STRUCTURE FORMATION
MATTEO VIEL
INAF and
INFN Trieste
SISSA LECTURE #4 – March 14th 2011
OUTLINE: LECTURES
1.
Structure formation: tools and the high redshift universe
2.
The dark ages and the universe at 21cm
3.
IGM cosmology at z=2=6
4.
IGM astrophysics at z=2-6
5.
Low redshift: gas and galaxies
6.
Cosmological probes LCDM scenario
OUTLINE: LECTURE 4
Galactic winds and metal enrichment
The evolution of the UV background
The Warm-Hot Intergalactic Medium
GALACTIC
WINDS
Galactic winds –I
Local galactic winds M82 optical and infra-red
Local galactic winds M82 X-ray
Galactic winds –II
Log overdensity
Theory: Galactic winds
do they destroy the forest ?
Log Temp
Flux
Temp.
Dens.
Theuns, MV, et al, 2002, ApJ, 578, L5
Feedback effects: Galactic winds-IV
Line widths distribution
Column density distribution function
Metal enrichment CIV systems at z=3
Strong Feedback e=1 ---- Role of the UV background
Mori, Ferrara, Madau 2000;
Rauch, Haehnelt, Steinmetz 1996;
Schaye et al. 2003
Soft background ---- Role of different feedback
e=0
e=1
e=0.1
Observations: the POD technique
Aguirre,Schaye, Theuns, 2002, ApJ, 576, 1
Cowie & Songaila, 1998, Nature, 394, 44
Pieri & Haehnelt, 2004, MNRAS, 347, 985
Pixel-by-pixel search using higher order transitions
Springel & Hernquist 2002,2003
Observations: the POD technique-II
NO SCATTER IN
THE Z-r relation
SCATTER IN
THE Z-r relation
Good fit to the median but not for the scatter
Schaye et al., 2003, ApJ, 596, 768
Observations: the POD technique-III
Lognormal fit
VARIANCE OF THE METALLICITY
Schaye et al., 2003, ApJ, 596, 768
When did the IGM become enriched – II ?
Adelberger et al. 2005
GALAXY-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 connection
UV BACKGROUND
Photoionization rate
Ionizing background – I
With the fluctuating Gunn – Peterson approximation
t ~ 1/ G -12
Bolton, Haehnelt, MV, Springel, 2005, MNRAS, 357, 1178
Ionizing background-II
Bolton, Haehnelt, MV, Springel, 2005, MNRAS, 357, 1178
Summary
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
Fukugita, Hogan, Peebles, 1998, ApJ, 503, 518
Cen & Ostriker 1999, ApJ, 514, 1L
WHIM - 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.
- WWHIM estimate.
- Systematic effects. Joint emission+absorption analysis
- Spatial distribution of WHIM and its bias
WHIM: model uncertainties – I
To asses model (random+systematic) uncertainties we have
used different techniques to simulate WHIM
WHIM: model uncertainties – II
• Semi analytic model (Viel et al. 2003)
• Hydro-dynamical model by Borgani
• Hydro-dynamical model (Viel 2006)
W = 0.7, Wm = 0.2457, Wb = 0.0463, h = 0.7,  = 0.85
L = 60 h
-1
Mpc, , NDM = 4003, NGAS = 4003, e = 2.5 h
-1
kpc
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)
Minimum flux (fluence) for detection
NOVII/Dz = 4–8
NOVIII/Dz=0.6–1.3
OVII Ka @z=0.46
EW=0.1 eV
OVI KLL
@z=0.26
EW=0.06 eV
OVII Ka @z=0.26
EW=0.1 eV
OVII Kb
@z=0.46
EW=0.072
WHIM as a mass tracer
Galaxy Light: Tully Catalog
Eulerian Hydro-simulation. Flat CDM
L=25 Mpc/h. l=32.6 Kpc/h. Cen et al. 2003
Biasing hypothesis
+
ADDING POWER
IGM distribution
Gas properties
OVII distribution
CLOUDY
WHIM: the observational state of the art
Nicastro et al 2002. PKS2155-304.
1 Absorber @ z~0
Nicastro et al 2005. Mark-421.
2 Absorbers @ z~0.011 and z~0.027
NeX
OVIII
OVII
OVII
NeIX
OVIII
NVI
CVI
But see Kaastra et al. 2006 and Rasmussen et al 2006
Summary - 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
WHIM and feedback - II