Speaker
Description
We present the discovery of an extraordinary overdensity around a source of the ALMA Large Program REBELS at z=7.35, among the most extreme proto-clusters known beyond z>7. Within just 21″×21″ (Δz<0.01), we identify 5 sources in [OIII]5007 with NIRCam/Grism observations, also showing in ALMA data as 4 of the brightest [CII] 158μm emission known at z>7. The properties of these galaxies show accelerated evolution in this overdense environment: one NIRCam dark source, a galaxy undergoing a major merger and high metallicities. These galaxies sit above the star-forming main sequence, with stellar masses and SFRs both ~1 dex higher than members of other known proto-clusters at comparable redshifts. These suggest elevated star formation linked to dynamical interactions within this dense environment. We compare this structure to simulations to identify analogous systems and use TNG300 results to trace their probable evolution to z=0, testing whether these most massive early structures effectively seed today's most massive clusters. This system offers a rare laboratory to study how overdense environments drive accelerated, bursty star formation and rapid dust enrichment at z>7, and allow us to understand more how the first large-scale structures in our Universe formed.
| Talk category | NOVA Network 1 |
|---|---|
| Second preference | Plenary |
| PhD relevance | 4th |
