Characterizing Galactic and Extragalactic Neutrino Fluxes with the IceCube Observatory

Anatoli Fedynitch^1*

¹Institute of Physics, Academia Sinica, Taipei, Taiwan

* Presenter:Anatoli Fedynitch, email:anatoli@gate.sinica.edu.tw

The IceCube Neutrino Observatory at the South Pole is a cubic kilometer of glacial ice, instrumented with 5,600 photodetectors to detect the Cherenkov light emitted by secondary particles emerging from interactions of neutrinos. IceCube has operated for more than a decade and has discovered several astrophysical neutrino sources: a distant blazar, a bright nearby Seyfert galaxy, and most recently, our Milky Way galaxy. The latter originates mostly due to the interactions of the cosmic ray pool with gas. However, a significant contribution from individual sources to the observed emission cannot, at present, be excluded and requires further studies.

One of the first observations from IceCube was the diffuse neutrino flux, the spectrum of neutrinos integrated over all sky directions. Until recently, this spectral shape had been observed as an unbroken power law with an index centered at about -2.5, surrounded by a wide confidence interval due to the systematic and statistical uncertainties of the individual event selections. The latest analysis, called GlobalFit, unifies the treatment of systematic uncertainties among different event selections, such as cascades and tracks, reaching unprecedented precision in measuring the characteristics of the diffuse flux. When applied to 10.5 years of data, the analysis indicates that there might be features in the diffuse flux that deviate from a single power law. In my contribution, I will report on these latest findings.

Keywords: Neutrinos, Diffuse emission, High Energy, Cosmic Rays