arXiv subjects

V. Buiten

Publications and source records attributed to V. Buiten.

6 recordsLinked to original sources

arXiv2026

The Multi-phase Biconical Outflow in the local IR-Luminous Merger IRASF01364-1042

We investigate the spatially-resolved ISM properties of the local ($z = 0.048$), IR-luminous ($L_{\rm IR} = 10^{11.87}$\,L$_\odot$), late-stage galaxy merger IRAS F01364-1042, combining multi-wavelength IFU observations from \textit{JWST/MIRI-MRS}, ALMA and Keck/KCWI. Using these datasets, we construct emission line maps of several key tracers of the ionized (e.g., [Ne\,II]\,12.8$μ$m, [O\,III]$\lambda5007$), warm molecular (e.g., \ce{H2}\,0-0\,S(3)), and cold molecular gas (e.g., CO (J$=2-1$)), and perform detailed decomposition of spectra extracted in resolved regions across the areas of emission. We confirm the presence of a multi-phase galactic biconical outflow along the minor axis of a highly inclined rotating disk. The inferred outflow velocities are $\sim\,$500 - 600\,km\,s$^{-1}$ $\sim\,$350\,km\,s$^{-1}$, and $\sim\,$200 - 300\,km\,s$^{-1}$, in the ionized, warm and cold molecular phase, respectively, with corresponding mass outflow rates of $\sim 0.3 - 2.3$, $\sim 31$, and $\sim 38 - 240$\,M$_\odot\,$yr$^{-1}$. The cold molecular phase dominates both the total mass outflow rate and the associated kinetic energy ($\sim\,2 - 8 \times 10^{42}$\,erg\,s$^{-1}$). We confirm, for the first time, a dust-obscured AGN in IRAS\,F01364-1042, via detection of the [Ne\,V]\,14.3$μ$m line. The low inferred AGN bolometric luminosity ($1.2 - 1.8 \times 10^{43}$\,erg\,s$^{-1}$) suggests that the nuclear starburst alone, with a star formation rate of $\sim 40 - 60$\,M$_\odot$\,yr$^{-1}$, can account for the energy required to drive the outflow, though a more active AGN phase in the recent past may have also played a role. Our work showcases the necessity of multi-wavelength observations for interpreting the gas dynamics in merger-driven dusty starbursts, and the capability of \textit{JWST/MIRI-MRS} to uncover obscured, low-luminosity AGN that may be common in these systems.

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arXiv2026

MICONIC: The multiphase circumnuclear region of Centaurus A as seen with JWST/MIRI MRS observations. I. Spectral inventory and properties of the warm molecular disk

Supermassive black holes power Active Galactic Nuclei (AGN), injecting energy that regulates accretion and shapes host galaxies. We investigate the morphology, excitation, and kinematics of molecular hydrogen (H2) in the inner circumnuclear disk of Centaurus A, the nearest radio galaxy. We present JWST/MIRI MRS integral-field spectroscopy of the central 170x100 pc2 at 0.3"-0.7" (5-12 pc) resolution, focusing on pure rotational H2 lines. The spectra show strong nuclear continuum and bright H2 emission from S(1) to S(8), including the first S(8) detection in Centaurus A. Optically thin nuclear lines enable maps of temperature, column density, and ortho-to-para ratio from spaxel-level excitation-diagram fitting. Warm H2 shows a complex morphology, dominating the central region where CO emission is weak or undetected. Low-excitation H2 lines trace an inhomogeneous ring with a 20-pc-radius cavity aligned with the jet's near side, suggesting that the jet affects the morphology of the molecular disk. Higher-excitation lines form filamentary structures around the AGN. Kinematics are rotational with an S-shaped distortion, indicating non-circular motions or a warped disk. A coherent, low-dispersion (70 km/s) streamer spirals inward. A power-law temperature distribution yields a warm (100-2000 K) H2 mass of (5.6+/-1.4)e5 Msun and a dynamical mass of 5e8 Msun within 100 pc. Shock excitation is supported by enhanced H2/continuum and H2/PAH ratios, elevated [Ne III]/[Ne II], and sub-equilibrium ortho-to-para ratios (1.6-2.4). Turbulent dissipation can balance H2 cooling and likely dominates heating beyond 30 pc. In the inner 100 pc of Centaurus A, AGN feeding and feedback are linked: shocks excite H2, regulate the gas temperature, and prevent cooling below 100 K, explaining the weak CO emission and lack of a massive outflow. These shocks may drive angular momentum loss and help fuel the nucleus.

