The Next Generation of IceCube Realtime Neutrino Alerts

TL;DR

IceCube's real-time neutrino alert system, initiated in 2016, has evolved to include new alert channels in 2019, enhancing multi-messenger astrophysics by providing timely neutrino detections likely of astrophysical origin.

Contribution

The paper introduces a new set of neutrino alert selections and channels in 2019, expanding the alert program for better multi-messenger observations.

Findings

20 alerts issued by 2019, including the first association with a gamma-ray blazar.

Introduction of 'Gold' and 'Bronze' alert channels with different likelihood thresholds.

Expected to deliver approximately 10 'Gold' and 20 'Bronze' alerts annually.

Abstract

In 2016, IceCube initiated a system of public real-time alerts that are typically issued within one minute, following the detection of a neutrino candidate event that is likely to be of astrophysical origin. The goal of these alerts is to enable multi-messenger observations that may identify the neutrino source. Through January 31, 2019, a total of 20 public alerts have been issued, with many of them receiving follow-up observations across multiple wavelength bands. One alert in particular, IceCube-170922A, was found to be associated with a flaring gamma-ray blazar, TXS 0506+056. This was the first >3 sigma association of a high-energy neutrino with an electromagnetic counterpart. In 2019, the IceCube collaboration is introducing a new set of neutrino candidate selections that expand the alert program. These new selections provide two alert channels. A "Gold" channel will issue alerts for neutrino candidates at least 50% likely to be of astrophysical origin and is expected to deliver $\sim$10 alerts per year. Additionally a more frequent "Bronze" channel will provide $\sim$20 alerts per year for neutrino candidates that are between 30% and 50% likely to be of astrophysical origin. We present the neutrino event selections used to generate these alerts, the expected alert rates, and a description of the alert message.