Prof. Dimitra Rigopoulou

Abstract:

We utilize James Webb Space Telescope/Mid Infrared Instrument (JWST/MIRI) Integral Field Unit observations from the Galaxy Activity, Torus and Outflow Survey to investigate the diverse range of ionized outflow rates of obscured active galactic nuclei (AGN) with similar bolometric luminosity and explore potential associations with AGN feedback. We explore spatial correlations between ionized emission potentially associated with fast shocks ([Fe II]5.34μm) and the excitation of H2. We further constrain our investigation to the inner 400 pc (the nuclear and circumnuclear regions r < 200 pc), and estimate the excitation temperature and column density of H2 assuming local thermodynamic equilibrium and using the S(1)–S(8) rotational H2 emission lines visible to JWST/MIRI spectroscopy. We report the molecular gas temperature of the deprojected 400 pc nuclear region to correlate with the ionized mass outflow rate. We also observe a stronger degree of spatial correlation between [Fe II]5.34μm emission and H2 gas temperature. We observe regions of enhanced [Fe II]5.34μm/[Ar II]6.99μm spatially coincident with the ionization cones of objects with higher ionized outflow rates and [Fe II]5.34μm/[Ar II]6.99μm in the deprojected 400 pc nuclear region to scale positively with both the ionized outflow rate and the estimated molecular gas temperature. We do not observe the estimated jet cavity power within the central 400 pc as strongly correlated with the ionized mass outflow rate or molecular gas temperature of the nuclear region. We take the preceding observations to suggest a higher degree of interaction between AGN outflows and the circumnuclear disk.

Abstract:

Abstract We present a detailed study of the inner regions of NGC 7582, a nearby Seyfert 2 galaxy, from the Galaxy Activity, Torus and Outflow Survey (GATOS). The galaxy hosts a circumnuclear star-forming disk and an AGN-driven biconical ionised outflow. Using JWST NIRSpec and MIRI/MRS integral-field spectroscopy, we analyse ionic emission lines spanning a wide range of ionisation potentials (IPs, ∼8–126 eV). Gaussian line-profile fitting reveals kinematic stratification: low-IP species (≲ 20 eV; e.g., [Fe II], [Ar II], [Ne II]) trace ordered disk rotation with PA ∼−12 ± 3○, while high-IP species (≳ 35 eV; e.g., [O IV], [Mg IV], [Ne V]) follow the outflow with PA ∼54 ± 10○. Outflowing gas exhibits systematically higher velocity dispersions (119 ± 13 km/s) than the disk (78 ± 11 km/s), consistent with turbulent or bulk motions. Intermediate-IP lines, [S III], [Ar III], and [Ne III], show contributions from both components, with the outflow characterised by higher dispersion, lower amplitude, and higher velocities in double-Gaussian fits. For these lines, a thin inclined disk plus one-dimensional outflow model enables robust separation and quantification of the disk and outflow velocity fields. The outflow is consistent with a hollow bicone capable of accelerating gas beyond the local escape velocity, implying most material is unlikely to be re-accreted. The ionisation cone opening angle shows no dependence on IP, indicating the AGN torus polar regions are largely unobscured. Our study provides new insights into AGN-driven outflows and circumnuclear disk dynamics, offering a framework to disentangle overlapping ISM kinematics in nearby active galaxies.

Abstract:

Luminous infrared (IR) galaxies are key sites of obscured stellar mass assembly at z > 0.5. Their star formation rates (SFRs) are often estimated using the luminosities of the 6.2 and 11.2 μm polycyclic aromatic hydrocarbon (PAH) features or those of the [Ne ii] and [Ne iii] fine-structure lines, as they are minimally affected by obscuration. It is uncertain whether the calibration of these features as SFR tracers depends on the starburst bolometric luminosity or the level of active galactic nucleus (AGN) activity. We here investigate the relationship between the luminosities of PAH and neon lines with SFR for highly luminous objects using radiative transfer modeling and archival observations of 42 local ultraluminous (≥1012L⊙) IR galaxies (ULIRGs). We find that PAH and [Ne ii] features arise mainly in star-forming regions, with small contributions from the AGN or host, but that the [Ne iii] line has a mixed contribution from both star formation and AGN activity. We present relations between LPAH and L[Ne II], and both starburst luminosity and SFR. We find relations for lower-luminosity (LIR ≃ 1010–1012L⊙) systems underestimate the SFRs in local ULIRGs by up to ∼1 dex. The 6.2 and 11.2 μm PAH features, and the [Ne ii] line, are thus good tracers of SFR in ULIRGs. We do not find that a more luminous AGN affects the relationship between SFR and PAH or neon luminosity but that it can make PAH emission harder to discern. Our results and derived relations are relevant to studies of star-forming and composite galaxies at z < 3 with the James Webb Space Telescope.