Deep Chandra Observations of ESO 428-G014. IV. The Morphology of the Nuclear Region in the Hard Continuum and Fe K alpha Line

We report the results of high-resolution subpixel imaging of the hard continuum and Fe K alpha line of the Compton-thick (CT) active galactic nucleus (AGN) ESO 428-G014, observed with Chandra ACIS. While the 3-4 keV emission is dominated by an extended component, a single nuclear point source is prominent in the 4-6 keV range. Instead, two peaks of similar intensity, separated by similar to 36 pc in projection on the plane of the sky are detected in the Fe K alpha emission. The SE knot could be marginally associated with the heavily obscured hard continuum source. We discuss four possible interpretations of the nuclear morphology. (1) Given the bolometric luminosity and likely black hole mass of ESO 428-G014, we may be imaging two clumps of the CT obscuring torus in the Fe K alpha line. (2) The Fe K alpha knots may be connected with the fluorescent emission from the dusty bicone, or (3) with the light echo of a nuclear outburst. (4) We also explore the less likely possibility that we may be detecting the rare signature of merging nuclei. Considering the large-scale kiloparsec-size extent of the hard continuum and Fe K alpha emission (Papers I and II), we conclude that the AGN in ESO 428-G014 has been active for at least 10(4) yr. Comparison with the models of Czerny et al. suggests high accretion rates during this activity.