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arXiv · 2301.08259

A new limit on intergalactic magnetic fields on sub-kpc scales from fast radio bursts

Hamsa Padmanabhan·Abraham Loeb
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Abstract

We use the measured scattering timescales of Fast Radio Bursts (FRBs) from the CHIME catalog to derive an upper limit on the magnetic field on sub-kpc scales in the intergalactic medium (IGM). A nonmagnetized, photoionized IGM is insufficient to explain the turbulent scattering at all redshifts, with a Warm-Hot component being marginally consistent with the data at $z \sim 1$. Accounting for the lower envelope of the temporal smearing distribution with a nonzero magnetic field leads to upper limits $B < 10-30$ nG on scales of 0.07-0.20 kpc in the IGM at $z \sim 1-2$. Our work introduces a novel technique to constrain small-scale magnetic fields in the IGM, in a regime unexplored by the Rotation and Dispersion Measures of FRBs.

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Hamsa Padmanabhan, Abraham Loeb. 2023-01-19. A new limit on intergalactic magnetic fields on sub-kpc scales from fast radio bursts. https://doi.org/10.3847/2041-8213%2Facc3a1

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