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arXiv2026

GOALS-JWST: Resolved multi-phase molecular gas in IRAS 20551-4250 using JWST and ALMA

Studying the content and distribution of molecular gas provides key insights into how feedback from Active Galactic Nuclei (AGN) and star formation influences galaxy evolution, since molecular gas is the primary fuel for star formation. Ultra-Luminous Infrared Galaxies (ULIRGs) are ideal candidates to study how AGN and/or starbursts affect the interstellar medium due to their intense AGN and star forming activity. We present spatially-resolved multi-phase molecular gas study of IRAS20551-4250, a nearby ($z=0.0429$) ULIRG, using JWST/MIRI-MRS and ALMA. Mid-infrared diagnostics do not rule out the presence of AGN in IRAS20551-4250. [OIII]$λ$5007 in VLT/MUSE data reveal ionised gas outflows with $w_{80}^{\rm [OIII]} \sim 790$ km s$^{-1}$ and $\dot{M}_{\rm out}^{\rm[OIII]}<0.01$ M$_{\odot}$ yr$^{-1}$. No outflows are observed in either molecular phases. JWST/MIRI-MRS data reveal several rotational transitions of warm H$_{2}$ (T$\sim500-1400$ K) within the central $\sim4\times4$ kpc$^{2}$ region. Excitation temperature maps suggest that the warm H$_{2}$ is primarily heated by UV radiation from the central source. The CO-based cold molecular component dominates the molecular gas mass, accounting for $>$95% of the total molecular gas mass. Warm H$_{2}$ maps show two tidal tails and the velocity centroid maps show disturbed, non-rotational motions and a systematic gradient across the field-of-view, similar to that of ALMA CO-based cold molecular gas and consistent with a late-stage merger. Together, our analysis indicate that the molecular gas composition in IRAS20551-4250 is consistent with ongoing star formation in the host galaxy and the outflows observed in ionised gas phase appear insufficient to expel the molecular gas or quench ongoing star formation.

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arXiv2026

MICONIC: JWST/MIRI-MRS reveals heavily reprocessed PAH emission in the circum-nuclear disc of Centaurus A

Polycyclic aromatic hydrocarbons (PAHs) are key dust components in galaxies and play a fundamental role in the physics of the interstellar medium (ISM), yet their response to AGN feedback remains debated. We present a spatially resolved analysis of PAHs in the central $7^{\prime\prime}\times12^{\prime\prime}$ ($\sim100\times200$ pc$^2$) of Centaurus A. We use JWST/MIRI-MRS observations at 5-28 $μ$m from the MIRI European consortium GTO program MICONIC, with angular resolution of $0.35^{\prime\prime}-1^{\prime\prime}$ (about 6-17 pc). We derive PAH moment-0 maps via local continuum subtraction and extract one-dimensional spectra from five regions of interest, including the nucleus, the circumnuclear disc, and a PAH-deficient region. The spectra are decomposed into continuum, emission lines, and PAHs to measure feature intensities and equivalent widths (EWs). PAH emission is primarily distributed in a ring-like structure with localized enhancements at $\sim40$ pc from the nucleus. A distinct PAH-deficient region is observed to the north-west, roughly perpendicular to the jet axis, and coincident with enhanced ionized-gas velocity dispersion and inflowing molecular streamers. The 11.3/7.7 $μ$m and 6.2/7.7 $μ$m ratios exceed model predictions for pericondensed PAHs, indicating processed populations with more open structures. The 11.3/12.7 $μ$m ratio suggests a dominance of solo hydrogen sites and partial dehydrogenation, particularly in the PAH-deficient region, where shocks likely drive erosion. The largest EWs are found in the ring, while reduced values in the deficient region point to partial destruction; in the nucleus, low EWs are mainly due to continuum dilution.

