Ponente
Descripción
NGC 4278 is a low-luminosity active galactic nucleus (AGN) in the local Universe. The detection of very-high-energy (VHE) gamma rays from NGC 4278 by the Large High Altitude Air Shower Observatory (LHAASO) has identified it as a newly discovered extragalactic TeV gamma-ray source. However, the physical origin of the VHE gamma-ray emission from NGC 4278 remains unclear.
In this study, we perform a comprehensive analysis of multi-wavelength and multi-messenger observations of NGC 4278 spanning a period up to 2024--2025. From the analysis of X-ray data obtained with Swift-XRT, we measure a flux of $1.17_{-0.10}^{+0.11} \times 10^{-12}~\mathrm{erg~cm^{-2}~s^{-1}}$ with a spectral index of $2.11_{-0.17}^{+0.17}$ in 2024--2025. We analyze Fermi-LAT data at the radio position of NGC 4278 from MJD 59274 to 60796, obtaining a test statistic (TS) value of 20.62. Additionally, we examine 10 years of public IceCube data to search for neutrino emission, but find no significant excess. We place upper limits on the neutrino flux from NGC 4278.
We employ the leptohadronic code AMES to model the multi-wavelength emission from a relativistic jet, fitting both flaring and quiescent states to constrain the physical parameters. Furthermore, we investigate the potential contribution of high-energy gamma rays from large-scale outflows driven by the accretion disk.
