Complementarity in Dark Energy measurements. Complementarity of optical data in constraining dark energy. Licia Verde. University of Pennsylvania

Size: px

Start display at page:

Download "Complementarity in Dark Energy measurements. Complementarity of optical data in constraining dark energy. Licia Verde. University of Pennsylvania"

Beverley Lawrence
5 years ago
Views:

1 Complementarity in Dark Energy measurements Complementarity of optical data in constraining dark energy Licia Verde University of Pennsylvania

2 The situation: SN 1A (Riess et al 04) CMB+ CMB(WMAP ext) H prior (HST Key project) LSS (2dF Verde et al 02)

3 Assuming a flat Universe. CMB (WMAPext) CMB+H SN(Riess et al 04)

4 Assuming a flat Universe. CMB (WMAPext) CMB+Galaxy surveys SN(Riess et al 04) But, why constant?

5 Assuming a flat Universe. Baryon oscill. SDSS Eisenstein et al. 05 CTIO +CMB+SN Jarvis et al 05 (75 sq degrees, no redshifts) + CFHTLS Sembloni et al 05 (3 sq degrees) But, why w constant? Why flatness?

6 THE SYMPTOMS Or OBSERVATIONAL EFFECTS of DARK ENERGY Recession velocity vs brightness of standard candles: dl(z) CMB acoustic peaks: Da to last scattering Da to z survey LSS: perturbations amplitude today, to be compared with CMB (or Matter density today)

7 HOW TO MAKE A DIAGNOSIS? Any modification of gravity of the form of f( R ) can be written as a quintessence model for a(t) This degeneracy is lifted when considering the growth of structure Effort in determining what the growth of structure is in a given Dark Energy model! combination of approaches!

8 We can measure dark energy because of its effects on the expansion history of the universe and the growth of structure a& ( t) a( t) = H ( z) = 1 (1 + z) dz dt SN: measure dl θ d L = (1 + z) (1 + CMB: A and ISW Sa(t) dt z') dz' dz' LSS or LENSING: Sg(z) or Sa(t) 0 z 2 H = H 2 0[ ρ( z) / ρ(0)] See Rocky&Josh talks AGES: H(z) S a(t) Standard clocks 1 dz 5/ 2 dz' H = + z Ω + Ω 0 (1 ) { m(0) Q (0) exp[3 wq ]} dt (1 + z') z 0 1/ 2

9 COMPLEMENTARITY IS THE KEY! The questions we want to ask: Is it a cosmological constant? A rolling scalar field? A fluid? Is it a w= -1? w(z)? Is it a breakdown of GR at horizon scales? Example: Measurements of the growth of cosmological structures will help to disentangle the two cases. Things could be going wrong in other ways Backreaction For not mentioning: control of systematics!

10 MEASURING DARK ENERGY Two ways (you may not have thought about) in which GEMINI & SUBARU can make a difference optical follow up for SZ surveys Clusters weak lensing masses Provide redshifts Bonds CD s Provide spectra of old high-redshift galaxies Highly volatile mutual funds

11 Surveys like ACT and SPT will detect thousands of clusters via the SZ effect. Clusters number counts ν growth of structure: Very sensitive to dark energy but also to clusters masses (& clusters physics) Fig. From Mohr et al 02 Optical follow up needed for redshifts and weak lensing masses

12 Using the KSZ signal (Hernandez-Monteagudo, LV, Jimenez, Spergel 2005-astro-ph/ ) The peculiar velocity field is sensitive to the onset of the late acceleration of the Universe. Recall that KSZ The power spectrum of the velocities is W=--1/3 W=--0.6 W=--1.0 Clusters probe linear scales Not POTENT, need redshifts not distances

13 KSZ sensitivity to w ACT -0.6 w WMAP Deep and narrow SPT w Wide and shallow Wm Sensitive to growth of velocity Insensitive to knowing the clusters mass (not counting clusters) Redshifts needed (from Hernandez-Monteagudo et al.2005) W(z)!

14 Back for some theory With J. Simon & R. Jimenez: Let s be bold Let s assume that the dark energy is given by a scalar field, this description includes the cosmological constant case and try to reconstruct the shape of the potential Theory wants V (q) but we can t observe q (PRD 71, 2005) See also Parkinson talk So we will go for V (z) then find a way to get back to V (q). V(q)=H/m p -1/2(r t +p t ) A FLAT potential Cosmological constant V ( z) + z α = λ (1 ) Ratra-Peebles case of a constant w

15 A mini-inflation? Introduce quantities similar to the horizon flow parameters in inflation ε Turns out that if you know you can reconstruct V (z) d log ε dn n n+ 1 =, N = ρ m, H, H& log Integration of a differential equation gives you q(z) which you can use to get back V (q) a a i ε 0 = H ( N i ) H ( N) and assume a flat universe and standard GR* * If you want to see the equations for the case of corrections to standard GR, please go to sec II of astro-ph/

16 Unfortunately. Data are not yet good enough for a fully non-parametric reconstruction Chebyshev to the rescue V ( z) M = Âλ T [ x( z)], x( z) = 2z z n n n= 0 max 1

17 No data, priors only K > 0 T > 0 ρ that is H 2 > 0 V 0 K 0 = ΩQ,0 + ρ Flatness c Ω m = From large-scale structure!, 0 ±

18 USING RELATIVE GALAXY AGES STANDARD CHRONOMETERS At z=0 dz/dt gives Ho and we have SDSS galaxies: H ( z) = 1 (1 + z) dz dt (Jimenez et al. 2003) The edge for z<0.2 (Jimenez et al. 2003) THE EDGE for SDSS EDR Similar trend found by Bernardi et al. (astro-ph/ ) using alpha-enhanced models The value of H0

19 GDDS McCarthy et al high z radiogalaxies + Treu et al sample From Simon, Verde, Jimenez (2005)

20 No data, priors only K > 0 T > 0 ρ that is H 2 > 0 V 0 K 0 = ΩQ,0 + ρ Flatness c Ω m = From large-scale structure!, 0 ±

21 Using galaxy ages From Simon, Verde, Jimenez (2005)

22 As a benchmark let s consider the Supernovae

23 Galaxies SN1A, Riess et al 04

24 CONSTRAINTS ON W w<-0.9 If V(z)=(1+az) a=3(w+1) Or: w 0 =-1 (in the w, wa parameterization)

25 Galaxies SN1A, Riess et al 04

26 Imagine what you could do with 2000 cosmic chronometers.

27 CONCLUSIONS complementarity Observations relying on different physics and affected by different systematics Optical observations are a key ingredient Two additional methods on the market: KSZ and cosmic chronometers And I have not mentioned: The meeting is still young Weak lensing, supernovae, cross-correlation of LSS with e.g. CMB, lensing and CMB, Baryonic oscillations,

28 3:Reconstruct w(z): cosmic chronometers Old, passively evolving galaxies Is it possible to obtain accurate ages? (From Jimenez, LV, Treu, Stern 2003)

29 3:Simulating the edge

The Nature of Dark Energy and its Implications for Particle Physics and Cosmology

The Nature of Dark Energy and its Implications for Particle Physics and Cosmology May 3, 27@ University of Tokyo Tomo Takahashi Department of Physics, Saga University 1. Introduction Current cosmological