the mid-infrared diagnostics offer a powerful tool for uncovering AGN missed by optical spectroscopy. The AGN bolometric luminosities in our sample inferred using our \[NeV\] line luminosities range from $\sim$ 3$\times$10$^{41}$ ergs s$^{-1}$ to $\sim$ 2$\times$10$^{43}$ ergs s$^{-1}$. Assuming that the AGN is radiating at the Eddington limit, this range corresponds to a lower mass limit for the black hole that ranges from $\sim$ 3$\times$10$^3$M$_{\odot}$ to as high as $\sim$ 1.5$\times$10$^5$M$_{\odot}$. These lower mass limits however do not put a strain on the well-known relationship between the black hole mass and the host galaxy’s stellar velocity dispersion established in predominantly early-type galaxies. Our findings add to the growing evidence that black holes do form and grow in low-bulge environments and that they are significantly more common than optical studies indicate.'
author:
- 'S. Satyapal, D. Vega, R. P. Dudik, N. P. Abel, & T. Heckman'
title: ' [*Spitzer*]{} Uncovers Active Galactic Nuclei Missed by Optical Surveys in 7 Late-type Galaxies'
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Introduction
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The vast majority of [*currently*]{} known active galactic nuclei (AGN) in the local Universe reside in host galaxies with prominent bulges (e.g. Heckman 1980a; Keel 1983b; Terlevich, Melnick, & Moles 1987; Ho, Filippenko, & Sargent 1997; Kauffmann 