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Abstract We present new CO(2–1) observations (resolution ∼1″ = 460 pc) of the Coma cluster jellyfish galaxy NGC 4858 obtained from the ALMA-JELLY large program. Analyzing this data alongside complimentary Subaru Hαand Hubble Space Telescope (F600LP / F350LP) observations, we find numerous structural and kinematic features indicative of the effects from strong, inclined ram pressure, including an asymmetric inner gas tail. We estimate a highly inclined disk-wind angle of ${\varphi }_{\text{DW}}=75_{-27}^{+10}$. By subtracting a simple circular velocity model, we find (1): gas clumps that are being accelerated by ram pressure, and (2): signatures of gas clumps that had been previously pushed out of the disk but are now falling inward. We also discuss head-tail morphologies in star complexes within the stellar disk that appear to be ram pressure stripping (RPS)-influenced. Lastly, we compare this galaxy to state-of-the-art galaxy “wind tunnel” simulations. We find that this galaxy is one of the best nearby examples of strong and inclined ram pressure gas stripping, and of gas that is perturbed by ram pressure but not fully stripped and falls back. We emphasize the importance of torques due to ram pressure in highly inclined interactions, which help drive gas inward on the side rotating against the wind, contributing to the formation of asymmetric inner RPS tails. 

Abstract. Flocculation controls mud sedimentation and organic carbon burial rates by increasing mud settling velocity. However, calibration and validation of floc settling velocity models in freshwater are lacking. We used a camera, in situ laser diffraction particle sizing, and suspended sediment concentration–depth profiles to measure flocs in Wax Lake Delta, Louisiana. We developed a new workflow that combines our multiple floc data sources to distinguish between flocs and unflocculated sediment and measure floc attributes that were previously difficult to constrain. Sediment finer than ∼10 to 55 µm was flocculated with median floc diameter of 30 to 90 µm, bulk solid fraction of 0.05 to 0.3, fractal dimension of ∼2.1, and floc settling velocity of ∼0.1 to 1 mm s−1, with little variation along water depth. Results are consistent with a semi-empirical model indicating that sediment concentration and mineralogy, organics, water chemistry, and, above all, turbulence control floc settling velocity. Effective primary particle diameter is ∼2 µm, about 2 to 6 times smaller than the median primary particle diameter, and is better described using a fractal theory. Flow through the floc increases settling velocity by an average factor of 2 and up to a factor of 7 and can be described by a modified permeability model that accounts for the effect of many primary particle sizes on flow paths. These findings help explain discrepancies between observations and an explicit settling model based on Stokes' law that depends on floc diameter, permeability, and fractal properties. 

Abstract. Coastal marsh survival relies on the ability to increase elevation and offset sea level rise. It is therefore important to realistically model sediment fluxes between marshes, tidal channels, and bays as sediment availability controls accretion. Traditionally, numerical models have been calibrated and validated using in situ measurements at a few locations within the domain of interest. These datasets typically provide temporal information but lack spatial variability. This paper explores the potential of coupling numerical models with high-resolution remote sensing imagery. Products from three sensors from the NASA Delta-X airborne mission are used. Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) provides vertical water level change on the marshland and was used to adjust the bathymetry and calibrate water fluxes over the marsh. AirSWOT yields water surface elevation within bays, lakes, and channels, and was used to calibrate the Chezy bottom friction coefficient. Finally, imagery from AVIRIS-NG provides maps of total suspended solids (TSS) concentration that were used to calibrate sediment parameters of settling velocity and critical shear stress for erosion. Three numerical models were developed at different locations along coastal Louisiana using Delft3D. The coupling enabled a spatial evaluation of model performance that was not possible using simple point measurements. Overall, the study shows that calibration of numerical models and their general performance will greatly benefit from remote sensing. 

