Speaker
Description
In 2013, neutrino observatory IceCube first reported discovery of high-energy (100 TeV and more) neutrinos of astrophysical origin. However, due to a bad spatial localization of these neutrinos (more than 1 arcdegree) origin of these neutrinoes stayed unknown. To find their progenitor, IceCube Collaboration organized multimessenger observations. Since 2016, IceCube Collaboration has published 183 public alerts on the detection of a high-energy neutrino event. One of the projects participating in these multimessenger observations is MASTER Global Robotic Net. Its nine telescopes spread all over the globe are able to rapidly slew on the neutrino event's location and have a wide FoV (2 by 2 arcdegrees), allowing it to find an optical counterpart of a neutrino event if any exists.
In 2017, IceCube detected a high-energy event named IceCube-170922A. It was subsequently found that a flaring blazar TXS0506+056 was located in the center of this event. Master telescope located in Crimea slew on its position 1 minute after the neutrino detection and it was found that blazar was 0.8 magnitude dimmer compared to observations a week before and an hour after the trigger. This finding led us to analyze the whole archive of our IceCube neutrino events observations to find if we had more of similar blazars. In this work we present an analysis of these observations and an excess of optically active blazars (flaring blazars and brighter than 15.2 mag) on a level of 4 sigma.