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STRUCTURE FORMATION. MATTEO VIEL. INAF and INFN Trieste. SISSA LECTURE #4 - March 23 th 2010. OUTLINE: LECTURES. Structure formation: tools and the high redshift universe The dark ages and the universe at 21cm IGM cosmology at z=2=6 IGM astrophysics at z=2-6
  • Structure formation: tools and the high redshift universe
  • The dark ages and the universe at 21cm
  • IGM cosmology at z=2=6
  • IGM astrophysics at z=2-6
  • 5. Low redshift: gas and galaxies
  • 6. Cosmological probes LCDM scenario
  • OUTLINE: LECTURE 4Galactic winds and metal enrichmentThe evolution of the UV backgroundThe Warm-Hot Intergalactic Medium GALACTIC WINDSGalactic winds –I Local galactic winds M82 X-rayLocal galactic winds M82 optical and infra-redTheory: Galactic winds do they destroy the forest ?Galactic winds –II Log overdensityLog TempFluxTemp.Dens.Theuns, MV, et al, 2002, ApJ, 578, L5Feedback effects: Galactic winds - IIINo FeedbackFeedbackDensityTemperatureFeedback effects: Galactic winds-IV Line widths distributionColumn density distribution functionMetal enrichment CIV systems at z=3 Strong Feedback e=1 ---- Role of the UV backgroundMori, Ferrara, Madau 2000; Rauch, Haehnelt, Steinmetz 1996; Schaye et al. 2003Soft background ---- Role of different feedbacke=0e=1 e=0.1Observations: the POD technique Aguirre,Schaye, Theuns, 2002, ApJ, 576, 1Cowie & Songaila, 1998, Nature, 394, 44Pieri & Haehnelt, 2004, MNRAS, 347, 985Pixel-by-pixel search using higher order transitionsSpringel & Hernquist 2002,2003Observations: the POD technique-II NO SCATTER INTHE Z-r relationSCATTER INTHE Z-r relationGood fit to the median but not for the scatterSchaye et al., 2003, ApJ, 596, 768Observations: the POD technique-IIIVARIANCE OF THE METALLICITYLognormal fitSchaye et al., 2003, ApJ, 596, 768 POD technique and proximity -IVUV background and metallicitySchaye, Aguirre et al. 2004,2005Lyman-break galaxies proximity effect(and galaxy-metals connection)Adelberger, Steidel et al. 2003-2006 Still problems from simulations?Aguirre et al. 2005SIMULATIONS’ PROBLEM:ENRICHED GAS IS 1) TOO HOT 2) NOT DENSE ENOUGH 3) TOO INHOMOGENEOUSLY DISTRIBUTEDEnergy drivenMomentum drivenOppenheimer & Dave’, aph/0605651PROBLEMS ALLEVIATED ??NEW KEY INPUTS: metal line cooling Vel wind ~ s galaxy x lum. factorWhen did the IGM become enriched – I ?EARLY METAL ENRICHMENT at z>6 CIV-LBG cross correlationfunctionPorciani & Madau 2005When did the IGM become enriched – II ?Adelberger et al. 2005The future-I cw : costant speed windmw: momentum drivennw: no windExploring the parameter space…(multi fitting as many observablesAs possible SFR, HI evolution, CDDF…)The future-II …with motivated chemodynamical modelsKawata & Rauch 2007GALAXY-IGM CONNECTION - Early or late metal enrichment???? PopIII objects?? Where are the metals? How far can they get? - Search for galactic winds. No definitive proof of galactic winds at high redshift. DEFINITIVE proof will be signatures of outflows in QUASAR PAIRS (within 2yrs)? - Lyman-break proximity effect? Is there still something odd? radiative transfer effects? - Better modelling of the ISM into cosmological hydro simulations ISM-IGM connectionUV BACKGROUNDIonizing background – I t ~ 1/ G-12With the fluctuating Gunn – Peterson approximationPhotoionization rateBolton, Haehnelt, MV, Springel, 2005, MNRAS, 357, 1178Ionizing background-II Bolton, Haehnelt, MV, Springel, 2005, MNRAS, 357, 1178Ionizing background and Helium reionization - III Bolton, Haehnelt, MV, Carswell, 2006, MNRAS, 366, 1368Ionizing background and the proximity effectDATA SIMULATIONSSummary
  • Metal enrichment: Significant progress made on the
  • understanding of the IGM-galaxy connection but still:
  • No proofs of strong galactic winds at high redshfit
  • No clues of who is polluting the IGM and to what extent.
  • PopIII? Lyman-break galaxies?
