Upper limits on the cosmic neutrino background from cosmic rays
Mar Císcar-Monsalvatje, Gonzalo Herrera, Ian M. Shoemaker
Abstract
Extragalactic and galactic cosmic rays scatter with the cosmic neutrino background during propagation to Earth, yielding a flux of relic neutrinos boosted to larger energies. If an overdensity of relic neutrinos is present in galaxies, and neutrinos are massive enough, this flux might be detectable by high-energy neutrino experiments. For a lightest neutrino of mass <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:msub> <a:mi>m</a:mi> <a:mi>ν</a:mi> </a:msub> <a:mo>∼</a:mo> <a:mn>0.1</a:mn> <a:mtext> </a:mtext> <a:mtext> </a:mtext> <a:mi>eV</a:mi> </a:math> , we find an upper limit on the local relic neutrino overdensity of <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"> <c:mo>∼</c:mo> <c:msup> <c:mn>10</c:mn> <c:mn>13</c:mn> </c:msup> </c:math> and an upper limit on the relic neutrino overdensity at TXS <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"> <e:mrow> <e:mn>0506</e:mn> <e:mo>+</e:mo> <e:mn>056</e:mn> </e:mrow> </e:math> of <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"> <g:mo>∼</g:mo> <g:msup> <g:mn>10</g:mn> <g:mn>10</g:mn> </g:msup> </g:math> . Future experiments like GRAND or IceCube-Gen2 could improve these bounds by orders of magnitude. Published by the American Physical Society 2024