MIRACLE. I. Unveiling the multi-phase, multi-scale physical properties of the active galaxy NGC 424 with MIRI, MUSE, and ALMA

We present an analysis of the multi-phase gas properties in the Seyfert II galaxy NGC 424, using spatially resolved spectroscopic data from JWST/MIRI, part of the Mid-InfraRed Activity of Circumnuclear Line Emission (MIRACLE) programme, as well as VLT/MUSE and ALMA. We traced the properties of the multi-phase medium, from cold and warm molecular gas to hot ionised gas, using emission lines such as CO (2-1), H2S(1), [O III]λ5007, [Ne III]15.55μm, and [Ne V]14.32μm. These lines reveal the intricate interplay between the different gas phases within the circumnuclear region, spanning a maximum scale of 7 × 7 kpc2 and a spatial resolution of 110 pc, with MUSE and ALMA, respectively. Exploiting the multi-wavelength and multi-scale observations of gas emission, we modelled the galaxy disc rotation curve from scales of a few parsec up to ∼5 kpc from the nucleus and inferred a dynamical mass of Mdyn = (1.09 ± 0.08) × 1010 M⊙ with a disc scale radius of RD = (0.48 ± 0.02) kpc. We detected a compact ionised outflow with velocities up to 103 kms−1, traced by the [O III], [Ne III], and [Ne V] transitions, with no evidence of cold or warm molecular outflows. We suggest that the ionised outflow might be able to inject a significant amount of energy into the circumnuclear region, potentially hindering the formation of a molecular wind, as the molecular gas is observed to be denser and less diffuse. The combined multi-band observations also reveal, mainly in the ionised and cold molecular gas phases, a strong enhancement of the gas velocity dispersion directed along the galaxy minor axis, perpendicular to the high-velocity ionised outflow, and extending up to 1 kpc from the nucleus. Our findings suggest that the outflow might play a key role in such an enhancement by injecting energy into the host disc and perturbing the ambient material.