Large scale structure analysis with the 6dF Galaxy Survey LBNL, Berkeley, January 2012 Florian Beutler PhD supervisors: Chris Blake, Heath Jones Lister Staveley-Smith, Peter Quinn + Matthew Colless 26.01.2012 International Centre for Radio Astronomy Research Outline of the talk Big picture: What is the nature of dark energy? 1 Testing the expansion history of the Universe (dark energy EoS): Baryon Acoustic Oscillations (BAO) 2 Testing General Relativity: Redshift space distortions What is 6dFGS? Spectroscopic survey of southern sky (17,000 deg 2). Primary sample from 2MASS with Ktot < 12:75; also secondary samples with H < 13:0, J < 13:75, r < 15:6, b < 16:75. Median redshift z ≈ 0:05 (≈ 220 Mpc). Effective volume ≈ 8x107h−3 Mpc3 (about as big as 2dFGRS). 125.000 redshifts (137.000 spectra). What is a correlation function? The correlation function is defined via the excess probability of finding a galaxy pair at separation s: 2 dP = n [1 + ξ(s)] dV1dV2 A correlation function measures the degree of clustering on different scales. We have to count the galaxies at different separations s and calculate the correlation function via DD(s) ξ(s) = − 1 RR(s) (In my analysis I used the Landy & Salay estimator) In the early, radiation dominated Universe, radiation pressure leads to spherical sound waves (only baryons). CDM continues to collapse. At the time of decoupling the wave stalls. We end up with spherical shell around an over-density. Preferred galaxy formation in over-densities. The radius of the sphere is a preferred distance scale -> standard ruler. First detections in 2dFGRS and SDSS, Cole et al. (2005), Eisenstein et al. (2005). Baryon Acoustic Oscillations Gravity causes collapse of matter to over-dense regions. CDM continues to collapse. At the time of decoupling the wave stalls. We end up with spherical shell around an over-density. Preferred galaxy formation in over-densities. The radius of the sphere is a preferred distance scale -> standard ruler. First detections in 2dFGRS and SDSS, Cole et al. (2005), Eisenstein et al. (2005). Baryon Acoustic Oscillations Gravity causes collapse of matter to over-dense regions. In the early, radiation dominated Universe, radiation pressure leads to spherical sound waves (only baryons). At the time of decoupling the wave stalls. We end up with spherical shell around an over-density. Preferred galaxy formation in over-densities. The radius of the sphere is a preferred distance scale -> standard ruler. First detections in 2dFGRS and SDSS, Cole et al. (2005), Eisenstein et al. (2005). Baryon Acoustic Oscillations Gravity causes collapse of matter to over-dense regions. In the early, radiation dominated Universe, radiation pressure leads to spherical sound waves (only baryons). CDM continues to collapse. We end up with spherical shell around an over-density. Preferred galaxy formation in over-densities. The radius of the sphere is a preferred distance scale -> standard ruler. First detections in 2dFGRS and SDSS, Cole et al. (2005), Eisenstein et al. (2005). Baryon Acoustic Oscillations Gravity causes collapse of matter to over-dense regions. In the early, radiation dominated Universe, radiation pressure leads to spherical sound waves (only baryons). CDM continues to collapse. At the time of decoupling the wave stalls. Preferred galaxy formation in over-densities. The radius of the sphere is a preferred distance scale -> standard ruler. First detections in 2dFGRS and SDSS, Cole et al. (2005), Eisenstein et al. (2005). Baryon Acoustic Oscillations Gravity causes collapse of matter to over-dense regions. In the early, radiation dominated Universe, radiation pressure leads to spherical sound waves (only baryons). CDM continues to collapse. At the time of decoupling the wave stalls. We end up with spherical shell around an over-density. The radius of the sphere is a preferred distance scale -> standard ruler. First detections in 2dFGRS and SDSS, Cole et al. (2005), Eisenstein et al. (2005). Baryon Acoustic Oscillations Gravity causes collapse of matter to over-dense regions. In the early, radiation dominated Universe, radiation pressure leads to spherical sound waves (only baryons). CDM continues to collapse. At