High-resolution Simulations Research Articles

Impact of H I cooling and study of accretion disks in asymptotic giant branch wind-companion smoothed particle hydrodynamic simulations

Context. High-resolution observations reveal that the outflows of evolved low- and intermediate-mass stars harbour complex morphological structures that are linked to the presence of one or multiple companions. Hydrodynamical simulations provide a way to study the impact of a companion on the shaping of the asymptotic giant branch (AGB) star out-flow. Aims. Using smoothed particle hydrodynamic (SPH) simulations of an AGB star undergoing mass loss, which also has a binary companion, we study the impact of including H I atomic line cooling on the flow morphology. We also study how this affects the properties of the accretion disks that form around the companion. Methods. We used the PHANTOM code to perform high-resolution 3D SPH simulations of the interaction of a solar-mass companion with the outflow of an AGB star, using different wind velocities and eccentricities. We compared the model properties, computed with and without the inclusion of H I cooling. Results. The inclusion of H I cooling produces a sizeable decrease in the temperature, up to one order of magnitude, in the region closely surrounding the companion star. As a consequence, the morphological irregularities and relatively energetic (bipolar) outflows that were obtained without H I cooling no longer appear. In the case of an eccentric orbit and a low wind velocity, these morphologies are still highly asymmetric, but the same structures recur at every orbital period, making the morphology more regular. Flared accretion disks, with a (sub-)Keplerian velocity profile, are found to form around the companion in all our models with H I cooling, provided the accretion radius is small enough. The disks have radial sizes ranging from about 0.4 to 0.9 au and masses around 10−7−10−8 M⊙. For the considered wind velocities, mass accretion onto the companion is up to a factor of 2 higher than predicted by the standard Bondi Hoyle Littleton rate, ranging between ~4 to 21% of the AGB wind mass loss rate. The lower the wind velocity at the location of the companion, the larger and the more massive the disk and the higher the mass accretion efficiency. In eccentric systems, the disk size, disk mass, and mass accretion efficiency vary, depending on the orbital phase. Conclusions. H I cooling is an essential ingredient to properly model the medium around the companion where density-enhanced wind structures form and it favours the formation of an accretion disk.

Enhancing 3D planetary atmosphere simulations with a surrogate radiative transfer model

Abstract This work introduces an approach to enhancing the computational efficiency of 3D atmospheric simulations by integrating a machine-learned surrogate model into the OASIS global circulation model (GCM). Traditional GCMs, which are based on repeatedly numerically integrating physical equations governing atmospheric processes across a series of time-steps, are time-intensive, leading to compromises in spatial and temporal resolution of simulations. This research improves upon this limitation, enabling higher resolution simulations within practical timeframes. Speeding up 3D simulations holds significant implications in multiple domains. Firstly, it facilitates the integration of 3D models into exoplanet inference pipelines, allowing for robust characterisation of exoplanets from a previously unseen wealth of data anticipated from JWST and post-JWST instruments. Secondly, acceleration of 3D models will enable higher resolution atmospheric simulations of Earth and Solar System planets, enabling more detailed insights into their atmospheric physics and chemistry. Our method replaces the radiative transfer module in OASIS with a recurrent neural network-based model trained on simulation inputs and outputs. Radiative transfer is typically one of the slowest components of a GCM, thus providing the largest scope for overall model speed-up. The surrogate model was trained and tested on the specific test case of the Venusian atmosphere, to benchmark the utility of this approach in the case of non-terrestrial atmospheres. This approach yields promising results, with the surrogate-integrated GCM demonstrating above 99.0% accuracy and 147 factor GPU speed-up of the entire simulation compared to using the matched original GCM under Venus-like conditions.

