Left
: a blazar is accelerating protons that produce
pions, which produce neutrinos and gamma rays. Neutrinos
are always the result of a hadronic reaction such as the
one displayed here. Gamma rays can be produced in both
hadronic and electromagnetic interactions (Credit :
IceCube/NASA). Right : a high-energy neutrino
detected by IceCube on Sept. 22, 2017, with an estimated
energy of 290 TeV. The neutrino event display shows a
muon, created by the interaction of a neutrino with the
ice very close to IceCube, which leaves a track of light
while crossing the detector. In this display, the light
collected by each sensor is shown with a colored sphere.
The color gradient, from red to green/blue, shows the
time sequence (Credit: IceCube Collaboration).
Distribution of ANTARES events in the (RA, DEC)
coordinates around the position of TXS 0506+056. The
inner (outer) green line depicts the one (five) degree
distance from the position source location, indicated as
a gray star. The red point denotes a shower-like event,
whereas the blue points indicate track-like events. The
dashed circles around the events indicate the angular
error estimate. Different shades of red and blue
correspond to the values assumed by the energy
estimators, the right legend shows the color scales. The
number of hits is used for shower-like events and a
parameter ρ for track-like events.