The Multimessenger Contribution of Ultra-High-Energy Cosmic Rays from Gamma-Ray Bursts
It has long been debated whether gamma-ray bursts (GRBs) could serve as potential sources of ultra-high-energy cosmic rays (UHECRs). In this study, we consider GRBs as sources of UHECR injection with an injection index of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML&...
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| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-01-01
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| Series: | Universe |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2218-1997/11/1/22 |
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| Summary: | It has long been debated whether gamma-ray bursts (GRBs) could serve as potential sources of ultra-high-energy cosmic rays (UHECRs). In this study, we consider GRBs as sources of UHECR injection with an injection index of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>α</mi><mo>=</mo><mn>2</mn></mrow></semantics></math></inline-formula> and propagate them through the extragalactic magnetic field within the framework of CRPropa 3. The baryon loading factor <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>f</mi><mrow><mi>C</mi><mi>R</mi></mrow></msub></semantics></math></inline-formula> is taken into account to quantify the rate of UHECR energy injection. In the benchmark case with a jet opening angle of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>θ</mi><mi>j</mi></msub><mo>=</mo><mn>1</mn></mrow></semantics></math></inline-formula> and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>f</mi><mrow><mi>C</mi><mi>R</mi></mrow></msub><mo>=</mo><mn>1</mn></mrow></semantics></math></inline-formula>, we find that both high- and low-luminosity populations contribute to less than 10% of the UHECR spectrum. The most constrained scenario suggests <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>f</mi><mrow><mi>C</mi><mi>R</mi></mrow></msub><mo>≤</mo><mn>15</mn></mrow></semantics></math></inline-formula>, indicating that GRBs are less efficient in producing the all-sky UHECR intensity. The high-energy diffuse neutrinos and gamma rays resulting from interactions between UHECRs from GRBs and extragalactic background photons do not dominate the observations of Fermi-LAT or IceCube. |
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| ISSN: | 2218-1997 |