Lensing of Fast Radio Bursts as a Probe of Compact Dark Matter

Julian B. Muñoz; Ely D. Kovetz; Liang Dai; Marc Kamionkowski

doi:10.1103/PhysRevLett.117.091301

paper

Lensing of Fast Radio Bursts as a Probe of Compact Dark Matter

arXiv:1605.00008 · doi:10.1103/PhysRevLett.117.091301

Abstract

The possibility that part of the dark matter is made of massive compact halo objects (MACHOs) remains poorly constrained over a wide range of masses, and especially in the $20 - 100 M_{⊙}$ window. We show that strong gravitational lensing of extragalactic fast radio bursts (FRBs) by MACHOs of masses larger than $\sim 20 M_{⊙}$ would result in repeated FRBs with an observable time delay. Strong lensing of an FRB by a lens of mass $M_{L}$ induces two images, separated by a typical time delay $\sim$ few $\times (M_{L} /30 M_{⊙})$ milliseconds. Considering the expected FRB detection rate by upcoming experiments, such as CHIME, of $1 0^{4}$ FRBs per year, we should observe from tens to hundreds of repeated bursts yearly, if MACHOs in this window make up all the dark matter. A null search for echoes with just $1 0^{4}$ FRBs, would constrain the fraction $f_{DM}$ of dark matter in MACHOs to $f_{DM} ≲ 0.08$ for $M_{L} ≳ 20 M_{⊙}$ .

6 Pages, 4 Figures. Published in PRL

Lensing of Fast Radio Bursts as a Probe of Compact Dark Matter

Abstract

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