Large Neutrino Secret Interactions, Small Impact on Supernovae

Understand

When hypothetical neutrino secret interactions ($\nu$SI) are large, they form a fluid in a supernova (SN) core, flow out with sonic speed, and stream away as a fireball.

• For the first time, we tackle the complete dynamical problem and solve all steps, systematically using relativistic hydrodynamics.
• The impact on SN physics and the neutrino signal is remarkably small.
• For complete thermalization within the fireball, the observable spectrum changes in a way that is independent of the coupling strength.