A Cross-correlation Study between IceCube Neutrino Events and the FERMI Unresolved Gamma-Ray Sky

Journal Article · Tue Jul 04 00:00:00 EDT 2023 · The Astrophysical Journal

DOI:https://doi.org/10.3847/1538-4357/acd172· OSTI ID:1995998

Negro, Michela ^[1]; Crnogorčević, Milena ^[2]; Burns, Eric ^[3]; Charles, Eric ^[4]; Marcotulli, Lea ^[5]; Caputo, Regina ^[6]

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1. University of Maryland, Baltimore, MD (United States); NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States); SLAC
2. NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States); University of Maryland, College Park, MD (United States)
3. Louisiana State University, Baton Rouge, LA (United States)
4. Kavli Institute for Particle Astrophysics and Cosmology (KIPAC), Stanford University, CA (United States); SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)
5. Yale University, New Haven, CT (United States)
6. NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States)

With the coincident detections of electromagnetic radiation together with gravitational waves (GW170817) or neutrinos (TXS 0506+056), the new era of multimessenger astrophysics has begun. Of particular interest are the searches for correlation between the high-energy astrophysical neutrinos detected by the IceCube Observatory and gamma-ray photons detected by the Fermi Large Area Telescope (LAT). So far, only sources detected by the LAT have been considered in correlation with IceCube neutrinos, neglecting any emission from sources too faint to be resolved individually. Here we present the first cross-correlation analysis considering the unresolved gamma-ray background (UGRB) and IceCube events. We perform a thorough sensitivity study, and, given the lack of identified correlation, we place upper limits on the fraction of the observed neutrinos that would be produced in proton–proton or proton–$$γ$$ interactions from the population of sources contributing to the UGRB emission and dominating its spatial anisotropy (aka blazars). Our analysis suggests that, under the assumption that there is no intrinsic cutoff and/or hardening of the spectrum above Fermi-LAT energies, and that all gamma rays from the unresolved blazars dominating the UGRB fluctuation field are produced by neutral pions from $p–p$ ($p–γ$) interactions, up to 60% (30%) of such a population may contribute to the total neutrino events observed by IceCube. This translates into an O (1%) maximum contribution to the astrophysical high-energy neutrino flux observed by IceCube at 100 TeV.

• Research Organization: SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)
• Sponsoring Organization: National Aeronautics and Space Administration (NASA); USDOE; USDOE Office of Science (SC)
• Grant/Contract Number: AC02-76SF00515
• OSTI ID: 1995998
• Alternate ID(s): OSTI ID: 1996626
• Journal Information: The Astrophysical Journal, Journal Name: The Astrophysical Journal Journal Issue: 1 Vol. 951; ISSN 0004-637X
• Publisher: IOP Publishing
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
Blazars
Gamma-rays
Neutrino astronomy