Study of the PeV Neutrino, $\gamma$-rays and UHECRs around The Lobes of Centaurus A

TL;DR

This study investigates the potential connection between ultra-high-energy cosmic rays, PeV neutrinos, and gamma rays around Centaurus A's lobes, analyzing cosmic ray composition, acceleration mechanisms, and magnetic deflections.

Contribution

It provides a detailed analysis of UHECR acceleration in Centaurus A's lobes, focusing on composition, maximum energies, and magnetic deflections, and assesses the association with IceCube neutrino events.

Findings

UHECRs could be accelerated inside Centaurus A's lobes.

Light nuclei like carbon/nitrogen are the most promising UHECR candidates.

No conclusive evidence links the IceCube event IC35 to UHECRs from Centaurus A.

Abstract

Pierre Auger observatory reported the distribution of arrival directions of the highest energy cosmic rays. These events were collected in 10 years of operations with declinations between -90$^\circ$ and +45$^\circ$. The IceCube neutrino telescope reported the detection of 82 extraterrestrial neutrinos in the High-Energy Starting Events catalog. The highest-energy neutrino event (IC35) reported in this catalog had an energy of 2004$^{+236}_{-262}$ TeV and its reconstruction was centered at RA=$208.4^\circ$ and DEC=$-55.8^\circ$ (J2000). Being Centaurus A the nearest radio-loud active Galactic nucleus and one of the potential candidates for accelerating cosmic rays up to $\sim\, 10^{20}$ eV, we show that the ultra-high-energy cosmic rays (UHECRs) around the direction of Centaurus A (15$^\circ$ radius) could be accelerated inside the giant lobes. Studying the composition of UHECRs through the photo-disintegration processes, the maximum energy that these can reach in the giant lobes and the average deflecting angles that nuclei undergo due to Galactic and extragalactic magnetic fields, it is shown that the most promise candidates of UHECR composition are light nuclei such as carbon/nitrogen nuclei. Considering the interactions of the relativistic carbon nuclei with photon fields (extragalactic background light and synchrotron) and materials (inside and outside the lobes), we do not find enough evidence to associate the IC35 event with the UHECRs reported by Pierre Auger observatory.