Three flavor neutrino conversions in supernovae: slow & fast instabilities

Abstract

Self induced neutrino flavor conversions in the dense regions of stellar core collapse are almost exclusively studied in the standard two flavor scenario. Linear stability analysis has been successfully used to understand these flavor conversions. This is the first linearized study of three flavor fast instabilities. The 'fast' conversions are fascinating distinctions of the dense neutrino systems. In the fast modes the collective oscillation dynamics are independent of the neutrino mass, growing at the scale of the large neutrino-neutrino interaction strength (10 5 km −1 ) of the dense core. This is extremely fast, in comparison to the usual 'slow' collective modes driven by much smaller vacuum oscillation frequencies (10 0 km −1 ). The three flavor analysis shows distinctive characteristics for both the slow and the fast conversions. The slow oscillation results are in qualitative agreement with the existing nonlinear three flavor studies. For the fast modes, addition of the third flavor opens up possibilities of influencing the growth rates of flavor instabilities when compared to a two flavor scenario.

Fast neutrino flavor conversion modes in multidimensional core-collapse supernova models: The role of the asymmetric neutrino distributions

“…However, neutrinos could also undergo the so-called fast flavor conversions on scales as short as a few cm in the densest regions of the SN core [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36]. Unlike the traditional collective modes which occur on scales determined by the neutrino vacuum frequency ω = ∆m 2 /2E (∼ O(1) km for a 10 MeV neutrino and atmospheric mass splitting), fast modes occur on scales ∼ G −1 F n −1 ν with n ν and G F being the neutrino number density and the Fermi coupling constant, respectively.…”

Fast oscillations, collisionless relaxation, and spurious evolution of supernova neutrino flavor

“…These phenomena can be understood in isolation by appealing to Eqs. (11), (15), and (19), respectively. In a linear analysis, they correspond to the fast, bipolar, and multi-zenith-angle instabilities.…”

Three-flavor collective neutrino conversions with multi-azimuthal-angle instability in an electron-capture supernova model

“…If the employed supernova model gives f νx = f νy , the third term, j = 3, is canceled. In this situation, the e − x and e − y sectors are decoupled in the linear regime [65].…”