Radio galaxies in 6dFGS: influence of the supercluster

environment ?

Credits : A Flight Through the Universe -- Swinburne University -- P. Bourke

Jean-Christophe Mauduit1, Gary Mamon1, Gary J. Hill2

1 Institut d’Astrophysique de Paris, 2 University of Texas at Austin

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 ?

No clear picture from various studies !

Degeneracy pb: RG types, redshift, environments …

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

Motivations

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

Brand et al. 03

And in local superclusters z < 0.1?

Shapley supercluster (SSC)

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 ?

FLASH – FLAIR Hydra Shapley(Kaldare et al. 2003) Hydra-Centaurus cat based (UKST)limit of

3141 galaxies with redshift

7.16Jb

Optical input catalogs: 6dFGRS U FLASH

FLASH

6dF

6dFGS: 6 degree Field Galaxy Survey (Jones et al. 2004)

K 12.75, 52081 galaxies

only quality factor of Q = 4

doubles removal

selection in FLASH area

4018 galaxies retrieved

6365 galaxies total

A tour of the area via the

final catalog

Shapley supercluster

Core (A3558)

Northwestern extension(Abell 3528)

Front Eastern Wall

Broad connecting arm

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

mJyS GHz 5.34.1

Redshift catalogues :

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

Cross-ID within 15”

Radio contours start from 3σ by step of √2

Visually checked matches

Overall distribution of radio galaxies in LSS

Radio galaxies trace fairly well the overall large scale structure

Restriction to “SSC area” in velocity space due to the completeness limit :

10000 < v < 18800 kms-1

Highly incomplete beyond 20000 kms-1

Pb for statistical investigation of the area : Malmquist bias

‘’Blind’’ classification between AGNs & SBGs

Figure from Sadler et al. 02

also shown is Machalski & Godlowski 00

AGN / SBG limit :

1.23)log( RL

In our radio galaxy sample : SFGs, SBGs, AGNs ?

Rough radio galaxy classification

29 AGNs & 155 SBGs

Yun et al. 01 :

Selection effects

Volume-limited sample :

vvv 1439014390

1

min2min 14

c

vvS

c

vvDL LR

S 7.0

SFG / SBG limit : 31.22)log( RL

+ AGN / SBG limit :

Legend :

Black = All galaxies

Red = AGNs

Blue = SBGs

Green = Clusters

A qualitative view of the

RG distribution in the area

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

Data (black)

Fit & simulated catalog (red) (α,δ) plots

(α,v) plots

black ellipse shows SSC cut out

Taking care of the boundary problems

Random catalog generation

( α,δ )

( αrdm,δrdm

)

(α,v )

(αrdm,vrdm )

The raw statistics

Log LRLog LR/LK

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 …

3 Mpc20 Mpc

Lradio/LK vs rho_env

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

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

5.11/0 virrr

(see Lokas & Mamon 2001)

Cumulated cluster profiles

Same situation for radio-loud

Radio-quiet prefer outer regions

Radio-loud follow overall distrib.

Radio-quiet seem more concentrated inside clusters

1/0 virrr

Results differ from more general investigations of Best 04, Kauffmann et al. 04

( SFG fraction decrease with increasing density)

Temporary results !

5.1/0 virrr

Comparison to projected NFW profiles

Projected mass profiles

e.g. : Lokas & Mamon 2001

NFW mass profiles (NFW 1997)

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 ?

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

SSC through cosmic flows ?

Hoffman et al. astro-ph/0102190

SSCPossible detection :

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 ?

dHczpec 0v

nD

Thank you !

Clusters velocity dispersions vs distance to SSC center

angular

z-space

Lradio Lradio / LK

There is a significant anti-correlation at large scales – reinforced by SSC cut out !

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 ?

Reminder: large-scale structures scales (LSS)

Typical scales of structures :

Groups & poor clusters :

,

,

Rich clusters :

,

,

Superclusters :

,

Mpchr 111.0

Mpchr 121

Mpchr 1100

1750 skm

1250 skm

152Cclusters/S N

303gals N

30030gals N