1. The AGN Butcher-Oemler Effect
Specifically acknowledge John and Dan
Paul Martini
The Ohio State University

2. Collaborators John Mulchaey (Carnegie) Dan Kelson (Carnegie)
Jason Eastman (Ohio State)
Greg Sivakoff (Ohio State)
Kim-Vy Tran (Leiden)

3. Motivations AGN feedback on galaxy clusters and cluster galaxies
Do AGN preheat the intracluster medium?
What are the triggers of AGN?
When I first gave a talk on AGN in clusters, AGN feedback was the last item on this list, but increasing interest in feedback in clusters have moved it up to number one. My main motivation is black hole evolution, particularly AGN fueling and lifetimes, while work on this question has greatly increased my interest in galaxy evolution, particularly in clusters vs. the field.
Allen et al.

4. The Butcher-Oemler Effect

5. The Butcher-Oemler Effect
0.04 < z < 0.08
0.4 < z < 0.8
Galaxy Fraction with [OII]
Poggianti et al. (2006)

6. Galaxy Evolution in Clusters
From Treu et al. (2003)

7. AGN Identification Eastman et al. (2007)
Identification technique: Chandra data, obtained ground-based images, follow-up counterparts to X-ray sources.
Most are not obvious AGN based on emission-lines
Eastman et al. (2007)

8. Determine Cluster Membership
Eastman et al. (2007)

9. AGN Classification
40 X-ray sources in 8 clusters with 0.06 < z < 0.3
vs. LMXBs
vs. hot halos
Multiwavelength strategy to rule out other X-ray emission mechanisms
Kim & Fabbiano
O’Sullivan et al.
35 are classified as AGN
Only 4 show AGN spectral signatures
Martini et al. (2006)

10. Evolution of the AGN Fraction
fA =
NX (L>LX; MR<-20)
Ngal (MR<-20)
Comparison of AGN in the low and high-redshift clusters shows:
11 low-z clusters have 2 AGN with LX,H >1043 erg/s in over 1600 member galaxies
4 high-z clusters have 8 AGN with LX,H > 1043 in over 400 member galaxies

11. An AGN Butcher-Oemler Effect
Factor of >10 increase in the cluster AGN fraction
Due to systematics, this is likely an underestimate
Eastman, Martini, et al. (2007), Sivakoff et al. (2007)

12. An AGN Butcher-Oemler Effect
More pronounced than the field evolution (Ueda et al. 2003)
Evidence for environment-dependent downsizing
Eastman, Martini, et al. (2007), Sivakoff et al. (2007)

13. The Butcher-Oemler Effect

14. AGN Butcher-Oemler Effect
fB + offset
Rate of evolution is consistent with blue galaxy fraction

15. Cosmology Implications?
Evolution:
Cluster environment provides a unique set of conditions to explore triggering, AGN feedback
May have implications for clustering properties of high-redshift X-ray sources
X-ray:
AGN can be a significant fraction (>10%) of the cluster LX, which impacts selection
SZ:
A comparable evolution in radio sources could bias SZ selection vs. redshift
Implications for accretion mechanism
Need more data to see if these are better tracers than emission-line galaxies or BO galaxy fraction evolution
Again note these data do not cover the entire cluster, but work to probe out to larger radii is underway.