Speaker
Description
The Large High Altitude Air Shower Observatory (LHAASO) has recently released the highest-energy measurements of the diffuse gamma-ray flux, offering the opportunity to study the spatial distribution and energy spectrum of Galactic cosmic rays (CRs) in the TeV-PeV sky through a multi-messenger approach. In addition, the high-precision CR observations by the same collaboration have revealed a pronounced feature in the proton spectrum at $\sim3-4$ PeV (associated to the CR 'knee'), while their observations of diffuse gamma-rays above $100$ TeV do not exhibit a corresponding spectral break. This persistent tension between the two observed components seems to challenge conventional scenarios, in which the local CR distribution is representative of the Galactic CR sea. In this work, we explore as a possible alternative, the scenario of a dominating contribution of a local PeVatron in the Cygnus region (an Ultra-High-Energy gamma-ray cocoon observed by LHAASO) to the CR 'knee'. We develop a two-population model of the Galactic CR flux, which we compare to the latest CR data available by satellite missions and ground-based observatories. We contrast the diffuse gamma-ray flux predicted from our model with recent observations and discuss the conditions of the CR populations that may alleviate the aforementioned tension. Finally, we also consider the contribution of our model to the diffuse neutrino flux and compare it with observations of the Galactic Plane by the IceCube Neutrino Observatory.
(Based on work arXiv:2603.21665)
