Weighing the dark side of the universe

Transcription

1 Weighing the dark side of the universe Department of Physics The University of Tokyo Yasushi Suto June 18, 2004 Particle Physics Group Seminar Tsukuba University

2 Hierarchical structure in the universe Galaxy Dwarf group galaxy Solar system Large-scale structure Star cluster Galaxy Galaxy cluster Weighing the universe 2

3 Clustering of luminous objects on the light-cone (shallow universe) (universe on the light (local universe) (universe on the light-cone) z=0.05 (150h -1 Mpc) CfA redshift survey: de Lapparent et al.(1986) Cosmic evolution along the light-cone is directly accessible now! z=0.2 (600h - 1 Mpc) Las Campanas redshift survey: Schectman et al. (1996) z=3 (~1h - 1 Gpc) 2dF QSO survey: Weighing the universe 3

4 A slice of the universe: Tour of SDSS Data Release 1 shallow universe from Japanese TV program Science ZERO (NHK) Weighing the universe 4

5 Looking into the past /PR/96/01.html Weighing the universe 5

6 Distant universe observed by Subaru telescope Weighing the universe 6

7 Widest-separation separation gravitationally lensed quasar images Subaru 8.2m telescope Subaru image Inada et al. Nature 426(2003)810 gravitational bending lensing cluster of light path (6.2 billion yrs away) QSO J1004 (9.8 billion yrs Zoomed Subaru image away) 1 SDSS 2.5m telescope ,000 light yrs apart SDSS image Weighing the universe 7

8 General relativistic mirage from the universe 10Gyrs ago Weighing the universe 8

9 Exploring the edge of the universe NASA/WMAP Science Team Weighing the universe 9

10 13.7Gyr 0.2Gyr CMB: Cosmic Microwave Background time 0.38Myr 3min sec relic thermal photons from the ancient universe the present reionization CMB photons recombination Big-bang history large-scale structure galaxy cluster galaxy formation first objects light element synthesis generation of quantum fluctuations Recombination of protons and electrons = decoupling of baryons and photons Weighing the universe 10

11 From the infant universe to the present NASA/WMAP Science Team Weighing the universe 11

12 WMAP: Wilkinson Microwave Anisotropy Probe NASA/WMAP Science team Weighing the universe 12

13 Progress in mapping the CMB sky Weighing the universe 13

14 Sound waves in the CMB sky seed fluctuations acoustic oscillations CMB anisotropy pattern NASA/WMAP Science team Weighing the universe 14

15 Geometry of the universe from the CMB sky curvature changes the characteristic angular scale of the CMB anisotropy pattern NASA/WMAP Science team Weighing the universe 15

16 ancient document in cipher CMB all-sky map a cipher key spherical harmonics δt θ, ϕ ) T ( = a lm Y lm ( θ, ϕ ) l, m deciphered data temperature spectrum C = grammar to understand the universe cold dark matter model imprinted information age, geometry, and composition of the universe l a lm a * lm Weighing the universe 16

17 Angular power spectrum of CMB temperature fluctuations observed by WMAP baryon density Ω b spectral index of primordial fluctuations n s δt T ( θ, ϕ ) = a Y lm lm( θ, ϕ ) C = l matter density Ω 0 l, m a lm a * lm Spergel et al. ApJS 148(2003)175 curvature of the universe Ω Κ = Ω m +Ω Weighing the universe -1 17

18 age of the universe: 13.7 Gyr universe is spatially flat universe reionized at 0.2Gyr after Big-bang cosmic matter is dominated by dark matter cosmic energy is dominated by dark energy Weighing the universe 18

19 Cosmological parameters (WMAP+( WMAP+others) NASA/WMAP Science Team Weighing the universe 19

20 Results: weighing the universe baryons ordinary matter makes up merely 4 percent of the entire mass of the universe dark matter dark energy galaxies and clusters are surrounded by invisible mass an order-of-magnitude more massive than their visible part unknown elementary particles? universe is dominated by even more exotic component! homogeneously fills the universe (unclustered) repulsive force (negative pressure; equation of state:p= ) Einstein s cosmological constant? Weighing the universe 20

21 dark energy or cosmological constant? Cosmic equation of state p=wρ ρ(t (t) a(t) -3(w+1) w=-1: cosmological constant -1<w<0: time-varying dark energy WMAP+others w< w<-0.78 (95%) Weighing the universe 21

22 More intriguingly, most of the cosmic baryon dark matter dark energy is also dark baryons composition of cosmic baryons stars hot gas Cosmic Baryon Budget: Fukugita, Hogan & Peebles ApJ 503 (1998) 518 Weighing the universe 22

