DEIMOS observations of WISE-selected, optically obscured AGNs

Abstract

While there are numerous criteria for photometrically identifying active galactic nuclei (AGNs), searches in the optical and UV tend to exclude galaxies that are highly dust obscured. This is problematic for constraining models of AGN evolution and estimating the AGN contribution to the cosmic X-ray and IR backgrounds, as highly obscured objects tend to be underrepresented in large-scale surveys. To address this, we identify potentially obscured AGNs using mid-IR color colors from the Wide-field Infrared Survey Explorer (WISE) catalog. This paper presents the results of optical spectroscopy of obscured AGN candidates using Keck DEIMOS, and their physical properties derived from these spectra. We find that a W1 − W2 > 0.8 color criterion effectively selects AGNs with a higher median level of E(B − V) extinction compared to the AGNs found in the SDSS DR7 survey. This optical extinction can be measured using SED modeling or by using r −W1 as a measure of optical to IR flux. We find that specific, targeted observations are necessary to find the most highly optically obscured AGNs, and that additional far-IR photometry is necessary to further constrain the dust properties of these AGNs.

Galaxy and Mass Assembly (GAMA): A $\textit{WISE}$ study of the activity of emission-line systems in G23

“…2019) and similar trends are also seen in the radio (Leahy et al 2019), the mid-infrared (Ching et al 2017;Lam et al 2018) and others.…”

Galaxy and Mass Assembly (GAMA): A WISE Study of the Activity of Emission-line Systems in G23

“…The different techniques show some disagreements from one wave band to the other. For example, a substantial number of galaxies classified as X-ray AGNs appear to be SF in the optical (Agostino & Salim 2019), and similar trends are also seen in the radio (Leahy et al 2019), the mid-infrared (Ching et al 2017;Lam et al 2018), and others.…”