Double-peaked AGN. I. Dual AGN candidates

Galaxies with double-peaked narrow AGN emission lines in the Sloan Digital Sky Survey (SDSS) are plausible dual AGN candidates, but their double-peaked profiles could also be the result of gas kinematics or AGN-driven outflows and jets on small or large scales.

To help distinguish between these scenarios, we have obtained spatial profiles of the AGN emission via follow-up long-slit spectroscopy of 81 double-peaked narrow-line AGNs in SDSS at 0.03<=z<=0.36 using Lick, Palomar, and MMT Observatories. We find that all 81 systems exhibit double AGN emission components with ~kpc projected spatial separations on the sky (0.2h^-1^_70_kpc<{Delta}x<5.5h^-1^_70_kpc; median {Delta}x=1.1h^-1^_70_kpc), which suggests that they are produced by kiloparsec-scale dual AGNs or kiloparsec-scale outflows, jets, or rotating gaseous disks.