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MATTEO VIEL

MATTEO VIEL. THE LYMAN- a FOREST AS A COSMOLOGICAL PROBE. Contents and structures of the Universe – La Thuile (ITALY), 19 March 2006. 80 % of the baryons at z=3 are in the Lyman- a forest. baryons as tracer of the dark matter density field

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MATTEO VIEL

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  1. MATTEOVIEL THE LYMAN-a FOREST AS A COSMOLOGICAL PROBE Contents and structures of the Universe – La Thuile (ITALY), 19 March 2006

  2. 80 % of the baryons at z=3 are in the Lyman-a forest baryons as tracer of the dark matter density field dIGM~dDMat scales larger than the Jeans length ~ 1 com Mpc optical depth: t ~ (dIGM )1.6 T -0.7

  3. GOAL: the primordial dark matter power spectrum from the observed flux spectrum Maximum sensitivity of WMAP CMB physics z = 1100 dynamics Continuum fitting Lya physics z < 6 dynamics + termodynamics Temperature, metals, noise Tegmark & Zaldarriaga 2002 CMB + Lyman a Long lever arm Relation: P FLUX (k) - P MATTER (k) ?? Constrain spectral index and shape

  4. RESULTS: POST- WMAP I LYMAN-a + CMB

  5. SDSS vs LUQAS McDonald et al. astro-ph/0405013 Kim, Viel et al. 2004, MNRAS, 347, 355 SDSS LUQAS 3000 LOW RESOLUTION LOW S/N 30 HIGH RESOLUTION HIGH S/N

  6. Wm = 0.26 WL = 0.74 Wb=0.0463 H0 = 72 km/sec/Mpc - 60 Mpc/h 2x4003 GAS+DM 2.5 com. kpc/h softening length GADGET –II code COSMOS computer – DAMTP (Cambridge) DM GAS STARS NEUTRAL HYDROGEN

  7. LUQAS SDSS DATA 27 high res z~2.125 QSO spectra 3000 QSO spectra z>2.2 THEORY: SIMULATIONS full hydro simulations `calibrated’ simulations THEORY: METHOD 3D flux inversion 1D flux modelling ADVANTAGES band power large redshift range DRAWBACKS only z=2.1 (and 2.72) and 34 parameters modelling larger error bars RESULTSno large running, scale invariant, `high’ power spectrum amplitude

  8. Cosmological implications: combining the forest data with WMAP Viel, Haehnelt, Springel, MNRAS, 2004, 354, 684 Viel, Weller, Haehnelt, MNRAS, 2004, 355,L23 s8= 0.93 ± 0.07 n=0.99 ± 0.03 d ns/ d ln k Seljak et al. 2004 SDSS Seljak et al. 2004 In the Seljak analysis WMAP+Ly-a constrains running three times better than WMAP+all the rest s8= 0.90 ± 0.03 n=0.98 ± 0.02 nrun = -0.003 ± 0.010 nrun=-0.033± 0.025

  9. Inflation and dark energy Viel, Weller, Haehnelt, MNRAS, 2004, 355, L23 V = inflaton potential T/S = r < 0.45 (95% lim.) r = 0.50 ± 0.30 SDSS Seljak et al. 2005 T/S

  10. RESULTS: POST- WMAP II LYMAN-a + CMB

  11. WMAP + LUQAS (high res) sample WMAP I + Lyman-a high-res WMAP III + Lyman-a high-res (credit: Antony Lewis) s8= 0.87 ± 0.04 n = 0.97 ± 0.04 n run (0.002 Mpc-1)= 0.005 ± 0.030 New COSMOMC version with WMAP3 and Lyman-a downloadble http://cosmologist.info/ Tension between WMAP3 and high resolution Lyman-a… 1.5 s discrepancy for SDSS it could be worse…

  12. WMAP + SDSS flux power constraints Best fit WMAP3 SDSS analysis Seljak et al. 2005, PRD best fit amplitude from SDSS Lyman-a and WMAP1 is 3.5s off the new WMAP3 value

