Abstract The microwave-enhanced spark discharge (MESD) has gained significant attention for its applications in emission spectrometry and ignition enhancement. However, the underlying mechanisms governing the transition between discharge regimes and the interaction between metals (from electrode material) and microwave energy remain inadequately understood. This study comprehensively investigates a MESD through power diagnostics, schlieren imaging, and optical emission spectroscopy (OES) under various pressure conditions, focusing on plasma properties in both glow and arc discharge regimes. The experimental results reveal a distinct transition from glow to arc discharge with increasing microwave energy input. In the glow regime, the plasma exhibits diffusive behavior with pressure-dependent energy absorption, while the arc regime demonstrates bright plasma with pressure-independent energy absorption. There is a leap in energy absorption during the glow-to-arc transition. OES confirms that gas excitation governs the glow regime, whereas metal ionization dominates the arc regime. The rotational temperature of N 2 (C–B) serves as a reliable gas temperature indicator, showing a significant surge to approximately 8000 K during the transition, with the arc plasma achieving maximum heating efficiencies exceeding 90% under atmospheric pressure. Furthermore, while the electron temperature remains relatively stable (∼0.7 eV), the electron number density increases substantially with absorbed energy in the arc regime. The overall order of magnitude of electron number density is approximately 10 22 m −3 . The transition mechanism is attributed to enhanced electron generation through secondary electron emission and thermionic emission from electrode materials with the aid of microwave field. The additional electron production creates a self-reinforcing feedback loop, sustaining the arc discharge by supporting metal evaporation and microwave heating.

Abstract CO 2 is an important, stable, and abundant molecule in the Universe, but it is very difficult to detect because it has no observable pure rotational transitions. The unique sensitivity and resolution of the James Webb Space Telescope provide a fresh way to investigate it. CO 2 is typically found in the solid phase (ice) on grain mantles in dense molecular clouds, but is less commonly detected in the gas phase (compared to common molecules such as CO and H 2 O) and has mostly been found in protostellar and protoplanetary environments. Here, we report and characterize the first observations of gas-phase CO 2 absorption toward two IR-bright regions of the Galactic Center, thanks to the high sensitivity of JWST. Using an LTE model, we find a CO 2 gas excitation temperature between 20 and 50 K, a column density around 2 × 10 15 cm −2 and a radial velocity with respect to the local standard of rest consistent with 0. We also report: (1) simultaneous detections of C 2 H 2 and HCN absorption bands (near 13.7 and 14.0 μ m, respectively), with column density ratios of 1:3 and 3:2 with respect to gas-phase CO 2 , and (2) CO 2 ice absorption with an ice-to-gas abundance ratio of 90, consistent with previous findings. We conclude that the absorbing medium is likely in the foreground, most likely from one or more somewhat clumpy cloud(s), located between 0.15 and 4 kpc away from Earth. Additionally, we detected point-like CO 2 emission likely associated with a Galactic Center evolved star (IRS 11SW), which is also spatially coincident with a previously reported X-ray source, raising the possibility that the system is a symbiotic binary.

The population of the little red dots (LRDs) may represent a key phase of supermassive black hole (SMBH) growth. A cocoon of dense excited gas is emerging as a key component to explain the most striking properties of LRDs, such as strong Balmer breaks and Balmer absorption, as well as the weak IR emission. To dissect the structure of LRDs, we analyzed new deep JWST/NIRSpec PRISM and G395H spectra of FRESCO-GN-9771, one of the most luminous known LRDs at z = 5.5. These spectra reveal a strong Balmer break, broad Balmer lines, and very narrow [O III ] emission. We revealed a forest of optical [Fe II ] lines, which we argue are emerging from a dense ( n H = 10 9 − 10 cm −3 ) warm layer with electron temperature T e ≈ 7000 K. The broad wings of H α and H β have an exponential profile due to electron scattering in this same layer. The high H α : H β : H γ flux ratio of ≈10.4 : 1 : 0.14 is an indicator of collisional excitation and resonant scattering dominating the Balmer line emission. A narrow H γ component, unseen in the other two Balmer lines due to outshining by the broad components, could trace the ISM of a normal host galaxy with a star formation rate of ∼5 M ⊙ yr −1 . The warm layer is mostly opaque to Balmer transitions, producing a characteristic P Cygni profile in the line centers suggesting outflowing motions. This same layer is responsible for shaping the Balmer break. The broadband spectrum can be reasonably matched by a simple photoionized slab model that dominates the λ > 1500 Å continuum and a low-mass (∼10 8 M ⊙ ) galaxy that could explain the narrow [O III ], with only a subdominant contribution to the UV continuum. Our findings indicate that Balmer lines are not directly tracing the gas kinematics near the SMBH and that the BH mass scale is likely much lower than virial indicators suggest.

