Study on the spectrum of the injected relativistic protons

TL;DR

This study investigates the spectral characteristics of relativistic protons injected during tidal disruptions of stars by black holes, aiming to explain observed TeV gamma-ray emissions near the Galactic Center.

Contribution

It provides a detailed analysis of the proton spectrum resulting from tidal disruption events and compares different stellar types and propagation mechanisms to observational data.

Findings

Proton spectrum index is about -1.9 for red giant disruptions.

Effective confinement of protons fits observational data.

Tidal disruption of stars can produce the observed gamma-ray emissions.

Abstract

About 10TeV gamma-ray emission within 10 pc region from the Galactic Center had been reported by 4 independent groups. Considering that this TeV gamma-ray emission is produced via a hadronic model, and the relativistic protons came from the tidal disruption of stars by massive black holes, we investigate the spectral nature of the injected relativistic protons required by the hadronic model. The calculation was carried on the tidal disruption of the different types of stars and the different propagation mechanisms of protons in the interstellar medium. Compared with the observation data from HESS, we find for the best fitting that the power-law index of the spectrum of the injected protons is about -1.9, when a red giant star is tidally disrupted, and the effective confinement of protons diffusion mechanism is adopted.