MATTEO VIEL THE LYMANa FOREST AS A COSMOLOGICAL

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 d IGM ~ d DM at scales larger than the Jeans length ~ 1 com Mpc optical depth: t ~ (d. IGM )1. 6 T -0. 7

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 Constrain spectral index and shape Relation: P FLUX (k) - P MATTER (k) ? ?

RESULTS: POST- WMAP I LYMAN-a + CMB

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

Wm = 0. 26 WL = 0. 74 Wb=0. 0463 H 0 = 72 km/sec/Mpc GADGET –II code COSMOS - 60 Mpc/h 2 x 4003 GAS+DM 2. 5 com. kpc/h softening length computer – DAMTP (Cambridge) DM STARS GAS NEUTRAL HYDROGEN

LUQAS DATA 27 high res z~2. 125 QSO spectra THEORY: SIMULATIONS full hydro simulations THEORY: METHOD 3 D flux inversion ADVANTAGES band power SDSS 3000 QSO spectra z>2. 2 `calibrated’ simulations 1 D flux modelling large redshift range DRAWBACKS only z=2. 1 (and 2. 72) and larger error bars 34 parameters modelling RESULTS no large running, scale invariant, `high’ power spectrum amplitude

Cosmological implications: combining the forest data with WMAP Viel, Haehnelt, Springel, MNRAS, 2004, 354, 684 Viel, Weller, Haehnelt, MNRAS, 2004, 355, L 23 s 8= 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 s 8= 0. 90 ± 0. 03 n=0. 98 ± 0. 02 nrun = -0. 003 ± 0. 010 nrun=-0. 033± 0. 025

Inflation and dark energy Viel, Weller, Haehnelt, MNRAS, 2004, 355, L 23 V = inflaton potential T/S = r < 0. 45 (95% lim. ) r = 0. 50 ± 0. 30 SDSS Seljak et al. 2005 T/S

RESULTS: POST- WMAP II LYMAN-a + CMB

WMAP + LUQAS (high res) sample WMAP I + Lyman-a high-res WMAP III + Lyman-a high-res (credit: Antony Lewis) s 8= 0. 87 ± 0. 04 n = 0. 97 ± 0. 04 n run (0. 002 Mpc-1)= 0. 005 ± 0. 030 New COSMOMC version with WMAP 3 and Lyman-a downloadble http: //cosmologist. info/ Tension between WMAP 3 and high resolution Lyman-a… 1. 5 s discrepancy for SDSS it could be worse…

WMAP + SDSS flux power constraints Best fit WMAP 3 SDSS analysis Seljak et al. 2005, PRD best fit amplitude from SDSS Lyman-a and WMAP 1 is 3. 5 s off the new WMAP 3 value

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

Cosmological implications: Warm Dark Matter particles LCDM WDM 0. 5 ke. V 30 comoving Mpc/h z=3 In general k FS ~ 5 Tv/Tx (m x/1 ke. V) Mpc-1 if light gravitinos k FS ~ 1. 5 (m x/100 e. V) h/Mpc Set by relativistic degrees of freedom at decoupling MV, Lesgourgues, Haehnelt, Matarrese, Riotto, PRD, 2005, 71, 063534

Cosmological implications: WDM, gravitinos, neutrinos WDM m WDM > 550 e. V > 2 ke. V sterile neutrino LCWDM (gravitinos) m grav< 16 e. V Set limits on the scale of Supersymmetry breaking L susy < 260 Te. V neutrinos Smn (e. V) < 0. 95 (95 %C. L. ) WMAP + 2 d. F + LYa

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

Fitting SDSS data with GADGET-2 this is SDSS Ly-a only !! M sterile neutrino > 10 Ke. V 95 % C. L. SDSS data only s 8 = 0. 91 ± 0. 07 n = 0. 97 ± 0. 04

Isocurvature perturbations This is a model in agreement with WMAP 3! Beltran, Garcia-Bellido, Lesgourgues, Viel, 2005, PRD, D 72, 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

SUMMARY Cosmological parameters: Lyman-a points to s 8 = 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 WD have been obtained From high res Lyman-a: gravitinos + Dark matter and isocurvature Models are in agreement with WMAP 3 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 cosmolog together with the CMB – TENSION with WMAP 3

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

Thermal state T = T 0 ( 1 + d) g-1 Thermal histories Flux power fractional differences Statistical SDSS errors on flux power

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

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. Statistical error 4% Systematic errors ~ 15 % t eff (z=2. 125)=0. 17 ± 0. 02 8% t eff (z=2. 72) = 0. 305 ± 0. 030 7% g = 1. 3 ± 0. 3 4% T 0 = 15000 ± 10000 K 3% Method 5% Numerical simulations 8% Further uncertainties 5%

Constraints on the evolution of the effective optical depth s 8 = 0. 7 s 8 = 0. 925 s 8 = 1

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!!!

The LUQAS sample Large sample Uves Qso Absorption Spectra (LP-UVES program P. I. J. Bergeron) # spectra high resolution 0. 05 Angstrom, high S/N > 50 low redshift, <z>=2. 25, Dz = 13. 75 redshift Kim, MV, Haehnelt, Carswell, Cristiani, 2004, MNRAS, 347, 355