Radio galaxies in 6dFGS: influence of the supercluster environment ?

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Radio galaxies in 6dFGS influence of the
supercluster environment ?
Jean-Christophe Mauduit1, Gary Mamon1, Gary J.
Hill2
1 Institut dAstrophysique de Paris, 2
University of Texas at Austin
Credits A Flight Through the Universe --
Swinburne University -- P. Bourke
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What do we know about radio galaxy environments ?

• Large scale studies with correlation functions
  5 lt r0 lt 15 h-1 Mpc
• Peacock Nicholson 91, Bahcall Chokshi 92,
  Blake Wall 02, Overzier et al. 03,
• Magliochetti et al. 04, Croom et al 04, Brand et
  al. 04
• RGs cluster more strongly than gals but less
  than rich clusters.
• but where are they ?

• AGNs in cores of compact groups, SBGs rise
  from core to halo, Coziol et al. 98
• AGNs found within 3 Mpc of a cluster center,
  Soechting et al 02
• Increase of RG activity in clusters, Miller
  Owen 99
• Decrease of , Giancintucci 03, Venturi
  et al. 00

No clear picture from various studies !
Degeneracy pb ? RG types, ? redshift, ?
environments
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Motivations

• If RGs trace structures
• good probes of LSS to high-z
• (RGs luminous, rare and radio
• non affected by dust)

And in local superclusters z lt 0.1?
Shapley supercluster (SSC)
Brand et al. 03

• Distribution of radio gals. in SC, cluster
  complexes and clusters

• Effects of environment on radio galaxies
• AGNs and starbursts triggered, starved ?
  
• Dependency on dynamical state of the
  structure ?

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Optical input catalogs 6dFGRS U FLASH
6365 galaxies total
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A tour of the area via the final catalog
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Cross-identification between radio and optical
galaxies

• Radio catalogue
• NVSS (Condon et al .1998)
• (FIRST not reaching far enough south)
• 99 complete at
• 45 resolution
• 68000 candidates

• Redshift catalogues
• FLASH (Kaldare et al. 2003)
• 6dFGS (Colless et al. 2001)

Cross-ID within 15
Visually checked matches
Radio contours start from 3s by step of v2
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Overall distribution of radio galaxies in LSS

• Radio galaxies trace fairly well the overall
  large scale structure

Highly incomplete beyond 20000 kms-1 Pb for
statistical investigation of the area Malmquist
bias
Restriction to SSC area in velocity space due
to the completeness limit 10000 lt v lt 18800
kms-1
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Blind classification between AGNs SBGs
In our radio galaxy sample SFGs, SBGs, AGNs ?
Figure from Sadler et al. 02 also shown is
Machalski Godlowski 00
AGN / SBG limit
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Rough radio galaxy classification

• Selection effects
• Volume-limited sample

Yun et al. 01
SFG / SBG limit
29 AGNs 155 SBGs
AGN / SBG limit
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A qualitative view of the RG distribution in the
area
Legend Black All galaxies Red AGNs Blue
SBGs Green Clusters
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Estimation of the environment density of RGs

• Use of Gaussian smoothed densities on different
  scales
• Compute comoving or ang. separations between
  RGs opt. gals
• Derive ? for
• Normalize to N random catalogs
• (same boudaries, smooth velocity distribution)

Projected space Redshift-space
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Taking care of the boundary problems
(a,v )
( a,d )
Random catalog generation
(ardm,vrdm )
( ardm,drdm )
Data (black) Fit simulated catalog (red)
(a,d) plots (a,v) plots black
ellipse shows SSC cut out
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The raw statistics
Log LR/LK
Log LR
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Estimating environment density of RGs
Lradio/LK vs rho_env

• Spearman tests on smoothed densities
• Significant anti-correlation at big scales (gt
  99 )
• when looking at Lradio/LK vs environment
• Characteristic cut scales
• - Maximum scale at which no loss of
  correlation/significance 3 Mpc
• - Loss of correlation/significance 20 Mpc
• Lets look at cluster complexes

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Distribution in clusters complexes

• KS test on radio luminosity in two cluster
  complexes
• red galaxies within 8 h-1 Mpc of center, black
  rest

• Lradio distrib. in A3558 complex could be
  similar to the rest of the area
• (c.f. also quantitative results from Venturi
  et al. 00)
• Lradio distrib. in A3528 complex significantly
  different

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Cluster selection and stacking

• 30 clusters in the area
• Table from Struble Rood 1999, include
  position, radii, members s
• using pure NFW model
• Re-selecting cluster galaxies with
• Stacking of clusters in SSC area in
  

(see Lokas Mamon 2001)
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Cumulated cluster profiles
Temporary results !
Same situation for radio-loud Radio-quiet prefer
outer regions
Radio-loud follow overall distrib. Radio-quiet
seem more concentrated inside clusters
Results differ from more general investigations
of Best 04, Kauffmann et al. 04 ( SFG fraction
decrease with increasing density)
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Comparison to projected NFW profiles
NFW mass profiles (NFW 1997)
Projected mass profiles e.g. Lokas Mamon 2001
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• Best (2004) finds 9 radio-loud AGNs in
  super-structure at z 0.084
• Brand et al. (2003) 12 RGs at z 0.3 in 100
  Mpc large superstructures
• SSC in a special dynamical state at z 0.05 ?
• Evidence for cluster-cluster merging !

• Equal-mass cluster merging
• more encounters but less merging (too rapid)
• rps more effective (cluster-cluster
  merging dynamics)
• depends on the dynamical state of the merging
• Substructure merging
• Epoch of merging event important, Hanami et al.
  99

Stops radio activity ?
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Summary

• Anti-correlation at large scales (significant
  for LR/LK)
• Cluster complexes different central one
  devoid of RGs
• No overall quenching inside clusters ? Not
  understood ... Work in progress
• Link cluster-cluster merger SC dynamics to RG
  activity
• Need to carry out similar analysis on other
  supercluster (w/ diff. dynamics and/or at higher
  redshift)

Radio galaxy distribution depends on the overall
dynamical state of the LSS
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SSC through cosmic flows ?
SSC
Possible detection
Hoffman et al. astro-ph/0102190
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Possible prospective studies

• 6dF-v 15 000 galaxies (E/S0)
• Distances FP
• Velocity fields and density fields
• Bias
• Shapley dynamics via 6dF-v ?
• a possible amount of ? 100 galaxy peculiar
  velocities in the SSC ?
• able to see internal flows within the SSC ?

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Thank you !
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Clusters velocity dispersions vs distance to SSC
center
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Lradio Lradio / LK
angular z-space
There is a significant anti-correlation at
large scales reinforced by SSC cut out !
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Reminder (1) radio galaxies

• AGNs Seyferts, FRI, FRII, Blazars
• unified scheme model
• radio-quiet/loud
• fueling of the BH
• SBGs SFR higher than average
• bright at radio, IR, X-ray
• result of interactions, tidal, collisions
• several periods of activity ?

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Reminder large-scale structures scales (LSS)

• Typical scales of structures
• Groups poor clusters
• , ,
• Rich clusters
• , ,
• Superclusters
• ,