Space Simulations Research
In grad school I researched small galaxies using big computers.
This page has several animations I made using simulation data. Citations are at the bottom of this page if you would like to read all the gorey details :)
FIRE (Feedback In Realistic Environments) [1,2]
Fly-by's and supernovae cause quenching of star formation in satellite galaxies
The FIRE simulations (GIZMO, paper) are cosmological zoom-in simulations. Cosmological means they start with initial conditions corresponding to the early universe, and evolve those forward with rules for physics and inflation at a low-ish resolution. Zoom-in means they identify a region of interest, and then re-simulate that region at much higher resolution. This allows for the galaxies to evolve in a realistic cosmological environment without the computational expense of simulating the entire thing at the high resolution.
The simulations I researched were systems around the same mass as the Large Magellanic Cloud, which is about 10 times less massive than the Milky Way galaxy. These animations are all from my second publication, in which I looked at the galaxies that orbited these systems and looked into when and how they stopped forming their stars (for those that did).
These first two videos are the same system, but with different properties represented in the coloring. The red-yellow colorscale video on the left is a temperature projection of the interstellar gas, and the blue-green-pink colorscale on the right is the density of the interstellar gas.
The next three videos are all density projections of different systems.
All of the above videos demonstrate the quenching of star formation of satellite galaxies by one or both of two different mechanisms:
-
Quenching by Ram Pressure Stripping occurs when fast-moving, dense gas (in this case, typically associate with another galaxy, usually the host) pushes the gas of a galaxy away, causing it to rarefy (become less dense), and possibly be totally removed from the galaxy. The resulting lack of dense gas causes star formation to halt.
-
Quenching by Stellar Feedback occurs when feedback processes, typically supernovae, cause gas to accelerate outwards from the galaxy, heating up, rarefying, and possibly leaving the gravitational potential of the galaxy. This can be done over time through multiple events, but these galaxies are so small that single events can be disruptive enough to quench star formation.
Formation of a stellar halo through tidal stripping of a satellite galaxy around a dwarf galaxy host
Stellar halos are a vast collection of stars orbiting a galaxy in highly elongated, very large orbits. These stars typically originated in other galaxies and were flung into such orbits through close encounters between the two galaxies, now orbiting the larger one. These structures have been known around larger galaxies like the Milky Way for some time, but this research shows that they can form around dwarf galaxies like the Large Magellanic Clouds as well.
The black points in the above movie are stars from the central galaxy, and different colors indicate stars from different satellite galaxies. Watch how their orbits change through gravitational interactions
SMUGGLE (Stars and MUtiphase Gas in GaLaxiEs) [3]
Projections of the evolution of an idealized dwarf galaxy run with different star formation models:
In constrast to the cosmological simulations I looked at in FIRE, these are idealized simulations that I ran on the UCR HPCC using AREPO and the SMUGGLE code. Each simulation started with the same idealized initial conditions but with a different star formation model, or with different parameters changed.
Stars are colored yellow and gas is colored blue
Radial Velocity Distributions
The following animated plots show the distance of things to the center of the galaxy on the x-axis, and the radial (inward-outward) speed of those things on the y-axis. Things above the halfway point vertically are moving away from the center (outward) and things below the halfway point vertically are moving toward the center (inward). These animations let you watch the fluctuation of matter distributed in the galaxies as they evolve! The videos labeled 'fiducial' are the standard star formation model, and those labeled eSF100 are the high efficiency models.
Stars
Gas
Dark Matter