evolution of the morphology density relation p. capak, b. mobasher, k. sheth, r. ellis, b. abraham,...
Post on 22-Dec-2015
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Evolution of the Morphology Density Relation
P. Capak, B. Mobasher, K. Sheth, R. Ellis, B. Abraham, N. Scoville
Morphology Density
• Increase in the fraction of early type galaxies with increased density– Environmental effect
• Morphology Classifier
• Density measure
• Evolution of the relation
Morphology Classifier
• Classified 1000 galaxies by eye in F814W and/or F606W bands
• Cleanest division based on Gini and Asymmetry
• Must be careful of redshift dependent effects
Density Estimator
• Used a version of Dressler’s projected density – Area defined by 10th
nearest neighbor a with Mv<-21
• Count out from center until there are statistically 10 objects at the same redshift as the object of interest
• Reproduce the morphology density relation at middle densities at all redshifts
Morphology Density Relation
Redshift Evolution
• Rate of Elliptical formation is higher in high density regions
• However Ellipticals still form in the field
Cosmic Time (yr)