1 / 9

The Assembly of Galaxy Clusters

Karl Andersson – Astro Lunch April 11, 2008. The Assembly of Galaxy Clusters. arXiv:0804.0426 Berrier et al. Question. ~60% of cluster galaxies are spheroidal (E, S0) Only ~30% of field galaxies How cluster galaxies transform to ‘’early-type’’? ‘’pre-processing’’ in a group environment?

malise
Download Presentation

The Assembly of Galaxy Clusters

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Karl Andersson – Astro Lunch April 11, 2008 The Assembly of Galaxy Clusters arXiv:0804.0426 Berrier et al.

  2. Question • ~60% of cluster galaxies are spheroidal (E, S0) • Only ~30% of field galaxies • How cluster galaxies transform to ‘’early-type’’? • ‘’pre-processing’’ in a group environment? • More frequent merging for cluster galaxies? • Internal cluster processes? • Ram pressure stripping • Cold gas ‘’strangulation’’ • Galaxy-galaxy ‘’harassment’’ Karl Andersson – Astro Lunch April 11, 2008

  3. Answer? • ~60% of cluster galaxies are spheroidal (E, S0) • Only ~30% of field galaxies • How cluster galaxies transform to ‘’early-type’’? • ‘’pre-processing’’ in a group enviroment? • More frequent merging for cluster galaxies? • Internal cluster processes! • Ram pressure stripping • Cold gas ‘’strangulation’’ • Galaxy-galaxy ‘’harassment’’ Karl Andersson – Astro Lunch April 11, 2008

  4. Setup • N-body simulation using Adaptive Refinement Tree (ART, Kravtsov et al. 1997) • 120 h-1 Mpc box with 5123 1.07 109 h-1 Msun particles • Sample of 53 clusters (1.0-5.8) 1014 h-1 Msun • with total 834 subhalos M>1011.5 h-1 Msun ==galaxies Karl Andersson – Astro Lunch April 11, 2008

  5. Origin • Most galaxy halos are accreted directly from the field Karl Andersson – Astro Lunch April 11, 2008

  6. Origin • Most galaxy halos are accreted directly from the field Makes group ‘’pre-processing’’ unlikely Karl Andersson – Astro Lunch April 11, 2008

  7. Timescales • Average cluster galaxies spend little time in a group environment, ~4 Gyr in cluster Karl Andersson – Astro Lunch April 11, 2008

  8. Merging • Field halos are more likely to have had a recent (< 6 Gyr) merger than cluster subhalos Merging is probably not the main cause of galaxy transformation Karl Andersson – Astro Lunch April 11, 2008

  9. Summary • Cluster galaxies are accreted mostly from the field – spend little time in group environment • Mergers are more common for field galaxies than for cluster galaxies • ~50% of cluster galaxies have spent 4 Gyr or more within cluster at z=0 • Internal cluster processes operate on ~4 Gyr (gravitational), ~1 Gyr (intra-cluster medium related) timescales Karl Andersson – Astro Lunch April 11, 2008

More Related