A concordance scenario for the observed neutrino from a Tidal Disruption Event. (arXiv:2005.06097v3 [astro-ph.HE] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Winter_W/0/1/0/all/0/1">Walter Winter</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lunardini_C/0/1/0/all/0/1">Cecilia Lunardini</a>
During a tidal disruption event, a star is torn apart by the tidal forces of
a supermassive black hole, with about 50% of the star’s mass eventually
accreted by the black hole. The resulting flare can, in extreme cases of
super-Eddington mass accretion, result in a relativistic jet. While tidal
disruption events have been theoretically proposed as sources of high-energy
cosmic rays and neutrinos, stacking searches indicate that their contribution
to the diffuse extragalactic neutrino flux is very low. However, a recent
association of a track-like astrophysical neutrino with a tidal disruption
event (AT2019dsg) indicates that some tidal disruption events can accelerate
cosmic rays to PeV energies. Here we introduce a phenomenological concordance
scenario with a relativistic jet to explain this association: an expanding
cocoon progressively obscures the X-rays emitted by the accretion disk, while
at the same time providing a sufficiently intense external target of
back-scattered X-rays for the production of neutrinos via proton-photon
interactions. We also reproduce the delay (relative to the peak) of the
neutrino emission by scaling the production radius with the black body radius.
Our energetics and assumptions for the jet and the cocoon are compatible with
expectations from numerical simulations of tidal disruption events.
During a tidal disruption event, a star is torn apart by the tidal forces of
a supermassive black hole, with about 50% of the star’s mass eventually
accreted by the black hole. The resulting flare can, in extreme cases of
super-Eddington mass accretion, result in a relativistic jet. While tidal
disruption events have been theoretically proposed as sources of high-energy
cosmic rays and neutrinos, stacking searches indicate that their contribution
to the diffuse extragalactic neutrino flux is very low. However, a recent
association of a track-like astrophysical neutrino with a tidal disruption
event (AT2019dsg) indicates that some tidal disruption events can accelerate
cosmic rays to PeV energies. Here we introduce a phenomenological concordance
scenario with a relativistic jet to explain this association: an expanding
cocoon progressively obscures the X-rays emitted by the accretion disk, while
at the same time providing a sufficiently intense external target of
back-scattered X-rays for the production of neutrinos via proton-photon
interactions. We also reproduce the delay (relative to the peak) of the
neutrino emission by scaling the production radius with the black body radius.
Our energetics and assumptions for the jet and the cocoon are compatible with
expectations from numerical simulations of tidal disruption events.
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