Disentangling the Hadronic Components in NGC 1068
The recent detection of high-energy neutrinos by IceCube in the direction of the nearby Seyfert/starburst galaxy NGC 1068 implies that radio-quiet active galactic nuclei can accelerate cosmic-ray ions. Dedicated multimessenger analyses suggest that the interaction of these high-energy ions with ambi...
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| Format: | Article |
| Language: | English |
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IOP Publishing
2023-01-01
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| Series: | The Astrophysical Journal Letters |
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| Online Access: | https://doi.org/10.3847/2041-8213/acf296 |
| _version_ | 1827818734074462208 |
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| author | Marco Ajello Kohta Murase Alex McDaniel |
| author_facet | Marco Ajello Kohta Murase Alex McDaniel |
| author_sort | Marco Ajello |
| collection | DOAJ |
| description | The recent detection of high-energy neutrinos by IceCube in the direction of the nearby Seyfert/starburst galaxy NGC 1068 implies that radio-quiet active galactic nuclei can accelerate cosmic-ray ions. Dedicated multimessenger analyses suggest that the interaction of these high-energy ions with ambient gas or photons happens in a region of the galaxy that is highly opaque for GeV–TeV gamma rays. Otherwise, the GeV–TeV emission would violate existing constraints provided by the Fermi Large Area Telescope (LAT) and the Major Atmospheric Gamma Imaging Cherenkov. The conditions of high optical depth are realized near the central supermassive black hole (SMBH). At the same time, the GeV emission detected by the Fermi LAT is likely related to the galaxy’s sustained star formation activity. In this work, we derive a 20 MeV–1 TeV spectrum of NGC 1068 using 14 yr of Fermi LAT observations. We find that the starburst hadronic component is responsible for NGC 1068's emission above ∼500 MeV. However, below this energy, an additional component is required. In the 20–500 MeV range, the Fermi LAT data are consistent with hadronic emission initiated by non-thermal ions interacting with gas or photons in the vicinity of the central SMBH. This highlights the importance of the MeV band to discover hidden cosmic-ray accelerators. |
| first_indexed | 2024-03-12T00:58:39Z |
| format | Article |
| id | doaj.art-f471c07cb7d545689a2a90b6c37bc34b |
| institution | Directory Open Access Journal |
| issn | 2041-8205 |
| language | English |
| last_indexed | 2024-03-12T00:58:39Z |
| publishDate | 2023-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal Letters |
| spelling | doaj.art-f471c07cb7d545689a2a90b6c37bc34b2023-09-14T11:59:14ZengIOP PublishingThe Astrophysical Journal Letters2041-82052023-01-019542L4910.3847/2041-8213/acf296Disentangling the Hadronic Components in NGC 1068Marco Ajello0https://orcid.org/0000-0002-6584-1703Kohta Murase1https://orcid.org/0000-0002-5358-5642Alex McDaniel2https://orcid.org/0000-0002-8436-1254Department of Physics and Astronomy, Clemson University , Clemson, SC 29631, USADepartment of Physics; Department of Astronomy & Astrophysics; Center for Multimessenger Astrophysics, Institute for Gravitation and the Cosmos, The Pennsylvania State University , University Park, PA 16802, USA; School of Natural Sciences, Institute for Advanced Study , Princeton, NJ 08540, USA; Center for Gravitational Physics and Quantum Information, Yukawa Institute for Theoretical Physics, Kyoto University , Kyoto, Kyoto 606-8502, JapanDepartment of Physics and Astronomy, Clemson University , Clemson, SC 29631, USAThe recent detection of high-energy neutrinos by IceCube in the direction of the nearby Seyfert/starburst galaxy NGC 1068 implies that radio-quiet active galactic nuclei can accelerate cosmic-ray ions. Dedicated multimessenger analyses suggest that the interaction of these high-energy ions with ambient gas or photons happens in a region of the galaxy that is highly opaque for GeV–TeV gamma rays. Otherwise, the GeV–TeV emission would violate existing constraints provided by the Fermi Large Area Telescope (LAT) and the Major Atmospheric Gamma Imaging Cherenkov. The conditions of high optical depth are realized near the central supermassive black hole (SMBH). At the same time, the GeV emission detected by the Fermi LAT is likely related to the galaxy’s sustained star formation activity. In this work, we derive a 20 MeV–1 TeV spectrum of NGC 1068 using 14 yr of Fermi LAT observations. We find that the starburst hadronic component is responsible for NGC 1068's emission above ∼500 MeV. However, below this energy, an additional component is required. In the 20–500 MeV range, the Fermi LAT data are consistent with hadronic emission initiated by non-thermal ions interacting with gas or photons in the vicinity of the central SMBH. This highlights the importance of the MeV band to discover hidden cosmic-ray accelerators.https://doi.org/10.3847/2041-8213/acf296Gamma-ray astronomyAGN host galaxiesCosmological neutrinos |
| spellingShingle | Marco Ajello Kohta Murase Alex McDaniel Disentangling the Hadronic Components in NGC 1068 The Astrophysical Journal Letters Gamma-ray astronomy AGN host galaxies Cosmological neutrinos |
| title | Disentangling the Hadronic Components in NGC 1068 |
| title_full | Disentangling the Hadronic Components in NGC 1068 |
| title_fullStr | Disentangling the Hadronic Components in NGC 1068 |
| title_full_unstemmed | Disentangling the Hadronic Components in NGC 1068 |
| title_short | Disentangling the Hadronic Components in NGC 1068 |
| title_sort | disentangling the hadronic components in ngc 1068 |
| topic | Gamma-ray astronomy AGN host galaxies Cosmological neutrinos |
| url | https://doi.org/10.3847/2041-8213/acf296 |
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