Towards Powerful Probes of Neutrino Self-Interactions in Supernovae

Understand

Neutrinos remain mysterious.

• As an example, enhanced self-interactions ($\nu$SI), which would have broad implications, are allowed.
• At the high neutrino densities within core-collapse supernovae, $\nu$SI should be important, but robust observables have been lacking.
• We show that $\nu$SI make neutrinos form a tightly coupled fluid that expands under relativistic hydrodynamics.