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

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

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

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  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. 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 ? What do we know about radio galaxy 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 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 FLASH • 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 6dF 6365 galaxies total

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

  6. Radio catalogue NVSS (Condon et al .1998) (FIRST not reaching far enough south) 99% complete at 45” resolution 68000 candidates Cross-identification between radio and optical galaxies • 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 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 < v < 18800 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,v ) ( α,δ ) 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/LK Log LR

  14. 3 Mpc 20 Mpc Estimating environment density of RGs Lradio/LK vs rho_env • 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 …

  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 fromStruble & 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. Temporary results ! 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 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 ? SSC Possible detection : Hoffman et al. astro-ph/0102190

  22. 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 ?

  23. Thank you !

  24. Clusters velocity dispersions vs distance to SSC center

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

  26. 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 ?

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

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