M 30 M ), increasing sensitivity contributes more to the f DM bound than increasing the number of FRBs. We suggested to do so by stacking repeating FRBs (a focus of several recent strong lensing analyses [31][32][33][34]) and demonstrated the potential to improve the constraints on PBH dark matter.…”