The brightest galaxies at Cosmic Dawn

Understand

Recent JWST observations suggest an excess of $z\gtrsim10$ galaxy candidates above most theoretical models.

• Here, we explore how the interplay between halo formation timescales, star formation efficiency and dust attenuation affects the properties and number densities of galaxies we can detect in the early universe.
• We calculate the theoretical upper limit on the UV luminosity function, assuming star formation is 100% efficient and all gas in halos is converted into stars, and that galaxies are at the peak age for UV emission (~10 Myr).
• This upper limit is ~4 orders of magnitude greater than current observations, implying these are fully consistent with star formation in $\Lambda$CDM cosmology.