The [OIII] profiles of infrared-selected active galactic nuclei: More
  powerful outflows in the obscured population
  We explore the kinematics of ionized gas via the [O III] $\lambda$5007
emission lines in active galactic nuclei (AGN) selected on the basis of their
mid-infrared (IR) emission, and split into obscured and unobscured populations
based on their optical-IR colors. After correcting for differences in redshift
distributions, we provide composite spectra of spectroscopically and
photometrically defined obscured/Type 2 and unobscured/Type 1 AGN from 3500 to
7000 \AA. The IR-selected obscured sources contain a mixture of narrow-lined
Type 2 AGN and intermediate sources that have broad H$\alpha$ emission and
significantly narrower H$\beta$. Using both [OIII] luminosities and AGN
luminosities derived from optical-IR spectral energy distribution fitting, we
find evidence for enhanced large-scale obscuration in the obscured sources. In
matched bins of luminosity we find that the obscured population typically has
broader, more blueshifted \OIII\ emission than in the unobscured sample,
suggestive of more powerful AGN-driven outflows. This trend is not seen in
spectroscopically classified samples, and is unlikely to be entirely explained
by orientation effects. In addition, outflow velocities increase from small to
moderate AGN $E(B-V)$ values, before flattening out (as traced by FWHM) and
even decreasing (as traced by blueshift). While difficult to fully interpret in
a single physical model, due to both the averaging over populations and the
spatially-averaged spectra, these results agree with previous findings that
simple geometric unification models are insufficient for the IR-selected AGN
population, and may fit into an evolutionary model for obscured and unobscured
AGN.
