We present new NuSTAR and Chandra observations of NGC 3393, a galaxy reported to host the smallest separation dual AGN resolved in the X-rays. While past results suggested a 150 pc separation dual AGN, three times deeper Chandra imaging, combined with adaptive optics and radio imaging suggest a single, heavily obscured, radio-bright AGN. Using VLA and VLBA data, we find an AGN with a two-sided jet rather than a dual AGN and that the hard X-ray, UV, optical, NIR, and radio emission are all from a single point source with a radius <0.2". We find that the previously reported dual AGN is most likely a spurious detection resulting from the low number of X-ray counts (<160) at 6-7 keV and Gaussian smoothing of the data on scales much smaller than the PSF (0.25" vs. 0.80" FWHM). We show that statistical noise in a single Chandra PSF generates spurious dual peaks of the same separation (0.55±0.07" vs. 0.6") and flux ratio (39±9% vs. 32% of counts) as the purported dual AGN. With NuSTAR, we measure a Compton-thick source (NH=2.2±0.4×1024 cm−2) with a large torus half-opening angle, {\theta}=79 which we postulate results from feedback from strong radio jets. This AGN shows a 2-10 keV intrinsic to observed flux ratio of 150. Using simulations, we find that even the deepest Chandra observations would severely underestimate the intrinsic luminosity of NGC 3393 above z>0.2, but would detect an unobscured AGN of this luminosity out to high redshift (z=5).
@article{arxiv.1505.03524,
title = {Broadband Observations of the Compton-thick Nucleus of NGC 3393},
author = {Michael J. Koss and C. Romero-Canizales and L. Baronchelli and S. H. Teng and M. Balokovic and S. Puccetti and F. E. Bauer and P. Arevalo and R. Assef and D. R. Ballantyne and W. N. Brandt and M. Brightman and A. Comastri and P. Gandhi and F. A. Harrison and B. Luo and K. Schawinski and D. Stern and E. Treister},
journal= {arXiv preprint arXiv:1505.03524},
year = {2015}
}
Comments
Accepted for publication in ApJ. 15 Figures and 4 tables