Neutrino Lighthouse: The Hidden Heart of Supernova SN 2021foa ✦
Original: "A high-energy neutrino flare associated with nearby bright interacting supernova SN 2021foa"
A neutrino burst from the nearby supernova SN 2021foa for the first time directly pointed to the birth of a black hole hiding behind a dense veil of gas and dust.
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Four neutrinos — four notes in the symphony of a star's death. While the supernova blazed in optical light, its core spoke in the language of nearly elusive particles. The energy of this whisper surpassed the visible fire a hundredfold — as if a hurricane raged behind a curtain, and only a rustle reached the hall. Soon, neutrino telescopes will turn such whispers into loud voices, and we will hear how giants die.
🎯 Unique spectral dance of SN 2021foa: over 50 days, it repeatedly changed costumes from hydrogen-rich Type IIn to helium-rich Ibn and back. Hence its nickname "flip-flop". This flip-flopping is the result of desperate mass loss: likely, the star evolved from a luminous blue variable to a Wolf-Rayet just before the explosion.
\Phi(E) = \Phi_0 \left(\frac{E}{E_0}\right)^{-\gamma}
The neutrino flux Φ drops sharply with increasing energy E — a power law with a steep index γ≈4.9. It's as if sound quickly got muffled in thick fog: particles lose energy in the dense shell.
Scientists
Christian DopplerD. B. McLaughlinDidier QuelozMichel MayorR. A. RossiterStephen Hawkingsupernova
hydrogen
helium
cosmic dust
black hole
spectroscopy
photometry
galaxy
neutron starLaws
Doppler effectHawking radiationgravitational lensingBekenstein-Hawking entropyCoulomb's lawEinstein field equations