Title:	Cosmogenic gamma-ray and neutrino fluxes from blazars associated with IceCube events
Authors:	Das, Saikat Razzaque, Soebur Gupta, Nayantara
Keywords:	astroparticle physics galaxies: active gamma rays: general neutrinos
Issue Date:	4-Feb-2022
Publisher:	EDP Sciences
Citation:	Astronomy & Astrophysics, 2022, Vol.658, Article No. L6
Abstract:	Context. Blazars constitute the vast majority of extragalactic γ-ray sources. They can also contribute a sizable fraction of the diffuse astrophysical neutrinos detected by IceCube. In the past few years, the real-time alert system of IceCube has led to the multiwavelength follow-up of very high-energy neutrino events of plausible astrophysical origin. Spatial and temporal coincidences of a number of these neutrino events with γ-ray blazars provide a unique opportunity to decipher cosmic-ray interactions in the relativistic jets. Aims. The aim of this work is to test if the γ-ray blazars associated with the IceCube neutrino events are also sources of ultra-high-energy cosmic rays (UHECRs; E > 1018 eV). Methods. Assuming that blazars accelerate UHECRs, we calculate the “guaranteed” contribution to the line-of-sight cosmogenic γ-ray and neutrino fluxes from four blazars associated with IceCube neutrino events. We compare these fluxes with the sensitivities of the upcoming γ-ray imaging telescopes, such as the CTA, and with the planned neutrino detectors, such as IceCube-Gen2. Results. We find that detection of the cosmogenic neutrino fluxes from the blazars TXS 0506+056, PKS 1502+106, and GB6 J1040+0617 would require UHECR luminosity ≳10 times the inferred neutrino luminosity from the associated IceCube events, with the maximum UHECR proton energy Ep, max ≈ 1020 eV. Cosmogenic γ-ray emission from blazars TXS 0506+056, 3HSP J095507.9 +355101, and GB6 J1040+0617 can be detected by the CTA if the UHECR luminosity is ≳10 times the neutrino luminosity inferred from the associated IceCube events and for Ep, max ≳ 1019 eV. Conclusions. Detection of cosmogenic neutrino and/or γ-ray flux(es) from blazars associated with IceCube neutrinos may lead to the first direct signature(s) of UHECR sources. Given their relatively low redshifts and hence total energetics, TXS 0506+056 and 3HSP J095507.9+355101 should be the prime targets for upcoming large neutrino and γ-ray telescopes.
Description:	Open Access
URI:	http://hdl.handle.net/2289/7893
ISSN:	0004-6361 1432-0746 (Online)
Alternative Location:	https://ui.adsabs.harvard.edu/abs/2022A%26A...658L...6D/abstract https://arxiv.org/abs/2108.12120 https://doi.org/10.1051/0004-6361/202142123
Copyright:	2022 ESO
Appears in Collections:	Research Papers (A&A)

Items in RRI Digital Repository are protected by copyright, with all rights reserved, unless otherwise indicated.