Theory 98/Cosmic/Dark matter halos
Halo Concentration Records Formation
The claim
The concentration of a dark matter halo is set by the ratio of its formation time to the time it has been accreting, so early-forming halos are more concentrated.
01Mechanism
Concentration reflects how much of the halo formed when the universe was denser; the ratio records that history.
02Prediction
Concentration should track the ratio.
03Refutation
Concentration tracking mass alone would remove formation time.