The complex structure of low luminosity AGN : NGC 4579

Abstract

We have modelled the low luminosity AGN NGC 4579 by explaining both the continuum and the line spectra. It was found that the nuclear emission is dominated by an AGN. However, a young starburst, an older starburst with age of 4.5 Myr, and shock dominated clouds with velocities of 100, 300, and 500 km/s also contribute. HII regions appear in the the extended regions (about 1 kpc), where radiation and shock dominated clouds with Vs=100 km/s prevail. The continuum SED of NGC 4579 is characterized by the strong flux from an old stellar population. Emissions in the radio range show synchrotron radiation from the base of the jet outflowing from the accretion disc within 0.1 pc from the active centre. Radio emission within intermediate distances (10-20 pc) is explained by the bremsstrahlung from gas downstream of low velocity shocks (Vs=100 km/s) reached by a relatively low radiation flux from the AC. In extended regions (>100 pc) the radio emission is synchrotron radiation created by the Fermi mechanism at the shock front. The shocks are created by collision of clouds with the jet. ~