Project: Looking for Dark Matter in the Rotation Curves of the Hubble Tuning Fork Galaxy Diagram
Department of Natural Sciences: Physics
Project adviser: Dr. Scott Schneider
Researched by: Ceré L. Rettig
Project Summary as of: 10/16/2014
What is a galaxy rotation curve?
Galaxy rotation curves are a graphical analysis obtained from the magnitude of the orbital velocities of visible stars in a particular galaxy and their radial distance from the galaxies center, typically depicted with a scatter plot.
What is the Hubble Tuning Fork Galaxy Diagram?
The Hubble Tuning Fork Galaxy Diagram is a way to classify galaxies. Mr. Edwin Hubble believed that the elliptical galaxies (E0, E3, E5, E7) are early galaxies and that the lenticular (S0), and spiral galaxies (Sa, Sb, Sc, SBa, SBb, SBc) or late galaxies evolved from the elliptical galaxies. In this model the lenticular galaxies are viewed as a transition type between the elliptical and spiral galaxies. While this evolution model has been found to be incorrect, this is a good diagram used for galaxy classification.
What is dark matter?
Dark matter accounts for effects that appear to be the result of mass where such mass cannot be seen. It attracts or exerts a gravitational inward pull on the visible matter surrounding it.
Are we sure it is not dark energy?
Yes, because dark energy repels or pushes outward.
What is already known about spiral galaxy rotation curves?
The existing programs that will be used were created by:
Dane Falberg is another student at Lawrence Technological University who is working on an astrophysics project advised by Dr. Scott Schneider. I will use his project to understand, and build my own genetic algorithm program using Java.
- Research galaxy rotation curves for the six different types of spiral galaxies.
- Investigate mathematical models for ordinary matter and dark matter to generate rotation curves.
- Research genetic algorithms.
- Study Dane Falberg’s programing with genetic algorithms.
- Create the software, to fit galaxy rotation.
- If time is available see if this process can be done with lenticular galaxies.
J.Q. Feng and C.F. Gallo, Res. Astron. Astrophys. 11 1429-1449, 1 (2011).
Charbonneau, Astrophys. J. Suppl. Ser. 101 309-334, 1 (1995)
Sofue and V. Rubin, Ann. Rev. Astron. Astrophys. 39 181-0015, 1(2000).
What I’ve been working on:
- Researching galaxy rotation curves for spiral galaxies, including: mathematical models for ordinary matter and dark matter to generate rotation curves.
- Read Charbonneau 1995 and found sources (data related).
- Researching Vera Rubin and her work on galaxy rotation curves.
- Read Sofue and Rubin 2000 and in progress of finding sources.
- E-mailed Vera Rubin about data sets.
Why Vera Rubin?
Vera Rubin’s work on galaxy rotation curves is why it is possible for my project to exist today. The discovery of her work was presented to both myself and Dr. Scott in the series finale of COSMOS: A Spacetime Odyssey with Neil deGrasse Tyson.
“We have peered into a new world and have seen that it is more mysterious and more complex than we had imagined. Still more mysteries of the universe remain hidden. Their discovery awaits the adventurous scientists of the future. I like it this way.”
Genetic Algorithm Software
I will not be learning with Dane Falberg’s programming with genetic algorithms, it is too complicated. Will creating a genetic algorithm program using Python. Why Python? Dr. Scott felt it was a good language to work with. I’ve also heard it is widely used and simple to learn for someone not familiar with programming. How was this decided? Well, one of the sources for the Charbonneau 1995 article, Genetic Algorithms + Data Structures = Evolution Programs which has a much more simplistic way of using genetic algorithms.
Am I effectively working through my project objectives?
Yes, I would like to use the scientific writing style outlined in my Introduction to Senior Projects in Science course, to improve upon my scientific writing skills.