Dissecting the Extended X-ray Emission in the Merging Pair NGC 6240
  We present a detailed spectral and imaging analysis of the central $15''$
radius ($\sim 7.5 \text{ kpc}$) region of the merger galaxy NGC 6240 that makes
use of all the available \textit{Chandra}-ACIS data ($0.3 - 3 \text{ keV}$
effective exposure of $\sim 190 \text{ ks}$). This region shows extended X-ray
structures with lower energy counterparts imaged in CO, [O III] and H$\alpha$
line emission. We find both photo-ionized phases of possible nuclear excitation
and thermal shock-excited emission in the different large-scale components: the
north-west "loop" detected in H$\alpha$, the region surrounding the two nuclei,
the large outflow region to the north-east detected in [O III], and the
southern X-ray extensions. The latter could be the ionization cone of the
northern nucleus, with the N counterpart being obscured by the galaxy disk. The
radial distribution of the X-ray surface brightness suggests a confined hot
interstellar medium at $r < 2.5 \text{ kpc}$, with a free-flowing wind at
larger radii; if the confinement is magnetic, we estimate B-field values of
$\sim 100\,\mu \text{G}$ , similar to those measured in the halo of M82. The
thermal gas of the extended halo at $kT \sim 1 \text{ keV}$ absorbs soft X-rays
from the AGN, but not the extreme ultraviolet radiation leading to a rapid
increase in $F_{\text{[O III]}}/F_{\text{X}}$ beyond $\sim 3 \text{ kpc}$. The
$\alpha$ element to Fe abundance ratios of the thermal components in the
different regions of the extended X-ray emission are generally compatible with
SNe II yields, confirming the importance of the active star formation in NGC
6240.
