Large-Scale Structure beyond the 2dF Galaxy Redshift Survey

1. Large-Scale Structure beyond the 2dF Galaxy Redshift Survey Gavin Dalton Kyoto FMOS Workshop January 2004 (Oxford & RAL)

2. Overview • Summary of 2dFGRS design • Key results… defining contemporary cosmology • Key results… galaxies as tracers of LSS • Key results… relationship to CMB measurements • FMOS Possibilities – LSS beyond z=1 • Input data: Wide-Field IR imaging surveys • Survey Design Issues

3. Results from the 2dF Galaxy Redshift Survey Target: 250,000 redshifts to B<19.45 (median z = 0.11) 250 nights AAT 4m time 1997-2002

4. Final 2dFGRS Sky Coverage NGP SGP Final redshift total: 221,283

5. 2dFGRS Redshift distribution • N(z) Still shows significant clustering at z < 0.1 • The median redshift of the survey is <z> = 0.11 • Almost all objects have z < 0.3.

6. Cone diagram: 4-degree wedge

7. Fine detail: 2-deg NGP slices (1-deg steps) 2dFGRS: bJ < 19.45 SDSS: r < 17.8

8. 2dFGRS power-spectrum results Dimensionless power: d (fractional variance in density) / d ln k Percival et al. MNRAS 327, 1279 (2001)

9. Confidence limits Wmh = 0.20 ± 0.03 Baryon fraction = 0.15 ± 0.07 ‘Prior’: h = 0.7 ± 10% & n = 1

10. Power spectrum: Feb 2001 vs ‘final’

11. Model fits: Feb 2001 vs ‘final’ Wmh = 0.20 ± 0.03 Baryon fraction = 0.15 ± 0.07 Wmh = 0.18 ± 0.02 Baryon fraction = 0.17 ± 0.06 if n = 1: or Wmh = 0.18 e1.3(n-1)

12. r Redshift-space clustering s p • z-space distortions due to peculiar velocities are quantified by correlation fn (,). • Two effects visible: • Small separations on sky: ‘Finger-of-God’; • Large separations on sky: flattening along line of sight

13. Fit quadrupole/monopole ratio of (,) as a function of r with model having 0.6/b and p (pairwise velocity dispersion) as parameters Model fits to z-space distortions  and   = 0.4, p= 300,500 • Best fit for r>8h-1Mpc (allowing for correlated errors) gives:  = 0.6/b = 0.43  0.07 p =385  50 km s-1 • Applies at z = 0.17, L =1.9 L* (significant corrections)  = 0.3,0.4,0.5; p= 400 99% 

14. Early PC3 PC2 PC1 Late Mean spectrum Galaxy Properties:Spectral classification by PCA • Apply Principal Component analysis to spectra. • PC1: emission lines correlate with blue continuum. • PC2: strength of emission lines without continuum. • PC3: strength of Balmer lines w.r.t. other emission. • Define spectral types as sequence of increasing strength of emission lines • Instrumentally robust • Meaning: SFR sequence

17. Clustering as f(L) Clustering increases at high luminosity: b(L) / b(L*) = 0.85 + 0.15(L/L*) suggests << L* galaxies are slightly antibiased - and IRAS g’s even more so: b = 0.8

18. Redshift-space distortions and galaxy type • Passive: •  = m0.6/b = 0.46  0.13 p =618  50 km s-1 • Active: •  = m0.6/b = 0.54  0.15 p =418  50 km s-1 Consistent with Wm = 0.26, bpassive = 1.2, bactive = 0.9

19. Power spectrum and galaxy type shape independent of galaxy type within uncertainty on spectrum

20. Relation to CMB results curvature baryons total density Combining LSS & CMB breaks degeneracies: LSS measures Wmh only if power index n is known CMB measures n and Wmh3 (only if curvature is known)

21. 2dFGRS + CMB: Flatness CMB alone has a geometrical degeneracy: large curvature is not ruled out Adding 2dFGRS power spectrum forces flatness: | 1 - Wtot | < 0.04 Efstathiou et al. MNRAS 330, L29 (2002)

22. Impact of WMAP

23. likelihood contours pre-WMAP + 2dFGRS 147024 gals scalar only, flat models

24. likelihood contours post-WMAP + 2dFGRS 147024 gals scalar only, flat models - WMAP reduces errors by factor 1.5 to 2

25. likelihood contours post-WMAP + 2dFGRS 213947gals scalar only, flat models

26. Vacuum equation of state (P = w rc2) w shifts present horizon, so different Wm needed to keep CMB peak location for given h w < - 0.54 similar limit from Supernovae: w < - 0.8 overall 2dFGRS

27. Key Points • Basic underlying cosmology now well determined • CMB + 2dFGRS implies flatness • CMB + Flatness measures Wm h3.4 = 0.078 • hence h = 0.71 ± 5%, Wm = 0.26 ± 0.04 • w < - 0.54 by adding HST data on h (agrees with SN) • Clustering enhanced as F(L) • Different bias for different galaxy types, but shape of P(k) is identical. • Many diverse science goals realised in a single survey design

28. FMOS Possibilities for LSS at z>1 • Wavelength Range (single exposure) 0.9mm<l<1.8mm • OII enters at z=1.4 • 4000Å break enters at z=1.2 • Hα enters at z=0.4 • OII leaves at z=3.8 • Hα leaves at z=1.74 Complex p(z) due to atmospheric bands and OH mask. New field setup time is FAST • Sensitivity: Clear IDs for H=20 magnitude limit: 20 minutes for late-types (50 minutes for early types) [But P(k) shape insensitive to type!!!] • Could obtain as many as 7000 galaxy spectra/night!

29. Input Data: Wide-Field IR Surveys • Natural starting point is the UKIDSS DXS • 35 square degrees to K=21.5, J=22.5 (5) ~ 60000 galaxies (zP1, HO20) UKIDSS fields: 2-year plan LAS DXS UDS GPS GCS

30. Upcoming wide-field IR imaging - VISTA 1.67 degree focal plane, 16 2048x2048 HgCdTe arrays Single instrument survey telescope

31. VISTA Capabilities • FOV 1.67 degrees • Pixel sampling 0.33 arcseconds • YJHK filter set as baseline (3 empty slots) • 70% of VISTA time must be dedicated to ‘public’ surveys with emphasis on meeting the science goals of the original VISTA consortium • Extension of UKIDSS DXS in 1 year would cover 500 square degrees. • Commissioning begins April 2006 • Data processing and archiving in common with UKIDSS – fast access to final catalogues. • ESO effectively committed to supporting UKIDSS/VISTA operations with complementary VST surveys.

32. FMOS Survey Design Issues • Optimal survey speed influenced by reconfiguration and field acquisition times… • Possibilities for large-scale surveys with relatively bright limits. • Optimal use of telescope time may dictate merged surveys (c.f. 2dF GRS & QSO surveys) with multiple science goals (i.e. evolution; clusters; EROs; SWIRE all may be included in LSS survey). • Input data for ambitious surveys will be available on appropriate timescales, but much preparation required. • No problem with spreading a large survey over several years since effectively no competition! – e.g. think in terms of a survey of ~100 FMOS nights over 5 years.