The Leo Triplet

Many of our projects here at Duke use a program called GalSim.
https://github.com/GalSim-developers/GalSim

This is a program to make simulated images of galaxies and stars. It is also the image driver for the imSim simulation program we are working on here at Duke called imSim: https://github.com/LSSTDESC/imSim

To use it logon to cosmology-01 and then (like before if you have logged out):

source /var/phy/project/lsst/LSST-Duke.sh

Then type:

setup galsim

Then, copy this directory:

/var/phy/project/lsst/galsim-2.1.4/examples

somewhere into your area. If you did things correctly you can go into the directory and type:

python demo1.py

It will run and then put a ‘fits’ file in the ‘output’ directory that you can look at with ds9. If that worked you are ready to start.

I would like you to read and try to understand demo1.py. You could play with it by writing your own program to understand it, or make a Jupyter notebook or something. Once you have done this I would like you to run and understand in the same way if you can demo2.py, demo3.py and demo5.py.

You might need to look things up or ask questions to understand some of the things. Don’t be shy about asking.

Then, if you have done all of those I would like you try something which will put together all of the knowledge that you have learned so far. It might be some work to figure it out. But, when you finish you will know how to use the program.

I would like you to try to make a simple version of this:

http://apod.nasa.gov/apod/ap150509.html

There is enough information in the text to figure out how to make this. But one thing: there is no easy way to make a galaxy on its “edge” so just make galaxies from the front with about the correct size and aspect ratio and make them the proper distance apart. Go ahead and add stars.

Now try to make your galaxies more realistic by giving them a color gradient between the bulge and the disk like you see in the image.