Neutrino Oscillations and Decoherence in Short-GRB Progenitors

Abstract

Neutrinos are produced in cosmic accelerators, like active galactic nuclei (AGNs), blazars, supernova (SN) remnants and gamma-ray bursts (GRBs). On their way to the Earth they experience flavor-oscillations. The interactions of the neutrinos coming from the source with other particles, e.g. intergalactic primordial neutrinos or heavy-mass right-handed neutrinos, in their way to the detector may transform the original wave packet in pointer states. This phenomenon, known as decoherence, becomes important in the reconstruction of processes at the source. In this work we study neutrino emission in short GRBs by adopting the Fireshell Model. We consider e − e + -pair annihilation as the main channel for neutrino production. We compare the properties of the neutrino-flux with the characteristic photon-signal produced once the transparency condition is reached. We study the effects of flavor-oscillations and decoherence as neutrinos travel from the region near the blackhole (BH) event-horizon outwards. We consider the source to be in thermal equilibrium, and calculate energy distribution functions for electrons and neutrinos. To compute the effects of decoherence we use a Gaussian model. In this scenario the emitted electron-neutrinos transform into pointer states consisting of 67.8% electronneutrinos and 32.2% as a combination of mu and tau neutrinos. We found that decoherence plays an important role in the evolution of the neutrino wave packet, leading to the detected pointer states on Earth.

Testing dark matter distributions by neutrino–dark matter interactions

“…For the purpose of the present calculations we shall esti-mate the change in the neutrino-oscillation pattern due to interactions with DM. The formalism has been presented in Penacchioni and Civitarese [25,26]. For the sake of concreteness we shall omit giving the details here.…”

“…Since neutrinos can change their flavor composition while traveling from the source to the detector, it is then extremely appealing to think that neutrinos produced outside our galaxy can evolve on their way to Earth through interactions with DM particles. In previous works [24][25][26] we have explored this possibility and found that it is indeed the case.…”

“…In actual calculations we have adopted the squared-mass differences extracted from the available neutrino oscillation data [29] and m DM is varied according to each model for the DM distribution. Concerning the values of U, they will reflect the local dependence given by the DM distribution, as explained in the next section (see also [24,25]).…”

Time Delay between Neutrinos and Gamma-Rays in Short Gamma-Ray Bursts

“…In Penacchioni & Civitarese (2019) we have analysed the effects due to oscillations and decoherence on the neutrino flux accompanying a short GRB (NS-NS merger) at redshift z = 0.9. We have considered e − − e + pair annihilation as the only source for neutrinos in order to simplify the model.…”

“…In this work we aim at the calculation of the time difference between the arrival of neutrinos and photons from a short GRB originated by a NS-NS merger. We have adopted the Fireshell model Bianco et al (2009) to describe the dynamics of the source, as done in Penacchioni & Civitarese (2019). According to this model, the inner part of the merged system collapses to a black hole (BH).…”