  • the amplitude, shape of the (fluctuating?) UV background
  • is quite uncertain
  • WHIM WHIM - I Cen & Ostriker 1999, ApJ, 514, 1LFukugita, Hogan, Peebles, 1998, ApJ, 503, 518WHIM - II Possibility of detecting the WHIM in absorption with EDGE (Explorer of Diffuse Emission and Gamma-ray burst Explosions) characterize its physical state, spatial clustering and estimate the baryon mass density of the WHIM. - WHIM models and uncertainties. - Probability of WHIM detections. - WWHIMestimate. - Systematic effects. Joint emission+absorption analysis - Spatial distribution of WHIM and its biasWHIM: model uncertainties – I To asses model (random+systematic) uncertainties we have used different techniques to simulate WHIM = 0.7, m = 0.2457, b = 0.0463, h = 0.7, = 0.85L = 60 h-1Mpc, , NDM = 4003,NGAS = 4003, = 2.5 h-1kpcWHIM: model uncertainties – II
  • Semi analytic model (Viel et al. 2003)
  • Hydro-dynamical model by Borgani
  • Hydro-dynamical model (Viel 2006)
  • Gadget-2 SPH code. Metallicity model: Z/Zsun=min(0.2,0.025.r–1/3)Simple star formation prescription. No Feedback.Ions: OVI (KLL), OVIIKa, OVII Kb, OVIII, CV, NeIX, MgXI FeXVII.Hybrid collisional ionization + (X+UV) photoionization.Independent spectra drawn by stacking outputs out to z=0.5 (Dz=0.1)NOVII(W>0.1eV)/z=1-4NOVIII(W>0.1eV)/z=0.1-0.4X-ray background source candidates Bright Blazars with fluence of ~ 2.510-5 erg cm-2 in ~70 ks Pros: Very Bright. Cons: RareBright QSOs with fluxes> 5*10-12 erg cm-2 s –1 keV –1 Pros: Not too Rare. Cons: Very Nearby (faint)GRB afterglows with fluence of ~ 310-6 erg cm-2 in ~60 ksCons: Bright (distant). Not too rare (~10 per year).8Estimated using BeppoSAX results. confirmed by SwiftMinimum flux (fluence) for detection NOVII/Dz = 4–8NOVIII/Dz=0.6–1.3OVII Ka @z=0.26EW=0.1 eVOVII Ka @z=0.46 EW=0.1 eVOVII Kb @z=0.46 EW=0.072OVI KLL@z=0.26EW=0.06 eVMinimum flux (fluence) for detection The ratio of the EWs of 2 lines from ions of the same element uniquely define the ionization balance of the absorber.- From 30 GRBs with fluence3.2 x 10-6 erg/cm2 one expects 10-20 line pairs of at least 2 oxygen ions.-10-20 detections would bring relative errors down to a ~20 % level Measuring WWHIM: Systematic errorsOVII R-spacedVpOVII z-spaceDepartures from ionization equilibrium (Yoshikawa and Sasaki 2006) and the inhomogeneous distribution of WHIM (Kawahara et al. 2006) are potential sources of systematic errors. However some systematics may actually increase the chance of WHIM detection.Coherent infall motions boost the EW of the strongest OVII absorbers up by ~30% (OVIII by ~15%)Joint emission-absorption analysisEmission ~ r2 – Absorption ~ rJoint emission-absorption analysis -IQSO pairs?Viel, Branchini, Cen, Matarrese, Mazzotta, Ostriker, 2003, MNRAS, 341,792WHIM as a mass tracerSigad Branchini & Dekel 2001The large scatter in the gas vs. DM relation makes WHIM a poor tracer of the underlying mass density fluctuation field.Probing WHIM spatial distributionAbsorption analyses could measure the “size of the WHIM filaments’ using nearby ~20 bright QSOs pairs separated by <20’ (Viel et al 2003). A 3s level determination, however, requires ~40 Msec observation.A much better option is to study the angular correlation properties of the WHIM emission signal. Theoretical models provide robust prediction for the WHIM 2-point angular correlation function3C273VIRGOWHIM as a mass tracerEulerian Hydro-simulation. Flat LCDM L=25 Mpc/h. l=32.6 Kpc/h. Cen et al. 2003 GalaxyLight: TullyCatalogBiasing hypothesis+ADDING POWERIGM distributionGas propertiesOVII distributionCLOUDYWHIM: the observational state of the artNicastro et al 2002. PKS2155-304. 1 Absorber @ z~0Nicastro et al 2005. Mark-421. 2 Absorbers @ z~0.011 and z~0.027NeXOVIIIOVIIOVIINeIXNVICVIOVIIIBut see Kaastra et al. 2006 and Rasmussen et al 2006Summary - WHIM
  • Best bright background sources ? GRBs
  • Unambiguous WHIM at detection at z>0 ? Yes
  • Measuring WWHIM ? Yes. e~20%
  • Tracing Dark Matter (Wm) ? No
  • WHIM spatial distribution ? Yes. Emission
  • ..alternative observational strategies are also possible WHIM and feedbackNo feedback Galactic windsGalactic winds coupled Black holesWHIM and feedback - II
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