Magellan Spectroscopy of Low-Redshift Active Galactic Nuclei

TL;DR

This paper provides a detailed spectral atlas of 94 low-redshift active galactic nuclei, analyzing emission lines and correcting classifications, to better understand black hole and host galaxy relationships.

Contribution

It offers the first comprehensive spectral decomposition and measurements for many objects, including reclassification of some AGN types.

Findings

Identification of misclassified narrow-line sources

Spectral measurements of key emission lines

Insights into black hole and host galaxy properties

Abstract

We present an atlas of moderate-resolution (R ~ 1200-1600) optical spectra of 94 low-redshift (z < 0.5) active galactic nuclei taken with the Magellan 6.5 m Clay Telescope. The spectra mostly cover the rest-frame region 3600-6000 Ang. All the objects have preexisting Hubble Space Telescope imaging, and they were chosen as part of an ongoing program to investigate the relationship between black hole mass and their host galaxy properties. A significant fraction of the sample has no previous quantitative spectroscopic measurements in the literature. We perform spectral decomposition of the spectra and present detailed fits and basic measurements of several commonly used broad and narrow emission lines, including [O II] 3727, He II 4686, Hbeta, and [O III] 4959, 5007. Eight of the objects are narrow-line sources that were previously misclassified as broad-line (type 1) Seyfert galaxies; of these, five appear not to be accretion-powered.