Neutrino Oscillations at Supernova Core Bounce Generate the Strongest Gravitational-Wave Bursts

Abstract

During the core bounce of a supernova collapse resonant active-to-active ($\nu_a \to \nu_a$), as well as active-to-sterile ($\nu_a \to \nu_s$) neutrino ($\nu$) oscillations can take place. Besides, over this phase weak magnetism increases antineutrino ($\bar{\nu}$) mean free paths, and thus its luminosity. Because the oscillation feeds mass-energy into the target $\nu$ species, the large mass-squared difference between species ($\nu_a \to \nu_s$) implies a huge amount of power to be given off as gravitational waves ($L_{\textrm{GWs}} \sim 10^{49}erg s$^{-1}$), due to anisotropic but coherent $\nu$ flow over the oscillation length. This anisotropy in the $\nu$-flux is driven by both the {\it universal spin-rotation} and the spin-magnetic coupling. The new spacetime strain estimated this way is still several orders of magnitude larger than those from $\nu$ diffusion (convection and cooling) or quadrupole moments of the neutron star matter. This new feature turns these bursts the more promising supernova gravitational-wave signal that may be detected by observatories as LIGO, VIRGO, etc., for distances far out to the VIRGO cluster of galaxies.