Learning the Universe: GalactISM Simulations of Resolved Star Formation and Galactic Outflows across Main-sequence and Quenched Galactic Environments

We present a suite of six high-resolution chemodynamical simulations of isolated galaxies, spanning observed disk-dominated environments on the star-forming main sequence, as well as quenched, bulge-dominated environments. We compare and contrast the physics driving star formation and stellar feedback among the galaxies, with a view to modeling these processes in cosmological simulations. We find that the mass loading of galactic outflows is coupled to the clustering of supernova explosions, which varies strongly with the rate of galactic rotation Ω = v circ/R via the Toomre length, leading to smoother gas disks in the bulge-dominated galaxies. This sets an equation of state in the star-forming gas that also varies strongly with Ω, so that the bulge-dominated galaxies have higher midplane densities, lower velocity dispersions, and higher molecular gas fractions than their main-sequence counterparts. The star formation rate in five out of six galaxies is independent of Ω and is consistent with regulation by the midplane gas pressure alone. In the sixth galaxy, which has the most centrally concentrated bulge and thus the highest Ω, we reproduce dynamical suppression of the star formation efficiency in agreement with observations. This produces a transition away from pressure-regulated star formation.

Micro-structure-property relationship of heavily drawn steel wires for large span suspension bridge cables

The outstanding combination of high strength and ductility of bridge cable steel wire is attributed to the cold drawing process with intermediate equivalent strain. However, the micro-structure-property relationship of heavily drawn steel wires for large span suspension bridge cables is not well understood. In this study, defects-controlled deformation in nano-scale interfaces between ferrite and cementite phases with heavily cold drawing process was investigated using high-resolution transmission electron microscopy and molecular dynamics simulation. The excessive thinning of the cementite lamellar thickness observed from the morphology suggested the evolution of the Fe3C/Fe interface in the cold-drawn wires, namely, the partial cementite deformation during the drawing process. Drawing strain played a major role in the occurrence of partial cementite nano-crystallisation. This was because the change in cementite morphology was the primary cause of cementite free energy increase, which ultimately led to cementite phase instability. The decrease of yield strength during the drawing process of the bridge cable steel wire was caused by the inverse Hall-Petch effect resulted from the nodule rotation. When the nodule morphology became flat, the inverse Hall-Petch effect was suppressed. At this time, the strengthening mechanism caused by cementite nano-crystallisation ensured the improvement of tensile strength of steel wire when the dislocation density was close to saturation.

Comparison and Applications for the State-of-art Astrophysics Simulations: Evidence from THESAN and illustrisTNG

The understandings of the formation of galaxy have been remarkably improved into a new level due to the simulations in astrophysics. Early models using simple N-body simulations were limited due to computational power. Later on, the development of algorithms had enhanced accuracy and scalability. In the modern era (2000s-present), due to the high-resolution simulation supported by projects including the MillenniumTNG and THESAN significantly enhanced the detailed studies of the formation and evolution of galaxy. This study compares the differences of application and comparison between the simulations of the two projects, the MillenniumTNG and THESAN, specific in the concept of high-redshift. While the two projects dive into deep using different methods and taking different angles, they share the same overarching goals of having further understanding of the early universe and the high-redshift galaxies. In particular, the two projects complement each other through their simulations and observations, pursuing better insights into the cosmos at large.

Investigation of the characteristics of low-level jets over North America in a convection-permitting Weather Research and Forecasting simulation

Abstract. In this study, we utilized a high-resolution (4 km) convection-permitting Weather Research and Forecasting (WRF) simulation spanning a 13-year period (2000–2013) to investigate the climatological features of low-level jets (LLJs) over North America. The 4 km simulation enabled us to represent the effects of orography and the underlying surface on the boundary layer winds better. Focusing on the continental US and the adjacent border regions of Canada and Mexico, this study not only identified several well-known large-scale LLJs, such as the southerly Great Plains LLJ and the summer northerly California coastal LLJ, but also the winter Quebec northerly LLJ which received less focus before. All these LLJs reach their peak in the nighttime in the diurnal cycle. Thus, the different thermal and dynamic mechanisms forming these three significant LLJs are investigated in this paper. Inertial oscillation theory dominates in the Great Plain LLJ, and the California coastal LLJ is formed by the baroclinic theory, whereas the Quebec LLJ is associated with both theories. Moreover, the high-resolution simulation revealed climatic characteristics of weaker and smaller-scale LLJs or low-level wind maxima in regions with complex terrains, such as the northerly LLJs in the foothill regions of the Rocky Mountains and the Appalachians during the winter. This study provides valuable insights into the climatological features of LLJs in North America, and the high-resolution simulation offers a more detailed understanding of LLJ behavior near complex terrains and other smaller-scale features.

