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We present GBT-EDGE, a new CO(1-0) survey using the Green Bank Telescope to map 62 nearby (10-140 Mpc) galaxies spanning the star-forming main sequence (SFMS), green valley, and red sequence. The galaxy sample is selected from the CALIFA survey with integral field spectroscopy (IFS), which provides a representative census of local galactic environments. Combining the CO dataset with CALIFA's optical IFS measurements, we derive molecular gas masses, star formation rates (SFR), metallicities, and stellar mass densities to measure star formation efficiency (SFE) and investigate the physical drivers of galaxy quenching. We obtain a median molecular gas depletion time of $$2.10^{+2.35}_{-1.31}$$, $$6.90^{+17.00}_{-3.67}$$, and $$127.7^{+201.6}_{-113.4}$$ Gyr for our sample of main sequence, green valley, and red galaxies, respectively, assuming a Galactic CO-to-H2 conversion factor. By applying various conversion factor prescriptions, we also confirm a systematic decrease of SFE with galaxy's offset below the SFMS, regardless of the adopted prescription. This suggests that the low SFR in some quenched galaxies is primarily driven by suppressed SFE rather than an absence of molecular gas. Our results provide evidence that galaxies below the main sequence can retain substantial molecular gas reservoirs comparable to star-forming galaxies, but they exhibit longer depletion times and form stars inefficiently, possibly due to the combined effects of low gas density and morphological quenching mechanisms. 

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. 

Abstract The gas-phase velocity dispersions in disk galaxies, which trace turbulence in the interstellar medium, are observed to increase with lookback time. However, the mechanisms that set this rise in turbulence are observationally poorly constrained. To address this, we combine kiloparsec-scale Atacama Large Millimeter/submillimeter Array observations of CO(3−2) and CO(4−3) with Hubble Space Telescope observations of Hαto characterize the molecular gas and star formation properties of seven local analogs of main-sequence galaxies atz∼ 1–2, drawn from the DYNAMO sample. Investigating the “molecular gas main sequence” on kiloparsec scales, we find that galaxies in our sample are more gas-rich than local star-forming galaxies at all disk positions. We measure beam-smearing-corrected molecular gas velocity dispersions and relate them to the molecular gas and star formation rate surface densities. Despite being relatively nearby (z∼ 0.1), DYNAMO galaxies exhibit high velocity dispersions and gas and star formation rate surface densities throughout their disks, when compared to local star-forming samples. Comparing these measurements to predictions from star formation theory, we find very good agreements with the latest feedback-regulated star formation models. However, we find that theories that combine dissipation of gravitational energy from radial gas transport with feedback overestimate the observed molecular gas velocity dispersions. 

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. 

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 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. 

In this paper, we study the filamentary substructure of 3.3 $$\mu$$m polycyclic aromatic hydrocarbon (PAH) emission from JWST/NIRCam observations in the base of the M 82 star-burst driven wind. We identify plume-like substructure within the PAH emission with widths of $$\sim$$50 pc. Several of those plumes extend to the edge of the field-of-view, and thus are at least 200–300 pc in length. In this region of the outflow, the vast majority ($$\sim$$70 per cent) of PAH emission is associated with the plumes. We show that those structures contain smaller scale ‘clouds’ with widths that are $$\sim$$5–15 pc, and they are morphologically similar to the results of ‘cloud-crushing’ simulations. We estimate the cloud-crushing time-scales of $$\sim$$0.5–3 Myr, depending on assumptions. We show this time-scale is consistent with a picture in which these observed PAH clouds survived break-out from the disc rather than being destroyed by the hot wind. The PAH emission in both the mid-plane and the outflow is shown to tightly correlate with that of Pa $$\alpha$$ emission (from Hubble Space Telescope data), at the scale of both plumes and clouds, though the ratio of PAH-to-Pa $$\alpha$$ increases at further distances from the mid-plane. Finally, we show that the outflow PAH emission reaches a local minimum in regions of the M 82 wind that are bright in X-ray emission. Our results are consistent cold gas in galactic outflows being launched via hierarchically structured plumes, and those small scale clouds are more likely to survive the wind environment when collected into the larger plume structure.