Sensitivity floor for primordial black holes in neutrino searches

Primordial black holes (PBHs) formed in the early Universe are well-motivated dark matter (DM) candidates over a wide range of masses. These PBHs could emit detectable signals in the form of photons, electrons, and neutrinos through Hawking radiation. We consider the null observations of astrophysical <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:msub><a:mover accent="true"><a:mi>ν</a:mi><a:mo stretchy="false">¯</a:mo></a:mover><a:mi>e</a:mi></a:msub></a:math> flux from several neutrino detectors and set new constraints on the PBHs as the dominant DM component to be above <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:mn>6.4</e:mn><e:mo>×</e:mo><e:msup><e:mn>10</e:mn><e:mn>15</e:mn></e:msup><e:mtext> </e:mtext><e:mtext> </e:mtext><e:mi mathvariant="normal">g</e:mi></e:math>. We also estimate the expected constraints with JUNO for the prospects in the near future. Lastly, we note that the diffuse supernova neutrino background (DSNB) is an unavoidable isotropic background. We thus estimate the sensitivity floor for PBH parameter space due to the DSNB and show that it is challenging for neutrino detectors to identify PBHs as they constitute 100% of the DM above a mass of <h:math xmlns:h="http://www.w3.org/1998/Math/MathML" display="inline"><h:mn>9</h:mn><h:mo>×</h:mo><h:msup><h:mn>10</h:mn><h:mn>15</h:mn></h:msup><h:mtext> </h:mtext><h:mtext> </h:mtext><h:mi mathvariant="normal">g</h:mi></h:math>.