Revisiting the complex nuclear region of NGC 6240 with Chandra
  We present a reanalysis of the cumulative ACIS S Chandra data set pointed at
the double AGNs of the NGC 6240 merging galaxy, focusing on the hard energy
bands containing the hard spectral continuum (5.5-5.9 keV), the redshifted Fe I
K alpha line (6.0-6.4 keV), and the redshifted Fe XXV line (6.4-6.7 keV). We
have used to the full the Chandra telescope angular resolution, and we have
modeled the Chandra PSF by comparing pre-flight calibration model to the data
for the two bright AGNs. With two complementary approaches: (1) studying the
residuals after PSF subtraction, and (2) producing reconstructed Expectation
through Markov Chain Monte Carlo (EMC2) images, we are able to resolve
structures extending from 1 kpc to <200 pc in the S AGN. The latter are within
the sphere of influence of this BH. We find significant extended emission in
both continuum and Fe lines in the 2'' (1 kpc) region surrounding the nuclei,
in the region between the N and S AGN, and in a sector of PA 120-210 deg.
extending to the SE from the centroid of the S AGN surface brightness. The
extended Fe I K alpha emission is likely to originate from fluorescence of
X-ray photons interacting with dense molecular clouds, providing a
complementary view to recent high-resolution ALMA studies. The non-thermal
emission is more prevalent in the region in between the two active X-ray
nuclei, and in the N AGN. We do not find strong evidence of X-ray emission
associated with the 3rd nucleus recently proposed for NGC 6240.