Collisions Between Dark Matter Confined High Velocity Clouds and Magnetized Galactic Disks: The Smith Cloud. II.

We present high-resolution simulations of high velocity clouds (HVCs) colliding with the outer part of the Galactic disk. All of the simulations include a 3 × 108 M ⊙ dark matter subhalo. Three simulations model a dark matter subhalo without a gaseous component, while eight simulations model a dark matter subhalo accompanied by a gaseous cloud of mass 2–8 × 106 M ⊙. Half of the simulations include the coherent component of the Galaxy's magnetic field. Each simulation spans ∼40 million years before the collision and ∼40 million years after the collision. The collisions between the gas cloud and disk splash gas into the halo, punch half-kiloparsec-size holes in the disk, and form long-lived, multi-kiloparsec-size shells. Each shell encloses a bubble of relatively cool gas. Holes and shells of these scales would be observable, and some have been observed in the past. We determine the fate of the HVC gas, temperature, composition, and ionization state of the bubble and shell gas, size and longevity of the holes, and effects of cloud density. Simulations show that the clouds do not survive the chaos of passage through the disk, but instead become part of the splash, bubble, and shell. Some dark matter clouds may appear to carry material with them long after the collision, but this material is shell gas that was captured by the dark matter subhalo. These results have ramifications for the Smith Cloud and other clouds hypothesized to have hit the Galactic disk.

The hydromechanical coupled numerical method in pseudo-3D axisymmetric domain with cracks extension and coalescence applies to the decompression failure problem

The stress-strain state of the saturated porous media determines the behavior of fracturing, which defines the efficiency of developing tight oil, shale, coalbed, and thermal energy fields. Therefore, reliable hydromechanical coupled simulations with destruction reconstruction are critical.The proposed innovative simulator has a strong interrelation between fluid flow and rock deformation of porous media and realizes a fully coupled pseudo-transient numerical method by high-performance computing (HPC) tools. To increase the detail of the results in the problem, a finite difference numerical algorithm was implemented in the axisymmetric cylindrical domain, which reduces from three to two dimensions without loss of precision. Highly efficient parallelization using CUDA on the GPU computes meshes of up to one billion cells, allowing the simulation of a total core sample to sub-micrometer resolution in an appropriate time. The algorithm has been validated to find the exact solution to the cylinder problem. The proposed model accounts for cracks propagation with their coalescence within a single computational static grid, which keeps timing close to the continuous model.This comprehensive implementation enables solving industrial problems, such as modeling core sample damage during rapid decompression. High-resolution simulations help reconstruct fracture propagation, analyze the initial stress state, and identify critical damage factors. The comparison with the exact solution to the cylinder problem confirmed the reliability of the algorithm. The calculation results show a strong dependence of decompression failure on the coalescence and elongation of cracks, influenced significantly by the rock's cohesion. Microcracks length and distribution play a decisive role in the decompressive destruction behavior of the rock sample. For the first time, the simulations demonstrated the decompressive destruction of a core sample during an uncontrolled, rapid core retrieval operation.

