Association of IceCube neutrinos with radio sources observed at Owens Valley and Mets”ahovi Radio Observatories. (arXiv:2009.10523v3 [astro-ph.HE] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Hovatta_T/0/1/0/all/0/1">T. Hovatta</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lindfors_E/0/1/0/all/0/1">E. Lindfors</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kiehlmann_S/0/1/0/all/0/1">S. Kiehlmann</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Max_Moerbeck_W/0/1/0/all/0/1">W. Max-Moerbeck</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hodges_M/0/1/0/all/0/1">M. Hodges</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Liodakis_I/0/1/0/all/0/1">I. Liodakis</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lahteenmaki_A/0/1/0/all/0/1">A. Lahteenmaki</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Pearson_T/0/1/0/all/0/1">T. J. Pearson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Readhead_A/0/1/0/all/0/1">A. C. S. Readhead</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Reeves_R/0/1/0/all/0/1">R. A. Reeves</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Suutarinen_S/0/1/0/all/0/1">S. Suutarinen</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tammi_J/0/1/0/all/0/1">J. Tammi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tornikoski_M/0/1/0/all/0/1">M. Tornikoski</a>

Identifying the most likely sources for high-energy neutrino emission has
been one of the main topics in high-energy astrophysics ever since the first
observation of high-energy neutrinos by the IceCube Neutrino Observatory.
Active galactic nuclei with relativistic jets, also known as blazars, have been
considered to be one of the main candidates because of their ability to
accelerate particles to high energies. We study the connection between radio
emission and IceCube neutrino events using data from the Owens Valley Radio
Observatory (OVRO) and Mets”ahovi Radio Observatory blazar monitoring
programs. We identify sources in our radio monitoring sample that are
positionally consistent with IceCube high-energy neutrino events. We estimate
their mean flux density and variability amplitudes around the neutrino arrival
time, and compare these with values from random samples to establish the
significance of our results. We find radio source associations within our
samples with 15 high-energy neutrino events detected by IceCube. Nearly half of
the associated sources are not detected in the $gamma$-ray energies, but their
radio variability properties and Doppler boosting factors are similar to the
$gamma$-ray detected objects in our sample, meaning that they could still be
potential neutrino emitters. We find that the number of strongly flaring
objects in our statistically complete OVRO samples is unlikely to be a random
coincidence (at $2sigma$ level). Based on our results, we conclude that
although it is clear that not all neutrino events are associated with strong
radio flaring blazars, observations of large-amplitude radio flares in a blazar
at the same time as a neutrino event are unlikely to be a random coincidence.

Identifying the most likely sources for high-energy neutrino emission has
been one of the main topics in high-energy astrophysics ever since the first
observation of high-energy neutrinos by the IceCube Neutrino Observatory.
Active galactic nuclei with relativistic jets, also known as blazars, have been
considered to be one of the main candidates because of their ability to
accelerate particles to high energies. We study the connection between radio
emission and IceCube neutrino events using data from the Owens Valley Radio
Observatory (OVRO) and Mets”ahovi Radio Observatory blazar monitoring
programs. We identify sources in our radio monitoring sample that are
positionally consistent with IceCube high-energy neutrino events. We estimate
their mean flux density and variability amplitudes around the neutrino arrival
time, and compare these with values from random samples to establish the
significance of our results. We find radio source associations within our
samples with 15 high-energy neutrino events detected by IceCube. Nearly half of
the associated sources are not detected in the $gamma$-ray energies, but their
radio variability properties and Doppler boosting factors are similar to the
$gamma$-ray detected objects in our sample, meaning that they could still be
potential neutrino emitters. We find that the number of strongly flaring
objects in our statistically complete OVRO samples is unlikely to be a random
coincidence (at $2sigma$ level). Based on our results, we conclude that
although it is clear that not all neutrino events are associated with strong
radio flaring blazars, observations of large-amplitude radio flares in a blazar
at the same time as a neutrino event are unlikely to be a random coincidence.

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