TeV Emission in NGC 4278: Shock Energetics Insufficient, Compact Origin Favored
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| Format: | Preprint |
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2025
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| _version_ | 1866908527414476800 |
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| author | Domínguez, Alberto |
| author_facet | Domínguez, Alberto |
| contents | The Large High Altitude Air Shower Observatory recently detected TeV emission from the low-luminosity active galactic nucleus (LLAGN) NGC 4278. Integral-field spectroscopy with MEGARA revealed ionized outflows on hundred-parsec scales with kinetic power $\dot E_{\rm shock} \sim 10^{38}$ erg s$^{-1}$, well below the TeV luminosity $L_γ \gtrsim 10^{41}$ erg s$^{-1}$. The implied efficiencies, $η\gtrsim 1000$, are far above unity, showing that shocks cannot account for the TeV emission. Contemporaneous Fermi-Large Area Telescope and Swift data, consistent with a compact synchrotron self-Compton jet component, favor a nuclear origin. NGC 4278 is the first low-ionization nuclear emission-line region (LINER)/LLAGN of its class detected at TeV energies, a benchmark for LINERs with outflows and a prime target for the Cherenkov Telescope Array Observatory. I conclude that the TeV photons arise from a compact nuclear accelerator, while optical outflows trace larger-scale jet--ISM interactions that coexist but do not power the TeV radiation. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2509_07527 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | TeV Emission in NGC 4278: Shock Energetics Insufficient, Compact Origin Favored Domínguez, Alberto High Energy Astrophysical Phenomena Astrophysics of Galaxies The Large High Altitude Air Shower Observatory recently detected TeV emission from the low-luminosity active galactic nucleus (LLAGN) NGC 4278. Integral-field spectroscopy with MEGARA revealed ionized outflows on hundred-parsec scales with kinetic power $\dot E_{\rm shock} \sim 10^{38}$ erg s$^{-1}$, well below the TeV luminosity $L_γ \gtrsim 10^{41}$ erg s$^{-1}$. The implied efficiencies, $η\gtrsim 1000$, are far above unity, showing that shocks cannot account for the TeV emission. Contemporaneous Fermi-Large Area Telescope and Swift data, consistent with a compact synchrotron self-Compton jet component, favor a nuclear origin. NGC 4278 is the first low-ionization nuclear emission-line region (LINER)/LLAGN of its class detected at TeV energies, a benchmark for LINERs with outflows and a prime target for the Cherenkov Telescope Array Observatory. I conclude that the TeV photons arise from a compact nuclear accelerator, while optical outflows trace larger-scale jet--ISM interactions that coexist but do not power the TeV radiation. |
| title | TeV Emission in NGC 4278: Shock Energetics Insufficient, Compact Origin Favored |
| topic | High Energy Astrophysical Phenomena Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2509.07527 |