The multi-phase ISM in the nearby composite AGN-SB galaxy NGC 4945:
  large (parsecs) scale mechanical heating
  We aim at carrying out a comprehensive study of the nearby composite AGN-SB
galaxy, NGC 4945, using spectroscopic and photometric data from the Herschel
satellite. In particular, we want to characterize the thermal structure in this
galaxy by a multi-transitions analysis of the spatial distribution of the 12^CO
emission at different spatial scales using HIFI, PACS, SPIRE as well as APEX
data. We combined the 12^CO/IR flux ratios and the LTE analysis of the 12^CO
images to derive the thermal structure of the Interstellar Medium (ISM) for
spatial scales raging from <200 pc to 2 kpc. From the 12^CO analysis we found
clear trend in the distribution of the derived temperatures and the 12^CO/IR
ratios. It is remarkable that at intermediate scales (360 pc-1 kpc) we see
large temperatures in the direction of the X-ray outflow while at smaller
scales (<200 pc-360 pc), the highest temperature, derived from the high-J
lines, is not found toward the nucleus, but toward the galaxy plane. The
thermal structure derived from the 12CO multi-transition analysis suggests that
mechanical heating, like shocks or turbulence, dominates the heating of the ISM
in the nucleus of NGC 4945 located beyond 100 pc from the center of the galaxy.
This result is further supported by the Kazandjian et al. 2015 models, which
are able to reproduce the emission observed at high-J (PACS) 12^CO transitions
when mechanical heating mechanisms are included. Shocks and/or turbulence are
likely produced by the barred potential and the outflow, observed in X-rays.