High-sensitivity multi-element analysis of low-volume samples remains a challenge in plasma-based analytical methods because optimal excitation conditions differ among elements and conventional steady-state plasma require relatively large sample volumes. In this study, we developed a voltage-modulated helium plasma in which the applied voltage was continuously varied over short time intervals to dynamically control the plasma energy state. The fundamental characteristics of plasma were evaluated in terms of gas temperature, emission spectrum, and excitation temperature. Under steady-state operation, plasma length, gas temperature, and excitation temperature increased with increasing applied voltage, confirming that the plasma energy state can be controlled by applied voltage. In the voltage-modulated plasma, emission intensity and excitation temperature responded rapidly to voltage changes, enabling the generation of plasma with different energy states within a short time. Notably, the excitation temperature, one of the key indicators of the plasma energy state, was dynamically varied over a wide range of approximately 1900–3600 K. In addition, voltage modulation effectively suppressed the overall increase in plasma gas temperature caused by Joule heating, while maintaining high-energy plasma states during high-voltage periods. These results demonstrate that voltage-modulated plasma generation enables rapid switching between energy states optimized for different elements, offering a practical strategy for high-sensitivity multi-element analysis with significantly reduced sample consumption. The proposed method is particularly suitable for the analysis of small-volume and heat-sensitive samples.

Galaxy clusters produce a very hostile environment for galaxies: their gas gets stripped by ram pressure, they undergo galaxy interactions, and their star formation is quenched. Clusters, like Abell 2142, grow not only through galaxy accretion but also through galaxy group infall. Our goal was to study the physical and dynamical state of the most conspicuous infalling group, which is located at a projected distance of 1.3 Mpc from the Abell 2142 centre. The galaxy group G is the leading edge of a spectacular 700 kpc long X-ray tail of hot gas stripped by ram pressure. The infalling galaxies are not quenched yet and are ideal objects for studying the transformation processes due to the cluster environment. We used integral field spectroscopy from MaNGA to derive stellar and gas kinematics, and MegaCam for photometry. Stellar populations (with age and metallicity) were obtained through full-spectrum fitting using NBURSTS . The gas kinematics and excitation were derived from the line emission of H α , [N II ], [O III ], and H β . The group contains four galaxies, two of which are merging and partly superposed on the line of sight. With a simple parametric model for each velocity field, we succeeded in disentangling the contribution of each galaxy and derived their physical state and kinematics. They are primarily rotating discs, but perturbations and out-of-equilibrium gas manifest as regions of elevated dispersion and as tidal tails and loops of intra-group material. All galaxies show sustained star formation, with a global star formation rate of 42 M ⊙ /yr. We conclude that the long X-ray tail must have come from the hot intra-group medium, present before the group infall, and does not correspond to the ram-pressure stripping of the galaxy gas. Ongoing interactions between the group members enhance the star formation activity by inducing mixing of dense gas from their gas-rich galactic discs.

