Probing Neutrino Emission from X-ray Blazar Flares observed with Swift-XRT. (arXiv:2107.14632v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Stathopoulos_S/0/1/0/all/0/1">Stamatios I. Stathopoulos</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Petropoulou_M/0/1/0/all/0/1">Maria Petropoulou</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Giommi_P/0/1/0/all/0/1">Paolo Giommi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Vasilopoulos_G/0/1/0/all/0/1">Georgios Vasilopoulos</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Padovani_P/0/1/0/all/0/1">Paolo Padovani</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mastichiadis_A/0/1/0/all/0/1">Apostolos Mastichiadis</a>
Blazars are the most extreme subclass of active galactic nuclei with
relativistic jets emerging from a super-massive black hole and forming a small
angle with respect to our line of sight. Blazars are also known to be related
to flaring activity as they exhibit large flux variations over a wide range of
frequency and on multiple timescales, ranging from a few minutes to several
months. The detection of a high-energy neutrino from the flaring blazar TXS
0506+056 and the subsequent discovery of a neutrino excess from the same
direction have naturally strengthened the hypothesis that blazars are cosmic
neutrino sources. While neutrino production during gamma-ray flares has been
widely discussed, the neutrino yield of X-ray flares has received less
attention. Motivated by a theoretical scenario where high energy neutrinos are
produced by energetic protons interacting with their own X-ray synchrotron
radiation, we make neutrino predictions over a sample of a sample of X-ray
blazars. This sample consists of all blazars observed with the X-ray Telescope
(XRT) on board Swift more than 50 times from November 2004 to November 2020.
The statistical identification of a flaring state is done using the Bayesian
Block algorithm to the 1 keV XRT light curves of frequently observed blazars.
We categorize flaring states into classes based on their variation from the
time-average value of the data points. During each flaring state, we compute
the expected muon plus anti-muon neutrino events as well as the total signal
for each source using the point-source effective area of Icecube for different
operational seasons. We find that the median of the total neutrino number (in
logarithm) from flares with duration $<30$ d is $mathcal{N}^{(rm
tot)}_{nu_{mu}+bar{nu}_{mu}} sim 0.02$.
Blazars are the most extreme subclass of active galactic nuclei with
relativistic jets emerging from a super-massive black hole and forming a small
angle with respect to our line of sight. Blazars are also known to be related
to flaring activity as they exhibit large flux variations over a wide range of
frequency and on multiple timescales, ranging from a few minutes to several
months. The detection of a high-energy neutrino from the flaring blazar TXS
0506+056 and the subsequent discovery of a neutrino excess from the same
direction have naturally strengthened the hypothesis that blazars are cosmic
neutrino sources. While neutrino production during gamma-ray flares has been
widely discussed, the neutrino yield of X-ray flares has received less
attention. Motivated by a theoretical scenario where high energy neutrinos are
produced by energetic protons interacting with their own X-ray synchrotron
radiation, we make neutrino predictions over a sample of a sample of X-ray
blazars. This sample consists of all blazars observed with the X-ray Telescope
(XRT) on board Swift more than 50 times from November 2004 to November 2020.
The statistical identification of a flaring state is done using the Bayesian
Block algorithm to the 1 keV XRT light curves of frequently observed blazars.
We categorize flaring states into classes based on their variation from the
time-average value of the data points. During each flaring state, we compute
the expected muon plus anti-muon neutrino events as well as the total signal
for each source using the point-source effective area of Icecube for different
operational seasons. We find that the median of the total neutrino number (in
logarithm) from flares with duration $<30$ d is $mathcal{N}^{(rm
tot)}_{nu_{mu}+bar{nu}_{mu}} sim 0.02$.
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