We present emission-line flux distributions and ratios for the inner \approx 200 pc of the narrow-line region of the Seyfert 2 galaxy NGC 1068 , using observations obtained with the Gemini Near-infrared Integral Field Spectrograph ( NIFS ) in the J , H and K bands at a spatial resolution of \approx 10 pc and spectral resolution of \approx 5300 .
The molecular gas emission – traced by the K-band H _ { 2 } emission lines – outlines an off-centered circumnuclear ring with a radius of \approx 100 pc showing thermal excitation .
The ionized gas emission lines show flux distributions mostly outlining the previously known [ O iii ] \lambda 5007 ionization bicone .
But while the flux distributions in the H i and He ii emission lines are very similar to that observed in [ O iii ] , the flux distribution in the [ Fe ii ] emission lines is more extended and broader than a cone close to the nucleus , showing a “ double bowl ” or ‘ hourglass ” structure ” .
This difference is attributed to the fact that the [ Fe ii ] emission , besides coming from the fully ionized region , comes also from the more extended partially ionized regions , in gas excited mainly by X-rays from the active galactic nucleus .
A contribution to the [ Fe ii ] emission from shocks along the bicone axis to NE and SW of the nucleus is also supported by the enhancement of the [ Fe ii ] ( 1.2570 \mu m ) / [ P ii ] ( 1.1885 \mu m ) and [ Fe ii ] ( 1.2570 \mu m ) /Pa \beta emission-line ratios at these locations and is attributed to the interaction of the radio jet with the NLR .
The mass of ionized gas in the inner 200 pc of NGC 1068 is M _ { H II } \approx 2.2 \times 10 ^ { 4 } ~ { } { M _ { \odot } } , while the mass of the H _ { 2 } emitting gas is only M _ { H _ { 2 } } \approx 29 { M _ { \odot } } .
Taking into account the dominant contribution of the cold molecular gas , we obtain an estimate of the total molecular gas mass of M _ { cold } \approx 2 \times 10 ^ { 7 } { M _ { \odot } } .