# Numerical Galaxy Formation and Cosmology

## Benjamin Moster and Ewald Puchwein

### Lent term 2016

We will present state-of-the-art techniques for
simulating the formation of galaxies and other cosmic structures on modern supercomputers.
This includes techniques for following the gravitational collapse
of structures, the hydrodynamics and a variety of star formation
and feedback physics. In addition, there will be practical
examples, i.e. simulations that can be performed and analyzed by
the participants on their own laptop computers.

Topics that will be covered:

- Motivation for simulations & Semi-Analytic models
- Initial conditions for simulations
- Gravity algorithms & parallelization
- Hydrodynamics schemes (adaptive mesh refinement, moving-mesh, smoothed
particle hydrodynamics)
- Following radiative cooling & photoheating
- Subresolution physics (star formation, supernova & AGN
feedback)
- Semi-Analytic models
- How to use the Gadget2 code (examples: cosmological box,
galaxy collision)

**Lecture 1** (Ben, Jan 13)

topics:

- introduction to cosmological simulations and semi-analytic
models
- cosmological initial conditions

slides

**Lecture 2** (Ewald, Jan 20)

topics:

- the N-body approach
- self-gravity algorithms
- parallelization
- time integration
- simulation results (collisionless runs)

slides

**Lecture 3** (Ewald, Jan 27)

topics:

- hydrodynamics & numerical hydro schemes (Eulerian & moving-mesh)

- advection, slope/flux limiters
- Riemann solvers

slides
advection code

**Lecture 4** (Ben, Feb 3)

topics:

- smoothed particle hydrodynamics
- radiative cooling/heating
- subresolution models for star formation and feedback

slides

**Lecture 5** (Ben, Feb 10)

topics:

- halo and subhalo finders
- semi-analytic galaxy formation models
- empirical galaxy formation models

slides

**Lecture 6** (Ewald, Feb 17)

topics:

- Exercise 1: Performing a cosmological simulation with the Gadget-2 code

slides

**Lecture 7** (Ben, Feb 24)

topics:

- Exercise 2: Galaxy mergers

slides
merger codes

**Lecture 8** (Ewald, Mar 2)

topics:

- Exercise 1 - part 2: Analyzing a cosmological simulation (halo finding,
halo mass function, maps)

slides
postprocessing code

**The Gadget-2 code**

In the second half of the course we will do some exercises with
the Gadget-2 cosmological simulation code. It can be downloaded
here:

http://www.mpa-garching.mpg.de/gadget/gadget-2.0.7.tar.gz