Voyager 1 $e^\pm$ Further Constrain Primordial Black Holes as Dark Matter

TL;DR

This study uses Voyager 1 data to place new constraints on primordial black holes as dark matter candidates, especially for masses below 10^{16}g, by analyzing Hawking radiation-induced cosmic rays beyond the heliopause.

Contribution

It provides the first local galactic constraints on sub-10^{16}g primordial black holes as dark matter, complementing cosmological limits.

Findings

PBHs with mass less than 10^{16}g contribute less than 0.1% to dark matter

Voyager-1 data beyond the heliopause enables new local constraints

Limits are robust for both monochromatic and lognormal PBH mass distributions

Abstract

Primordial Black Holes (PBHs) with a mass $M \lesssim {10^{17}}$g are expected to inject sub-GeV electrons and positrons in the Galaxy via Hawking radiation. These cosmic rays are shielded by the solar magnetic field for Earth-bound detectors, but not for Voyager-1, which is now beyond the heliopause. We use its data to constrain the fraction of PBHs to the dark matter in the Galaxy, finding that PBHs with $M<10^{16}$g cannot contribute more than 0.1% (or less for a lognormal mass distribution). Our limits are based on local galactic measurements and are thus complementary to those derived from cosmological observations.