The Trials and Transport of Cosmic Metals

1
The Trials and Transport of Cosmic Metals

• Rob Wiersma Leiden Observatory

Joop Schaye, Claudio Dalla Vecchia, Craig Booth,
Marcel Haas, Freeke van de Voort, Luca
Tornatore, Volker Springel, Tom Theuns
2
Metal distribution

• The cosmic metal distribution is still unknown
• density-temperature-metallicity space
• IGM-ICM-ISM-stars
• Large/medium/small halos?
• Missing metals problem
• Excess metals problem

3
Observed metal distribution at z 2
Missing 3 - 63
IGM (DLAs Lya forest) lt 37
Galaxies (Gas Stars) 30 - 60
Bouché et al. (2007)?
4
OWLS OverWhelmingly Large Simulations

• Cosmological simulations (N-body/SPH)?
• Default runs use 2 x 5123 (gas, dark matter)
  particles over a 25 Mpc/h box (to z 2) and a
  100 Mpc/h box (to z 0)?

5
OWLS The Philosophy

• Vary physics (feedback strength, cooling, etc.)
  as well as numerical parameters (box size and
  resolution)?
• Keep simple prescriptions for things we cant
  resolve

6
OWLS The Code (GADGET 2 and then some)?

• New star formation recipe
• Fully chemodynamical
• Following 11 elements
• Enrichment from
• Type Ia Supernovae
• Type II Supernovae
• AGB Stars
• Stellar winds
• Major cooling improvements
• Element by element treatment
• Considers the effect of photoionization on metals

7
(No Transcript)
8
Mass and Metal Mass Distribution
5123 particles 100 Mpc/h box z 0
9
Where are the metals?
5123 particles 100 Mpc/h box
nH gt 10-1 cm-3
nH lt 10-1 cm-3
Stars
10
Phases where the metals lie
11
Box Size Test
100 Mpc, 5123 particles
25 Mpc, 1283 particles
12
Box Size Test
13
Resolution Test
25 Mpc, 5123 particles
25 Mpc, 1283 particles
14
Resolution Test
15
OWLS Cooling

• Using CLOUDY, we construct cooling tables that
• Element by element treatment
• Considers the effect of photoionization on metals
• Thus cooling is tabulated as a function of
  temperature, density, redshift, and abundance of
  element X
• Freely available at http//www.strw.leidneuniv.nl/
  WSS08

16
(No Transcript)
17
Cooling and Feedback Dependence
5123 particles 100 Mpc/h box
No metal-line cooling
Fiducial model
No metal-line cooling or feedback
18
Cooling and Feedback Dependence
5123 particles 100 Mpc/h box z 0
19
OWLS winds

• Use Type II Supernovae to drive galactic winds
• In simulations this can be done by kicking gas
  particles
• Default model has
• mass loading 2 x star forming mass
• velocity 600 km/s
• (see Dalla Vecchia and Schaye 2008)?

20
Wind dependence Constant Energy
5123 particles 25 Mpc/h box
Mass Loading 8, Velocity 300 km/s
Mass Loading 1, Velocity 848 km/s
21
Wind dependence Constant Energy
5123 particles 25 Mpc/h box z 2
22
Alternative Wind Models

• Can scale parameters (mass loading and wind
  velocity) with environment, time, etc.
• Energy driven
• Winds use a constant fraction supernova energy
• Momentum driven
• Wind energy can vary (i.e., contribution of
  radiation pressure on dust grains)?
• (cf. Oppenheimer and Davé 2006, Oppenheimer and
  Davé 2008)?

23
Wind dependence Constant Energy
5123 particles 100 Mpc/h box
Sound speed scaled winds
Fiducial model
24
Wind dependence Constant Energy
5123 particles 100 Mpc/h box z 0
25
Wind dependence Momentum driven
5123 particles 25 Mpc/h box
Halo mass scaled winds
Fiducial model
26
Wind dependence Momentum driven
5123 particles 25 Mpc/h box z 2
27
OWLS star formation

• Abandon subgrid model
• Above nH 0.1 cm-3 enforce an equation of state
  such that the Jeans length is independent of mass
• Randomly sample the Kennicutt Schmidt law (n
  1.4) from equation of state gas
• (see Schaye and Dalla Vecchia 2007)?

28
Star formation law dependence
5123 particles 25 Mpc/h box
Steep KS law
Fiducial model
29
Star formation law dependence
5123 particles 25 Mpc/h box z 2
30
Summary
Also star formation law, cosmology, IMF
(Extreme)?
No influence Type Ia supernova rate,
reionization history, IMF (Salpeter vs.
Chabrier), ISM equation of state
31
O/Fe as a function of redshift
5123 particles 100 Mpc/h box
32
Conclusion

• Under most models
• At z 2, metals are distributed evenly among the
  stars, ISM and ICM/IGM
• At z 0,
• 40 - 60 of metals are locked in stars
• 30 - 50 of metals are in the IGM
• Material dragged along in winds can result in
  abundance ratios that differ from Type II SN
  yields (particularly around low mass halos)?

33
(No Transcript)
34
(No Transcript)
35
a-Enhancement in Stars
36
Metallicity Evolution