The Clowes-Campusano Large Quasar Group Survey

Transcription

1 The Clowes-Campusano Large Quasar Group Survey L. Haberzettl G. Williger (UofL, USA) J.T. Lauroesch (UofL, 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. Soechting (Univ. Lancashire, UK) K. Harris (Univ. Lancashire, UK) C. Haines (Univ. Birmingham, UK) J. Loveday (Univ. Sussex, UK) D. Valls-Gabaud (Obs. de Paris, F) N. Nesvadba (Obs. de Paris, F)

2 Outline Background - How to find them? - Significance of LQGs - History of the CCLQG The CCLQG Survey LBGs in the CCLQG Future

3 Background: LQGs discovered first by Webster 1982 close triplet + one more distant QSO at z~0.37 scales ~75 h-1 Mpc 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 Mpc with concentrations of 5-20 QSO's to large to be virialized, probable relics of large scale fluctuations rare (4σ) structures, ~1/3 space density of super-clusters

4 How to find them? duration of QSO phase ~107 yr much shorter than timescale for quiescent evolution of AGN and age of Universe at any time only small number of galaxies in QSO phase QSOs should be randomly distributed comparing real QSO distributions to catalogs of random object distributions using spatial correlation functions ξ(r) = (<DD(r)>nr2/<RR(r)>n2) - 1 search for Large Scale Structures

5 Barrow et al Zwicky Galaxy Catalog galaxies in the North Galactic Cap with Pmag 14 mag and δ 0 and b 40 Random Sample galaxies over the same sky area

6 Minimal Spanning Tree (e.g. Barrow et al. 1985) generalization of the nearest-neighbor or friend-of-friend method connecting points with unique path distribution in tree length: 1D: w1(l) = 1/l0 exp(-l/l0) with <l> = l0 2D: w2(l) = 2l/l02 exp(-l2/l02) with <l> = (2π)/2 l0 minimal tree if sum of length of segments is minimal MST can be used to identify under- and over-dense regions

7 defining thresholds for max. (over-dense) and min. (under-dense) length of branches lt and the min. number of objects in a domain M 3D: density of clusters with l lt is higher than minimum density ρt <ρ><l3>/lt3 strongly depends on the choice of lt,m and determining the statistical significance

8 Finding Structures (Barrow et al. 1985) two reduction methods to find structures a) pruning: remove all branches with k p b) separating: remove edges who exceed cut-off length

9 MST pruned to level 10 (branches k 10 removed) mean edge length:<lz> = rad (1.232 ) and <lr> = (1.530 )

10 MST pruned and separated cut-offs: 2<lz> and 1.6<lr> rad (3.142 ) separation in both cases

11 Barrow et al Zwicky Galaxy Catalog galaxies in the North Galactic Cap with Pmag 14 mag and δ 0 and b 40 Random Sample galaxies over the same sky area

12 3D-MST pruned and separated cut-offs: 3<lCfA> and 1.8<lr> 10.2 Mpc separation in both cases only branches with 10 edges are shown

13 frequency distribution of MST(Zwicky) shows excess of large and small lz frequency distribution of MST (random) follows Gauss distribution centered on <lr>

14 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 (BJ 20.0 mag) on scales ~60 h-1 Mpc Clowes & Campusano (1991) CCLQG 18 QSOs at z~1.3 (BJ 20 mag) on scales ~120x240 h-2 Mpc2 elongated overall and clumpy inner structure Komberg et al. (1996) 10 LQGs from nearest neighbor method QSOs with M < -23 mag B z ~ and h-1 Mpc scales

15 Pilipenko (2007) extended QSO clusters search in 2dF+SDSS QSO catalogs (> 100,000 QSOs) 18 new LQG identified by MST + 2 LQG confirmed 6 16 QSOs on scales ~ h-1 Mpc two groups of LQGs 14 LQGs with 6 8 members on scales ~60 h-1 Mpc spatial overdensity l03/<l3> 10 6 LQGs with members on scales ~140 h-1 Mpc (Jumbo LQGs) spatial overdensity l03/<l3> 4 space density: <ρ> 7 h3 Gpc3 ~ Jumbo LQGs morphologies: <ε> = 0.8 walls+blobs (ε = Ltrunk/Ltree<1) rather than filaments (ε~1)

16 History of the Clowes-Campusano LQG automated search on UKST objective-prism plate (~25.3 deg2) UJ5846P ESO/SERC field 927 α= 10:40:00 δ=+05:30:00 61 QSOs (29 S-band + 32 W-band) with 0.14<z< QSOs with 1.2 z 1.4 selection effect by the objective-prism Ly-α emission shifted in the blue at z>1.8 <z> = cover 2.5 x 5 on the sky banana like structure 8 additional QSOs from spectr. follow-up (Clowes et al. 1999)