Abstract We present an analysis of near-infrared (NIR) emission-line properties, active galactic nucleus (AGN) diagnostics, and circumnuclear gas dynamics for 453 hard X-ray selected (14–195 keV) AGNs from the BAT AGN Spectroscopic Survey NIR Data Release 3 (DR3; 〈 z 〉 = 0.036, z < 1.0). This dataset is the largest compilation of rest-frame NIR spectroscopic observations of hard-X-ray-selected AGNs and includes the full DR2 sample. Observations were obtained with the Very Large Telescope X-Shooter, a multiwavelength (0.3–2.5 μ m) spectrograph ( R = 4000–18,000), using a ≥ 2 σ detection threshold, enabling broad analysis of emission features. We find that NIR coronal lines, particularly [Si vi ] λ 1.964, are more reliable tracers of AGN luminosity than optical O III , showing a tighter correlation with hard X-ray luminosity ( σ = 0.25 dex) than O III λ 5007 ( σ = 0.55 dex). Broad Paschen lines (Pa α and Pa β ) are detected in 12% of Seyfert 2 and 57% of Seyfert 1.9 galaxies, consistent with previous hidden broad-line region (BLR) studies. We introduce a refined NIR diagnostic diagram ([Fe ii ] λ 1.257 μ m/Pa β and H 2 λ 2.122 μ m/Br γ ) that effectively distinguishes AGN, star-forming, and composite sources even when contamination limits individual diagnostics or only upper limits are available. Additionally, we find a moderate correlation ( p ≈ 7.4 × 10 −3 ) between hot molecular gas mass (traced by H 2 2.121 μ m) and X-ray luminosity, while its relation with Eddington ratio is weaker. The hot-to-cold gas mass ratio spans 4 orders of magnitude, averaging ∼3 × 10 −7 , indicating diverse molecular gas excitation processes likely driven by star formation and AGN feedback. Our results underscore the value of NIR spectroscopy in probing AGN activity, obscured BLRs, and the complex interactions between AGNs and their circumnuclear environments.

Abstract The sulfur chemistry in protoplanetary disks influences the properties of nascent planets, including potential habitability. Although the inventory of sulfur molecules in disks has gradually increased over the last decade, CS is still the most commonly observed sulfur-bearing species, and it is expected to be the dominant gas-phase sulfur carrier beyond the water snow line. Despite this, few dedicated multiline observations exist, and thus, the typical disk CS chemistry is not well constrained. Moreover, it is unclear how that chemistry—and in turn, the bulk volatile sulfur reservoir—varies with stellar and disk properties. Here, we present the largest survey of CS to date, combining both new and archival observations from the Atacama Large Millimeter/submillimeter Array, Submillimeter Array, and Northern Extended Millimeter Array of 12 planet-forming disks, covering a range of stellar spectral types and dust morphologies. Using these data, we derived disk-integrated CS gas excitation conditions in each source. Overall, CS chemistry appears similar across our sample with rotational temperatures of ≈10–40 K and column densities between 10 12 and 10 13 cm −2 . CS column densities do not show strong trends with most source properties, which broadly suggests that CS chemistry is not highly sensitive to disk structure or stellar characteristics. We do, however, identify a positive correlation between stellar X-ray luminosity and CS column density, which indicates that the dominant CS formation pathway is likely via ion-neutral reactions in the upper disk layers, where X-ray-enhanced S + and C + drive abundant CS production. Thus, using CS as a tracer of gas-phase sulfur abundance requires a nuanced approach that accounts for its emitting region and dependence on X-ray luminosity.

Abstract The ultraluminous infrared galaxy (ULIRG) IRAS 00183-7111 (z = 0.328) is one of the three ULIRGs that are currently known to host an active galactic nucleus (AGN) with small-scale radio jets. We present a detailed study of the link between galaxy merger, AGN ignition, radio jet expansion and kpc-scale molecular outflow in IRAS 00183-7111, using high-resolution Atacama Large Millimeter/sub-millimeter Array (ALMA) observations of the 12CO(1-0) and 12CO(3-2) lines and very deep i-band VLT Survey Telescope (VST) imaging. The latter allows us to put constraints on the assembly history of the system, suggesting that it formed through a major merger between two gas-rich spirals, likely characterised by a prograde encounter and no older than ≈2 Gyr. The recent merger channelled about (1.5 ± 0.3) × 1010 M⊙ of molecular gas in the central regions of the remnant, as traced by the CO detections. The spatial correlation between the CO distribution and the radio core suggests that this gas likely contributed to the ignition of the AGN and thus to the launch of the radio jets. Furthermore, by comparing the relative strength of the two CO transitions, we find extreme gas excitation (i.e. Tex ≫ 50 K) around the radio lobes, supporting the case for a jet-ISM interaction. A qualitative study of the CO kinematics also demonstrates that, despite the overall disturbed dynamical state with no clear signs of regular rotation, at least one non-rotational kinematic component can be identified and likely associated to an outflow with vout ≈ 439 km s−1 and $\dot{M_{\rm out}}\approx 609$ M⊙ yr−1.

