Symmetric and standard matter neutrino resonances above merging compact objects

Abstract

Matter-neutrino resonances (MNR) can occur in environments where the flux of electron antineutrinos is greater than the flux of electron neutrinos. These resonances may result in dramatic neutrino flavor transformation. Compact object merger disks are an example of an environment where electron antineutrinos outnumber neutrinos. We study MNR resonances in several such disk configurations and find two qualitatively different types of matter-neutrino resonances: a standard MNR and a symmetric MNR. We examine the transformation that occurs in each type of resonance and explore the consequences for nucleosynthesis.

Matter-neutrino resonance transitions above a neutron star merger remnant

“…When presenting results for single neutrino trajectories, we follow Ref. [37] and plot weighted survival probabilities of electron neutrinos and anti-neutrinos,…”

“…One of the major consequences of the neutrino self interaction potential in supernovae is the prediction of a pendulum-like oscillation referred to as a nutation/bipolar oscillation. This type of oscillation is also expected to occur for at least some merger neutrinos [36,37].…”

“…In merger remnants this condition can be fulfilled either (1) because leptonization requires that antineutrinos outnumber neutrinos initially or (2) because the geometry of the system causes the relative contributions of neutrino and antineutrinos to the self interaction potential to shift as the neutrinos travel along their trajectories. This geometric effect comes from the extension of the neutrino emitting surface significantly beyond the antineutrino emitting surface, for a discussion see [37] The matter neutrino resonance is not naively expected to occur in supernovae because both potentials have the same sign. However, if Non Standard Interactions (NSIs) exist with significant strength they can trigger MNR transitions in supernovae [42].…”

“…Standard MNR transitions occur in regions where the neutrino self interaction potential begins as the largest potential in the system, but declines in magnitude eventually reaching the same magnitude as the matter potential. The other type of MNR transformation fully converts both electron neutrinos and antineutrinos symmetrically in short range and is called a Symmetric MNR transition [37]. Symmetric MNR transitions differ from Standard MNR transitions in that they occur when geometric effects cause the system to pass from a region where antineutrinos dominate the neutrino self interaction potential to a region where neutrinos dominate this potential [37,40].…”

“…The other type of MNR transformation fully converts both electron neutrinos and antineutrinos symmetrically in short range and is called a Symmetric MNR transition [37]. Symmetric MNR transitions differ from Standard MNR transitions in that they occur when geometric effects cause the system to pass from a region where antineutrinos dominate the neutrino self interaction potential to a region where neutrinos dominate this potential [37,40]. Both types of transformation may well influence nucleosynthesis [37,38] as MNR transitions typically occur closer to the emitting surface of neutrinos than other large scale oscillation phenomena.…”