Near-infrared spectroscopic imaging of the circum-nuclear environment of NGC 1068

We report #<=#1'' resolution imaging of the 2.1212#mu#m H_2 v=1-0 S(1) and 1.6435#mu#m Fe-lines towards the nucleus of the Seyfert 2 galaxy NGC 1068. The H_2 emission is concentrated at the nucleus and extends ca 5'' (340 pc) east-west, with several embedded knots which probably represent concentrations of dense, massive molecular clouds. The brightest H_2 knot is centered 0.3'' south-west of the near-infrared continuum peak and, due to a total molecular hydrogen column density likely exceeding 10"2"3 cm"-"2, may contribute significantly to the obscuration of the broad line region in the nucleus of NGC 1068. In contrast the Fe-emission extends over #>=#8'', is elongated along position angle ca 35 and tracks the narrow line region (NLR) and the central collimated part of the twin radio jet. Our observations suggest that the radio continuum and optical line emission observed towards the NLR region arises at the interface between the nuclear outflow/jet and molecular clouds in the circumnuclear environment. The Fe-emission also originates in the dense (n(H_2)>10"4 cm"-"3) outflow/cloud interfaces and may be produced in gas exposed to X-ray radiation from the active nucleus or in gas which is interacting with the outflow for the nucleus. For densities below 10"7 cm"-"3 the gas phase abundance of iron appears to be significantly enhanced along the jet axis. We propose that this enhancement may be due to efficient grain destruction by fast shocks in the outflowSIGLEAvailable from TIB Hannover: RN 9303(248) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman