Another age problem in the early universe?

[Garth]

I have on several occasions on PF flagged up examples where it appears that there is an age problem in the early universe, in other words highly evolved objects have been observed whose existences are difficult to explain at their high red shifts in the standard \LambdaCDM cosmological model.

Another example has been recently published in the Journal of the Korean Astronomical Society (48: 21-55, February 2015) and on the physics arXiv Massive Structures of Galaxies at High Redshifts in the Great Observatories Origins Deep Survey Fields

8. CONCLUSIONS
Using the multi-wavelength data, we identied 59 Massive Structures of Galaxies (MSGs) from the combined areas of the GOODS-South and the GOODS-North fields with signicances of 3:5 - 8 \sigma from z = 0:6 to z ~ 4:5. Among them, ~20% of MSGs show plausible associations with AGN/radio sources.
In comparison with a simulation data set, we find a discrepancy between the observed number densities of MSGs and those from the simulation at z > 1 (M > 7 X 10¹³M_\odot ). The discrepancy becomes more signicant at higher redshifts (z > 2) by a factor of ~5 or more. Even after considering possible systematic effects, our result implies that there are too many massive structures at z > 2 compared to the \LambdaCDM prediction. By tweaking the conditions for the initial density fluctuation or baryonic physics in galaxy formation, one may be able to explain the result within the \LambdaCDM cosmology framework, but as of now the overabundance of MSGs at z > 2 stands as a challenge to the models based on the \LambdaCDM cosmology.

(emphasis mine)

Garth

 

[Chronos]

Given the variance is sensitive to the assumptions employed in the Millenium simulation, this result is not altogether surprising. We already knew, for example, that the apparent mass of high z black holes that power ancient quasars is a challenge to explain under LCDM, so it is reasonable to expect the answer to both enigmas is probably related.

 

[marcus]

As they say in the conclusions of the article Garth quoted:
" By tweaking the conditions for the initial density fluctuation or baryonic physics in galaxy formation, one may be able to explain the result within the ΛCDM cosmology framework. ..."

It sounds like what we have here is a tweaking problem---adjusting the initial conditions of the standard cosmic model to get a better fit to all the data.