Starburst superwind and LINER activity in NGC 4945

Spectra (3700-10000 Å) and continuum + line images of NGC4945 at optical (V,R,Z,[O III],H +[N II]) and IR (J,H,K,L,H2,Br ) wavelengths reveal a conical wind–blown cavity. The Br and L band images trace a starburst disc or ring with no morphological similarity to the more extended H2 emission which shows the cavity and indicates that it is confined by molecular material heated by shocks or X-rays. The spectra reveal significant bulk motions (< 600 km/s); line ratios typical of LINERS and the discovery of prominent [C I] which is very weak in Seyferts 1–2 while strong in supernova remnants, including the X–ray excited filaments of the Crab. Shock excitation at the surface of the cavity provides a likely explanation for the line emission although photoionization by X-rays associated with the superwind or the suspected Seyfert nucleus detected in hard X–rays cannot be excluded.