Relativistic plasmas in AGN jets

Abstract

Abstract. Relativistic jets of plasma are a key ingredient of many types of Active Galactic Nuclei (AGN). Today we know that AGNs are powered by the accretion of inter stellar material into the gravitational field of a Super Massive Black Hole and that this process can release as much power as a whole galaxy, like the Milky Way, from a region that is comparable to the Solar System in size. Depending on the properties of the central energy source, a large fraction of this power can be involved in the acceleration of magnetized plasmas at relativistic speeds, to form large scale jets. The presence of jets affects the spectrum of AGNs through the emission of synchrotron radiation and Inverse Compton scattering of low energy photons, thus leading to a prominent non-thermal spectrum, some times extending from radio frequencies all the way up to γ-ray energies. Here we review some characteristic processes of radiation emission in AGN jets, which lead to the emission of photons in the radio, optical, X-ray and γ-ray bands, and we present the results of a spectroscopic campaign of optical counterparts. We discuss our observations and their connection with γ-ray properties in a scenario that traces the role of relativistic jets in different classes of AGNs, detected both in the local as well as in the remote Universe.PACS. 52.25.Os Emission, absorption and scattering of electromagnetic radiation -52.27.Ny Relativistic plasmas -98.54.Cm Active and peculiar galaxies and related systems (including BL Lacertae objects, blazars, Seyfert galaxies, Markarian galaxies, and active galactic nuclei) -98.70.Rz γ-ray sources; γ-ray bursts

X-ray Properties of 3C 111: Separation of Primary Nuclear Emission and Jet Continuum

“…Being accelerated at shock fronts inside the jet, these electrons emit synchrotron radiation visible at a wide range of wavelengths from radio to ulraviolet. These accelerated electrons/positrons in the most cases are distributed over the energies following power-law dependency N(E) ∝ E −γ e [44]. Such distribution of charged particles generates self-absorbed synchrotron emission with spectral distribution:…”

Multi-Frequency Databases for AGN Investigation—Results and Perspectives

“…By requiring that the X-ray spectra of the sources are dominated by a power-law contribution, we reduce to a total number of 2389 sources, 2300 out of which are confirmed active galaxies. Similar methods have been widely used in the literature (e.g Massaro et al, 2014Massaro et al, , 2015Álvarez Crespo et al, 2016a,b,c), and they were specifically adapted in our catalogues to investigate the nature of unclassified γ-ray sources (Chiaro et al, 2016;La Mura et al, 2017).…”