The extended highly-ionized gas in radio galaxies.

REYNALDI, VICTORIA; FEINSTEIN, CARLOS

Gramado, Rio Grande do Sul

Conferencia; Galactic Nuclei and their connection with stars and the environment.; 2012

Universidad Federal de Rio Grande do Sul

A sample of 3CR radio galaxies is being studied in order to understand what kind of ionizing mechanism best explains the excitation of the large-scale ionized gas known as Extended Emission-Line Region (EELR) in the vicinity of powerful radio galaxies.The sample has been imaged by Hubble Space Telescope, so the presence and morphology of those regions are previoulsly known. Long-slit spectra of the nebular regions were obtained with GMOS/Gemini.Photoionization due to active nucleus can be taking place even when these regions extend over tens of kiloparsecs from the AGN. However, each galaxy in the sample was already classified as Fanaroff-Riley II and the EELRs are roughly aligned with the radio axis defined by the pass of the radio-jet, so expanding radiative shocks, driven by the jet itself, can not be neglected as another possibility to trigger the emission.Both photoionization as well as shock-ionization models were tested through line-ratios. We present our results in the form of diagnostic analysis for the photoionization models with matter-bounded clouds (Binette, Wilson & Storchi-Bergmann, 1996) as well as the grids of ionizing radiative shocks (Allen et al. 2008).