1. The Clowes-Campusano Large Quasar Group Survey G. Williger (UL, USA) L. Haberzettl (UL, USA) J.T. Lauroesch (UL, USA) M. Graham (Caltech, USA) R. Davé (Steward Obs., USA) A. Koekemoer (STScI, USA) L. Campusano (Univ. de Chile, CL) R. Clowes (Univ. Lancashire, UK) I. Söchting (Oxford Univ., UK) K. Harris (Univ. Lancashire, UK) C. Haines (Univ. Birmingham, UK) J. Loveday (Univ. Sussex, UK) D. Valls-Gabaud (Obs. de Paris, F) M. Lehnert (Obs. De Paris, F) N. Nesvadba (Univ. Paris-Sud, F)

2. The Clowes-Campusano LQG Survey Outline Background - Why important? - How to find them? - LQG "zoo" The CCLQG Survey Lyman Break Galaxies in the CCLQG Future

3. Why Large Quasar Groups Important Quasars - Signatures of physical mechanisms - supermassive black holes+high accretion - massive haloes - feeding by gas-rich (major?) mergers? - associated with high star formation - Quenching in high density regions (gas stripping etc.) - feedback mechanisms - strong winds - high ionization Quasars thrive in somewhat overdense but not too overdense regions

4.  duration of quasar phase << timescale for  quiescent evolution of AGN and age of Universe LIFETIMES: ~10-30 (1-100?) Myr scales at any time only small number of galaxies in quasar phase Quasars: a stage of galaxy formation

5. Large Quasar Groups: Efficient Sites of Quasar-Galaxy Relations Galaxies bear signatures of merger rates   give clue to recent merger activity in region Galaxies give star formation histories   clue to past merger/galaxy formation in region Galaxies give measure of halo masses Deep, wide galaxy surveys with lots of quasars   efficient laboratories for studying physical mechanisms in both galaxy and quasar evolution

6.  DISCOVERY: Webster 1982 → close triplet + one more distant QSO at z~0.37 scales ~75 h -1 Mpc  soon after: two other LQGs: Crampton et al. (87,89; 23 QSOs) at z~1.1 Clowes & Campusano (1991; 18 QSOs) z~1.3  large irregular shaped, filamentary structures on scales of 50-200 Mpc with concentrations of 5-20 QSO's  too large to be virialised, probable relics of large scale fluctuations  CURRENT VIEW: rare (4σ) structures, ~1/3 space density of galaxy super-clusters (Pilipenko 2007) Background: LQGs

7. Assumption: quasars randomly distributed among galaxies with sufficient gas accretion  compare real QSO distributions to random  catalogues usual spatial correlation functions not efficient for finding filamentary structures Alternatives: minimal spanning tree, skeletons, spine of cosmic web How to find Large Quasar Groups

8. How to Find Structures Barrow et al. 1985 2 Zwicky Galaxy Catalog 2 Random Sample 1091 galaxies in the North Galactic Cap with Pmag ≤ 14 mag and δ≥ 0 and b ≥ 40 ° 1091 galaxies over the same sky area

9. Minimal Spanning Tree (e.g. Barrow et al. 1985)  generalization of the nearest-neighbour or friend-of-friend method connect points with unique path distribution in tree length: 1D: w 1 (l) = 1/l 0 exp(-l/l 0 ) with = l 0 2D: w 2 (l) = 2l/l 0 2 exp(-l 2 /l 0 2 ) with = √( 2 π)/2 l 0 ⇩ minimal tree if sum of length of segments is minimal  MST can be used to identify under- and over-dense regions

10. Minimal Spanning tree  define thresholds l t for  maximum (over-dense)  minimum (under-dense) length of branches l t and  minimum number of objects in a domain M  3D: density of clusters with l ≥ l t is higher than threshold density if ρ t h  /l t 3 (strongly depends on the choice of l t,M, determines statistical significance)

11. Finding Structures in MST  two reduction methods to find structures a) prune: strip branches of level k (≥3 connections) of dead-end connections b) Prune + separate: also remove edges above a cutoff length

12. The Clowes-Campusano LQG Survey MST pruned to level 10 (branches k ≤ 10 removed) mean edge length: = 0.0215 rad (1.232 ° ) and = 0.0267 (1.530 ° ) random

13. MST: pruned and separated cut-offs: 2 and 1.6 0.043 rad (3.142 ˚ ) separation in both cases random

14. The Clowes-Campusano LQG Survey Barrow et al. 1985 2 Zwicky Galaxy Catalog 2 Random Sample 1091 galaxies in the North Galactic Cap with Pmag ≤ 14 mag and δ≥ 0 and b ≥ 40 ° 1091 galaxies over the same sky area

