## Friday, January 27, 2012

### redshift space

what's the finger-of-god-effect and the Kaiser-effect in galaxy surveys?

## Friday, January 20, 2012

### SZ-effect

in the thermal Sunyaev-Zel'dovich effect there's an interaction between a galaxy cluster's electrons and the CMB photons. Does a galaxy cluster become colder in time due to the thermal SZ-effect?

for bonus points: does a cluster get slowed down by the kinetic SZ-effect? if yes, relative to which frame of reference?

## Friday, January 13, 2012

### dark energy

what do the cosmological constant and dark energy have in common? why are they different? why is it wrong to say that Lambda is just DE with $w=-1$? could there be a cosmology with Lambda and DE at the same time?

## Friday, January 6, 2012

### Hubble function

in cosmology we can measure the Hubble function $H(a)$ and the growth function $D_+(a)$. do they carry the same information? could one compute $D_+$ with the knowledge of only $H$ and vice versa? are there cosmologies where this is NOT possible?