We present mid infrared ( MIR ) spectra of the Seyfert 2 ( Sy 2 ) galaxy NGC 1808 , obtained with the Gemini ’ s Thermal-Region Camera Spectrograph ( T-ReCS ) at a spatial resolution of \sim 26 pc .
The high spatial resolution allowed us to detect bright polycyclic aromatic hydrocarbons ( PAHs ) emissions at 8.6 \mu m and 11.3 \mu m in the galaxy centre ( \sim 26 pc ) up to a radius of 70 pc from the nucleus .
The spectra also present [ Ne ii ] 12.8 \mu m ionic lines , and H _ { 2 } S ( 2 ) 12.27 \mu m molecular gas line .
We found that the PAHs profiles are similar to Peeters ’ s A class , with the line peak shifted towards the blue .
The differences in the PAH line profiles also suggests that the molecules in the region located 26 pc NE of the nucleus are more in the neutral than in the ionised state , while at 26 pc SW of the nucleus , the molecules are mainly in ionised state .
After removal of the underlying galaxy contribution , the nuclear spectrum can be represented by a Nenkova ’ s clumpy torus model , indicating that the nucleus of NGC 1808 hosts a dusty toroidal structure with an angular cloud distribution of \sigma = 70 ^ { \circ } , observer ’ s view angle i = 90 ^ { \circ } , and an outer radius of R _ { 0 } \sim 0.55 pc .
The derived column density along the line of sight is N _ { H } = 1.5 \times 10 ^ { 24 } cm ^ { − 2 } , which is sufficient to block the hard radiation from the active nucleus , and would explain the presence of PAH molecules near to the NGC 1808 ’ s active nucleus .