Search for Neutrino Emission from Hard X-Ray AGN with IceCube


Abbasi R., Ackermann M., Adams J., Agarwalla S. K., Aguilar J. A., Ahlers M., ...More

ASTROPHYSICAL JOURNAL, vol.981, no.2, 2025 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 981 Issue: 2
  • Publication Date: 2025
  • Doi Number: 10.3847/1538-4357/ada94b
  • Journal Name: ASTROPHYSICAL JOURNAL
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, Aerospace Database, INSPEC, zbMATH, Directory of Open Access Journals, DIALNET
  • Middle East Technical University Affiliated: Yes

Abstract

Active galactic nuclei (AGN) are promising candidate sources of high-energy astrophysical neutrinos, since they provide environments rich in matter and photon targets where cosmic-ray interactions may lead to the production of gamma rays and neutrinos. We searched for high-energy neutrino emission from AGN using the Swift-BAT Spectroscopic Survey catalog of hard X-ray sources and 12 yr of IceCube muon track data. First, upon performing a stacked search, no significant emission was found. Second, we searched for neutrinos from a list of 43 candidate sources and found an excess from the direction of two sources, the Seyfert galaxies NGC 1068 and NGC 4151. We observed NGC 1068 at flux phi(nu mu) (+ (nu) over bar mu) = 4.02(-1.52)(+1.58) x 10(-11) TeV-1 cm(-2) s(-1) normalized at 1 TeV, with a power-law spectral index gamma = 3.10(-0.22)(+0.26), consistent with previous IceCube results. The observation of a neutrino excess from the direction of NGC 4151 is at a posttrial significance of 2.9 sigma. If interpreted as an astrophysical signal, the excess observed from NGC 4151 corresponds to a flux phi(nu mu) (+ (nu) over bar mu) = 1.51(-0.81)(+0.99) x 10(-11) TeV-1 cm(-2) s(-1) normalized at 1 TeV and gamma = 2.83(-0.28)(+0.35).