17 clustering scale ~1 (~35 h-1 Mpc) power spectrum analysis Power Spectrum Analysis 2D MST Q=1 no clustering

18 CCLQG z~1.3 3 x MgII-absorber overdensity Williger et al LQG z~0.8 2 x MgII-absorber overdensity discovery of 2nd foreground LQG

19 Haines et al CTIO BTC 4m V,I data ~0.25 deg2 subfield 31 x 27 h-2 Mpc2 at z ~ x overdensity in red galaxies 3 x overdensity in red galaxies dashed contour 1.65 gal. arcmin-2

20 Clowes-Campusano Large Quasar Group Survey ~2 deg2 imaging and spectroscopy survey from UV NIR

21 Existing Data Set: 2 x 1.2 GALEX FUV+NUV mlim~24 mag SDSS u,g,r,i,z ~1.6 Bok g mlim ~ 26 mag 2 x 1 CFHT r+z mlim ~ 26 mag mlim ~ 24 mag ~1.2 KPNO 2.1m FLAMINGOS NIR J+Ks ~600 Magellan IMACS spectra 2 additional GALEX observations as part of the Deep Imaging Survey

22 Survey Summary Telescope Band Size expos. Time Status N: 22902s (FUV); 38623s (NUV) S: 20827s (FUV); 33021s (NUV) analyzed 3σ detect. limit (Abmag) ~25 (FUV), ~25 (NUV) ~25 (FUV), ~25 (NUV) GALEX FUV,NUV 1.2 deg 2.1m KPNO J, Ks 1.6x1.6 deg2 N: 7200s (J); 9600 (Ks) 75% reduced ~20 (J) 2.3m Bok g reduced CFHT r,z 1.2x1.2 deg2 N: 16800s N: 15800s (r); 3720s (z) 1 deg2 S: 6120s (r); 3400s (z) 6.5 Magellan A 0.6x0.7deg2 N: 12600s analyzed 25% reduced ~26.5 N: ~27.5 (r), ~25.5 (z) S: ~27 (r), ~25.5 (z)

23 FUV NUV completeness of GALEX data IRAF+Galfit: N - GALEX background - IRAF artificial galaxy catalog - Galfit photometry - SExtractor search S 80-90% complete down to mfuv,nuv = 24 mag ~70% complete down to mnuv = 24.5 mag

24 Survey Aim galaxy populations in LQGs Lyman red Break Galaxies (LBGs) galaxy population environmental red sequence/blue cloud at z~1 in dense environment QSO/AGN effects on galaxy evolution feedback mechanism Large Scale Structure (LSS) formation and evolution

25 Lyman Break Galaxies (LBGs) search for LBGs at z~1 using FUV-dropout technique Lyman Break 912 Å at z~1 FUV-dropout examples: FUV NUV FUV NUV SDSS

26 LBG search + selection criteria GALEX NUV selected sample: ~15,800 objects SDSS DR5 cross-correlation: ~13,800 primary counter parts selection criteria for LBGs from Burgarella et al. (2006): mnuv 24.5 mag + FUV NUV 2 additional selection criteria: SDSS photo type = GALAXY resulting sample of 1,023 LBG candidates

27 photometric redshifts: Hyperz (Bolzonella et al. 2000) 7 band photometry FUV,NUV+5 SDSS bands compared to SDSS spectroscopy & MegaZ catalog zsdss = 0.06 for z 0.4 zmegaz = 0.08 for 0.4 z 0.8

28 photometric redshift distribution z = 0.05 LBG candidates LQG@z~0.8 CCLQG@z~1.3

29 selecting redshift+luminosity limited subsample 2 redshift bins in front of the LQGs LQG@z~0.8 CCLQG@z~1.3 bright: MNUV M*NUV faint: MNUV > M*NUV Arnouts et al. (2005)

30 SFHs of averaged LBG SEDs 2-fit of averaged and normalized LBG SEDs to library of PÈGASE models 3 Gyr tbest 7 Gyr although fits with 250 tyoungest 800 are acceptable CCLQG@z~1.3 3 Gyr tbest 7 Gyr

31 ~500 Myr results for best fitting ages show significant older tbest than Burgarella et al (250 tbest 500 Myr) ~250 Myr Burgarella sample include fainter LBGs younger star bursts younger averaged SEDs? Role of dust?

32 LBG concentrations + filaments LBGs in proximity to QSOs QSO feedback mechanism?

33 red galaxies tend to avoid QSOs formation of large filaments

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35 Future Plans immediate future: - Bok+90prime observations g in southern field medium band imaging (N,S) - CFHT queue observation r+z extend existing field ~5 deg2

36 next projects: - stellar masses of LQG galaxies (LBG+red) - spatial correlation analysis - color evolution at z~1-1.5? - global SFRs at z~1? - LSB galaxies - AGN contribution in the LQGs - search for more jumbo LQGs - morphologies of LQG galaxies

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