We investigated the interplay between dense molecular gas, star formation, and active galactic nucleus (AGN) feedback in the luminous IR galaxy NGC 1068 at sub-kiloparsec scales. We present the HCN (4-3) and HCO+ (4-3) maps of NGC 1068 obtained with JCMT as part of the Mapping the dense molecular gas in the strongest star-forming galaxies (MALATANG) project, and perform spatially resolved analyses of their correlations with IR luminosity and soft X-ray emission. The spatially resolved relations between the luminosities of IR dust emission and dense molecular gas tracers (L_ IR -L'_ dense ) are found to be nearly linear, without clear evidence of excess contributions from AGN activity. The spatially resolved X-ray emission (L^ ̊m gas _ 0.5 2, – keV ) displays a radially dependent twofold correlation with the star formation rate (SFR), suggesting distinct gas-heating mechanisms are at play in areas between the galaxy center and the outer regions. A super-linear scaling is obtained in galactic center regions with SFR surface densities (Σ_̊m SFR) $>$ 8.2 times 10 -6 $ M_⊙ yr^-1 kpc^-2: log(L^ ̊m gas _ 0.5 2, – keV /erg s^-1) = 2.2 log(SFR/M_⊙ yr$^ -1 ) + 39.1. We further find a statistically significant super-linear correlation (β = 1.34 ± 0.86) between L^ ̊m gas _ 0.5 2, – keV /SFR and the HCN(4–3)/CO(1–0) intensity ratio, whereas no such trend is seen for HCO+$(4-3)/CO(1-0) or CO(3-2)/CO(1-0). These findings indicate that AGN feedback does not dominate star formation regulation on sub-kiloparsec scales, and that the excitation of dense gas traced by HCN (4-3) may be more directly influenced by high-energy feedback processes compared to HCO$^+ (4-3) and CO (3-2).

In this paper, a highly sensitive methane (CH4) and ammonia (NH3) dual-gas photoacoustic spectroscopy (PAS) gas sensor based on a dual-path high-spot-density multipass cell (MPC) and dual-frequency photoacoustic cell (PAC) was demonstrated for the first time. A dual-path MPC mathematical model was established to achieve multiple independent rings and 223 excitations of dual gases. In order to integrate with the MPC more conveniently, the designed dual-frequency PAC was used to excite the Helmholtz resonance mode. A Raman fiber amplifier (RFA) and an erbium-doped fiber amplifier (EDFA) were employed to amplify the output power of the two diode lasers to enhance the excitation intensity. The experimental results indicated that when the output power was set as 50 and 300 mW, respectively, the 2f signals for CH4 and NH3 detection with the high-spot-density MPC showed 41.91-fold and 41.30-fold enhancements compared to the system without MPC, demonstrating significant performance improvement. The minimum detection limits (MDLs) of CH4 and NH3 were found to be 65 and 374 ppb, respectively, when the average time of the CH4/NH3-PAS dual-gas sensor was 1000 s.

Applying diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) to nonthermal plasma catalysis is important to gain mechanistic information to advance the electrified technology. However, conventional DRIFTS cells are often suboptimal, exhibiting unstable, non‐uniform discharges and failing to replicate the plasma characteristics of practical reactors such as dielectric barrier discharge (DBD) systems. This study devises a dome‐type DRIFTS flow cell that enables stable glow discharge, closely emulating the electric field distribution and flow dynamics of DBD reactors. The dome cell exhibits excellent operational stability over extended durations (>1 h) and under various plasma conditions (e.g., different excitation modes and gas switching), while delivering high‐fidelity IR signals. Using the dome cell, operando DRIFTS studies of plasma catalytic CO2 methanation under pulse excitation are conducted. The results reveal that, for a Ni/MgAlOx catalyst, i) the surface reaction mainly follows the Langmuir–Hinshelwood mechanism with formate hydrogenation as the rate‐determining step, and ii) the Eley‐Rideal/Langmuir–Rideal mechanism indeed exists under plasma conditions but contributes marginally. This robust DRIFTS platform provides a reliable in situ and/or operando diagnostic tool for plasma catalytic systems, while offering mechanistic insights essential for rational catalyst/system design and optimization.

