Transcript Abnormal Star Clusters and Galaxy Formation

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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
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Structure of a Disk Galaxy
The Theorists Prediction
The Project
Data Collection & Analysis
Simulation
Calculations
Results
Future Project
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Structure of a Disk Galaxy
Like the Milky Way
Bulge
Disk
Halo
Image courtesy of Sloan Digital Sky Survey (SDSS)
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The Theorists Prediction
• 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
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Our Project
Image courtesy of the SDSS
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Data Collection
• 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
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Simulation
Error
Bars
Significance
Bars
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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.