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Low-luminosity active galactic nuclei (LL AGNs) have radiatively inefficient accretion flows (RIAFs), where thermal electrons naturally emit not only synchrotron photons but also soft gamma rays via the Comptonization of their synchrotron photons. We find that without any nonthermal electron population, these upscattered photons from LL AGNs naturally account for the MeV gamma-ray background, whose origin has been a mystery. The model also allows proton acceleration via turbulence or reconnections, producing high-energy neutrinos via hadronuclear interactions. We demonstrate that our RIAF model can simultaneously reproduce the soft (MeV) gamma-ray and high-energy (PeV) neutrino backgrounds. The proposed model is consistent with the latest x-ray observations of nearby LL AGNs and testable by future MeV gamma-ray telescopes.
Mysteries about the origin of high-energy cosmic neutrinos have deepened by the recent IceCube measurement of a large diffuse flux in the 10-100 TeV range. Based on the standard disk-corona picture of active galactic nuclei (AGN), we present a phenom
The majority of the activity around nearby (z ~ 0) supermassive black holes is found in low-luminosity active galactic nuclei (LLAGN), the most of them being classified as low ionization nuclear emission regions. Although these sources are well studi
We have examined ROSAT soft X-ray observations of a complete, distance-limited sample of Seyfert and LINER galaxies. X-ray data are available for 46 out of 60 such objects which lie within a hemisphere of radius 18 Mpc. We have constructed radial pro
We calculate the diffuse $gamma$-ray emission due to the population of misaligned AGN (MAGN) unresolved by the Large Area Telescope (LAT) on the {it Fermi} Gamma-ray Space Telescope ({it Fermi}). A correlation between the $gamma$-ray luminosity and t
Low luminosity active galactic nuclei are more abundant and closer to us than the luminous ones but harder to explore as they are faint. We have selected the four sources NGC 315, NGC 4261, NGC 1275, and NGC 4486, which have been detected in gamma ra