Probing a diffuse flux of axionlike particles from Galactic supernovae with neutrino water Cherenkov detectors

In this article, we claim that axionlike particles (ALPs) with MeV masses can be produced with semirelativistic velocities in core-collapse supernovae (SNe), generating a diffuse galactic flux. We show that these ALPs can be detected in neutrino water Cherenkov detectors via <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mi>a</a:mi><a:mi>p</a:mi><a:mo stretchy="false">→</a:mo><a:mi>p</a:mi><a:mi>γ</a:mi></a:math> interactions. Using Super-Kamiokande data, we derive new constraints on the ALP parameter space, excluding a region spanning more than one order of magnitude in the ALP-proton coupling above cooling bounds for ALP masses in the range of 1–80 MeV and ALP-proton couplings between <d:math xmlns:d="http://www.w3.org/1998/Math/MathML" display="inline"><d:mrow><d:mn>8</d:mn><d:mo>×</d:mo><d:msup><d:mrow><d:mn>10</d:mn></d:mrow><d:mrow><d:mo>−</d:mo><d:mn>6</d:mn></d:mrow></d:msup><d:mi>–</d:mi><d:mn>2</d:mn><d:mo>×</d:mo><d:msup><d:mrow><d:mn>10</d:mn></d:mrow><d:mrow><d:mo>−</d:mo><d:mn>4</d:mn></d:mrow></d:msup></d:mrow></d:math>. We show that the future Hyper-Kamiokande will be able to probe couplings as small as <f:math xmlns:f="http://www.w3.org/1998/Math/MathML" display="inline"><f:mn>2.5</f:mn><f:mo>×</f:mo><f:msup><f:mn>10</f:mn><f:mrow><f:mo>−</f:mo><f:mn>6</f:mn></f:mrow></f:msup></f:math>, fully closing the allowed region above SN 1987A cooling bounds.