Galaxies Flashcards
What is the gas/dynamical matter ratio in elliptical respectively spiral galaxy
1% for ellitical
10% for spiral
Do spiral or elliptical galaxies have ongoing starformation?
Only spirals
Which of spirals and elliptical are redder?
Elliptical
What is the fundamental plane?
The fundamental plane is a set of bivariate correlations connecting some of the properties (radius, brightness, velocity dispersion) of normal elliptical galaxies
What is the Schechter function?
Most stars lie within the galaxy that obey this luminosity function within 10% margins. It describes the potential in terms of the luminosity
When was the star formation peak?
10 Gyr ago (z=2)
Where are red galaxies more dominant? And where are blue galaxies more dominant?
Red: Clusters, because they are generally ellipticals
Blue: Field populations, because they are generally spirals
What are the 8 steps in galaxy evolution?
- Free spiral galaxy
- Small group
- Merging phase
- Coallescence
- Blow-out
- Quasar
- Decay
- Dead elliptical
Did the first stars (pop. III) have high metallicity?
No, it was low
How are high-redshift galaxies detected?
By filtering techniques such as the Lyman-alpha break.
What is the most common type of galaxy?
Dwarf (then spirals and lastly ellipticals)
What is the Sersic profile?
General galaxy brightness profile with r^{1/n} where n=1 means exponential (disk) and n=4 means de Vaucouleur (elliptical, bulge)
Explain the Faber-Jackson relation
Luminosity is proportional to the velocity dispersion to the power of four for elliptical galaxies
Explain the shapes triaxial, oblate and prolate
triaxial - different lenghts for all three axes
oblate - frispee or clementine
prolate - cigarr or american football
