Journal Article

PUBDB-2021-02589

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Multi-wavelength radiation models for low-luminosity GRBs, and the implications for UHECRs

Rudolph, A. (Corresponding author)DESY* ; Bosnjak, Z. ; Palladino, A.DESY* ; Sadeh, I.DESY* ; Winter, W.DESY*

2022
Oxford Univ. Press Oxford

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Please use a persistent id in citations: doi:10.1093/mnras/stac433

Report No.: DESY-21-103; arXiv:2107.04612

Abstract: We study the prompt phase of low-luminosity Gamma-Ray Bursts (LL-GRBs) as potential source of very-high-energy (VHE) gamma rays and ultra-high-energy cosmic rays (UHECRs).We model the spectral energy distribution of three representative examples (with observed properties similar to GRBs 980425, 100316D and 120714B) self-consistently in a leptonic synchrotron self-Compton (SSC) scenario using the internal shock model for the relativistic outflow. To investigate the conditions under which inverse Compton radiation may lead to a peak in the GeV-TeV range potentially observable in Imaging Atmospheric Cherenkov Telescopes (IACTs), we vary the fraction of the energy budget supplying the magnetic field. As a second step, we determine the maximal energies achievable for UHECR nuclei. Assuming LL-GRBs to power the observed UHECR flux, we derive constraints on the baryonic loading and typical GRB duration by explicitly calculating the contribution of LL-GRBs to the diffuse extragalactic gamma-ray background. We find that LL-GRBs are potential targets for multi-mavelength studies and may be in reach of current/ future IACTs and optical/ UV instruments.For comparable sub-MeV emission and similar jet properties, the multi-wavelength predictions show a strong dependence on the magnetic field: weak (strong) magnetic fields induce high (low) fluxes in the VHE regime and low (high) fluxes in the optical. However, VHE emission might be suppressed by $\gamma \gamma $-absorption close to the source (especially for high magnetic fields) or interactions with the extragalactic background light for redshifts $z > 0.1$.For UHECRs, we find that the maximal energies of iron nuclei (protons) can be as high as $\simeq 10^{11}$~GeV ($10^{10}$~GeV) if the magnetic energy density is large (where we predict a weak VHE component). These high energies are possible by decoupling the production regions of UHECR and gamma-rays in our multi-zone model. Finally, we find basic consistency with the energy budget needed to accommodate the UHECR origin from LL-GRBs.

Keyword(s): cosmic radiation: UHE ; cosmic radiation: spectrum ; gamma ray: burst ; energy: internal ; iron: nucleus ; gamma ray: background ; energy: high ; magnetic field: high ; energy: density ; energy: magnetic ; VHE ; acceleration ; optical ; shock waves ; messenger ; spectral ; energy spectrum ; synchrotron ; decoupling ; redshift ; Cherenkov counter: atmosphere ; imaging ; suppression

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Contributing Institute(s):

1. Gammaastronomie (Z_GA)
2. Theoretische Astroteilchenphysik (Z_THAT)

Research Program(s):

1. 613 - Matter and Radiation from the Universe (POF4-613) (POF4-613)

Experiment(s):

1. Ultraviolet Transient Astronomy Satellite
2. Cherenkov Telescope Array

Appears in the scientific report 2022

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Database coverage:
; Clarivate Analytics Master Journal List ; Current Contents - Physical, Chemical and Earth Sciences ; Ebsco Academic Search ; Essential Science Indicators ; IF >= 5 ; JCR ; Nationallizenz ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection

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