Jorryt Matthee

Three years have passed since the JWST began revealing its sharp and sensitive view of the distant Universe (1). One of its discoveries that has generated intense debate is a population of light sources that were identified in the early Universe (about a few hundred to a billion years after the Big Bang). These red and compact astronomical objects, nicknamed “little red dots” (2), are so common that they are easily found with the JWST despite the telescope’s small field of view.

Abstract Galaxy clusters are the most massive, gravitationally bound structures in the Universe. They emerged through hierarchical structure formation of large-scale dark matter and baryon overdensities. Early galaxy ‘proto-clusters’ are believed to have substantially contributed to the cosmic star-formation rate density and served as ‘hotspots’ for the reionization of the intergalactic medium.

Abstract With stunning clarity, the JWST has revealed the Universe’s first billion years. The scientific community is analysing a wealth of JWST imaging and spectroscopic data from that era, and is in the process of rewriting the astronomy textbooks. Here, as a result of the 2024 ISSI Breakthrough Workshop, we provide a snapshot of the great progress made towards understanding the initial chapters of our cosmic history 1.5 years into the JWST science mission.