Non-variable cosmologically distant gamma-ray emitters as an imprint of propagation of ultra-high-energy protons

Abstract

The acceleration cites of ultra-high-energy (UHE) protons can be traced by the footprint left by these particles propagating through cosmic microwave background (CMB) radiation. Secondary electrons produced in extended region of several tens of Mpc emit their energy via synchrotron radiation predominantly in the initial direction of the parent protons. It forms a non-variable and compact (almost point-like) source of high energy gamma rays. The importance of this effect is increased for cosmologically distant objects; because of severe energy losses, UHE protons cannot achieve us even in the case of extremely weak intergalactic magnetic fields. Moreover, at high redshifts the energy conversion from protons to secondary particles becomes significantly more effective due to the denser and more energetic CMB in the past. This increases the chances of UHE cosmic rays to be traced by the secondary synchrotron gamma radiation. We discuss the energy budget and the redshift dependence of the efficiency of energy transfer from UHE protons to synchrotron radiation. The angular and spectral distributions of radiation in the gamma- and X-ray energy bands are calculated and discussed in the context of their detectability by Fermi LAT and Chandra observatories.

References in corpus (9)

• Evidence for strong extragalactic magnetic fields from Fermi observations of TeV blazars
• EGMF Constraints from Simultaneous GeV-TeV Observations of Blazars
• Lower limit on the strength and filling factor of extragalactic magnetic fields
• Time Delay of Cascade Radiation for TeV Blazars and the Measurement of the Intergalactic Magnetic Field
• Role of line-of-sight cosmic ray interactions in forming the spectra of distant blazars in TeV gamma rays and high-energy neutrinos
• Angular, spectral, and time distributions of highest energy protons and associated secondary gamma-rays and neutrinos propagating through extragalactic magnetic and radiation fields
• No evidence for gamma-ray halos around active galactic nuclei resulting from intergalactic magnetic fields
• Detectability of ultrahigh energy cosmic ray signatures in gamma rays
• Mechanics and kinetics in the Friedmann-Lemaitre-Robertson-Walker space-times

Cited by in corpus (3)

• TeV gamma rays from blazars beyond z=1?
• Synchrotron pair halo and echo emission from blazars in the cosmic web: application to extreme TeV blazars
• Acceleration and propagation of ultrahigh energy cosmic rays