Dwarf Galaxies and Galaxy Formation Valerie Bick University of California, Santa Cruz Research Mentor: Constance Rockosi Home Institution: California Polytechnic State University, San Luis Obispo Image courtesy of Hope.co.nz 1

Outline Structure of a Disk Galaxy The Theorists Prediction The Project Data Collection & Analysis Simulation Calculations Results Future Project 2

Bulge Halo Disk Image courtesy of Sloan Digital Sky Survey (SDSS) Structure of a Disk Galaxy Like the Milky Way 3

The Theorists Prediction 4 Theorists predict Milky Way partially formed by dwarf galaxies Dwarf galaxies interact with gravitational potential of Milky Way and are pulled apart, yet stars maintain the same average Doppler velocity

Our Project Image courtesy of the SDSS 5

Data Collection 6 Retrieved data from Sloan Digital Sky Survey/SkyServer Stars with all same absolute magnitude  fainter stars = farther away Split data into fainter and brighter stars

Simulation 7 Significance Bars Error Bars

Calculations Red bars: uncertainty in each bin = √(number of objects in each bin, for the model) Significance calculation: - Ratio: amount of data outside model uncertainty - Significance calc: √((data – model)²)/√(model) 8

Results Peaks ≥ 10% of the total data are robustly detectable As the percentage increases, the peaks are easier to detect Test sensitivity could be improved if fit model independently of data Model is equally sensitive to half-max peaks and center peaks 9

Conclusions & Future Expand our method: –Implement model independent of data –Apply to entire data set & check curve fit –Optimize the amount of data and bin size Use the results to answer the ultimate question: did dwarf galaxies contribute to the formation of the galaxy’s disk? 10

Many Thanks To… Connie Rockosi Lynne Raschke Hilary O’Bryan The Center for Adaptive Optics Funding provided through the Center for Adaptive Optics, a National Science Foundation Science and Technology Center (STC), AST