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AY202a Galaxies & Dynamics Lecture 3: Galaxy Characteristics

AY202a Galaxies & Dynamics Lecture 3: Galaxy Characteristics. Galaxy Properties vs Morphology. blue. Type vs Color This is essentially star formation rate and history B-V. cI Im-Sd Sc Sb Sa S0/a

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AY202a Galaxies & Dynamics Lecture 3: Galaxy Characteristics

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  1. AY202a Galaxies & DynamicsLecture 3: Galaxy Characteristics

  2. Galaxy Properties vs Morphology blue Type vs Color This is essentially star formation rate and history B-V cI Im-Sd Sc Sb Sa S0/a E/S0 U-B red

  3. JPH ‘76

  4. Color vs Magnitude --- for Ellipticals less luminous galaxies are lower metallicity and thus bluer. CM for the Virgo Cluster from Visvanathan & Sandage (1978) Use as a distance indicator?

  5. SDSS (u-r) vs M Baldry et al 2004

  6. SDSS

  7. Color Gradients --- most galaxies get bluer with radius. Combination of CFR + [Fe/H] Liu, C-Z. et al. 2009, Research in Astron. Astrophys. X

  8. De Vaucouleurs

  9. HI content Type MH/M E 10-6 – 10-3 S0 0.005 Mort Sa 0.03 Roberts Sb 0.05 Sc 0.1 Im 0.2 – 0.5

  10. Spirals HI vs T

  11. Internal Motions 1970’s improvements in detectors enabled research on several questions: 1. Do E’s rotate appropriately? 2. Does σ vary with L? 3. Are E’s triaxial? 4. Are S’s stable? Illingworth 1977 Theory Data

  12. NGC 253

  13. M33 NRAO Bureau & Freeman Optical Rotation Curves Radio 21-cm HI Velocity Maps

  14. Luminosity vs Internal Motions For Ellipticals, L vs σ = Faber-Jackson For Spirals, L vs v = Tully-Fisher TF 1977 FJ 1976

  15. K-Band TF Masters et al. 2008

  16. Comparison of FJ & TF relations note the scatter. C. Kochanek

  17. Kinematics & Luminosity What drives the kinematics vs L relations? 1. Assume galaxies are self-similar in form <μ(r)> ~ μe 2. Assume they are made of similar stars M/L similar L ~ 4 πRe2μe where Re is the galaxy’s effective radius G m M / Re = ½ m V2 circularorbits, flat rotation  M ~ ½ V2 R / G and Re = L½ /(4 πμe)1/2 Thus M = ½ V2 L½ / (4 πμeG )1/2 = 1/4 V2 L½ / (πμeG )1/2 so for constant M/L , L½ = 1/4 V2 / (πμeG )1/2 or L ~ const V4 (shades of Opik) )1/2

  18. The Fundamental Plane For E Galaxies, the combination of σ vs L + D vs L + μ vs L , if M/L is well behaved  The Fundamental Plane (DD, 7 Sam) Re = f(σ,L) or even better f(σ,L,[Fe/H]) log Re = 0.36(<Ie> / μB) + 1.4 log σ0 Ditto for Sprials. TF implication is that M/L varies by most a factor of 2 over a factor of 100 in Luminosity.

  19. Galaxy Spectra & SED’s

  20. Spectra

  21. M77 a.k.a. NGC1068

  22. Starburst

  23. The Cosmic Spectrum Glazebrook & Baldry from the 250,000 2dF Galaxy Spectra

  24. Morphology Density Relation Dressler (1980) studied the gross morphologies of galaxies in 14 clusters.

  25. <L> and color, too…. SDSS

  26. Remember: Reading Assignment For this Wednesday NFW “The Structure of Cold Dark Matter Halos,”1996, ApJ...463..563 & The preface to Zwicky’s “Catalogue of Compact and Post-Eruptive Galaxies” Read, Outline, be prepared to discuss Zwicky’s comments and the NFW profile.

  27. Accepting suggestions……What should we read next week?Topic: Galactic Structure & Internal Dynamics

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