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Abstract We present an analysis of the Hα-emitting ionized gas in the warm phase of the NGC 253 outflow using integral field spectroscopy from the Multi Unit Spectroscopic Explorer. In each spaxel, we decompose Hα, [Nii], and [Sii] emission lines into a system of up to three Gaussian components, accounting for the velocity contributions due to the disk and both intercepted walls of an outflow cone. In the approaching southern lobe of the outflow, we find maximum deprojected outflow velocities down to ∼−500 km s⁻¹. Velocity gradients of this outflowing gas range from ∼−350 to −550 km s⁻¹kpc⁻¹with increasing distance from the nucleus. Additionally, [Nii]/Hαand [Sii]/Hαintegrated line ratios are suggestive of shocks as the dominant ionization source throughout the wind. Electron densities, inferred from the [Sii] doublet, peak at 2100 cm⁻³near the nucleus and reach ≲50 cm⁻³in the wind. Finally, at an uncertainty of 0.3 dex on the inferred mass of 4 × 10⁵M_⊙, the mass-outflow rate of the Hα-emitting gas in the southern outflow lobe is ∼0.4M_⊙yr⁻¹. This yields a mass-loading factor ofη ∼ 0.1 and a ∼2% starburst energy efficiency. 

Neutral atomic gas (H I) effectively traces galactic dynamics across mid to large galactocentric radii. However, its limitations in observing small-scale changes within the central few kiloparsecs, coupled with the often observed H Ideficit in galactic centers, necessitates the use of molecular gas emission as a preferred tracer in these regions. Understanding the dynamics of both neutral atomic and molecular gas is crucial for a more complete understanding of how galaxies evolve, funnel gas from the outer disk into their central parts, and eventually form stars. In this work we aim to quantify the dynamics of both, the neutral atomic and molecular gas, in the nearby spiral galaxies NGC 1512, NGC 4535, and NGC 7496 using new MeerKAT H Iobservations together with ALMA CO (2-1) observations from the PHANGS collaboration. We use the analysis tool^3DBarolo to fit tilted ring models to the H Iand CO observations. A combined approach of using the H Ito constrain the true disk orientation parameters before applying these to the CO datasets is tested. This paper sets expectations for the results of the upcoming high-resolution H Icoverage of many galaxies in the PHANGS-ALMA sample using MeerKAT or VLA, to establish a robust methodology for characterizing galaxy orientations and deriving dynamics from combing new H Iwith existing CO data. 

Abstract We present the largest catalog to date of star clusters and compact associations in nearby galaxies. We have performed aV-band-selected census of clusters across the 38 spiral galaxies of the PHANGS–Hubble Space Telescope (HST) Treasury Survey, and measured integrated, aperture-corrected near-ultraviolet-U-B-V-Iphotometry. This work has resulted in uniform catalogs that contain ∼20,000 clusters and compact associations, which have passed human inspection and morphological classification, and a larger sample of ∼100,000 classified by neural network models. Here, we report on the observed properties of these samples, and demonstrate that tremendous insight can be gained from just the observed properties of clusters, even in the absence of their transformation into physical quantities. In particular, we show the utility of the UBVI color–color diagram, and the three principal features revealed by the PHANGS-HST cluster sample: the young cluster locus, the middle-age plume, and the old globular cluster clump. We present an atlas of maps of the 2D spatial distribution of clusters and compact associations in the context of the molecular clouds from PHANGS–Atacama Large Millimeter/submillimeter Array. We explore new ways of understanding this large data set in a multiscale context by bringing together once-separate techniques for the characterization of clusters (color–color diagrams and spatial distributions) and their parent galaxies (galaxy morphology and location relative to the galaxy main sequence). A companion paper presents the physical properties: ages, masses, and dust reddenings derived using improved spectral energy distribution fitting techniques. 

Abstract The spectral line energy distribution of carbon monoxide contains information about the physical conditions of the star-forming molecular hydrogen gas; however, the relation to local radiation field properties is poorly constrained. Using ∼1–2 kpc scale Atacama Large Millimeter Array observations of CO(3−2) and CO(4−3), we characterize the CO(4−3)/CO(3−2) line ratios of local analogues of main-sequence galaxies at z ∼ 1–2, drawn from the DYnamics of Newly Assembled Massive Objects (DYNAMO) sample. We measure CO(4−3)/CO(3−2) across the disk of each galaxy and find a median line ratio of R 43 = 0.54 − 0.15 + 0.16 for the sample. This is higher than literature estimates of local star-forming galaxies and is consistent with multiple lines of evidence that indicate DYNAMO galaxies, despite residing in the local universe, resemble main-sequence galaxies at z ∼ 1–2. Comparing with existing lower-resolution CO(1−0) observations, we find R 41 and R 31 values in the range ∼0.2–0.3 and ∼0.4–0.8, respectively. We combine our kiloparsec-scale resolved line ratio measurements with Hubble Space Telescope observations of H α to investigate the relation to the star formation rate surface density and compare this relation to expectations from models. We find increasing CO(4−3)/CO(3−2) with increasing star formation rate surface density; however, models overpredict the line ratios across the range of star formation rate surface densities we probe, in particular at the lower range. Finally, Stratospheric Observatory for Infrared Astronomy observations with the High-resolution Airborne Wideband Camera Plus and Field-Imaging Far-Infrared Line Spectrometer reveal low dust temperatures and no deficit of [C ii ] emission with respect to the total infrared luminosity. 

