Cosmic Clues from Amaterasu: Blazar-driven Ultrahigh-energy Cosmic Rays?
The detection of the Amaterasu event of energy 244 EeV by the Telescope Array, one of the most energetic ultrahigh-energy cosmic rays (UHECRs; E ≳ 0.1 EeV) observed to date, invites scrutiny of its potential source. We investigate whether the nearby blazar PKS 1717+177 at redshift z = 0.137, locate...
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2025-01-01
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| Online Access: | https://doi.org/10.3847/2041-8213/ade99f |
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| author | Saikat Das Srijita Hazra Nayantara Gupta |
| author_facet | Saikat Das Srijita Hazra Nayantara Gupta |
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| description | The detection of the Amaterasu event of energy 244 EeV by the Telescope Array, one of the most energetic ultrahigh-energy cosmic rays (UHECRs; E ≳ 0.1 EeV) observed to date, invites scrutiny of its potential source. We investigate whether the nearby blazar PKS 1717+177 at redshift z = 0.137, located within $2\mathop{.}\limits^{^\circ }5$ of the reconstructed arrival direction, could explain the event under a proton-primary hypothesis. Using a one-zone jet model, we fit the multiwavelength spectral energy distribution of the source, incorporating both leptonic and hadronic cascade emissions from photohadronic interactions inside the jet. Our model supports a cosmic-ray origin of the very-high-energy ( ε _γ ≳ 100 GeV) γ -ray flux and predicts a subdominant neutrino flux, 1 one order of magnitude lower than from TXS 0506+056. Under Lorentz invariance violation, UHECRs escaping the blazar jet above a specific energy can propagate unattenuated over hundreds of Mpc due to an increase in energy loss length for certain parameter choices. In such a scenario, the Amaterasu event can have a plausible origin from this blazar. Our analysis indicates negligible deflection in the Galactic magnetic field, implying a strong extragalactic magnetic field is required. Our findings provide a compelling multimessenger framework linking UHECRs, γ -rays, and neutrinos and motivate targeted searches by current and future high-energy neutrino telescopes during increased γ -ray or X-ray activity of this blazar. |
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| institution | Kabale University |
| issn | 2041-8205 |
| language | English |
| publishDate | 2025-01-01 |
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| spelling | doaj-art-d0239b4d6f8344808ef4fb6b856c85b02025-08-20T03:50:49ZengIOP PublishingThe Astrophysical Journal Letters2041-82052025-01-019881L810.3847/2041-8213/ade99fCosmic Clues from Amaterasu: Blazar-driven Ultrahigh-energy Cosmic Rays?Saikat Das0https://orcid.org/0000-0001-5796-225XSrijita Hazra1https://orcid.org/0009-0007-0381-8069Nayantara Gupta2https://orcid.org/0000-0002-1188-7503Department of Physics, University of Florida , Gainesville, FL 32611, USA ; saikatdas@ufl.eduAstronomy & Astrophysics Group, Raman Research Institute , Sadashivanagar, Bangalore 560080, Karnataka, IndiaAstronomy & Astrophysics Group, Raman Research Institute , Sadashivanagar, Bangalore 560080, Karnataka, IndiaThe detection of the Amaterasu event of energy 244 EeV by the Telescope Array, one of the most energetic ultrahigh-energy cosmic rays (UHECRs; E ≳ 0.1 EeV) observed to date, invites scrutiny of its potential source. We investigate whether the nearby blazar PKS 1717+177 at redshift z = 0.137, located within $2\mathop{.}\limits^{^\circ }5$ of the reconstructed arrival direction, could explain the event under a proton-primary hypothesis. Using a one-zone jet model, we fit the multiwavelength spectral energy distribution of the source, incorporating both leptonic and hadronic cascade emissions from photohadronic interactions inside the jet. Our model supports a cosmic-ray origin of the very-high-energy ( ε _γ ≳ 100 GeV) γ -ray flux and predicts a subdominant neutrino flux, 1 one order of magnitude lower than from TXS 0506+056. Under Lorentz invariance violation, UHECRs escaping the blazar jet above a specific energy can propagate unattenuated over hundreds of Mpc due to an increase in energy loss length for certain parameter choices. In such a scenario, the Amaterasu event can have a plausible origin from this blazar. Our analysis indicates negligible deflection in the Galactic magnetic field, implying a strong extragalactic magnetic field is required. Our findings provide a compelling multimessenger framework linking UHECRs, γ -rays, and neutrinos and motivate targeted searches by current and future high-energy neutrino telescopes during increased γ -ray or X-ray activity of this blazar.https://doi.org/10.3847/2041-8213/ade99fHigh energy astrophysicsActive galactic nucleiGamma-ray astronomyUltra-high-energy cosmic radiationNeutrino astronomyBlazars |
| spellingShingle | Saikat Das Srijita Hazra Nayantara Gupta Cosmic Clues from Amaterasu: Blazar-driven Ultrahigh-energy Cosmic Rays? The Astrophysical Journal Letters High energy astrophysics Active galactic nuclei Gamma-ray astronomy Ultra-high-energy cosmic radiation Neutrino astronomy Blazars |
| title | Cosmic Clues from Amaterasu: Blazar-driven Ultrahigh-energy Cosmic Rays? |
| title_full | Cosmic Clues from Amaterasu: Blazar-driven Ultrahigh-energy Cosmic Rays? |
| title_fullStr | Cosmic Clues from Amaterasu: Blazar-driven Ultrahigh-energy Cosmic Rays? |
| title_full_unstemmed | Cosmic Clues from Amaterasu: Blazar-driven Ultrahigh-energy Cosmic Rays? |
| title_short | Cosmic Clues from Amaterasu: Blazar-driven Ultrahigh-energy Cosmic Rays? |
| title_sort | cosmic clues from amaterasu blazar driven ultrahigh energy cosmic rays |
| topic | High energy astrophysics Active galactic nuclei Gamma-ray astronomy Ultra-high-energy cosmic radiation Neutrino astronomy Blazars |
| url | https://doi.org/10.3847/2041-8213/ade99f |
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