1. Radio galaxies in 6dFGS: influence of the supercluster environment ?
Jean-Christophe Mauduit1, Gary Mamon1, Gary J. Hill2
1 Institut d’Astrophysique de Paris, 2 University of Texas at Austin
Credits : A Flight Through the Universe -- Swinburne University -- P. Bourke

2. What do we know about radio galaxy environments ?
Large scale studies with correlation functions : 5 < r0 < 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 …

3. 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 < 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 ?

4. Optical input catalogs: 6dFGRS U FLASH
FLASH – FLAIR Hydra Shapley
(Kaldare et al. 2003)
Hydra-Centaurus cat based (UKST)
limit of
3141 galaxies with redshift
6dFGS: 6 degree Field Galaxy Survey (Jones et al. 2004)
K 12.75, galaxies
only quality factor of Q = 4
doubles removal
selection in FLASH area
4018 galaxies retrieved
6dF
6365 galaxies total

5. A tour of the area via the final catalog
Shapley supercluster
Broad connecting arm
Front Eastern Wall
A tour of the area via the final catalog
Core (A3558)
Northwestern extension
(Abell 3528)

6. 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 3σ by step of √2

7. Overall distribution of radio galaxies in LSS
Radio galaxies trace fairly well the overall large scale structure
Highly incomplete beyond kms-1
Pb for statistical investigation of the area : Malmquist bias
Restriction to “SSC area” in velocity space due to the completeness limit :
10000 < v < kms-1

8. ‘’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 :

9. Rough radio galaxy classification
Selection effects
Volume-limited sample :
Yun et al. 01 :
SFG / SBG limit :
29 AGNs & 155 SBGs
+ AGN / SBG limit :

10. A qualitative view of the RG distribution in the area
Legend :
Black = All galaxies
Red = AGNs
Blue = SBGs
Green = Clusters

11. 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 ρ for :
Normalize to N random catalogs
(same boudaries, smooth velocity distribution)
Projected space
Redshift-space

12. Taking care of the boundary problems
( α,δ )
(α,v )
Random catalog generation
(αrdm,vrdm )
( αrdm,δrdm )
Data (black)
Fit & simulated catalog (red)
(α,δ) plots (α,v) plots
black ellipse shows SSC cut out

13. The raw statistics
Log LR
Log LR/LK

14. Estimating environment density of RGs
Spearman tests on smoothed densities
Significant anti-correlation at big scales (> 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
Let’s look at cluster complexes …
Lradio/LK vs rho_env
3 Mpc
20 Mpc

15. 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

16. Cluster selection and stacking
30 clusters in the area
Table from Struble & Rood 1999, include: position, radii, members & σ
using pure NFW model :
Re-selecting cluster galaxies with :
Stacking of clusters in SSC area in
(see Lokas & Mamon 2001)

17. Cumulated cluster profiles
Temporary results !
Radio-loud follow overall distrib.
Radio-quiet seem more concentrated inside clusters
Same situation for radio-loud
Radio-quiet prefer outer regions
Results differ from more general investigations of Best 04, Kauffmann et al. 04
( SFG fraction decrease with increasing density)

18. Comparison to projected NFW profiles
NFW mass profiles (NFW 1997)
Projected mass profiles
e.g. : Lokas & Mamon 2001

19. 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 ?

20. 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

21. SSC through cosmic flows ?
Possible detection :
SSC
Hoffman et al. astro-ph/

22. Possible prospective studies
6dF-v : 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 ?

23. Thank you !

24. Clusters velocity dispersions vs distance to SSC center

28. Lradio Lradio / LK
angular
z-space
There is a significant anti-correlation at large scales – reinforced by SSC cut out !

30. 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 ?

31. Reminder: large-scale structures scales (LSS)
Typical scales of structures :
Groups & poor clusters :
, ,
Rich clusters :
Superclusters : ,