A Search for Low-Luminosity AGNs in a Complete Sample of Nearby Galaxies

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Session 17 -- Normal Galaxies
Oral presentation, Monday, 10:30-12:00, Wheeler Room

[17.05] A Search for Low-Luminosity AGNs in a Complete Sample of Nearby Galaxies

L.C.Ho, A.V.Filippenko (UCB), W.L.W.Sargent (CIT)

We present preliminary results of an optical, spectroscopic survey of the nuclei of the 500 brightest galaxies in the northern sky. The long-slit spectra were obtained with the Hale 5-m reflector at Palomar Observatory, covering the wavelengths 4200$-$5200 \AA\ and 6200$-$6900 \AA\ with 2$-$4 \AA\ resolution and signal-to-noise ratios of $\sim$ 100. The primary purpose of the survey is to search for low-luminosity active galactic nuclei (LLAGNs) in the centers of nearby galaxies by (1) detecting broad H$\alpha$ emission and (2) modelling the narrow emission-line spectra. Special care is taken to remove the underlying starlight which often contaminates the spectra in order to obtain accurate measurements of line fluxes. The results of this survey will have many astrophysical applications, including quantifying the faint end of the local AGN luminosity function.

We summarize the statistical properties of the survey, describe our methods of analysis, and present some preliminary results. Analysis of a small subsample of the survey suggests that $\sim$ 25\% of the low-ionization emission-line objects in the literature, previously thought to be LLAGNs, may be nuclear H~II regions powered by young stars.

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