1. Time Variability Selection of Quasars in the Sloan Digital Sky Survey
Keira Brooks, Senior
University of Washington
Astronomy and Physics

2. Nature of quasars
Quasars are supermassive black holes surrounded by an accretion disk
Quasars out-shine their galaxy, causing them to look like stars from Earth
Because they look like stars, they are hard to identify

3. The Problem
LSST will need to use colors and variability to identify quasars
We used SDSS to develop the required methodology

4. Utilizing quasar uniqueness
How do we know SDSS quasars are not stars?
Spectra of quasars look unlike stars
SDSS has found 100,000 quasars but LSST will find 10 million
Spectra are expensive to obtain, but variability is easy to measure
Stars have smoother light curves than quasars
Use statistical models for stellar and quasar variability

5. Using these models We ask which model better fits a particular source
Knowing that quasars have long time scales, we also apply such a cut
Our method can clean star dominated samples (1 quasar per 10 stars) to obtain quasar dominated samples (only 1 star per 10 quasars)‏

6. Conclusions
We developed a new method for finding quasars (a publication is in preparation)‏
This project was a great experience that cultivated my interest in this type of research