MIRACLE II: Unveiling the multi-phase gas interplay in the circumnuclear region of NGC 1365 via multi-cloud modeling

TL;DR

The paper presents a comprehensive, multi-wavelength study of the circumnuclear gas in NGC 1365, combining JWST/MIRI, VLT/MUSE, and ALMA data to map ionized, warm molecular, and cold molecular phases. A novel, fully self-consistent multi-cloud framework (HOMERUN) together with 3D kinematic modeling (MOKA$^{3D}$) disentangles AGN- and SF-driven emission, deriving robust outflow masses, geometry, and energetics from 60 emission lines spanning $\sim$10–130 eV ionization. The results show a clear AGN-driven, high-IP outflow with a collimated axis, while the molecular gas largely traces disk rotation; mid-IR diagnostics reveal AGN- and shock-excitation that optical diagnostics miss due to extinction. The work underscores the necessity of self-consistent, multi-phase analysis to accurately quantify AGN feedback and its role in galaxy evolution, illustrating significant discrepancies with classical methods that rely on single-phase assumptions. The combined JWST+MUSE+ALMA approach provides a powerful blueprint for characterizing circumnuclear gas and feedback in nearby active galaxies.

Abstract

We present a multi-phase study of the gas in the circumnuclear region (~1.1x1.0 kpc^2) of the nearby Seyfert 1.8 galaxy NGC 1365, observed in the context of the Mid-IR Activity of Circumnuclear Line Emission (MIRACLE) program. We combined spatially resolved spectroscopic observations from JWST/MIRI, VLT/MUSE, and ALMA to investigate the ionized atomic gas and the warm and cold molecular phases. MIRI data revealed over 40 mid-IR emission lines from ionized and warm molecular gas. Moment maps show that both cold and warm molecular gas follow the rotation of the stellar disk along the circumnuclear ring. The ionized gas displays flux and kinematic patterns that depend on ionization potential (IP): low-IP species (<25 eV) trace the disk, while higher-IP lines (up to ~120 eV) trace outflowing material. The [O III]5700 and [Ne V]14 lines both trace the southeast nuclear outflow cone. Additionally, [Ne V]14 detects the northwest counter-cone, obscured in the optical and thus invisible in [O III]5700. Mid-IR diagnostics, unlike optical ones, clearly reveal the AGN as the primary ionization source in the nucleus. Emission from high-IP species is spatially coincident with the ionization cones and not with star-forming regions. Using the [Ne V]24/[Ne V]14 ratio, we derive an electron density of (750+-440) cm^(-3), in agreement with values from the [S II] optical doublet. For the first time, we apply a fully self-consistent approach combining advanced photoionization and kinematic models (HOMERUN+MOKA3D) to constrain intrinsic outflow properties, overcoming the limitations of simplified classical methods. Exploiting the synergy of JWST/MIRI and VLT/MUSE, HOMERUN reproduces fluxes of over 60 emission lines from optical to mid-IR, disentangling AGN and star formation contributions and yielding robust estimates of outflow mass, geometry, and energetics.

Figures (12)

