USRA/SOFIA Science Center
Shock-enhanced [CII] detections in galaxies with FIFI-LS
We report observations of galaxies with FIFI-LS where the [CII] emission is boosted by the presence of shocks in the intergalactic medium. Shocks can arise from the interaction of jets from the galactic nucleus with the intergalactic medium or from dissipation of mechanical energy, as in the case of galaxy interactions. Although these cases are not tipycally considered by models of [CII] emission, their effect can be important. We studied with FIFI-LS two cases of central active nuclei interacting with the intergalactic medium and one case of collisional ring galaxy. In all these cases we find that an important fraction of the [CII] emission is linked to the effect of shocks and turbulence. For instance, in the case of NGC 4258 we find that approximately 40% of the emission in the central part of the galaxy is due to shocks. Since galaxy interactions and AGN-galaxy feeback are frequent events at high redshift, these observations suggest that, in some cases, [CII] could be a biased indicator of star formation for high-redshift galaxies.