Gamma-ray counterparts of 2WHSP high-synchrotron-peaked BL Lac objects as possible signatures of ultra-high-energy cosmic ray emission. Issue 2 (9th July 2020)

• Record Type: Journal Article
• Authors: Toomey, Michael W; Oikonomou, Foteini; Murase, Kohta
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 497:Issue 2(2020)
• Page Start: 2455
• Page End: 2468
• Publication Date: 2020-07-09
• Subjects: galaxies: active -- galaxies: high-redshift -- gamma rays: galaxies; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/staa1990
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: We present a search for high-energy γ-ray emission from 566 Active Galactic Nuclei at redshift z > 0.2, from the 2WHSP catalogue of high-synchrotron peaked BL Lac objects with 8 yr of Fermi -LAT data. We focus on a redshift range where electromagnetic cascade emission induced by ultra-high-energy cosmic rays can be distinguished from leptonic emission based on the spectral properties of the sources. Our analysis leads to the detection of 160 sources above ≈5σ (TS ≥25) in the 1–300 GeV energy range. By discriminating significant sources based on their γ-ray fluxes, variability properties, and photon index in the Fermi -LAT energy range, and modelling the expected hadronic signal in the TeV regime, we select a list of promising sources as potential candidate ultra-high-energy cosmic ray emitters for follow-up observations by Imaging Atmospheric Cherenkov Telescopes.