INFRARED DIAGNOSTICS FOR THE EXTENDED 12 μm SAMPLE OF SEYFERTS

Abstract

We present an analysis of Spitzer IRS spectroscopy of 83 active galaxies from\nthe extended 12 micron sample. We find rank correlations between several\ntracers of star formation which suggest that (1) the PAH feature is a reliable\ntracer of star formation, (2) there is a significant contribution to the\nheating of the cool dust by stars, (3) the H$_2$ emission is also primarily\nexcited by star formation. The 55-90 vs. 20-30 spectral index plot is also a\ndiagnostic of the relative contribution of Starburst to AGN. We see there is a\nlarge change in spectral index across the sample. Thus, the contribution to the\nIR spectrum from the AGN and starburst components can be comparable in\nmagnitude but the relative contribution also varies widely across the sample.\nWe find rank correlations between several AGN tracers. We search for\ncorrelations between AGN and Starburst tracers and we conclude that the AGN and\nStarburst tracers are not correlated. This is consistent with our conclusion\nthat the relative strength of the AGN and Starburst components varies widely\nacross the sample. Thus, there is no simple link between AGN fueling and Black\nHole Growth and star formation in these galaxies. The distribution of Sil 10\nmicron and 18 micron strengths is consistent with the clumpy torus models of\nSirocky et al. We find a rank correlation between the [NeV] 14 micron line and\nthe 6.7 micron continuum which may be due to an extended component of hot dust.\nThe Sy 2s with a Hidden Broad Line Region (HBLR) have a higher ratio of AGN to\nStarburst contribution to the SED than Sy 2s without an HBLR. This may\ncontribute to the detection of the HBLR in polarized light. The Sy 2s with an\nHBLR are more similar to the Sy 1s than they are to the Sy 2s without an HBLR.\n