# ICRC 2021

Jul 12 – 23, 2021
Online
Europe/Berlin timezone

## The Neutrino Contribution of Gamma-Ray Flares from Fermi Bright Blazars

Jul 12, 2021, 6:00 PM
1h 30m
06

#### 06

Talk MM | Multi-Messenger

### Speaker

Kenji Yoshida (Shibaura Institute of Technology)

### Description

High-energy neutrinos are expected to be produced during gamma-ray flares of blazars through the interaction of high-energy cosmic rays in the jet with photons. As a matter of fact, a high-energy neutrino event, IC-170922A, was detected at the time of a gamma-ray flare from blazar TXS 0506+056 at the level of 3 sigma significance. In this work, we present a statistical study of blazar gamma-ray  flares aiming to constrain their contribution to the blazar neutrino output. We selected 145 gamma-ray bright blazars listed in the Fermi Large Area Telescope (LAT) monitored list and constructed their weekly binned light curves. Using a Bayesian Blocks algorithm to the light curves, we determined the fraction of time spent in the flaring state (flare duty cycle) and the fraction of energy released during each flare. Furthermore, we estimated the neutrino energy flux of each gamma-ray flare by using the general scaling relation $L_\nu \propto (L_\gamma)^\gamma$, $\gamma=1.5-2$, normalized to the quiescent X-ray flux of each blazar. Comparison of the estimated neutrino energy flux with the declination-dependent IceCube sensitivity enables us to constrain the standard neutrino emission models of gamma-ray flares. We also provide the upper-limit contribution of flares of gamma-ray bright blazars to the isotropic diffuse neutrino flux.

### Keywords

AGN; Blazar gamma-ray flares; Isotropic neutrino background

Subcategory Experimental Results

### Primary authors

Kenji Yoshida (Shibaura Institute of Technology) Maria Petropoulou Petropoulou (Princeton University) Kohta Murase (Penn State University) Foteini Oikonomou (ESO)