• Figure 1: MIRI, MUSE, and ALMA observations of NGC 1365. Upper left: Continuum map from MUSE data obtained collapsing the data in the wavelength range 5200-5800 Å. Upper right: [OIII]$\lambda5007\text{\AA}\xspace$ flux map from MUSE data in the ALMA FoV. Lower left: [FeVII]$\lambda6087\text{\AA}\xspace$ flux map from MUSE data in the MIRI Ch4 FoV. Lower right: [S III]18.51$\mu$m flux map from MIRI data. Dashed orange rectangles represent the MIRI MRS channels FoV. Blue and green circles of radius of 0.7 represent the regions from which we extracted the spectra shown in Fig. \ref{['fig: spectra']}. Cyan and blue contours represent arbitrary levels of CO(3-2) flux from ALMA and [OIII]$\lambda5007\text{\AA}\xspace$ from MUSE, respectively. The star marks the position of the nucleus based on the ALMA data (see Section \ref{['app:ALMA_data']}). In the lower panels, the violet and orange circles represent the MUSE and MIRI PSF, respectively. The ALMA beam is shown as a cyan oval.
• Figure 2: Integrated spectra of NGC 1365 from MIRI MRS data. The blue and green curves represent the integrated spectra extracted from the 0.7 radius apertures marked by the circles in the lower right panel of Fig. \ref{['fig: comparison fov']}. These apertures sample regions dominated by the stellar disk and outflow emission, respectively. Detected emission lines are marked with vertical lines: ionized gas emission lines are labeled in yellow, H$_2$ rotational lines in cyan, and H I recombination lines in green. We annotate the main PAH features with gray arrows. The names of each MIRI MRS sub-channel are indicated, and the gray regions represent the overlapping spectral ranges of two adjacent sub-channels.
• Figure 3: Moment maps of ionized and molecular gas emission in NGC 1365, tracing both the rotating disk and the outflowing gas components. From top to bottom: [NeV]$\lambda14\mu\mathrm{m}$, [NeII]$\lambda13\mu\mathrm{m}$, H$_2$$0-0$ S(1), and CO(3-2) moment maps. From left to right, we show the flux, the line-of-sight velocity (LOSV), and the velocity dispersion map. The contours represent arbitrary flux levels of [NeV]$\lambda14\mu\mathrm{m}$ emission. The star marks the nucleus position. The maps size is 870$\times$910 pc$^2$. Spaxels with S/N < 5 are masked.
• Figure 4: Channel maps of ionized gas species tracing the outflow kinematics from MIRI and MUSE data. Upper panel: Channel maps of [NeV]$\lambda14\mu\mathrm{m}$ emission lines from MIRI data. Lower panel: Channel maps of [OIII]$\lambda5007\text{\AA}\xspace$ emission from WFM MUSE data. Contours indicate velocity dispersion levels of 97, 114, and 130 km s$^{-1}$ in the [NeV]$\lambda14\mu\mathrm{m}$ emission. Velocity bins are indicated at the top of every panel in kilometers per second and are computed relative to the same systemic velocity. The star marks the position of the nucleus based on the ALMA data (see Section \ref{['app:ALMA_data']}).
• Figure 5: Comparison between mid-IR and optical diagnostic diagrams. Top panels, from left to right: Diagnostic diagram of [NeIII]$\lambda15\mu$m/[NeII]$\lambda12\mu$m vs [OIV]$\lambda14\mu$m/[NeII]$\lambda12\mu$m, [NeIII]$\lambda15\mu$m/[NeII]$\lambda12\mu$m vs [NeV]$\lambda14\mu$m/[NeII]$\lambda12\mu$m, and [SII]$\lambda\lambda6716,6731$/H$\alpha$ vs [OIII]$\lambda5007\text{\AA}\xspace$/H$\beta$. In the mid-IR diagnostic diagrams, data points are color-coded by their proximity to the SF-, AGN-, and shocks-excitation models, based on the predictions by Feltre+23. In the [SII] BPT diagram, the solid curve defines the theoretical upper bound for pure SF Kewley+01, while the dashed one separates Seyfert galaxies from LINERs Kewley+06. The lower panels show spatially resolved excitation maps, where each pixel is color-coded based on its position in the corresponding diagnostic diagram. In the mid-IR diagnostic diagrams, shock-excited spaxels are in orange, AGN-excited spaxels in green, overlapping spaxels are in red, and spaxels not reproducible with any single model are in gray. In the [SII] BPT diagram, Seyfert-excited spaxels are in green, and SF-excited spaxels are in purple. Solid black contours represent arbitrary [NeV]$\lambda14\mu\mathrm{m}$ flux levels, while dashed black contours represent arbitrary levels of CO(3-2) flux from ALMA data. Circles are the regions where colored crosses in the upper panels and spectra in Fig. \ref{['fig: spectra']} are extracted from, integrated with a radius of 0.7. The star marks the position of the nucleus based on the ALMA data (see Section \ref{['app:ALMA_data']}). Spaxels with S/N < 10 are masked.