Abstract Current methods of identifying the ionizing source of nebular emission in galaxies are well defined for the era of single-fiber spectroscopy, but still struggle to differentiate the complex and overlapping ionization sources in some galaxies. With the advent of integral field spectroscopy, the limits of these previous classification schemes are more apparent. We propose a new method for distinguishing the ionizing source in resolved galaxy spectra by use of a multidimensional diagnostic diagram that compares emission-line ratios with velocity dispersion on a spaxel-by-spaxel basis within a galaxy. This new method is tested using the Sydney-Australian-Astronomical-Observatory Multi-object Integral-Field Spectrograph Galaxy Survey (SAMI) Data Release 3 (DR3), which contains 3068 galaxies atz< 0.12. Our results are released as ionization maps available alongside the SAMI DR3 public data. Our method accounts for a more diverse range of ionization sources than the standard suite of emission-line diagnostics; we find 1433 galaxies with a significant contribution from non-star-forming ionization using our improved method as compared to 316 galaxies identified using only emission-line ratio diagnostics. Within these galaxies, we further identify 886 galaxies hosting unique signatures inconsistent with standard ionization by Hiiregions, active galactic nuclei, or shocks. These galaxies span a wide range of masses and morphological types and comprise a sizable portion of the galaxies used in our sample. With our revised method, we show that emission-line diagnostics alone do not adequately differentiate the multiple ways to ionize gas within a galaxy. 

Abstract Wetlands in the Mississippi River Delta are rapidly degrading. Sea level rise and low sediment supply are widely recognized as the two main factors contributing to land‐to‐water conversion. To determine what marsh areas are more resilient, it is fundamental to identify the drivers that regulate marsh accretion and degradation. In this study, a combination of field data and aerial images is used to determine these drivers in Terrebonne Bay, Louisiana, USA. We find that accretion and degradation patterns depend on whether the marsh is located inland in a sheltered area or facing open water. In the first case, the distance to the nearby channel is important, because during flooding of the marsh platform more sediment is deposited in the proximity of channel banks. The accretion rates of marshes facing open water are high and correlate to fetch, a proxy for the ability of waves to resuspend bottom sediment. These areas are more resilient to sea level rise, but waves are also the main mechanism of degradation, as these marshes tend to degrade by edge erosion. Consequently, we propose a bimodal evolution trajectory of the marshes in Terrebonne Bay: marshes close to the bay and facing open water accrete rapidly but are affected by lateral erosion due to waves, whereas sheltered marshes accrete slowly and degrade in large swathes due to insufficient sediment supply. 

ABSTRACT Ram pressure stripping (RPS) is an important mechanism for galaxy evolution. In this work, we present results from HST and APEX observations of one RPS galaxy, ESO 137-002 in the closest rich cluster Abell 3627. The galaxy is known to host prominent X-ray and H α tails. The HST data reveal significant features indicative of RPS in the galaxy, including asymmetric distribution of dust in the galaxy, dust filaments, and dust clouds in ablation generally aligned with the direction of ram pressure, and young star clusters immediately upstream of the residual dust clouds that suggest star formation (SF) triggered by RPS. The distribution of the molecular gas is asymmetric in the galaxy, with no CO upstream and abundant CO downstream and in the inner tail region. A total amount of ∼5.5 × 109 M⊙ of molecular gas is detected in the galaxy and its tail. On the other hand, we do not detect any active SF in the X-ray and H α tails of ESO 137-002 with the HST data and place a limit on the SF efficiency in the tail. Hence, if selected by SF behind the galaxy in the optical or UV (e.g. surveys like GASP or using the Galex data), ESO 137-002 will not be considered a ‘jellyfish’ galaxy. Thus, galaxies like ESO 137-002 are important for our comprehensive understanding of RPS galaxies and the evolution of the stripped material. ESO 137-002 also presents a great example of an edge-on galaxy experiencing a nearly edge-on RPS wind. 

ABSTRACT We present a comparison of galaxy atomic and molecular gas properties in three recent cosmological hydrodynamic simulations, namely SIMBA, EAGLE, and IllustrisTNG, versus observations from z ∼ 0 to 2. These simulations all rely on similar subresolution prescriptions to model cold interstellar gas that they cannot represent directly, and qualitatively reproduce the observed z ≈ 0 H i and H2 mass functions (HIMFs and H2MFs, respectively), CO(1–0) luminosity functions (COLFs), and gas scaling relations versus stellar mass, specific star formation rate, and stellar surface density μ*, with some quantitative differences. To compare to the COLF, we apply an H2-to-CO conversion factor to the simulated galaxies based on their average molecular surface density and metallicity, yielding substantial variations in αCO and significant differences between models. Using this, predicted z = 0 COLFs agree better with data than predicted H2MFs. Out to z ∼ 2, EAGLE’s and SIMBA’s HIMFs and COLFs strongly increase, while IllustrisTNG’s HIMF declines and COLF evolves slowly. EAGLE and simba reproduce high-LCO(1–0) galaxies at z ∼ 1–2 as observed, owing partly to a median αCO(z = 2) ∼ 1 versus αCO(z = 0) ∼ 3. Examining H i, H2, and CO scaling relations, their trends with M* are broadly reproduced in all models, but EAGLE yields too little H i in green valley galaxies, IllustrisTNG and SIMBA overproduce cold gas in massive galaxies, and SIMBA overproduces molecular gas in small systems. Using SIMBA variants that exclude individual active galactic nucleus (AGN) feedback modules, we find that SIMBA’s AGN jet feedback is primarily responsible by lowering cold gas contents from z ∼ 1 → 0 by suppressing cold gas in $$M_*\gtrsim 10^{10}{\rm \,M}_\odot$$ galaxies, while X-ray feedback suppresses the formation of high-μ* systems. 

