WeakLensing selected, Xray confirmed Clusters and the AGN closest to them

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Weak-Lensing selected, X-ray confirmed Clusters
and the AGN closest to them

• Dara Norman
• NOAO/CTIO

Collaborators Deep Lens Survey Team David
Wittman, Tony Tyson, Vera Margoniner - UC Davis,
Jack Hughes - Rutgers U. , Ian Dellantonio -
Brown U. Recent additions Ilona Soechting -
University of Oxford, Percy Gomez - Gemini
2006 November 6-8 Boston
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Motivation
The Cluster AGN Environment Clues to
Formation/Evolution

• Hierarchical structure formation scenarios may
  provide a framework for
• the evolution of galaxy clusters
• the growth of black holes
• the triggering of quasar activity

There is a wealth of evidence that AGN know about
the larger scale environment.
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Black Holes know about their host galaxies

• Black hole mass/velocity dispersion show a
  correlation
• e.g. Ferrarese Merritt, 2000
• Gebhardt et al., 2000

Black Hole Mass (Msun)
Velocity Dispersion (kms-1)
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AGN know about their neighbors

• Evidence of mergers in host galaxies
• e.g. Hutchings, et al. 2002

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Quasars know about Large Scale Structure (?)

• N-body simulations with toy models of quasar
  formation can re-produce B-band quasar luminosity
  function
• e.g. Kauffmann Haehnelt, 2000

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Survey of AGN in DLS Clusters

• Main Goals
• Determine if AGN triggering and evolution is
  influenced by the cluster environment.
• Compare the weak lensing, X-ray gas and dynamical
  mass environments of AGN
• Compare the AGN fraction in DLS clusters to other
  samples.

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Deep Lens Survey
DLS Cluster 3

• Sample of total mass overdensities is selected
  from the Deep Lens Survey
• Five 2º x 2 fields
• 3x3 grid of Mosaic Fields (35x35)
• R 26.5
• 50 galaxies/arcmin2
• BVRz imaging
• Main Survey Goals
• Measure cosmic shear due to large scale
  structures
• Measure the cluster mass function to z1

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dls.physics.ucdavis.edu
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A Unique Cluster Sample

• The DLS clusters are the only sample of clusters
  discovered solely by their mass properties
  through weak gravitational lensing techniques.
• Lensing provides the only way to measure cluster
  mass that is not dependent on dynamical state.
• Provides an opportunity to identify young and
  forming clusters

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DLS Cluster Sample

• 20 shear selected mass overdensities discovered
  to date.
• Suggests about 8 clusters per sq. deg.
• DLS sample of clusters
• Mass Range 4x1013 - 6x1014 M? and
• Redshift range of main clusters 0.19 - 0.68

DLS Clu 2
DLS Clu 8
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Wittman et al. 2006 ApJ 643 128
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DLS overdensities are true X-ray clusters

• 8 have Chandra X-ray data (20 ks) also taken.
• Most show evidence of substructure (mass and
  X-ray), which may indicate merger activity.
• (e.g Motl et al., 2004, Mohr et al., 1993)

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Weak lensing discovered, X-ray Confirmed Clusters
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X-ray point source distribution

• Chandra observations also reveal a large number
  of X-ray point sources in these cluster fields.
• These sources appear to show an aversion to the
  most massive regions of the cluster.
• Seen before in optical.
• Söchting, et al. (2000, 2004)
• Voronoi tesselation technique

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Field X-ray point sources
123 X-ray point sources with S/N gt 2 in 3
cluster fields Limiting flux is 8 x 10-15 ergs
s-1 cm-1 Clusters have redshifts of 0.3, 0.3 and
0.68
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R-band matches

• 68 sources match DLS R band sources to 1.5
• R magnitudes 16.2 - 26
• Good photmetric redshifts are currently available
  for 31 sources

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X-ray point source Surface Density

• For all sources in the field X-ray sources show
  two peaks,
• a strong peak in the central 0.25 Mpcs and
• a broad peak in surface density at about 1.25 -
  1.75 Mpc, true for both z0.3 and 0.68 clusters.

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X-ray point source Surface Density
Ruderman Ebeling,2005 see similar trend for 51
massive clusters in the Massive Cluster
Survey. But only for relaxed galaxies.
Ruderman and Ebeling, 2005
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X-ray point source Surface Density
Several sources are known to be background.
Elimination of these and HR lt -0.5 increases
surface density in the center but keeps the 1.4
Mpc peak. Are these infall regions where AGN
activity is triggered?
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Need for spectroscopic data for point sources
and cluster galaxies

• Kinematical studies of the cluster galaxies
• At these low redshifts, photo-z errors result in
  mis-identifications of cluster membership.
• Statistical gravitational lensing of background
  sources can be significant for these lower
  redshift fields.
• Background sources can be brighted into a flux
  limited sample by lensing.
• Angular Correlation measures for Radio and
  Optical AGN show over densities on scales of
  0.7-1.0 Mpc at z0.3

Models from Dolag and Bartelmann, 1997
Norman Impey, 2000
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Future Plans

• 5 Additional clusters for analysis
• More DLS color data is now available for
  measuring additional photometric redshifts
• Applications for 4m time to get redshifts of
  brighter sources
• 8m time on young merging cluster galaxies for
  kinematical analysis of these clusters.
• Determine the AGN fraction in young and merging
  clusters.
• Address the possibility of statistical lensing in
  these clusters.

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Summary

• DLS cluster sample is the ONLY cluster sample
  selected by weak lensing shear techniques and is
  not dependent on cluster dynamical state.
• A large number of identified clusters show X-ray
  substructure.
• X-ray point sources in the fields of DLS weak
  gravitational lensing discovered fields show and
  aversion to the densest mass distribution as
  determined by gravitational shear mass maps.
  Surface density shows peaks in the core and at
  1.5 Mpc.
• Spectroscopic redshifts for X-ray sources are
  needed in order to eliminate contamination by
  background sources. An accurate census of
  cluster (versus background) AGN is essential to
  the use of their distribution to understand
  cluster formation and AGN triggering.