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The nearly edge-on galaxy NGC4945 is one of the closest galaxies where an AGNand starburst coexist, and is one of the brightest sources at 100 keV. Near andmid-infrared spectroscopy have shown very strong obscuration of its centralregion, rivaled only in strength by some of the most deeply obscured ULIRGs. Weaim to determine the spatial distribution of ISM features in the central426x426 pc^2 of NGC4945. We map the central region of NGC4945 in threeSpitzer-IRS modules (SH, SL and LL). We produce maps of the flux distributionof the starburst tracers [Ne II], [Ne III], [S III] and [S IV] at 12.81, 15.56,18.71 and 10.51 mum, respectively, and a map of the AGN narrow-line regiontracer [Ne V] at 14.32 mum. We also mapped the S(1), S(2) and S(3) purerotational lines of H2, which trace the distribution of warm molecularhydrogen. We obtained an extinction map (A_V) based on the apparent strength ofthe 9.7 mum silicate absorption feature. Our A_V map traces the contours of thestarburst ring but the highest extinction (A_V(9.85 mum)~60) is found at thenucleus. Within the uncertainty of the astrometry all emission lines are foundto peak on the nucleus, except for the warm molecular hydrogen emission whichshows a maximum 60-100 pc NW of the nucleus. We favour a scenario in which thelower H2 0-0 S(1) and S(2) rotational lines originate mainly from an unobscuredextra-nuclear component associated with the super-wind cone observed in the HSTNICMOS map of the H2 1-0 S(1) vibrational line. For the [Ne V] emission weinfer an attenuation of a factor 12-160 (A_V=55-112) based on a comparison ofthe ratio of our [Ne V] flux and the absorption-corrected 14-195 keV Swift-BATflux to the average [Ne V]/BAT ratio for Seyfert 1 nuclei. The high attenuationindicates that [Ne V] and [O IV] cannot be used as extinction-free tracers ofAGN power in galaxies with deeply buried nuclei.

The deeply obscured AGN of NGC4945 I. Spitzer-IRS maps of [Ne V], [Ne II], H2 0-0 S(1), S(2), and other tracers