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

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Outline

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

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Bulge

Halo

Disk

Image courtesy of Sloan Digital Sky Survey (SDSS)

Structure of a Disk GalaxyLike the Milky Way

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The Theorists Prediction4

• 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

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Data Collection6

• 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

Simulation7

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)

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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

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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?

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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-987683.

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