Strangulation in a high redshift cluster revealed by enhanced metallicities and ALMA molecular gas
- Author(s)
- Christian Maier
- Abstract
One of the most striking examples of a high-z cluster with an active core is XMMXCSJ2215.9-1738 at z~1.5. Using spectroscopic redshifts of about 100 galaxies in and around the cluster I computed the location of galaxies in the projected velocity-versus-position phase-space to separate the cluster sample into a virialized region of objects accreted longer ago and a region of infalling galaxies. I used KMOS spectroscopy of Halpha and [NII] covering a region that corresponds to about one virial radius, and found the computed metallicities of z~1.5 cluster galaxies inside half R200 to be enhanced compared to infalling galaxies and field galaxies at z~1.5 of similar masses. This indicates that the density of the intracluster medium in this massive cluster becomes high enough toward the cluster center such that the ram pressure exceeds the restoring pressure of the hot gas reservoir of cluster galaxies. This can remove the gas reservoir stopping the inflow of diluting gas thereby enhancing gas metallicities and initiating quenching. Although the galaxies continue to form stars, albeit at slightly lower rates, using the available cold gas in the disk which is not stripped: Molecular gas masses derived from ALMA CO(2-1) for several cluster galaxies suggest that the main component of the stripped gas is the neutral gas reservoir, while the molecular gas is relatively much less affected by the ram pressure, such that the galaxies continue to form stars from the molecular gas.
- Organisation(s)
- Department of Astrophysics
- DOI
- https://doi.org/10.5281/zenodo.4984663
- Publication date
- 06-2021
- Austrian Fields of Science 2012
- 103003 Astronomy, 103004 Astrophysics
- Keywords
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/54aaa45d-06b3-44bc-964f-cacca6e97207