Mapping the circumnuclear gas of the Active Galaxies NGC 4180 and MCG−06-30-15

Publication Year:
Usage 51
Abstract Views 39
Downloads 12
Repository URL:
Seelig, Trent
None provided
thesis / dissertation description
The growth of Super Massive Black Holes in galactic nuclei has been shown through em- pirical studies to be connected with the evolution of the host galaxy. The growth of the black hole through accretion of interstellar gas can generate enough energy to outshine the host galaxy; during this phase it is observed as an Active Galactic Nucleus (AGN). The nature of the feeding processes that regulate the accretion flow and the processes governing the feedback of radiative and mechanical energy to the host galaxy is still an active field of research. These processes may be investigated by mapping the ionized gas flows within the central kiloparsec of active galaxies. As part of a larger ongoing study, we have performed a detailed analysis of two AGN based on measurements of optical emission lines made from Integral Field Spectroscopy observations obtained from the GEMINI North and South Telescopes.In the LINER galaxy NGC 4180, we identified two distinct kinematic components of the emission line profile of the circumnuclear gas, a narrow component that extends across the entire field of view and a broader, blueshifted component confined to the nucleus. We find that the gas traced by the narrow component is photoionized by a combination of the AGN and young stars, whereas the gas of the broader component is primarily AGN photoionized. We also identify redshifted residuals in the narrow component, correlated with increased velocity dispersion, that extends across the field of view. We find that the kinematic and morphological features of our observations are well explained by a regularly rotating galactic disk, an ionization cone perpendicular to the disk within which there is a gas outflow, and a spiral arm passing behind the nucleus in outflow. Furthermore, we estimate the mass outflow rate of ionized gas along the ionization cone to be ∼ 4 × 10−5 M⊙ yr−1.In the Seyfert 1 galaxy, MCG−06-30-015, which was recently discovered to host a counter rotating core, we find the gas in the central kiloparsec to be predominantly AGN photoionized. A principal component analysis reveals evidence of mass inflow into the nucleus from two spiral arms originating in the counter rotating disk. We estimate the total mass inflow rate from both arms to be ∼ 3×10−2 M⊙ yr−1. The kinematic and morphological features of our observations are well explained by a geometric model of the central kiloparsec which includes a counter rotating disk partially illuminated by an ionization cone that is inclined towards the viewer.