the time of decoupling the wave stalls. We end up with spherical shell around an over-density. Preferred galaxy formation in over-densities. First detections in 2dFGRS and SDSS, Cole et al. (2005), Eisenstein et al. (2005). Baryon Acoustic Oscillations Gravity causes collapse of matter to over-dense regions. In the early, radiation dominated Universe, radiation pressure leads to spherical sound waves (only baryons). CDM continues to collapse. At the time of decoupling the wave stalls. We end up with spherical shell around an over-density. Preferred galaxy formation in over-densities. The radius of the sphere is a preferred distance scale -> standard ruler. Baryon Acoustic Oscillations Gravity causes collapse of matter to over-dense regions. In the early, radiation dominated Universe, radiation pressure leads to spherical sound waves (only baryons). CDM continues to collapse. At the time of decoupling the wave stalls. We end up with spherical shell around an over-density. Preferred galaxy formation in over-densities. The radius of the sphere is a preferred distance scale -> standard ruler. First detections in 2dFGRS and SDSS, Cole et al. (2005), Eisenstein et al. (2005). Motivation 1 The sound horizon scale is set by the physical matter- and baryon 2 2 density, Ωmh and Ωbh . 2 We can get these two values from the CMB ! the BAO scale in the galaxy survey turns into a standard ruler. 3 A standard ruler enables a distance measurement. The ultimate cosmology tool! 4 This enables us to measure the Friedmann eq., H(z) 1=2 h −3 −3(1+w)i H(z) = H0 Ωma + ΩΛa : 5 At low redshift, a ≈ 1, a distance measurement constrains only H0 (similar to the distance ladder technique). Results 0.05 6dFGS data 0.04 best fit 2 Ωmh = 0.12 2 0.03 Ωmh = 0.15 no­baryon fit 0.02 (s) ξ 0.01 0 ­0.01 ­0.02 20 40 60 80 100 120 140 160 180 200 s [h­1 Mpc] Results @ξ(s) 0.05 2 1 Crocce & Scoccimarro (2008), ξmodel(s) = B(s)b ξ(s) ∗ G(r) + ξ1(r) Sanchez et al. (2008), @s6dFGS data Z 1 0.041 1 best fit ξ1(r) = 2 dk kPlin(k)j1(rk) 2 2π 0 Ωmh = 0.12 Z 1 2 0.03 1 2 Ωmh = 0.15 ξ(r) = 2 dk k Plin(k)j0(rk) 2π 0 no­baryon fit 2 G0.02~ (k) = exp −(k=k∗) Eisenstein et al. (2007), Eisenstein, Seo & White (2007) (s) ξ 0.01 0 ­0.01 ­0.02 20 40 60 80 100 120 140 160 180 200 s [h­1 Mpc] Results 0.05 6dFGS data 0.04 best fit 2 Ωmh = 0.12 2 0.03 Ωmh = 0.15 no­baryon fit 0.02 (s) ξ 0.01 0 ­0.01 ­0.02 20 40 60 80 100 120 140 160 180 200 s [h­1 Mpc] Results 0.05 6dFGS data 0.04 best fit 2 Ωmh = 0.12 2 0.03 Ωmh = 0.15 no­baryon fit 0.02 (s) ξ 0.01 0 χ2 = 1:12 DV = 456 ± 27 Mpc 2 ­0.01 Ωmh = 0:138 ± 0:02 b = 1:81 ± 0:13 ­0.02 20 40 60 80 100 120 140 160 180 200 s [h­1 Mpc] Cosmological implications 70 ] ­1 Mpc ­1 60 [km s 0 H 6dFGS Ω 2 50 mh prior Ω 2 6dFGS + mh prior 0.15 0.2 0.25 0.3 0.35 0.4 Ωm 6dFGS: H0 = 67 ± 3:2 km/s/Mpc SH0ES project: H0 = 73:8 ± 2:4 km/s/Mpc (Riess et al. 2011) WMAP7: H0 = 70:3 ± 2:5 km/s/Mpc (Komatsu et al. 2010) Cosmological implications 70 ] ­1 Mpc ­1 60 [km s 0 H 6dFGS Ω 2 50 mh prior Ω 2 6dFGS + mh prior 0.15 0.2 0.25 0.3 0.35 0.4 Ωm 6dFGS: H0 = 67 ± 3:2 km/s/Mpc SH0ES project: H0 = 73:8 ± 2:4 km/s/Mpc (Riess et al. 2011) WMAP7: H0 = 70:3 ± 2:5 km/s/Mpc (Komatsu et al. 2010) Cosmological implications 80 75 ] ­1 Mpc ­1 70 [km s 0 H 65 BAO WMAP­7 60 BAO+WMAP­7 without 6dFGS 55 ­1.5 ­1 ­0.5 w In a wCDM universe we find w = −0:97 ± 0:13. Cosmological implications 80 75 ] ­1 Mpc ­1 70 [km s 0 H 65 BAO WMAP­7 60 BAO+WMAP­7 without 6dFGS 55 ­1.5 ­1 ­0.5 w In a wCDM universe we find w = −0:97 ± 0:13. Cosmological implications 6dFGS: H0 = 67 ± 3:2 km/s/Mpc HST, Riess et al. (2011): 70 H0 = 73:8 ± 2:4 km/s/Mpc ] ­1 Mpc ­1 60 [km s 0 6dFGS H Ω h2 prior (N = 3) m eff Ω 2 6dFGS + mh prior 50 0.05 0.1 0.15 0.2 Ω 2 mh 2 Ωmh 3139 Neff = 3:04 + 7:44 − 1 0:1308 1 + zeq Cosmological implications 6dFGS: H0 = 67 ± 3:2 km/s/Mpc HST, Riess et al. (2011): 70 H0 = 73:8 ± 2:4 km/s/Mpc ] ­1 Mpc ­1 60 [km s 0 6dFGS H Ω h2 prior (N = 3) m eff Ω 2 6dFGS + mh prior Ω h2 prior (N = 4) 50 m eff Ω 2 6dFGS + mh prior 0.05 0.1 0.15 0.2 Ω 2 mh 2 Ωmh 3139 Neff = 3:04 + 7:44 − 1 0:1308 1 + zeq Cosmological implications hsdjfkisiahfdk6dFGS Blake et al. (2011) (Ωk = −0:004 ± 0:0062) Cosmological implications Blake et al.