ABSTRACT We present SAMI-H i, a survey of the atomic hydrogen content of 296 galaxies with integral field spectroscopy available from the SAMI Galaxy Survey. The sample spans nearly 4 dex in stellar mass ($$M_\star = 10^{7.4}-10^{11.1}~ \rm M_\odot$$), redshift z < 0.06, and includes new Arecibo observations of 153 galaxies, for which we release catalogues and H i spectra. We use these data to compare the rotational velocities obtained from optical and radio observations and to show how systematic differences affect the slope and scatter of the stellar-mass and baryonic Tully–Fisher relations. Specifically, we show that $$\rm H\alpha$$ rotational velocities measured in the inner parts of galaxies (1.3 effective radii in this work) systematically underestimate H i global measurements, with H i/$$\rm H\alpha$$ velocity ratios that increase at low stellar masses, where rotation curves are typically still rising and $$\rm H\alpha$$ measurements do not reach their plateau. As a result, the $$\rm H\alpha$$ stellar mass Tully–Fisher relation is steeper (when M⋆ is the independent variable) and has larger scatter than its H i counterpart. Interestingly, we confirm the presence of a small fraction of low-mass outliers of the $$\rm H\alpha$$ relation that are not present when H i velocity widths are used and are not explained by ‘aperture effects’. These appear to be highly disturbed systems for which $$\rm H\alpha$$ widths do not provide a reliable estimate of the rotational velocity. Our analysis reaffirms the importance of taking into account differences in velocity definitions as well as tracers used when interpreting offsets from the Tully–Fisher relation, at both low and high redshifts and when comparing with simulations. 

ABSTRACT The kinematic morphology–density relation of galaxies is normally attributed to a changing distribution of galaxy stellar masses with the local environment. However, earlier studies were largely focused on slow rotators; the dynamical properties of the overall population in relation to environment have received less attention. We use the SAMI Galaxy Survey to investigate the dynamical properties of ∼1800 early and late-type galaxies with log (M⋆/M⊙) > 9.5 as a function of mean environmental overdensity (Σ5) and their rank within a group or cluster. By classifying galaxies into fast and slow rotators, at fixed stellar mass above log (M⋆/M⊙) > 10.5, we detect a higher fraction (∼3.4σ) of slow rotators for group and cluster centrals and satellites as compared to isolated-central galaxies. We find similar results when using Σ5 as a tracer for environment. Focusing on the fast-rotator population, we also detect a significant correlation between galaxy kinematics and their stellar mass as well as the environment they are in. Specifically, by using inclination-corrected or intrinsic $$\lambda _{R_{\rm {e}}}$$ values, we find that, at fixed mass, satellite galaxies on average have the lowest $$\lambda _{\, R_{\rm {e}},\rm {intr}}$$, isolated-central galaxies have the highest $$\lambda _{\, R_{\rm {e}},\rm {intr}}$$, and group and cluster centrals lie in between. Similarly, galaxies in high-density environments have lower mean $$\lambda _{\, R_{\rm {e}},\rm {intr}}$$ values as compared to galaxies at low environmental density. However, at fixed Σ5, the mean $$\lambda _{\, R_{\rm {e}},\rm {intr}}$$ differences for low and high-mass galaxies are of similar magnitude as when varying Σ5 ($$\Delta \lambda _{\, R_{\rm {e}},\rm {intr}} \sim 0.05$$, with σrandom = 0.025, and σsyst < 0.03). Our results demonstrate that after stellar mass, environment plays a significant role in the creation of slow rotators, while for fast rotators we also detect an independent, albeit smaller, impact of mass and environment on their kinematic properties.