Diffuse star formation in the proto-cluster medium: witnessing the in-situ birth of a giant galaxy
Abstract
How did the most massive galaxies in the Universe form? Deep HST/ACS imaging has shown that a giant cluster galaxy in formation, the enigmatic Spiderweb Galaxy, is rapidly forming stars in-situ from a large reservoir of cold molecular gas across the intra-cluster medium. This proved to be the first observational support for predictions that giant cluster galaxies may condense out of accreted cold gas early in the history of the Universe. If this mode of in-situ star formation is common among massive high-z galaxies, then this may require us to revise our ideas about star formation and the early build-up of galaxies. We propose to analyze 12 orbits of WFC3 data of the one other Spiderweb-like galaxy for which deep 2-color imaging is available in the archive, namely 4C 41.17. This spectacular proto-cluster system is observed at z~4, which is the epoch where cosmic gas accretion peaks. The HST and complementary ALMA data show indications for filamentary accretion of cold gas, as well as diffuse star formation on scales of >100 kpc. Our goal is to carefully analyze the web of gas and young stars that make up the CGM/ICM, in order to gain new insights into the role that in-situ star formation plays in the early evolution of the most massive galaxies.
- Publication:
-
HST Proposal
- Pub Date:
- May 2020
- Bibcode:
- 2020hst..prop16123E