Oceanic eddy with submesoscale edge drives intense air-sea exchanges and beyond

Oceanic mesoscale eddies influence air-sea interaction and atmosphere dynamics through ventilating heat and moisture upward. However, whether the sea surface temperature (SST) gradient on the eddy edge could affect the heat and moisture release is still unknown because of the limited observations and coarse-resolution climate models. Using high-resolution atmospheric simulations, this study compares the atmospheric response to the mesoscale (~ 40 km) and submesoscale (~ 4 km) SST gradients at the edge of an eddy. Results show that submesoscale SST gradient drives stronger surface heat and moisture fluxes, enhancing the vertical mixing intensity by 2–3 times within and above the marine atmospheric boundary layer. As a result, one local precipitation event is found to be an order of magnitude larger overlying the eddy. Our findings highlight the importance of resolving oceanic submesoscale features for accurately predicting atmosphere dynamics and precipitation over the ocean.

Effect of slope on water run-off and soil vulnerability in an unglaciated sub-watershed: a case study of conservation practice siting

For maximization of soil and water quality benefits, the right agricultural conservation practices (CPs) should be practiced for the right place. The Agricultural Conservation Planning Framework (ACPF) is a tool that helps decision makers achieve precise conservation within a target watershed using rapid, low-cost Geographic Information System-based tools. ACPF takes the information on landscape characteristics and combines it with user input to identify locations susceptible to soil loss and water run-off and suggest potential CP locations. Suggested CPs may further be analyzed for urgency, installation cost, and effectiveness. In this study, ACPF was applied to analyze soil and water vulnerability within a small unglaciated sub-watershed in southwest Wisconsin and identify potential CP practices and recommended placement sites. To promote environmental sustainability in the agriculture sector, land managers are tasked with implementing CPs, but often lack adequate information on the most effective practice and placement strategy. Field-scale siting of CPs was achieved using high-resolution terrain derivatives and accurate simulation of the stream network. Slope disaggregation among soil loss vulnerability categories was also conducted. Greatest sources of vulnerability were associated with slope and erodibility factors, with average slope within cropped fields being 6% and erodibility being as high as 43%. Fields classified as critical for conservation had a mean slope of 7.4%. Suggested contour buffer strip (CBS) placement per field varied with slope, with steeper fields having denser placement. The results suggested that 3% of cropland could be removed from production if the recommended placement of CBS was implemented. A further 0.2% of the sub-watershed area would go to grassed waterways. The results support implementation of effective CPs based on local conditions and act as a tool to help reveal if existing practices in the sub-watershed are of a size and extent comparable to the predicted potential.

Analysis of postdisaster economy using high-resolution disaster and economy simulations.

We present an integrated framework that utilizes high-resolution seamless simulations of disasters and national economies for estimating the economic impacts of disasters. The framework consists of three components: a physics-based simulator to simulate the disaster and estimate the response of the infrastructure; a tool that estimates the losses suffered by the infrastructure based on its response; and an agent-based economic model (ABEM) that simulates the national economy considering the infrastructure damage and postdisaster decisions of the economic entities. The ABEM used in the framework has been implemented in a high-performance computing environment to simulate large economies at 1:1 scale. Furthermore, it has been calibrated to the Japanese economy using publicly available macroeconomic data and validated to the Japanese economy under the business-as-usual scenario. We demonstrate the integrated framework by simulating a potential Nankai-trough earthquake disaster and estimating its impacts on the Japanese economy. The seismic response of 1.8 million buildings of the Osaka-bay area has been estimated using a large-scale earthquake disaster simulator and corresponding repair costs are estimated using the Performance Assessment Calculation Tool. As per our estimates, repair costs amount to approximately 15 trillion Yen. Considering the investments made by impacted households and firms toward recovery, the postdisaster economy is simulated using the ABEM for 5 years under two recovery scenarios. Industrial production is expected to recover in three quarters whereas 10-13 quarters will be required to finish all the repairwork.

Inertia Drives Concentration-Wave Turbulence in Swimmer Suspensions.

We discover an instability mechanism in suspensions of self-propelled particles that does not involve active stress. Instead, it is driven by a subtle interplay of inertia, swimmer motility, and concentration fluctuations, through a crucial time lag between the velocity and the concentration field. The resulting time-persistent state seen in our high-resolution numerical simulations consists of self-sustained waves of concentration and orientation, transiting from regular oscillations to wave turbulence. We analyze the statistical features of this active turbulence, including an intriguing connection to the Batchelor spectrum of passive scalars.

