Extreme Value Statistics of the Halo and Stellar Mass Distributions at High Redshift: are JWST Results in Tension with {\Lambda}CDM?

Understand

The distribution of dark matter halo masses can be accurately predicted in the $\Lambda$CDM cosmology.

• The presence of a single massive halo or galaxy at a particular redshift, assuming some baryon and stellar fraction for the latter, can therefore be used to test the underlying cosmological model.
• A number of recent measurements of very large galaxy stellar masses at high redshift ($z > 8$) motivate an investigation into whether any of these objects are in tension with $\Lambda$CDM.
• We use extreme value statistics to generate confidence regions in the mass-redshift plane for the most extreme mass haloes and galaxies.