Dual active galactic nuclei ( AGNs ) and offset AGNs are kpc-scale separation supermassive black holes pairs created during galaxy mergers , where both or one of the black holes are AGNs , respectively .
These dual and offset AGNs are valuable probes of the link between mergers and AGNs but are challenging to identify .
Here we present Chandra /ACIS observations of 12 optically-selected dual AGN candidates at z < 0.34 , where we use the X-rays to identify AGNs .
We also present HST /WFC3 observations of 10 of these candidates , which reveal any stellar bulges accompanying the AGNs .
We discover a dual AGN system with separation \Delta x = 2.2 kpc , where the two stellar bulges have coincident [ O iii ] \lambda 5007 and X-ray sources .
This system is an extremely minor merger ( 460:1 ) that may include a dwarf galaxy hosting an intermediate mass black hole .
We also find six single AGNs , and five systems that are either dual or offset AGNs with separations \Delta x < 10 kpc .
Four of the six dual AGNs and dual/offset AGNs are in ongoing major mergers , and these AGNs are 10 times more luminous , on average , than the single AGNs in our sample .
This hints that major mergers may preferentially trigger higher luminosity AGNs .
Further , we find that confirmed dual AGNs have hard X-ray luminosities that are half of those of single AGNs at fixed [ O iii ] \lambda 5007 luminosity , on average .
This could be explained by high densities of gas funneled to galaxy centers during mergers , and emphasizes the need for deeper X-ray observations of dual AGN candidates .