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DWARFS IN HIPASS AND SDSS. Their properties merge smoothly with giants and show no extra Dark Matter. HOW MUCH GLOBAL INFORMATION/ GALAXY?. HOW MANY PHYSICAL PARAMETERS COULD CONTROL GALAXIES? - PowerPoint PPT Presentation
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DWARFS IN HIPASS AND SDSS
Their properties merge smoothly with giants and show no extra
Dark Matter
HOW MUCH GLOBAL INFORMATION/ GALAXY?
• HOW MANY PHYSICAL PARAMETERS COULD CONTROL GALAXIES?
• Total Mass, Baryon fract, Ang Mom,Radius, Concentration,Gas Mass,Age; ie SEVEN LESS 1 for Virial Theorem. Therefore SIX physical params.
• HOW MANY INDEPENDENT OBSERVABLES CAN BE MEASURED?
• Eg Lum, Radius, Concentration, M(HI), Internal Vel disp, Colour ……ie SIX too.
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ΔV( )2
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ΔV( )2
Dwarfs v ClustersGilmore et al 2007
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M/L ratios in Dwarfs Gilmore 2007
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Montage of ES galaxies
SB v Col Density
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HOW MUCH INDEPENDENCE?
• We find 200 objects in HI Blind survey coincident with SDSS images and correlate all the following props:Lum, Colour, Radius,M(HI), R(90)/R(50), and M(dyn).
• Each indep correl must reduce 6 independent variables by 1.
• We find 5 correls (one new).Thus HI selected Galaxies form a ONE PARAMETER SET.
• This is confirmed by Principal Component Analysis.
Concentration v Mass
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HIMASS versus opt radius
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Colour v Luminosity
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Mass v Luminosity
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SB versus Luminosity
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Dynamical Mass v R(cubed)
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Correlation plot for 5 variables, not including colour
Principal Components for 5 variables, no colour
Correlations between 6 variables including colour
Principal components including colour
Simulation.2 variables correlated, the third is random
PCA of above. Note random varbl. has strong PC2
OBSERVE THE REAL SKY
• This high degree of organisation is totally inconsistent with Hierarchical galaxy Formation.(at least 4) and mergers.
• Galaxy astronomers should look at their observations free of prejudices drawn from cosmological simulations which look increasingly misleading!
• Observations of Galaxies contain far more reliable information about the process of Gal formation than numerical simulations.