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Cosmology with WFMOS

Cosmology with WFMOS. Masahiro Takada (IPMU). Jan 14, 09 @NAOJ. Precision Cosmology Λ CDM structure formation scenario.  m h 2 =0.12770.008 etc ~96% of the Universe is dark, unknown: Dark Matter + Dark Energy. From WMAP website. >0.1% Neutrinos. Most Important Problems.

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Cosmology with WFMOS

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  1. Cosmology with WFMOS Masahiro Takada (IPMU) Jan 14, 09 @NAOJ

  2. Precision CosmologyΛCDM structure formation scenario • mh2=0.12770.008 etc • ~96% of the Universe is dark, unknown: • Dark Matter + Dark Energy From WMAP website >0.1% Neutrinos

  3. Most ImportantProblems • What is dark matter? • The nature of DM, neutrino masses • What is the cause of cosmic acceleration? • Dark energy or Modification of gravity • What is the beginning of Big-Bang? • The nature of inflation (early-time DE) WFMOS+HSC provide breakthrough data sets for addressing these fundamental problems with unprecedented accuracies

  4. DE mystery: Coincidence problem ln(i(a)) radiation (a^-4) • Late-time DE becomes dominant in the cosmic energy budget, only recently during the cosmic history matter (a^-3) ？ DE (a^~0) Now BBN CMB scale factor: a

  5. Note: DE Effect on CMB DE effect on CMB is small (Suto, MT, Aihara 07）

  6. Cosmic Acceleration (space-time curvature)=(matter) • Cosmological principles: homogeneous and isotropic • Gravity theory: e.g., Einstein gravity Hubble expansion Matter (CDM＋baryon) Dark Energy cosmoclogical const. (w=-1)： infinite expansion (z-1) H(t)=const. a(t)exp(Ht) (the late-time inflation) • Cosmological distances (SNe, BAO: baryon acoustic oscillation)

  7. Structure Formation- Growth of fluctuations - From WMAP Gravity Cosmic Expansion

  8. The density fluctuation field of total matter (mainly CDM) in the linear regime The 2nd-order diff. eqn. to govern the redshift evolution of density pert.: (FRW eqns ＋ linearized Einstein eqns.) Cosmic acceleration  the density growth is suppressed Growth of cosmic structures Friction due to cosmic exp. Gravitationalinstability where Dark energy matter(CDM＋baryon+)

  9. SCDM CDM Jenkins+99 CMB(z~1000) Growth Rate WFMOS (0.5<z<1.3,z~3) Weak Lensing (0.2<z<1) • The initial conditions on the perturbations are well constrained by the CMB • A variant in DE changes the growth of density perturbations • A test of gravity theory on cosmological scale

  10. WL(HSC) Galaxy Survey(WFMOS) CMB CDM scenario (bottom-up): P(k) k3P(k,z)/22~<2>R~1/k Length scales + Time evolution

  11. Caution: “light” is biased tracers of mass From the Virgo Consortium 85 Mpc/h Different types of galaxies (and clusters) trace the total matter (mostly DM) distribution in different ways

  12. Dark Energy Probes • Type-Ia SNe • Standard candle：DL(z) • pros： established cons： empirical, different pops • Galaxy clustering statistics (redshift: WFMOS) • Standard ruler + structure formation：　DA(z), H(z), + D(z) • pros： smaller systematics cons： galaxy bias….. • Weak gravitational lensing (imaging: HSC) • Structure formation + geometrical: DA(z), D(z) • pros：mapping DM cons：shape, photo-z…. • Cluster abundance (optical: WL, X-ray, SZ) • Structure formation + geometrical: DA2(z)/H(z), D(z) • pros： well-behaved biascons：mass-observable relation Large-scale structure probes

  13. Dark Energy Task Force A. Albrecht (UC Davis) G. Bernstein (Penn) R. Chan (LBNL) W. Freedman (Carnegie) J. Hewitt (MIT) W. Hu (Chicago) J. Huth (Harvard) M. Kamionkonski (Caltech) E. Kolb (Chair, Chicago) L. Knox (UC Davis) J. Mather (Goddard) S. Staggs (Princeton) N. Suntzeff (Texas A&M) astro-ph/0609591

  14. The DETF Report

  15. rBAO~150Mpc WFMOS BAO(see Taruya-san’s talk) dV r dV • Measure galaxy clustering strengths: 2pt correlations (or P(k))  DA(z) • Find a tiny excess in the galaxy clustering strengths Eisenstein et al 05

  16. Capability of WFMOS for BAO • The combination of the 8.2 aperture, the wide field (1.5sqdeg), high multiplex gain (~3000) gives WFMOS the unique capability: no competition before ~2020 • Target galaxies • 0.5<z<1.3 (~2000deg^2): red ellipticals and blue spirals, based on the DEEP2 survey (e.g., BRI cut; r_AB<24) • 2.5<z<3.5 (~300 deg^2): LBGs or LEAs; U-band needed • nP~1 defines an optimal number of fibers (3000 fibers) • A cosmological survey requires to cover a larger comoving volume (>1Gpc^3): deep and wide • Enables to cover a larger volume at higher redshifts with a fixed solid angle • Galaxy clustering information is cleaner at higher redshifts, more in the linear regime