This study investigates the generation of sound waves and their mechanisms in a microwave atmospheric pressure plasma jet (surfaguide), as these waves are produced in continuous-wave mode operation. Notably, these sound waves are observed within two specific power ranges: 220–370 W and 570–620 W. The potential causes of sound wave generation in continuous-wave mode are analyzed and attributed to the interaction of surface waves near the tip of the plasma column (underdense plasma region). This study explains the power coupling behavior of surface waves with plasma and their interaction while propagating along the interface of the plasma and dielectric tube in a surfaguide-based microwave atmospheric plasma jet. The sound waves are recorded and analyzed through Fast Fourier Transform (FFT) using the MATLAB code. Additionally, fluctuations in electron excitation temperature (Texc), electron density (ne), gas temperature, and plume length are analyzed during sound wave generations.

Abstract The carbon monoxide (CO) spectral line energy distributions (SLEDs) of galaxies contain a wealth of information about conditions in their cold interstellar gas. Here, we use galaxy-scale observations of the three lowest energy CO lines to determine SLEDs and line ratios in a sample of 47 nearby, predominantly star-forming galaxies. We find a systematic trend of higher gas excitation with increasing star formation rate (SFR) and SFR surface density (Σ SFR ), with the range of variations being even larger than predicted by simulations. Power-law fits of the CO line ratios as a function of SFR and Σ SFR provide a good description of the trends seen in our sample and also accurately predict values for a wide range of galaxy types compiled from the literature. Based on these fits, we provide prescriptions for estimating CO(1–0) luminosities and molecular gas masses using CO(3–2) or CO(2–1) in cases where CO(1–0) is not observed directly. We compare our observed SLEDs with molecular cloud models in order to examine how the physical properties of cold gas vary across the galaxy population. We find that gas conditions in star-forming and starburst galaxies lie on a continuum with increasing gas density in more actively star-forming systems.

ABSTRACT We present a detailed spectroscopic study of ionized gas in the nearby ($D\sim 3.3$ Mpc) dwarf galaxy NGC 2366, a local analogue of Green Pea galaxies, based on observations with the SCORPIO-2 instrument at the Russian 6-m BTA telescope. Using scanning Fabry–Perot interferometry and long-slit spectroscopy, we examine the gas kinematics, excitation mechanisms and chemical abundances across the disc of NGC 2366, including its prominent starburst region Mrk 71 and the companion region NGC 2363. We identified 20 regions with locally elevated H $\alpha$ velocity dispersion, only four of which correspond to known high-energy sources. We argue that one of the remaining objects can be a previously unidentified Wolf–Rayet star and two supernova remnants. For 15 H ii regions, we measure electron temperatures, oxygen and nitrogen abundances via the ‘direct’ $T_e$ method, with $12 + \log (\mathrm{O}/\mathrm{H})$ ranging from 7.6 to 8.0 in most of the regions. We show that Mrk 71 has higher oxygen abundance compared to the other H ii regions in the galaxy, contrary to the previous indirect estimates suggesting flat gradient throughout the galaxy. Together with the localized spatial variations of metallicity in the area, it is indicative of metal enrichment by the outflow from the super star cluster in the centre of Mrk 71.

