1. MATTEO VIEL THE LYMAN-  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-  forest baryons as tracer of the dark matter density field  IGM ~  DM at scales larger than the Jeans length ~ 1 com Mpc optical depth:  ~ (  IGM ) 1.6 T -0.7

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

4. RESULTS: POST- WMAP I LYMAN-   CMB

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

6. DM STARS GAS NEUTRAL HYDROGEN  m = 0.26   = 0.74  b =0.0463 H 0 = 72 km/sec/Mpc - 60 Mpc/h 2x400 3 GAS+DM 2.5 com. kpc/h softening length GADGET –II code COSMOS computer – DAMTP (Cambridge)

7. 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 RESULTS no large running, scale invariant, `high’ power spectrum amplitude LUQAS SDSS

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

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

10. RESULTS: POST- WMAP II LYMAN-   CMB

11. WMAP I + Lyman-  high-res WMAP III + Lyman-  high-res (credit: Antony Lewis) Tension between WMAP3 and high resolution Lyman-a… 1.5  discrepancy for SDSS it could be worse… WMAP + LUQAS (high res) sample New COSMOMC version with WMAP3 and Lyman-  downloadble http://cosmologist.info/  8 = 0.87 ± 0.04 n = 0.97 ± 0.04 n run (0.002 Mpc -1 )= 0.005 ± 0.030

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

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

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

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

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

17. M sterile neutrino > 10 KeV 95 % C.L. SDSS data only  8 = 0.91 ± 0.07 n = 0.97 ± 0.04 Fitting SDSS data with GADGET-2 this is SDSS Ly-  only !!

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

19. SUMMARY Cosmological parameters: Lyman-  points to  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 WDM have been obtained From high res Lyman-  : gravitinos + Dark matter and isocurvature Models are in agreement with WMAP3 Other measurements using Lyman-  based on different methods give the same answer (Zaroubi et al. 2005, Viel & Haehnelt 2006), systematics are now in better control Lyman-  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 = exp (-  eff ) Power spectrum of F/ Low resolution SDSS like spectra High resolution UVES like spectra

21. Thermal state T = T 0 ( 1 +  )  Statistical SDSS errors on flux power Thermal histories Flux power fractional differences

22. 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

23. Hydro-simulations: what have we learnt? Many uncertainties which contribute more or less equally (statistical error seems not to be an issue!) Statistical error4% Systematic errors~ 15 %  eff (z=2.125)=0.17 ± 0.02 8 %  eff (z=2.72) = 0.305 ± 0.030 7 %  = 1.3 ± 0.3 4 % T 0 = 15000 ± 10000 K 3 % Method5 % Numerical simulations8 % Further uncertainties5 % ERRORS CONTRIBUTION TO FLUCT. AMPL.

24. Constraints on the evolution of the effective optical depth  8 = 0.7  8 = 1  8 = 0.925

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

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