Speaker
Description
The high-energy neutrino emission observed from the Galactic plane by IceCube may contain contributions from both truly diffuse emission produced by cosmic-ray interactions with interstellar gas and a population of individually unresolved hadronic accelerators. Traditional likelihood-based inference is impractical here, since it would require explicit marginalization over the unknown number, positions, and luminosities of the sources, as well as over the events each realization produces, rendering the likelihood computationally intractable.
We therefore implement a forward model of the Galactic neutrino sky and perform simulation-based inference (SBI) within Falcon, a dynamic SBI framework that constrains population-level parameters directly from energy-binned neutrino sky maps. A convolutional neural network compresses the sparse maps into a learned representation of their spatial and spectral structure. This representation conditions a normalizing flow that approximates the joint posterior of the expected number of sources and the diffuse-emission normalization. Falcon adaptively generates simulations and retrains the neural posterior estimator, concentrating computational effort on the regions of parameter space relevant to the target observation.
Applied to a synthetic Galactic neutrino sky, the method recovers both injected parameters within their 68% credible intervals, and the inferred posterior exhibits the expected anticorrelation between the unresolved-source contribution and the diffuse normalization. The analysis further shows that SBI can exploit information beyond the total event count: the spatial granularity of the source population, together with a source spectrum harder than that of the diffuse component, provides complementary handles for separating the two contributions.
This proof of concept establishes a basis for applying SBI to increasingly realistic neutrino observations. Higher-statistics data with improved angular resolution, in particular from KM3NeT/ARCA and future neutrino telescopes, will carry substantially more spatial information and should tighten constraints on the abundance and Galactic distribution of unresolved hadronic accelerators.