Neutrino propagation hinders fast pairwise flavor conversions. (arXiv:1911.09110v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Shalgar_S/0/1/0/all/0/1">Shashank Shalgar</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Padilla_Gay_I/0/1/0/all/0/1">Ian Padilla-Gay</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tamborra_I/0/1/0/all/0/1">Irene Tamborra</a>
Neutrino flavor conversions may dramatically affect the inner working of
compact astrophysical objects as well as the synthesis of new elements. We
present the first sophisticated numerical solution of the neutrino flavor
conversion within a (2+1+1) dimensional setup: we include the advective term in
the neutrino equations of motion and track the flavor evolution in two spatial
dimensions, one angular variable, and time. Notably, the advective term hinders
the development of neutrino pairwise conversions, if the conditions favoring
such conversions (i.e., crossings between the angular distributions of $nu_e$
and $barnu_e$ or a non-negligible flux of neutrinos traveling backward with
respect to the main propagation direction) exist for time scales shorter than
the typical time scale of the advective term. As a consequence, fast pairwise
conversions can only occur when the conditions favoring flavor conversions are
self-sustained and global, such as the ones induced by the lepton emission
self-sustained asymmetry (LESA) in core-collapse supernovae. Our work
highlights the major impact of the dynamical evolution of the neutrino field on
the growth of flavor instabilities and the strong interplay between classical
and quantum effects. Critical limitations of the linear stability analysis,
used to predict neutrino flavor instabilities, are also pointed out.
Neutrino flavor conversions may dramatically affect the inner working of
compact astrophysical objects as well as the synthesis of new elements. We
present the first sophisticated numerical solution of the neutrino flavor
conversion within a (2+1+1) dimensional setup: we include the advective term in
the neutrino equations of motion and track the flavor evolution in two spatial
dimensions, one angular variable, and time. Notably, the advective term hinders
the development of neutrino pairwise conversions, if the conditions favoring
such conversions (i.e., crossings between the angular distributions of $nu_e$
and $barnu_e$ or a non-negligible flux of neutrinos traveling backward with
respect to the main propagation direction) exist for time scales shorter than
the typical time scale of the advective term. As a consequence, fast pairwise
conversions can only occur when the conditions favoring flavor conversions are
self-sustained and global, such as the ones induced by the lepton emission
self-sustained asymmetry (LESA) in core-collapse supernovae. Our work
highlights the major impact of the dynamical evolution of the neutrino field on
the growth of flavor instabilities and the strong interplay between classical
and quantum effects. Critical limitations of the linear stability analysis,
used to predict neutrino flavor instabilities, are also pointed out.
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