VERITAS follow-up observation of the blazar TXS 0506+056

TL;DR

This paper reports VERITAS gamma-ray observations of the blazar TXS 0506+056, focusing on its emission state and correlation with a high-energy neutrino event, to understand cosmic ray origins.

Contribution

It presents new VERITAS observations and multiwavelength data of TXS 0506+056, providing insights into its gamma-ray emission and variability over several years.

Findings

Detection of a quiet gamma-ray emission state during 2018-2021

Flux upper limits constrain blazar variability

Supports association between blazar activity and neutrino events

Abstract

The gamma-ray blazar TXS 0506+056 was found with an enhanced gamma-ray emission state in spatial and temporal coincidence with the IceCube high energy neutrino event IC170922A. This is the most significant association by far between a high-energy neutrino event and a blazar in a flaring state. Studying the time evolution and spectral behavior of the blazar emission may help in identifying the sources of the diffuse neutrino flux observed by IceCube and the origin of energetic cosmic rays. TXS 0506+056 was detected by the VERITAS gamma-ray observatory with a significance of 5.8 standard deviations above 110 GeV in a 35 hour data set collected between September 23, 2017 and February 6, 2018. Here we will present results from recent VERITAS observations and an associated multiwavelength campaign, collected between October 10, 2018 to March 1, 2021. A relatively quiet very high energy gamma-ray emission state was observed during this time period, and flux upper limits are used to constrain the potential variability of this blazar.