  17. z=1100 Subaru HSC/WFMOS Survey 21cm tomography Our observable universe z=50 z=10 z=5 z=3 z=2 z=1 Last Scattering Surface 共同座標スケール

  18. z=1100 z=50 z=10 Cosmic sampling variance z=3 z=5 z=2 z=1 • The measurement errors for CMB, galaxy P(k), WL,… are limited by the statistical errors, rather than the systematics • A larger surveyed volume allows the higher precision • CMB(z~1000): all-sky map already obtained, d_LSS~15Gpc • SDSS 2.5m (z<0.4, ~10^4 deg^2): d_SDSS/d_LSS~0.1 • Subaru 8.2m (HSC: <z>~1, WFMOS z~1+3): d_Subaru/d_LSS~0.5 • Ultimately: 21cm survey (z~10, SKA): d_21/d_LSS~0.7 • A wide redshift coverage (CMB+galaxy surveys+) LSS

  19. WFMOS allows to measure D_A(z) and H(z) at each redshift slice to a few % accuracies The expected DE constraints: σ(w)≈0.06 A wide redshift coverage: w≠-1 at anyz a big discovery Expected Performance of WFMOS

  20. The multi-color data sets of HSC would be valuable to find target galaxies for WFMOS (r_AB<24) A similar-type galaxy sample across redshifts would be most useful to trace the LSS (like LRGs in SDSS) Synergy of HSC and WFMOS (I) Luminous Red Galaxies (LRGs; r<19.5 ) (Eisenstein et al. 01) From Tegmark main galaxy sample:r<17.77

  21. Synergy of HSC and WFMOS (II) • HSC: WL • DM distribution in the LSS • WFMOS: galaxy clustering • View the LSS via biased tracers past present • Calibrating systematics: for WL, photo-z errors • For BAO, a direct measurement of galaxy bias • WL+BAO allows a stringent test of gravity theory

  22. Complementarity btw WL and BAO • Cosmological parameter constraints can be improved by combining BAO and WL, because the two have different dependences on cosmo paras.

  23. An example of measuring galaxy bias Galaxy-galaxy lensing (spec-z gals – background imaging gals) SDSS results (Mandelbaum+05) • More luminous and late-type galaxies reside in more massive halos 2D mass density profile [Msun/pc^2] Red: early-type Blue: late-type radius from galaxy center [kpc/h]

  24. State of the World USA(NASA/DOE) EU(ESA Cosmic Vision) • JDEM • Announcement of Opport. (selected mid 09) • WL+BAO+SNe (SNAP concept reset) • NIR infrared + optical • Spectroscopic (likely in NIR) + imaging • Launched in 2016 • ~$1 billion • Euclid • R&D study since mid 2008 • WL+BAO(+SNe) • NIR + optical • Spectroscopic + imaging • Launched in 2017 • ~$1 billion • BOSS (09-), HETDEX (10-): don’t have synergetic WL survey partner • HSC(11-)+WFMOS (15-) are unique: a window prior to JDEM/EUCLID

  25. Guaranteed Science: Neutrino Mass • A mixed DM model: Structure formation is induced by the density fluctuations of total matter • The neutrinos slow down LSS on small scales • On large scales >fs, the neutrinos can grow together with CDM • On small scales <fs, the neutrinos are smooth, =0, therefore weaker gravitational force compared to a pure CDM case  < fs  > fs CDM CDM Suppresses growth of total matter perturbations Total matter perturbations can grow!

  26. Effect of m_nu on nonlinear P(k) Saito, MT, Taruya, PRL, 2008 WFMOS achieves a few % accuracy in measuring P(k) at each k bins over k=[0.03,1] The suppression effect on P(k) due to neutrinos is enhanced in the weakly nonlinear regime

  27. An example: WL constraints on m_nu flat LambdaCDM + total neutrino mass WMAP5: m_nu<1.1 eV(95%CL) WMAP5+SN+BAO: m_nu<0.75eV WL+WMAP5+SN+BAO: m_nu<0.54eV Σmν [eV] Ichiki, MT, Takahashi 09 PRD in press

  28. Saito, MT, Taruya, PRL, 08 Forecast for WFMOS 0.5 Linear σ(M_ν)~0.13eV Neutrino total mass: σ(M_ν)[eV] 0.2 Marginalized error: σ(f_ν) σ(M_ν)~0.1eV 0.1 Non-Linear (PT) 0.05 0.01 0.1 1 Power spectrum amplitude @k=k_max: Δ^2(k_max;z)

  29. Summary • WFMOS delivers avery powerful data set for developingourunderstandingofcosmology • ConstrainingthenatureofDE(BAO),neutrinomasses,inflationmodels,theprimordialnon-Gaussianity • A valuable synergy of WFMOS and HSC • Unique complementaritybtwWL(LSS: HSC)andgalaxyclusteringmethods (geometrical: WFMOS) • Improvecosmologicalconstraintsandcalibratesystematicerrorsinherentineachmethods • Opens a window to test gravity theory on cosmological scales • Agoldenopportunity; prior to $1 billion projects, JDEM and EUCLID(launchedaround2017)

  30. The recent update of cluster abundance method • Vikhlinin et al. 08: use the improved mass estimates based on the Chandra observations of 36 and 49 clusters at <z>=0.55 and 0.05, respectively

  31. Vikhlinin et al. 08

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