Strongest gravitational waves from neutrino oscillations at supernova core bounce

TL;DR

This paper predicts that neutrino oscillations during supernova core bounce can produce extremely strong gravitational waves, potentially detectable by current observatories, and links sterile neutrinos to dark matter.

Contribution

It introduces a new computation of the anisotropy parameter and uses experimental constraints to estimate gravitational-wave emission from neutrino oscillations in supernovae.

Findings

Gravitational wave luminosity from neutrino oscillations can reach ~10^{49} erg/s.

Estimated spacetime strain is significantly larger than from other supernova processes.

Potential detectability of these gravitational waves by LIGO and VIRGO for distant supernovae.

Abstract

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 during the core bounce of a supernova collapse. 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 energy 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 asymmetric $\nu$-flux is driven by both the spin-magnetic and the {\it universal spin-rotation} coupling. The novel contribution of this paper stems from 1) the new computation of the anisotropy parameter $\alpha \sim 0.1-0.01$, and 2) the use of the tight constraints from neutrino experiments as SNO and KamLAND, and the cosmic probe WMAP, to compute the gravitational-wave emission during neutrino oscillations in supernovae core collapse and bounce. We show that the mass of the sterile neutrino $\nu_s$ that can be resonantly produced during the flavor conversions makes it a good candidate for dark matter as suggested by Fuller et {\it al.} (2003). The new spacetime strain thus estimated is still several orders of magnitude larger than those from $\nu$ difussion (convection and cooling) or quadrupole moments of neutron star matter. This new feature turns these bursts the more promissing supernova gravitational-wave signal that may be detected by observatories as LIGO, VIRGO, etc., for distances far out to the VIRGO cluster of galaxies.