High Resolution Mid-Infrared Imaging of Seyfert Nuclei: Testing the Evolutionary Hypothesis

University Of Florida, Gainesville FL

Investigators

Abstract

PROPOSAL NO: AST 0206617 PI: Pina, R K It is widely accepted that the power source in the 'central engine' of active galactic nuclei (AGN) arises from accretion of gas and dust onto a super massive black hole (SMBH). So-called "Unified Schemes" hold that the featureless continuum produced by the central engine is shrouded in a geometrically and optically thick torus of material, obscuring the central engine from some lines-of-sight. Unified models suggest that multiple classes of AGN result not from different physical characteristics, but rather arise from different lines-of-sight to the central engine, revealing varied physical conditions leading to the existing classification scheme. However, the idea that AGN classification depends solely on the line-of-sight to the central engine has been called into question by recent surveys of Seyfert (Sy) Types 1 and 2 galaxies. These surveys reveal that Sy-2 host galaxies typically have an increased level of star formation as compared to Sy-1. One hypothesis is that Seyfert central engines evolve over time from a Sy-2 to Sy-1. A key prediction of this theory is that Seyfert galaxies will display a decreasing amount of central star formation and/or warm dust throughout the evolution from Sy-2 to Sy-1. In order to test this theory an unbiased sample of various Seyfert in the mid-IR will be observed using the twin Gemini 8-meter class telescopes located in Hawaii and Chile.