ABSTRACT The $L_{\rm IR}{\!-\!}L_{\rm HCN}$ relation suggests that there is a tight connection between dense gas and star formation. We use data from the Close AGN Reference Survey (CARS) to investigate the dense gas – star formation relation in active galactic nuclei (AGN) hosting galaxies, and the use of dense gas as an AGN diagnostic. Our sample contains five Type-1 (unobscured) AGN that were observed with the Atacama Large Millimetre/submillimetre Array with the aim to detect HCN(4-3), HCO$^+$(4-3), and CS(7-6). We detect the dense gas emission required for this analysis in three of the five targets. We find that despite the potential impact from the AGN on the line fluxes of these sources, they still follow the $L_{\rm IR}{\!-\!}L_{\rm HCN}$ relation. We then go on to test claims that the HCN/HCO+ and HCN/CS line ratios can be used as a tool to classify AGN in the sub-mm HCN diagram. We produce the classic ionized emission-line ratio diagnostics (the so-called BPT diagrams), using available CARS data from the Multi Unit Spectroscopic Explorer. We then compare the BPT classification with the sub-mm classification made using the dense gas tracers. Where it was possible to complete the analysis we find general agreement between optical and sub-mm classified gas excitation mechanisms. This suggests that AGN can contribute to the excitation of both the low-density gas in the warm ionized medium and the high-density gas in molecular clouds simultaneously, perhaps through X-ray, cosmic ray, or shock heating mechanisms.

Abstract The CO(1–0) and [C i](1–0) emission lines are well-established tracers of cold molecular gas mass in local galaxies. At high redshift, where the interstellar medium is likely to be denser, there have been limited direct comparisons of both ground-state transitions. We present a comparison of [C i](1–0) and CO(1–0) emission in 20 unlensed dusty, star-forming galaxies at z ≥ 2–5. The CO(1–0)/[C i](1–0) ratio remains constant up to z = 5, supporting the reliability of [C i](1–0) as a gas–mass tracer. We use the CO(1–0), [C i](1–0), and 3 mm dust continuum measurements to cross–calibrate their respective gas mass conversion factors, finding no dependence of these factors on either redshift or infrared luminosity. Radiative transfer modeling shows that the warmer cosmic microwave background (CMB) at high redshift can significantly affect the [C i] as well as CO emission, which can change the derived molecular gas masses by up to 70% for the coldest kinetic gas temperatures expected. Nevertheless, the magnitude of the CMB effect on the CO/[C i] ratio is within the known scatter of the L CO ′ − L [ CI ] ′ relation. Precisely determining the CMB effect on individual line intensities would require well-sampled spectral line energy distributions to robustly model the gas excitation conditions. Finally, we note that adopting a variable CO gas–mass conversion factor for different galaxy populations implies [C i](1–0) and dust conversion factors that differ from canonically assumed values. However, the revised conversion factors are consistent with expectations for (super)solar metallicities likely to be found in high-redshift dusty galaxies.

Abstract We present a spatially resolved (∼3 pc pixel−1) analysis of the distribution, kinematics, and excitation of warm H2 gas in the nuclear starburst region of M83. Our JWST/MIRI integral field unit spectroscopy reveals a clumpy reservoir of warm H2 (>200 K) with a mass of ∼2.3 × 105 M ⊙ in the area covered by all four Medium Resolution Spectrometer (MRS) channels. We additionally use the [Ne ii] 12.8 μm and [Ne iii] 15.5 μm lines as tracers of the star formation rate (SFR), ionizing radiation hardness, and kinematics of the ionized interstellar medium (ISM), finding tantalizing connections to the H2 properties and stellar populations (e.g., broad and blueshifted [Ne ii] emission coincident with a region with >5 Myr old stellar populations, low SFR, and low H2 surface density.) Finally, qualitative comparisons to the trove of public, high-spatial-resolution multiwavelength data available on M83 shows that our MRS spectroscopy potentially traces all stages of the process of creating massive star clusters, from the embedded protocluster phase through the dispersion of ISM from stellar feedback.

