Ultra high energy cosmic rays and possible signature of black strings

TL;DR

This paper investigates how extra dimension effects influence black hole accretion mechanisms and UHECR production, providing new limits on cosmic ray sources based on gamma-ray observations.

Contribution

It introduces a parametrization of Kerr horizons considering extra dimensions and analyzes their impact on UHECR production limits from black hole sources.

Findings

Extra dimension effects modify black hole accretion mechanisms.

Upper limits on UHECR luminosity are derived from gamma-ray data.

Dependence of UHECR efficiency on black hole mass is discussed.

Abstract

Ultra high energy cosmic rays (UHECRs) probably originate in extreme conditions in which extra dimension effects might be important. In this paper we calculate the correction in black hole accretion mechanisms due to extra dimension effects in the static and rotating cases. A parametrization of the external Kerr horizons in both cases is presented and analysed. We use previous calculations of upper limits on the UHECR flux to set limits on the UHECR production efficiency of nine sources. The upper limit on the UHECR luminosity calculation is based on GeV-TeV gamma-ray measurements. The total luminosity due to the accretion mechanism is compared to the upper limit on UHECRs. The dependence of the UHECR production efficiency upper limit on black hole mass is also presented and discussed