Constructing and Simulating the Dynamics of Galaxies in AMUSE: A Continuation of a Very BRAVE Program Open Access

Zhang, Eric (Spring 2023)

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Many observations of galaxies have been conducted with spectral analysis, but it is difficult to

distinguish the extent of different structural components within a single galaxy based solely on ob-

servations. One way to solve this problem is by using simulations, as we can define specific stars

to different structural components of the galaxy. Therefore, simulations of galaxies of various mor-

phologies will enable us to understand the effects of different types of galaxy structures on the

measured properties of galaxies. Specifically, we want to find a way to isolate and separate the bulge

dynamics from the disk and any other structures. We use the simulation software Astrophysical

Multipurpose Software Environment (AMUSE) to create particle sets, allowing us to modify and

analyze specific stars within the Plummer model. AMUSE also lets us use other simulations with

robust hydrodynamics and solve observational problems such as light of sight and structure identifi-

cation. Our final goal is to create a simple simulation which has physical dynamics and structure to

previously observed spiral galaxies. We created two simulations which exhibited galactic structure

through a period of 10 Gyr. One has a total galactic mass of 1 × 1010 M⊙, which has parameters

close to the Milky Way galaxy, and one with a mass of 1 × 108 M⊙, which has parameters similar

to dwarf galaxies.

Table of Contents



1 Introduction 1

2 Methods 7

2.1 Galaxy Structure 7

2.2 Half-light Radius 12

2.3 An Introduction to Galactic Simulations And AMUSE 15

3 The Simulation Itself 18

3.1 Problems with the Original Script 18

3.2 The make galaxy Definition 20

3.3 The simulation Definition 24

3.4 The new option parser Definition 25

3.5 Reference Galaxies 26

4 Discussion and Analysis 29

4.1 The 1 × 108 M⊙ Galaxy and Adjusting Parameters 31

4.2 The 1 × 1010 M⊙ Galaxy and MW Parameters 34

4.3 The “Repulsion Force” Problem 36

5 Future Works 42

5.1 Simulation Problems 42

5.2 Compare with Observed Galaxies 43

6 Conclusion 45

A Milky Way Galaxy Simulation 46

A.1 Original Simulation Script 46

A.2 Modified Simulation Script 50

A.3 Table of Simulations 55

Bibliography 57

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