We present new JWST observations of the nearby, prototypical edge-on, spiral galaxy NGC 891. The northern half of the disk was observed with NIRCam in its F150W and F277W filters. Absorption is clearly visible in the mid-plane of the F150W image, along with vertical dusty plumes that closely resemble the ones seen in the optical. A ∼10 × 3 kpc²area of the lower circumgalactic medium (CGM) was mapped with MIRI F770W at 12 pc scales. Thanks to the sensitivity and resolution of JWST, we detect dust emission out to ∼4 kpc from the disk, in the form of filaments, arcs, and super-bubbles. Some of these filaments can be traced back to regions with recent star formation activity, suggesting that feedback-driven galactic winds play an important role in regulating baryonic cycling. The presence of dust at these altitudes raises questions about the transport mechanisms at play and suggests that small dust grains are able to survive for several tens of million years after having been ejected by galactic winds in the disk-halo interface. We lay out several scenarios that could explain this emission: dust grains may be shielded in the outer layers of cool dense clouds expelled from the galaxy disk, and/or the emission comes from the mixing layers around these cool clumps where material from the hot gas is able to cool down and mix with these cool cloudlets. This first set of data and upcoming spectroscopy will be very helpful to understand the survival of dust grains in energetic environments, and their contribution to recycling baryonic material in the mid-plane of galaxies. 

Abstract We present a¹²CO(J= 2−1) survey of 60 local galaxies using data from the Atacama Compact Array as part of the Extragalactic Database for Galaxy Evolution: the ACA EDGE survey. These galaxies all have integral field spectroscopy from the CALIFA survey. Compared to other local galaxy surveys, ACA EDGE is designed to mitigate selection effects based on CO brightness and morphological type. Of the 60 galaxies in ACA EDGE, 36 are on the star formation main sequence, 13 are on the red sequence, and 11 lie in the “green valley” transition between these sequences. We test how star formation quenching processes affect the star formation rate (SFR) per unit molecular gas mass, SFE_mol= SFR/M_mol, and related quantities in galaxies with stellar masses 10 ≤ log[M_⋆/M_⊙] ≤ 11.5 covering the full range of morphological types. We observe a systematic decrease of the molecular-to-stellar mass fraction ( $R_{\star }^{\mathrm{mol}}$) with a decreasing level of star formation activity, with green valley galaxies also having lower SFE_molthan galaxies on the main sequence. On average, we find that the spatially resolved SFE_molwithin the bulge region of green valley galaxies is lower than in the bulges of main-sequence galaxies if we adopt a constant CO-to-H₂conversion factor,α_CO. While efficiencies in main-sequence galaxies remain almost constant with galactocentric radius, in green valley galaxies, we note a systematic increase of SFE_mol, $R_{\star }^{\mathrm{mol}}$, and specific SFR with increasing radius. As shown in previous studies, our results suggest that although gas depletion (or removal) seems to be the most important driver of the star formation quenching in galaxies transiting through the green valley, a reduction in star formation efficiency is also required during this stage. 

Abstract M82 is an archetypal starburst galaxy in the local Universe. The central burst of star formation, thought to be triggered by M82's interaction with other members in the M81 group, is driving a multiphase galaxy-scale wind away from the plane of the disk that has been studied across the electromagnetic spectrum. Here, we present new velocity-resolved observations of the [Cii] 158μm line in the central disk and the southern outflow of M82 using the upGREAT instrument on board SOFIA. We also report the first detections of velocity-resolved (ΔV= 10 km s⁻¹) [Cii] emission in the outflow of M82 at projected distances of ≈1–2 kpc south of the galaxy center. We compare the [Cii] line profiles to observations of CO and Hiand find that likely the majority (>55%) of the [Cii] emission in the outflow is associated with the neutral atomic medium. We find that the fraction of [Cii] actually outflowing from M82 is small compared to the bulk gas outside the midplane (which may be in a halo or tidal streamers), which has important implications for observations of [Cii] outflows at higher redshift. Finally, by comparing the observed ratio of the [Cii] and CO intensities to models of photodissociation regions, we estimate that the far-ultraviolet (FUV) radiation field in the disk is ∼10^3.5G₀, in agreement with previous estimates. In the outflow, however, the FUV radiation field is 2–3 orders of magnitudes lower, which may explain the high fraction of [Cii] arising from the neutral medium in the wind.