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Paper: The broad-line region as supernova remnants
Volume: 31, Relationships Between Active Galactic Nuclei and Starburst Galaxies
Page: 147
Authors: Tenorio-Tagle, Guillermo; Terlevich, Roberto; Franco, Jose; Melnick, Jorge
Abstract: Supernova remnants evolving in a dense medium (n about 10**7 percc) become strongly radiative while still expanding at velocities of several thousands of km/s. Radiative cooling becomes important well before the thermalization of the ejecta is completed and makes the remnant miss the Sedov adiabatic track. As a result, the shocked matter undergoes a rapid condensation behind both the leading and the reverse shocks. Two concentric, high-density, fast moving thin shells are then formed. Both cool dense shells, as well as the freely expanding ejecta, and a section of the still dynamically unperturbed interstellar gas, are irradiated and ionized by the photon field produced by the radiative shocks. The emitted spectrum has emission-line ratios similar to those observed in the broad line region of low-luminosity active galactic nuclei. Our model combines analytic and numerical hydrodynamic simulations, together with static photoionization calculations to reproduce the observed properties of these broad-line regions.
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