Cosmic Expansion History from Euclid BAO Measurements Yun

Cosmic Expansion History from Euclid BAO Measurements Yun Wang (on behalf of the Euclid Galaxy Clustering SWG) Euclid Galaxy Clustering SWG Meeting London, March 21, 2012

Galaxy Clustering: Baryonic Acoustic Oscillations (BAO) as standard ruler Galaxies Percival et al. (2009, 2010) Euclid Consortium Microwave background (WMAP, e. g. Komatsu et al. 2009)

Reconstructing power spectra to 1% Simulated of the Euclid spectro. survey : 100 deg 2: effect of redshift errors (red dots). (A. Merson and C. Baugh mocks) Instrument Overall WP Breakdown Euclid Consortium GC redshift-survey: Power spectrum reconstruction with 20% of the Euclid data. (W. Percival) ESA SPR HQ Paris VG : 3 Jan. Sept. 19, 2012 12, 2011

w(z) from Baryonic Acoustic Oscillations SDSS LRGs at z~0. 35 20% of the Euclid slitless data at z~1 The largest volume of the Universe currently mapped Total effective volume (of Euclid) Veff = 19. 7 Gpc 3 h-3 Total effective volume Veff = 0. 26 Gpc 3 h-3 L 1 L 2 PRR Meeting Euclid Consortium ESTEC 27 May 2011

The unique power of Euclid: w(z) Euclid Consortium Fo. M > 400 (e. g. wp~0. 016 and wa~0. 16) In this case a cosmological constant is favoured by more than 100: 1 over model M: "decisive" statistical evidence in favour of the simplest model, in Bayesian terms A less precise experiment will not have enough statistical power to favour a cosmological constant over the more complex alternative

Euclid GC-1 -1 and WL-1 -1 optimal sky coverage , fixed-length survey Consortium With 15, 000 deg 2 for GC and WL: optimisation for a fixed time survey. Most efficient survey, allowsto do WL and GC simulatenously on the same area Instrument Overall WP Breakdown Euclid ESA SPR HQ Paris VG : 6 Jan. Sept. 19, 2012 12, 2011

Planck+Euclid+simulation: Fo. M L 0 requirement met Modified Gravity Dark Matter Initial Conditions Dark Energy mν/e. V f. NL wp wa Fo. M 0. 010 0. 027 5. 5 0. 015 0. 150 430 (WL+GC)+ CL+ISW 0. 009 0. 020 2. 0 0. 013 0. 048 1540 (Euclid All) 0. 007 0. 019 2. 0 0. 007 0. 035 4020 0. 200 0. 580 100 0. 100 1. 500 ~10 30 50 >10 >400 g Parameter Euclid Primary (WL+GC) Euclid All Euclid+Planck Current Improvement Factor 30 Instrument Overall WP Breakdown Euclid Consortium ESA SPR HQ Paris VG : 7 Jan. Sept. 19, 2012 12, 2011

DE Forecasting from GC • Propagate the measurement errors in ln. Pg(k) into measurement errors for the parameters pi: • ln. Pg(k) [Veff(k)]-1/2 =k·r/kr Yun Wang, 3/21/2012

Two Approaches: • “Full P(k)” method: parametrize P(k) using [H(zi), DA(zi), G(zi), Pshoti, n. S, mh 2, bh 2] • BAO “wiggles only”: P(k) P(k 0. 2, |z)[sin(x)/x]·exp[-(k s)1. 4 -k 2 nl 2/2] x=(k 2 s 2+ k//2 s//2)1/2 p 1=ln s -1=ln(DA/s); p 2=ln s //=ln(s. H); Yun Wang, 3/21/2012

Figure of Merit vs Redshift Accuracy Assuming Euclid Red Book Baseline: 15, 000 (deg)2 0. 65<z<2. 05 e(f, z) *Updated from Wang et al. (2010) Yun Wang, 3/21/2012

Expansion History H(z): BAO vs P(k) xh(z)=H(z)s xd(z)=DA(z)/s *Updated from Wang et al. (2010) for Euclid RB baseline *Based on Wang (2012) Yun Wang, 3/21/2012

Constraints on Growth Rate *Based on Wang (2012) Yun Wang, 3/21/2012

DE Fo. M vs Information Used xh(z)=H(z)s xd(z)=DA(z)/s p. NL=50% *Updated from Wang et al. (2010) for Euclid RB baseline *Based on Wang (2012) Yun Wang, 3/21/2012

Space/Ground Complementarity Ongoing ground-based surveys (Wiggle. Z, BOSS) enable better understanding of galaxy clustering, and improved modeling of systematic effects, which benefit Euclid. Overlaps in redshift range (BOSS, Big. BOSS, and Euclid) enable clustering statistics using multiple tracers (LRG, OII 3727, and H emitters), which improves DE constraints and the modeling of systematic effects. Yun Wang, 3/21/2012