Initiation of a Supercell by Convectively Generated Gravity Waves in the Simulated Kaiyuan Tornadic Event of 3 July 2019

Abstract An EF4-rated supercell tornado occurred on 3 July 2019 in Kaiyuan, China, causing heavy casualties. A three-level nested-grid high-resolution numerical simulation is used to investigate the initiation of the tornadic supercell. Automatic weather station (AWS) data, FY-4A visible satellite data, and Doppler radar data are used to verify the model simulation. The most important aspects of the simulated pre-supercell mesoscale convective system (MCS) and the initiation of the supercell agree with observations. Detailed investigation of the model results reveals that the initial cells form first above a convective boundary layer (CBL) on the dry side of a surface dryline. Above the CBL is a moist layer in terms of relative humidity and the layer is stable. Convectively generated gravity waves (GWs) emanating from the MCS and propagating southward along the stable layer above the CBL provide localized forcing for the actual triggering of initial cells at specific locations. The associated perturbation potential temperature and vertical velocity patterns confirm that the GWs trigger a series of cloud bands. The additional lifting by the updraft of a horizontal convective roll in the CBL underneath the GW updraft works together to promote faster growth of the initial cell that later becomes the supercell. Examination of the Scorer parameter profiles shows favorable conditions for vertical trapping of GWs along the wave guide in the stable layer, preventing the radiation of wave energy to the upper levels.

Projected changes in heatwaves over Central and South America using high-resolution regional climate simulations

Heatwaves (HWs) pose a severe threat to human and ecological systems. Here we assess the projected changes in heatwaves over Latin America using bias corrected high-resolution regional climate simulations under two Representative Concentration Pathway scenarios (RCPs). Heatwaves are projected to be more frequent, long-lasting, and intense in the mid-century under both RCP2.6 and RCP8.5 scenarios, with severe increases under the RCP8.5 scenario. Even under the low emissions scenario of RCP2.6, the frequency of heatwaves doubles over most of the region. A three- to tenfold rise in population exposure to heatwave days is projected over Central and South America, with climate change playing a dominant role in driving these changes. Results show that following the low emission pathway would reduce 57% and 50% of heatwave exposure for Central and South American regions respectively, highlighting the need to control anthropogenic emissions and implement sustainable practices.

SooSim, a landscape model for assessing mire habitat degradation and restoration

Open mires constitute a characteristic part of boreal natural landscapes, which is under various cumulative anthropogenic pressures. As a response, remaining mires are increasingly protected, and their degradation is addressed by ecological restoration (mostly drainage closure). To evaluate alternative environmental policies, there is a necessity for high-resolution landscape simulation models to assess future dynamics of mires under different management scenarios. We present such a model, SooSim, its R-script, and derivation and validation of its key parameters. SooSim iterates mire types and woody encroachment dynamics within 25 × 25 m grid at 1-year intervals. Management interventions (restoration; ditch renovation) are sequentially introduced based on priority rules in locations delineated prior to simulation. We applied SooSim to three management scenarios, compared with natural succession, until 2050 in Estonia. The ‘current’ (2022) database comprised >3.8 M mire pixels and > 7 M peatland-forest pixels (sparse-cover ones considered for mire restoration). The model parameterization, based on Lidar data, revealed rapid ongoing woody encroachment across all mire types, with significant positive feedback. The simulations revealed that, even in scenarios with intensive restoration (2500 ha annually), open mire conditions are reduced by >10 % until 2050, while few mire types lose >1 % in area. Ditch renovations mostly reduced restoration perspectives in currently forested peatlands. Thus, SooSim explicitly depicts a decision-making dilemma where mire restoration is time-sensitive but also uncertain. To address this and related land-use dilemmas in the environmental policy, landscape models such as SooSim have further importance as visualization tools to explain complex processes to a wide range of stakeholders.

