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The Satellite Mergers Usher Disc Galaxy Evolution (SMUDGE) simulations are a suite of four high-resolution, dynamical N-body simulations. This suite includes two different models of isolated, disk galaxies and two versions in which these same disk galaxies experience a minor merger with a satellite galaxy. These simulations were designed to be laboratories for the study of galactic dynamics rather than tailored models of the Milky Way, and the four available models enable the study of both the dynamics in isolated disks and the dynamics in merging, disequilibrium systems. 

Each host disk galaxy consists of a dark matter halo (~8×108 particles), a stellar bulge (2×107 particles), and a stellar disk (2×108 particles), with parameters for the initial conditions taken from Widrow & Dubinski (2005) (WD05). The satellite is the L2 model from Laporte et al. (2018). The initial conditions for the host were generated using Galactics (Kuijken & Dubinski 1995), and the simulations were run with the GPU accelerated N-body tree code Bonsai (Bédorf et al. 2012).

This data volume contains four simulations described below. See Hunt et al. (2021) for descriptions.

  1. D1: A highly stable disc galaxy (MWb from WD05) included for comparison with the merger model M1. Model D1 has lower time resolution (100 Myr) snapshots as it undergoes little evolution over 5 Gyr.
  2. D2: A more Milky Way-like isolated disc Galaxy (MWa from WD05) which forms a bar and spiral structure. Included for comparison with model M2.
  3. M1: Relatively calm merger of the satellite into host model D1. Model M1 is not tailored specifically to the Milky Way-Sagittarius interaction, but is instead intended to be a laboratory for examining merger dynamics and host galaxy response at high resolution in an otherwise stable disc galaxy.
  4. M2: Violent merger of the same satellite into model D2. The disc is significantly disrupted, and experiences a large degree of heating.

The provided example Jupyter Notebook (stored in SMUDGE/data01_01 and available in the SMUDGE GitHub repository) shows how to access both the individual timestep snapshots of a simulation and trajectories (orbits) for individual ‘star’ particles over a given time period.

The example Jupyter Notebook and the package for interfacing with the code ( are both stored in data01_01/. To copy these files into your own persistent storage, start a new compute terminal (open your SciServer Compute container, click ‘New’ on the right hand side, then select ‘terminal’ from the list of options) and type

cp /home/idies/workspace/SMUDGE/data01_01/file_to_copy  /home/idies/workspace/Storage/your_account/location

replacing ‘file_to_copy’, ‘your_account’, and ‘location’ accordingly, and then hit Enter.

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