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arXiv2025

MICONIC: JWST/MIRI MRS reveals a fast ionized gas outflow in the central region of Centaurus A

We present a kinematical study of the ionized and molecular gas in the central region (~7-14"~100-200pc) of the nearby radio galaxy Cen A. We used JWST/MIRI MRS 5-28$μ$m observations taken as part of the MIR Characterization of Nearby Iconic galaxy Centers (MICONIC) of the MIRI EC. The two gas phases present contrasting morphologies and kinematics. The brightest emission from the ionized gas, traced with a range of IP lines ([Fe II] to [Ne VI]), is extended along the direction of the radio jet. We also detected emission from low IP emission lines and H$_2$ transitions in the galaxy disk. Both gas phases present rotational motions but also complex kinematics. The observations reveal several ionized gas kinematical features that are consistent with simulation predictions of a jet-driven bubble and outflow interacting with the galaxy ISM. These include broad components in the nuclear line profiles ($σ$~600km/s), high velocities (~ +1000, -1400km/s) confined within the nuclear region, velocities of hundreds of km/s in several directions in the central 2", and enhanced velocity dispersions perpendicular to the radio jet. Moreover, we find evidence of shock excitation in the nuclear region based on MIR line ratios. We compared the ionized gas mass outflow rate with Cen A's AGN luminosity and radio jet power and demonstrate that both mechanisms provide sufficient energy to launch the outflow. The noncircular motions observed in the H$_2$ lines can be reproduced with either a warped rotating disk model or a radial component. The latter might be to related to gas streamers detected in cold molecular gas. There is no clear indication of a fast nuclear H$_2$ outflow, only a weak blueshifted component. This could be due to a relatively low nuclear warm H$_2$ column density and/or the limited geometrical coupling of Cen A's inner radio jet with the circumnuclear disk of the galaxy. (Abridged)

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arXiv2024

MICONIC: Dual active galactic nuclei, star formation, and ionised gas outflows in NGC 6240 seen with MIRI/JWST

As part of the guaranteed time observations program Mid-Infrared Characterization Of Nearby Iconic galaxy Centers (MICONIC), we used the medium-resolution spectrometer (MRS) of the Mid-Infrared Instrument (MIRI) on board of the JWST to study the nearby merger NGC6240. We aim to characterise the dual active galactic nuclei (AGN), the ionised gas outflows and the main properties of the interstellar medium over a mapped area of 6.6"x7.7". We obtained integral field spectroscopic mid-infrared data of NGC6240, resolving both nuclei for the first time in the full 5-28μm spectral range. We modelled the emission lines through a kinematic decomposition, finding that the fine-structure lines in the southern (S) nucleus are broader than for the northern (N) nucleus (full width at half maximum of $\geq$1500 vs ~700 km s^{-1} on average). High excitation lines, such as [NeV], [NeVI], and [MgV], are clearly detected in the N nucleus. In the S nucleus, the same lines can be detected but only after a decomposition of the PAH features in the integrated spectrum, due to a combination of a strong mid-IR continuum, the broad emission lines, and the intense star formation (SF). The SF is distributed all over the mapped FoV of 3.5kpc x 4.1kpc (projected), with the maximum located around the S nucleus. Both nuclear regions appear to be connected by a bridge region detected with all the emission lines. Based on the observed MRS line ratios and the high velocity dispersion (σ~600 km s^{-1}), shocks are also dominating the emission in this system. We detected the presence of outflows as a bubble north-west from the N nucleus and at the S nucleus. We estimated a ionised mass outflow rate of 1.4$\pm$0.3 M yr^{-1} and 1.8$\pm$0.2 M yr^{-1}, respectively. Given the derived kinetic power of these outflows, both the AGN and the starburst could have triggered them. [Abridged]

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