Galaxy Clusters and the Butcher-Oemler Effect:

Emily Cross and Kristine Salters

Galaxy Transformation by Environment

Environment &Population

“Like cities, each cluster has unique characteristics and population demographics: Coma, Virgo, and the Local Group are as different from each other as Toronto, Bangkok, and Rio de Janeiro”

(S&T: January 1988, page 16).

The Butcher-Oemler Effect

Galaxy cluster with high redshift have a higher blue star forming spiral population

Low redshift, low blue spiral population

Red shift 101

The

BOEffect

Galaxy Evolution

RED SHIFT

The evolutionary Sequence

Infalling spiral galaxy

Galaxy cluster

Clusters disrupting Star Formation

Merging Starburst Ram pressure stripping Tidal disruption

SF completely exhausted

The youths

But what about the awkward teen phase of galaxy evolution?

We had never seen the phase between the young blue spirals and the old red ellipticals until November

of 2008

Photo

The evolving properties of galaxies in clusters offer a unique opportunity to connect evolution on scales ranging from individual galaxies to overall cosmic evolution