PKS 2254+074: A Blazar in Likely Association with the Neutrino Event IceCube-190619A

TL;DR

This study suggests that the blazar PKS 2254+074 is likely associated with a high-energy neutrino event, supported by temporal and positional coincidence, gamma-ray flaring, and multi-wavelength brightening.

Contribution

First identification of a blazar likely associated with a PeV neutrino event through multi-wavelength observations and temporal coincidence.

Findings

Gamma-ray flare coincided with neutrino detection.

Optical and mid-infrared brightening observed during the flare.

High-energy photons indicated emission hardening during the flare.

Abstract

We report our study of the field of a $\simeq$0.2 PeV neutrino event IC-190619A. This neutrino belongs to Gold events, which more likely have an astrophysical origin. Among the two $\gamma$-ray sources within the neutrino's positional uncertainty region, we find that one of them, the BL-Lac--type blazar PKS~2254+074, had a $\gamma$-ray flare at the arrival time of the neutrino. The flare is determined to have lasted $\sim$2.5 yr in a 180-day binned light curve, constructed from the data collected with the Large Area Telescope (LAT) onboard {\it the Fermi Gamma-ray Space Telescope (Fermi)}. Accompanying the flare, optical and mid-infrared brightening is also seen. In addition, $\geq$10 GeV high energy photons from the source have been detected, suggesting a hardening of the emission during the flare. Given both the positional and temporal coincidence of PKS~2254+074 with IC-190619A, we suggest that this blazar is likely another member of a few recently identified (candidate) neutrino-emitting blazars.