23 hydrodynamical simulation with gas A (30h -1 Mpc) 3 box around a massive cluster at z=0 CDM SPH simulation Yoshikawa et al. 2001) Galaxy (cold clump) Dark matter All gas particles Hot gas (T>10 7 K) Warm gas (10 5 K<T<10 7 K) Weighing the universe 23

24 Four phases of cosmic baryons Dave et al. ApJ 552(2001) 473 Condensed: >1000, T<10 5 K Stars + cold intergalactic gas Diffuse: <1000, T<10 5 K Photo-ionized intergalactic medium Ly absorption line systems Hot: T>10 7 K X-ray emitting hot intra-cluster gas Warm-hot: 10 5 K<T<10 7 K Warm-hot intergalactic medium ( (WHIM) Weighing the universe 24

25 Emission lines of oxygen in WHIM OVII (561eV, 568eV, 574eV, 665eV), OVIII (653eV) Why oxygen emission lines? Most abundant other than H and He Good tracers of gas around T= K No other prominent lines in E= eV Not restricted to regions towards background QSOs systematic WHIM survey Weighing the universe 25

26 Searching for cosmic dark baryons with DIOS (Diffuse Intergalactic Oxygen Surveyor) Weighing the universe 26

27 DIOS: Diffuse Intergalactic Oxygen Surveyor A Japanese proposal of a dedicated X-ray mission to search for dark baryons PI: Takaya Ohashi (Tokyo Metropolitan Univ.) + Univ. of Tokyo, JAXA/ISAS, Nagoya Univ., Tokyo Metro. Univ. A dedicated small satellite with cost < 40M USD. Proposed launch in 2008 (not yet approved). Unprecedented energy spectral resolution: E=2eV in soft X-ray band (0.1-1keV) Aim at detection of 30 percent of the total cosmic baryons via Oxygen emission lines. Weighing the universe 27

28 Searching for dark baryons with DIOS (Diffuse Intergalactic Oxygen Surveyor) Mock simulations PASJ 55 (2003) 879 astro-ph/ , Univ of Tokyo: K. Yoshikawa Y.Suto JAXA/ISAS: N. Yamasaki K. Mitsuda Tokyo Metropolitan Univ.: T. Ohashi Nagoya Univ.: Y. Tawara A. Furuzawa Weighing the universe 28

29 Simulating the local universe Simulation by Dolag et al. (astro-ph/ ) Initial condition: smoothing the observed galaxy density field of IRAS 1.2 Jy galaxy survey (over 5h -1 Mpc), linearly evolving back to z=50 adiabatic run of dark matter and baryons (without cooling or feedback) in a canonical ΛCDM model Locating the WHIM in the local universe Yoshikawa, Dolag, Suto, Sasaki, Yamasaki, Ohashi, Mitsuda, Tawara, Fujimoto, Furush, Furuzawa, Ishida & Ishisaki (2004), in preparation Weighing the universe 29

30 2MASS map vs. simulated local universe Hydra-Centaurus Coma Pisces-Perseus A3627 Virgo Horologium Soft X-ray map of the simulated local universe (Yoshikawa et al. 2004) Weighing the universe 30

31 Tour of the simulated local universe K. Dolag (2003) Weighing the universe 31

32 Simulated gas distribution on the supergalactic plane gas temperature Coma Hydra Centaurus Virgo A3627 Pisces-Perseus gas density Weighing the universe 32 (adopted) metallicity

33 Mock observation of X-ray X filament extending around simulated A3627 S(0.5-2keV) T gas S(OVII) S(OVIII) 1 1 FOV Weighing the universe 33

34 Soft X-ray X excess of Coma XMM-Newton observations of the outskirts of Coma (Finoguenov, Briel & Henry 2003, A&A 410, 777) X-ray filament of 0.2keV warm gas? Finoguenov et al. (2003) simulated observation T=0.2keV) (1/8) (1/8) FOV Weighing the universe 34

35 Fraction of cosmic baryons detectable via oxygen emission OVII OVIII T>10 7 K T>10 7 K 10 6 K<T<10 7 K DIOS detection limit (T exp =10 5 s; S/N=10) 10 6 K<T<10 7 K DIOS detection limit (T exp =10 5 s; S/N=10) T<10 6 K T<10 6 K Weighing the universe 35

36 Conclusion: 99% of the universe is DARK Quite frustrating We finally realized that we have not yet understood 99% of the universe at all! (dark baryons 3%) cosmological observations in the 20 th century have identified previously unknown hierarchy of matter beyond the standard model of particle physics one needs to understand the meaning of cosmological parameters beyond mere precise estimates of their values from how much to why ( Weighing the universe 36