Supraglacial lake evolution and its drivers in Dronning Maud Land, East Antarctica

Abstract Supraglacial lakes on Antarctic ice shelves can have far-reaching implications for ice-sheet stability, highlighting the need to understand their dynamics, controls and role in the ice-sheet mass budget. We combine a detailed satellite-based record of seasonal lake evolution in Dronning Maud Land with a high-resolution simulation from the regional climate model Modèle Atmosphérique Régional to identify drivers of lake variability between 2014 and 2021. Correlations between summer lake extents and climate parameters reveal complex relationships that vary both in space and time. Shortwave radiation contributes positively to the energy budget during summer melt seasons, but summers with enhanced longwave radiation are more prone to surface melting and ponding, which is further enhanced by advected heat from summer precipitation. In contrast, previous winter precipitation has a negative effect on summer lake extents, presumably by increasing albedo and pore space, delaying the accumulation of meltwater. Downslope katabatic or föhn winds promote ponding around the grounding zones of some ice shelves. At a larger scale, we find that summers during periods of negative southern annular mode are associated with increased ponding in Dronning Maud Land. The high variability in seasonal lake extents indicates that these ice shelves are highly sensitive to future warming or intensified extreme events.

Long-term variation of the eddy kinetic energy in the Northeastern South China sea

The seasonal to interannual variability of eddy kinetic energy (EKE) in the Northeastern South China Sea (NE-SCS) has been widely studied and it is recognized that they are strongly related to the state of the Kuroshio pathway in the Luzon Strait. While, due to the lack of long-term observations and high-resolution simulations, the decadal change of EKE in NE-SCS remains unexplored. In this study, we show the EKE trend in the past ∼ 30 years in the NE-SCS by using satellite observation and global HYbrid Coordinate Ocean Model reanalysis with the Navy Coupled Ocean Data Assimilation. It is found that due to the weakening of the Kuroshio in the Luzon Strait since 1990 s, the Kuroshio shows an enhanced looping path in the NE-SCS, inducing stronger EKE in this region. Further analysis confirms that the energy transfer by baroclinic instability is dominant for the increasing of EKE, when the Kuroshio intrudes into the NE-SCS and brings more potential energy inside the circulation. The Kuroshio state along the Luzon Strait is the key for modulating the EKE in the NE-SCS. Furthermore, the long-term weakening of Kuroshio current along the Luzon strait during 1993–2020 is determined by the decreasing of subtropical mode water, corresponding to the positive phase of the Atlantic Multidecadal Oscillation. This study provides insight into the interaction between marginal sea (i.e., the SCS) and the open ocean (i.e., the western Pacific Ocean), finally linking to the global climate change.

Spatially Local Surrogate Modeling of Subgrid-Scale Effects in Idealized Atmospheric Flows: A Deep Learned Approach Using High-Resolution Simulation Data

Abstract We introduce a machine learned surrogate model from high-resolution simulation data to capture the subgrid-scale effects in dry, stratified atmospheric flows. We use deep neural networks (NNs) to model the spatially local state differences between a coarse-resolution simulation and a high-resolution simulation. The setup enables the capture of both dissipative and antidissipative effects in the state differences. The NN model is able to accurately capture the state differences in offline tests outside the training regime. In online tests intended for production use, the NN-coupled coarse simulation has higher accuracy over a significant period of time compared to the coarse-resolution simulation without any correction. We provide evidence of the capability of the NN model to accurately capture high-gradient regions in the flow field. With the accumulation of the errors, the NN-coupled simulation becomes computationally unstable after approximately 90 coarse simulation time steps. Insights gained from these surrogate models further pave the way for formulating stable, complex, physics-based spatially local NN models which are driven by traditional subgrid-scale turbulence closure models. Significance Statement Flows in the atmosphere are highly chaotic and turbulent, comprising flow structures of broad scales. For effective computational modeling of atmospheric flows, the effects of the small- and large-scale structures need to be captured by the simulations. Capturing the small-scale structures requires fine-resolution simulations. Even with the current state-of-the-art supercomputers, it can be prohibitively expensive to simulate these flows when computed for the entire earth over climate time scales. Thus, it is necessary to focus on the larger-scale structures using a coarse-resolution simulation while capturing the effects of the smaller-scale structures using some parameterization (approximation) scheme and incorporating it into the coarse-resolution simulation. We use machine learning to model the effects of the small-scale structures (subgrid-scale effects) in atmospheric flows. Data from a fine-resolution simulation is used to compute the missing subgrid-scale effects in coarse-resolution simulations. We then use machine learning models to approximate these differences between the coarse- and fine-resolution simulations. We see improved accuracy for the coarse-resolution simulations when corrected using these machine learned models.

