Friday, January 27, 2012

redshift space

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

Friday, January 20, 2012


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?