Neutrinos and Gamma Rays: Constraining the Very High Energy Emission of NGC 4151 and NGC 1068

VERITAS is a ground-based gamma-ray instrument operating in southern Arizona, USA with highest sensitivity in the very high energy (VHE) band (85 GeV - 30 TeV). This telescope is ideally situated to conduct follow-up observations of neutrino observations from violent astrophysical sources observed by the South Pole neutrino observatory IceCube. In cases where high-energy neutrinos are emitted from a source, they are anticipated to be accompanied by gamma-ray emissions during their production that can be observed by detectors like VERITAS. In a point source search from 12 years of IceCube data for high-energy neutrino emission from hard X-ray AGN, IceCube researchers identified a neutrino excess at the locations of NGC 4151 and NGC 1068 (M77) [Abbasi et al., 2024]. The respective significances were 2.9 and 4.2 standard deviations above background. This talk discusses an analysis of data taken by VERITAS in which the potential neutrino sources were in the field of view. For NGC 4151, we used 10.5 hrs of VERITAS data; for NGC 1068, 17.0 hrs were used. No statistically significant signal was identified by VERITAS on either source and upper limits on the flux of VHE gamma rays for NGC 4151 and NGC 1068 are presented. The upper limits for NGC 4151 complement the November 2023 FERMI-LAT detection of this source in the lower gamma ray range. The current interest and future search for Seyfert galaxies as possible neutrino sources will also be presented.