Uncovering the first-infall history of the LMC through its dynamical impact in the Milky Way halo

ABSTRACT The gravitational interactions between the LMC and the Milky Way cause dynamical perturbations in the MW halo, leading to biased distributions of stellar density and kinematics. We run 50 high-resolution N-body simulations exploring varying masses and halo shapes of the MW and LMC to study the evolution of LMC-induced perturbations. By measuring mean velocities of simulated halo stars, we identify a discontinuity between the first-infall and second-passage scenarios of the LMC’s orbital history. In the first-infall, the Galactocentric latitudinal velocity hovers around 16 km s$^{-1}$ for stars at 50–100 kpc, while it subsides to about 8 km s$^{-1}$ in the second-passage scenario. We demonstrate that, this reduced perturbation magnitude in the second-passage scenario is mainly due to the short dynamical times of the Galactic inner halo and the lower velocity of the LMC during its second infall into the MW. Using a subset of $\sim 1100$ RR Lyrae stars located in the outer halo (50 kpc $\le R_{\mathrm{GC}}\lt $ 100 kpc) with precise distance estimates from Gaia, we find the mean latitudinal velocity ($v_{b}$) in the Galactocentric frame to be $\langle v_{b} \rangle =18.1 \pm 4.1$ km s$^{-1}$. The observation supports the first-infall scenario with a massive LMC ($\sim$$2.1 \times 10^{11} \, \mathrm{M}_{\odot }$) at infall, an oblate MW halo with a virial mass $M_{200}\lt 1.4\times 10^{12}\,\mathrm{M}_{\odot }$ and a flattening parameter $q\gt 0.7$. Our study indicates that LMC-induced kinematic disturbances can reveal its orbital history and key characteristics, as well as those of the MW. This approach shows promise in helping determine fundamental parameters of both galaxies.

Dust Survival in Galactic Winds

We present a suite of high-resolution numerical simulations to study the evolution and survival of dust in hot galactic winds. We implement a novel dust framework in the Cholla hydrodynamics code and use wind tunnel simulations of cool, dusty clouds to understand how thermal sputtering affects the dust content of galactic winds. Our simulations illustrate how various regimes of cloud evolution impact dust survival, dependent on cloud size, wind properties, and dust grain size. We find that significant amounts of dust can survive in winds in all scenarios, even without shielding from the cool phase of outflows. We present an analytic framework that explains this result, along with an analysis of the impact of cloud evolution on the total fraction of dust survival. Using these results, we estimate that 60% of 0.1 μm dust that enters a starburst-driven wind could survive to populate both the hot and cool phases of the halo, based on a simulated distribution of cloud properties. We also investigate how these conclusions depend on grain size, exploring grains from 0.1 μm to 10 Å. Under most circumstances, grains smaller than 0.01 μm cannot withstand hot-phase exposure, suggesting that the small grains observed in the circumgalactic medium (CGM) are either formed in situ due to the shattering of larger grains, or must be carried there in the cool phase of outflows. Finally, we show that the dust-to-gas ratio of clouds declines as a function of distance from the galaxy due to cloud–wind mixing and condensation. These results provide an explanation for the vast amounts of dust observed in the CGMs of galaxies and beyond.