It has been shown that thermal solar neutrinos with energies around keV, arising from electroweak processes in the solar plasma, are kinematically accessible to large-volume dark matter detectors through electron ionization signatures. Analysis of XENONnT data in S2-only mode (ionization signal) set an upper limit on the flux of such neutrinos: η ≲ 1.2×10^8 times the Standard Model prediction. Combined searches with XENONnT, LZ, and PandaX yield slightly weaker constraints. The future XLZD experiment is expected to improve these limits by many orders of magnitude. While actual detection is still far off, this result establishes low-threshold direct search detectors as an effective tool for studying the lowest-energy neutrino sources in astrophysics, with important implications for stellar physics and beyond.
Dark matter detectors are like microphones of incredible sensitivity, able to hear a whisper in the roar of a rock concert. They search for rare nudges from dark matter particles. But in a new study, scientists tuned these microphones to a different sound—the faint “rustle” of solar neutrinos. Neutrinos are ghostly particles that pass through everything unhindered. Every second, a hundred billion of these “ghosts” fly through your fingernail, and you feel nothing. Ordinary neutrinos are loud, but these, born from the heat of the Sun, are almost noiseless: their energy is a thousand times less.
When a neutrino glances off an electron, the microphone picks up a flutter—as if a tiny membrane swayed from a breath. The signal hasn’t been caught yet, but it’s already clear: the same instruments that search for the universe’s invisible matter can peer into the blazing heart of a star. The irony is that a machine built to hunt the most mysterious substance can now tell us how ordinary solar plasma boils. A new generation of microphones will sharpen this picture.
🎯 Neutrinos flee the Sun’s core in a couple of seconds, while the light we see takes tens of thousands of years to struggle out.