To investigate the impact of winds and jets with a low to moderate power on the cold molecular gas reservoirs of active galactic nuclei (AGN), we present observations with a high angular resolution with ALMA CO(2–1) and CO(3–2) of a sample of six type 2 quasars (QSO2s) at z ∼ 0.1 from the quasar feedback (QSOFEED) sample. We used spatially resolved molecular line ratio maps, defined as R32 ≡ L′CO(3 − 2)/L′CO(2 − 1), and kinematic modeling to constrain the changes in the gas excitation and to identify gas outflows, respectively. The molecular outflows are co-spatial with regions with R32 > 1, indicating a higher temperature than in the disks and the presence of optically thin gas in the outflows. Considering more and less conservative scenarios to measure the outflow properties, we find mass outflow rates of 5 ≲ Ṁ ≲ 150 M⊙ yr−1, which is much lower than those expected from their AGN luminosities of ∼1045.5 − 46 erg s−1, based on scaling relations from the literature. The outflow kinetic energies might be driven by the combined action of jets and radiation pressure winds, and the radiative coupling efficiencies (ϵAGN ≡ Ėout/Lbol) range from 10−6 < ϵAGN < 10−4 and the jet coupling efficiencies (ϵjet ≡ Ėout/Pjet) from 10−3 < ϵAGN < 10−2. A linear regression including the six QSO2s follows the locus of ϵjet ∼ 0.1%, although we found no strong correlation because of the small-number statistics. Our results provide further evidence that AGN-driven jets/winds disturb the molecular gas kinematics and excitation within the central several kiloparsec of the galaxies. The coupling between compact jets and the interstellar medium might be relevant to AGN feedback, even in the case of radio-quiet galaxies, which are more representative of the AGN population. Finally, the warm (H2) and cold (CO) molecular gas phases seem to be tracing the same outflow. The main distinction between them is the mass they carry, while the warm ionized outflows ([OIII]) do not seem to be another face of the same outflow, as their orientation, velocity, and radius are different.

Abstract Film cooling holes are critical for reducing surface temperature and prolonging the service life of turbine blades in aeroengines. These holes are prone to defects such as shrinkage cavities and blockages after coating or long-term use. To address this, we propose an automated inspection system based on infrared image sequences generated by gas thermal excitation, integrating a robotic arm, an infrared camera, and deep learning techniques. A key innovation of our system is a dedicated image preprocessing pipeline designed to enhance the detectability of film cooling holes. This includes temporal differentiation to highlight dynamic thermal behavior, and local patch-based normalization to amplify grayscale contrast between the holes and their surroundings, thereby improving detection sensitivity and robustness. The system workflow includes: (1) analyzing the response of different blade types to various excitation signals; (2) collecting infrared sequences with a robotic arm to build a comprehensive dataset; and (3) applying deep learning algorithms, combined with the preprocessing techniques, for accurate localization and diameter estimation. Comparative experiments confirm the superiority of our approach over traditional inspection methods.

ABSTRACT We present a multiwavelength study of the gas distribution, kinematics, and excitation of the OH megamaser galaxy IRAS 09320+6134 (UGC 5101) using Gemini Multi-Object Spectrograph Integral Field Unit, Hubble Space Telescope, and Very Large Array observations. The HST ACS F814W i-band and H $\alpha +[$N ii$]\lambda \lambda 6548,84$ narrow-band images indicate that this galaxy is a late-stage merger. The ionized gas emission in the inner $\sim$2 kpc radius, traced by the GMOS data, is consistent with two kinematic components: (i) a rotating disc, observed as a narrow component in the emission-line profiles, with velocity dispersion of $\sigma \le 200$ km s$^{-1}$, and (ii) an outflow, traced by a broad component in the emission-line profiles, with $\sigma \ge 500$ km s$^{-1}$. The disc component is well reproduced by a model of rotation in a plane with similar orientation to that of the large-scale galaxy disc. The outflow component presents bulk velocities of up to $-500$ km s$^{-1}$ and corresponds to a mass outflow rate of $\dot{M}_o=0.122\pm 0.026 M_{\odot }\, \text{yr}^{-1}$. Emission-line ratio diagrams indicate that the gas excitation is mainly due to an active galactic nucleus, likely the driver of the outflow. The VLA radio image reveals a dominant radio core with two-sided emission along the NE–SW direction. The radio core’s spectral index and brightness temperature indicate AGN emission, with the extended emission resembling both in morphology and spectral index the emission observed in radio-quiet quasars. Combined with previous similar studies of other OH megamaser galaxies, this work supports that this phase is linked to the triggering of an AGN, which seems to occur in the final stages of a merger.