  13. SMALL SCALE POWER Warm dark matter ? New observational results from dwarf galaxies Neutrinos ? Isocurvature ?

  14. Cosmological implications: Warm Dark Matter particles WDM 0.5 keV LCDM 30 comoving Mpc/h z=3 In general if light gravitinos k FS ~ 5 Tv/Tx (m x/1keV) Mpc-1 k FS ~ 1.5 (m x/100eV) h/Mpc Set by relativistic degrees of freedom at decoupling MV, Lesgourgues, Haehnelt, Matarrese, Riotto, PRD, 2005, 71, 063534

  15. Cosmological implications: WDM, gravitinos, neutrinos WDM LCWDM (gravitinos) neutrinos m WDM > 550 eV m grav< 16 eV > 2keV sterile neutrino • mn (eV) < 0.95 (95 %C.L.) WMAP + 2dF + LYa Set limits on the scale of Supersymmetry breaking L susy< 260 TeV

  16. Can sterile neutrinos be the dark matter ? Biermann & Kusenko PRL 2006,96, 091301 - Molecular hydrogen and reionization - X-Ray backgrounds - Flux power evolution Abazaijan a-ph/0512631 Seljak et al. a-ph/0602430 Increasing z Flux power m (KeV) > 14 2 < m (KeV) < 8

  17. Fitting SDSS data with GADGET-2 this is SDSS Ly-a only !! M sterile neutrino > 10 KeV 95 % C.L. SDSS data only s8 = 0.91 ± 0.07 n = 0.97 ± 0.04

  18. Isocurvature perturbations This is a model in agreement with WMAP3! Beltran, Garcia-Bellido, Lesgourgues, Viel, 2005, PRD, D72, 103515 Fully correlated a:isocurvature fraction at k=0.05 Mpc-1 b:quantifies correlation between ISO and ADIABATIC modes n iso=1.9 ± 1.0 95% C.L. Anti correlated No iso Only iso n ad=0.95 n iso =3 n ad = 0.95 n iso =2

  19. SUMMARY • Cosmological parameters: Lyman-a points to • s8 = 0.9 n = 0.98 little running • substantial agreement between SDSS and LUQAS but SDSS has • smaller error bars (factor ~ 2), due to the different • theoretical modelling and wider range of redshift probed by SDSS • Constraints on inflationary models, isocurvature, neutrinos and WDM • have been obtained • From high res Lyman-a: gravitinos + Dark matter and isocurvature • Models are in agreement with WMAP3 • Other measurements using Lyman-a based on different methods • give the same answer (Zaroubi et al. 2005, Viel & Haehnelt 2006), • systematics are now in better control • Lyman-a forest is a complementary measurement of • the matter power spectrum and can be use to constrain cosmology • together with the CMB – TENSION with WMAP 3

  20. Mean flux Effective optical depth Low resolution SDSS like spectra High resolution UVES like spectra <F> = exp (- t eff) Power spectrum of F/<F>

  21. Thermal state T = T0 ( 1 + d) g-1 Thermal histories Flux power fractional differences Statistical SDSS errors on flux power

  22. Numerical modelling: HPM simulations of the forest Full hydro 200^3 part. HPM NGRID=600 HPM NGRID=400 MV, Haehnelt, Springel, astro-ph/0504641 FLUX POWER

  23. Hydro-simulations: what have we learnt? Many uncertainties which contribute more or less equally (statistical error seems not to be an issue!) ERRORS CONTRIBUTION TO FLUCT. AMPL.

  24. Constraints on the evolution of the effective optical depth s8 = 0.7 s8 = 0.925 s8 = 1

  25. Lack of power in the RSI model: haloes form later. Contrast with the large t inferred (Yoshida et al. 2003) Spergel et al. 2003 Peiris et al. 2003 Lyman-a does most of the job in constraining running!!!

  26. The LUQAS sample Large sample Uves Qso Absorption Spectra (LP-UVES program P.I. J. Bergeron) high resolution 0.05 Angstrom, high S/N > 50 low redshift, <z>=2.25, Dz = 13.75 # spectra redshift Kim, MV, Haehnelt, Carswell, Cristiani, 2004, MNRAS, 347, 355

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