Neutrino Observations of LHAASO Sources: Present Constraints and Future Prospects

Abstract

The Large High Altitude Air Shower Observatory (LHAASO) observed a dozen of gamma-ray sources with significant emission above 100 TeV, which are the possible accelerators of PeV cosmic-rays. The neutrino observations are required to answer whether these high energy gamma-rays are generated through hadronic process (by cosmic-rays) or leptonic process (by electrons). We use the Bayesian method and the ten-year (2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015)(2016)(2017)(2018) IceCube data to constrain the hadronic gamma-ray flux from LHAASO sources. The current observations constrain that the hadronic component contributes no more than ∼70% to the gamma-rays from Crab Nebula, which disfavors the hadronic origin of gamma-rays below hundreds of TeV. For other LHAASO sources, the 90% C.L. upper limits on hadronic gamma-ray flux are still higher than the gamma-ray flux observed. The uncertainties due to the source extension assumption and statistical approach are discussed quantitatively. We also evaluate the neutrino observation of LHAASO sources in the combined search using the current and future neutrino telescopes.

Ultra-High-Energy Cosmic Rays: The Intersection of the Cosmic and Energy Frontiers

“…Moreover, such hybrid observations have also allowed for searches for PeV gamma-ray emission from the southern hemisphere [84,85]. Although the sensitivity achieved with the data and analysis methods available now has not lead to a discovery, by improving analysis techniques and continued operation, IceCube may eventually discover PeV photon sources, in particular, since PeV photon sources are meanwhile known to exist and be observable with a square-kilometer size array [86,87].…”