15. The Clowes-Campusano LQG Survey 3D-MST pruned and separated cut-offs: 3 and 1.8 10.2 Mpc separation in both cases only branches with ≥ 10 edges are shown random

16. MST length distributions frequency distribution of MST(Zwicky) shows excess of large and small l zwicky frequency distribution of MST (random) follows Gauss distribution centered on random length

17. The Clowes-Campusano LQG Survey Statistical Significance of LQGs  first known LQGs:  Webster et al. (1982) – triplet at z~0.37 and one more distant QSO on scales ~75 h -1 Mpc  Crampton et al. (1987) – CCH LQG 18 QSOs at z~1.1 (B J ≤ 20.0 mag) on scales ~60 h -1 Mpc  Clowes & Campusano (1991) – CCLQG 18 QSOs at z~1.3 (B J ≤ 20 mag) on scales ~120 x 240 h -2 Mpc 2 elongated overall and clumpy inner structure  Komberg et al. (1996) 10 LQGs from nearest neighbor method  10 – 25 QSOs with M B < -23 mag  z ~ 0.6 – 2.1 and  40 – 160 h -1 Mpc scales

18. Pilipenko (2007) LQG survey  search in 2dF+SDSS QSO catalogs (> 100,000 QSOs)  18 new LQG identified by MST + 2 LQG confirmed  contain 6 – 16 QSOs on scales ~40 – 155 h -1 Mpc  LQG TYPES:  "Regular": 14 LQGs  6 – 8 members, scales ~60 h -1 Mpc,  spatial overdensity ≈ 10  "Jumbo": 6 LQGs  15 – 19 members, scales ~140 h -1 Mpc,  spatial overdensity ≈ 4  space density: ~ 7 h 3 Gpc 3 ⇨ ~500 – 1000 Jumbo LQGs  morphologies: walls+blobs rather than filaments

19. Clowes-Campusano LQG  automated search on UKST objective-prism plate (~25.3 deg 2 ) ESO/SERC field 927 (1045+05 J2000) 18 (up to 23+ depending on selection) quasars with 1.2≤z≤1.4, Bj<20.4 (BRIGHT!) = 1.27 selection effect by objective- prism -- Ly-α emission shifted out of selection band at z>1.8 cover 2.5 ° x 5 ° on the sky banana like structure

20. The Clowes-Campusano LQG Survey 2D MST Power Spectrum Analysis clustering scale ~1 ° (~35 h -1 Mpc) power spectrum analysis Q=1 no clustering

21. Subset of CCLQG (2.5x5 deg total, ~20 QSOs) CCLQG z~1.3LQG z~0.8 3 x MgII-absorber overdensity2 x MgII-absorber overdensity discovery of 2 nd foreground LQG Williger et al. 2002

22. Clowes-Campusano LQG Survey Galaxy populations in LQGs  Lyman Break Galaxies (LBGs)  red galaxy population  red sequence/blue cloud at z~1 in dense  environment (colour-density inversion  at z~1?)  Quasar-galaxy correlations/feedback  mechanism

23. Comparison to other wide deep fields Clowes-Campusano Large Quasar Group Survey ~2 deg 2 imaging and spectroscopic survey from UV – NIR

24. Early Results 0.5º subfield: Red Galaxies Haines et al. 2004 CTIO BTC 4m V,I data ~0.25 deg 2 subfield 31 x 27 h -2 Mpc 2 at z ~ 1.2 3 x overdensity in red galaxies 2 x overdensity in red galaxies dashed contours 1.65 gal. arcmin -2

25. The Clowes-Campusano LQG Survey 2 x 1.2 ˚ GALEX FUV+NUV m lim ~24.0 mag SDSS u,g,r,i,z ~1.6 ˚ Bok g m lim ~ 26 mag 2 x 1 ˚ CFHT r+z m lim ~ 26 mag m lim ~ 24 mag ~1.2 ˚KPNO 2.1m FLAMINGOS NIR J+Ks ~1° UKIRT Ks-band ~600 Magellan IMACS spectra Existing Data Set: 2 GALEX Medium Imaging Survey (used for WiggleZ bright LBGs)

26. The Clowes-Campusano LQG Survey Survey Summary

27. N S FUVNUV The Clowes-Campusano LQG Survey completeness of GALEX data IRAF+Galfit: - GALEX background - IRAF artificial galaxy catalog - Galfit photometry - SExtractor search 80-90% complete down to m FUV,NUV = 24 mag ~70% complete down to m NUV = 24.5 mag

28. Efficient search for z~1 galaxies Lyman Break 912 Å at z~1 search for LBGs at z~1 using FUV-dropout technique FUV NUV FUV-dropout examples: FUV NUVSDSS Lyman Break Galaxies (LBGs)

29. Lyman Break Galaxies: Star-Formers LBGs found over 0.5<z<7 Common technique, signature of young stars Z~4-5: lower mass systems, galaxies assembling Z~3: progenitors of massive ellipticals Z~2: use BzK technique (optical proxy), less massive systems (progenitors of grab-bag: S0, some massive spirals) Z~ 1: One field studied (Burgarella et al.)

