The obscured nucleus of NGC 3256,S. I. Anisotropic active galactic nucleus near-IR radiation field traced by CO v=1--0 with JWST NIRSpec

The southern nucleus of NGC 3256, a nearby luminous infrared (IR) interacting system (d=40,Mpc; L_̊m 11.6 $, excited by the $∼4.7 suggests a collimated radiation field, for which we estimate a small half-opening angle (15--20 for NGC 3256,S, which is similar to that of Type 2 AGNs. However, in contrast to Type 2 AGNs, a high covering factor of the obscuring material, possibly sustained by inflows linked to the galaxy merger and similar to that expected in deeply obscured compact obscured nuclei (CONs), is needed to explain the absence of extended high-ionization emission. Therefore, NGC 3256,S shares properties with CONs and Type 2 AGNs. hosts a deeply obscured low-luminosity active galactic nucleus (AGN) associated with a massive and fast bipolar collimated molecular outflow. NIRSpec observations revealed bright spatially resolved ro-vibrational CO v=1--0 4.67 this molecular outflow emission at the base of extending out to ∼300,pc, which is IR radiation from the southern dusty core. Using Monte Carlo radiative transfer models, we analyzed the CO v=1--0 band emission to determine the intensity of the ∼4.7 . We find that the core spectral luminosity density at ∼4.7 is ∼2--4 times higher than that inferred along our line of sight, indicating an anisotropic near-IR radiation field. Moreover, the slower than d^-2 decrease of the near-IR flux density across the outflow IR radiation field across the outflow base as seen by the material in the outflow base base and a diameter of the collimating structure of 15±5,pc. This is slightly smaller than the diameter of the obscuring envelope (25±5,pc). Combined with the expansion of this obscuring envelope, traced by the blueshifted CO v=1--0 absorption toward the nucleus, this suggests that the AGN is beginning to clear its environment. We estimate N_̊m H∼1022-23,cm^ -2