The molecular gas contents of z=1.6 (proto)-cluster galaxies and their last gasp of star formation
| Main Author: | Gregory Rudnick |
|---|---|
| Format: | Proceeding Journal |
| Terbitan: |
, 2017
|
| Online Access: |
https://zenodo.org/record/807723 |
Daftar Isi:
- In this talk I present two related topics. First, I discuss the constraints on the quenching efficiency and the age in stellar populations that we derive from deep HST G102 and G141 grism observations in a z=1.62 proto-cluster galaxy. We use the grism data to establish unambiguous membership for passive and star-forming galaxies and to measure the strength of the 4000-Angstrom break strength. We find a strongly mass-dependent passive fraction that is in excess of the field at the highest stellar masses. However, the strength of D4000 for passive galaxies is independent of mass and we interpret this as a lack of strong trends of stellar age with mass. We discuss possible explanations for our observations that there is no stellar age trend although more massive galaxies clearly quench more efficiently than lower mass galaxies. We then discuss the molecular gas properties in a set of 4 clusters at z=1.6. We find that most galaxies have gas fractions that are elevated with respect to the field for galaxies at similar redshift, stellar mass, and star formation rate. However, there is a significant cluster-to-cluster dispersion with galaxies in one cluster having molecular gas properties indistinguishable from the field. There is also some suggestion that the most quenched clusters have the lowest gas fractions but this requires more cluster molecular gas data to confirm this tentative picture.