30. The Clowes-Campusano LQG Survey LBG search + selection criteria GALEX NUV selected sample: ~15,800 objects SDSS DR5 cross-correlation: ~13,800 primary counterparts LBG selection criteria - Burgarella et al. (2006): m NUV ≤ 24.5 mag + FUV – NUV ≥ 2 additional selection criteria: resolved by Sloan Survey (SDSS) - extended source = galaxy resulting sample ~1000 LBG candidates

31. The Clowes-Campusano LQG Survey photometric redshifts: Hyperz (Bolzonella et al. 2000) 7 band photometry – FUV,NUV+5 SDSS bands compared to SDSS spectroscopy & MegaZ catalog z SDSS = 0.06 for z ≤ 0.4 z MegaZ = 0.08 for 0.4 ≤ z ≤ 0.8

32. The Clowes-Campusano LQG Survey photometric redshift distribution LBG candidates LQG@z~0.8 CCLQG@z~1.3 dz = 0.05-0.10

33. The Clowes-Campusano LQG Survey Arnouts et al. (2005) selecting redshift+luminosity limited subsample 2 redshift bins in front of the LQGs LQG@z~0.8 CCLQG@z~1.3 bright: M NUV ≤ M * NUV faint: M NUV > M * NUV

34. LBGs: old population component SFHs of stacked/averaged LBG SEDs χ 2 -fit of averaged and normalized LBG SEDs to library of PÉGASE models LQG@z~0.8 3 Gyr ≤ t best ≤ 7 Gyr CCLQG@z~1.3 3 Gyr ≤ t best ≤ 7 Gyr although fits with 250 ≤ t youngest ≤ 800 are acceptable

35. The Clowes-Campusano LQG Survey results for best fitting ages show significant older t best than Burgarella et al. 2007 (250 ≤ t best ≤ 500 Myr) Burgarella sample include fainter LBGs  younger star bursts  younger averaged SEDs? Our survey shallower, biased toward higher mass LBGs? ~500 Myr ~250 Myr

36. Results Affected by Confusion? GALEX point spread function ~5-6 arcsec Depth of NUV~23.5-24 begins to be affected by confusion Compare with deep, 1 arcsec resolution CFHT r-band images  ~20% of LBGs have >1 r-selected counterpart  Confusion effect is small compared to scatter (factor of few to 10-100) in stacked spectral energy distributions

37. QSOs on LBG Cluster Outskirts? LBG concentrations + filaments LBGs in proximity to QSOs  QSO feedback mechanism?

38. z~0.8 Quasar-LBG correlations 117 LBGs, 17 quasars, 10000 random quasar placements P=0.0027 P=0.0051,0.0056 1'~0.5 local Mpc

39. QSOs on (red) cluster outskirts? red galaxies tend to avoid QSOs formation of large filaments Need better photometric redshifts (near-IR) to bin in redshift

40. The Clowes-Campusano LQG Survey

41. Summary/Conclusions 1) Large quasar groups ~ quasar superclusters, useful laboratories for studying quasar-galaxy relations in large structure contexts 2) Clowes-Campusano LQG field being explored in 2 deg 2 multi-wavelength survey 3) z~1 LBGs several Gyr old, older than only other study – due to shallower survey, more massive LBGs? 4) LBG-quasar correlation suggested to eye but does not show robust statistical signal (yet?) – need more data

42. The Clowes-Campusano LQG Survey Future Plans future: - Bok+90prime observations g in southern field medium band imaging (N,S) (done Mar 2008) - AAT spectra - CFHT queue observation r+z extend existing field ~5 deg 2 - - GALEX PI team Medium Deep Survey Extension: 6 fields - - Science: individual galaxy SEDs, color-density relation, AGN, … - - Study LQG analogues in Millennium Simulation - - Mark Younger discovered 3 z~2 LQGs – theory v. data

43. The Clowes-Campusano LQG Survey next projects: - stellar masses of LQG galaxies (LBG+red) - spatial correlation analysis - color evolution at z~1-1.5? - global SFRs at z~1? - AGN contribution in the LQGs - search for more “jumbo” LQGs - morphologies of LQG galaxies - Other science: - LSB galaxies - Lya forest – galaxy correlations

44. The Clowes-Campusano LQG Survey