1. Star Formation at High Redshift: Observational Progress and Theoretical Perspectives Romeel Davé movie by B. Oppenheimer

2. Cosmic SF History Madau et al 1996 Hopkins & Beacom 2006 x10 from z=1-0 ~flat z=4-1 rising to z~4 - Systematics >~x2 - Sample overlap?

3. Breaking down cosmic SF  Bursty or quiescent?  How important are mergers?  How much is obscured?  Stellar mass growth vs. SFR?  Is hi-z SF systematically different?

4. Main Sequence of Galaxy Formation  SFR ~ M * 0.7-0.9, scatter 0.3 dex.  Evolves down independently of M *  SFR quiescent, not burst, dominated Noeske etal 07 z~0.2-1.1 Daddi etal 07 z~1.4-2.5 Elbaz etal 07 z~0.8-1.2 Labbe etal 10 z~7

5. SFR from mergers?  Close pairs: 3:1 mergers  Morphological: <30% global SF in interacting  BUT– Asymmetry: ~50% z~1 SF in “mergers”  Non-interacting galaxies dominate SFRD Robaina et al 2009 Jogee et al 2009 Shi+09

6. Bouwens+09 Obscured star formation  Most SF obscured; peaks at z~2.  LIRGs/ULIRGs dominate to z~1,2…but don’t interpret as local ULIRG analogs! Dust production SF to disks Seymour+09

7. SFR vs. dM * /dt  dM*/dt << SFR (+IMF) at z~2-3  Completeness? (Reddy+09)  Is SFR at z~2-3 fundamentally different? RD 08 Wilkins+ 09

8. How Do We Understand All this?  Computers !

9. A Not-totally-wrong Story for Star-forming Galaxies  Cold flows  Smooth accretion  Regulation by galactic outflows  The Galaxy-IGM connection  Truncation by mergers/AGN

10. Cold mode accretion   Cold flows dominategas infall for ALL star- forming galaxies.   Hot halos for >10 12 M  Infall from IGM disk R vir R cool Dekel+ 09 z=2, AMR  At z>~1-2, flowspenetrate hot halo.  At low-z, flowsbreak up intoclouds (HVCs?) z=2, 10 12 M  haloz=1, 10 13 M  halo Keres+ 09

11. Cold Mode -- in every hydro sim ever done

12. SFR tracks accretion  SFGs at all masses, epochs process accreted gas into stars on t<<t H Keres+09

13. Accretion is Smooth  Accretion is ~smooth (& filamentary).  Mergers subdominant. Keres etal 09

14. Generic predictions  Tight SFR-M * relation, evolves indep of M *  Mergers/bursts sub- dominant in SFRD.  Disturbed morphology due to rapid accretion  Early galaxies grow rapidly.  … too rapidly!  Need feedback. RD 08 Bournaud+ 07: Unstable disk sim Data: Bouwens+06 z~6 RD et al 06

15. Feedback Regulates SF Halo mass function, scaled by b/m. Baldry+ 08

16. Cosmic Feedback Cycle

17. Outflows: Observations & Implications   Common at z~1+:   Σ SFR >>0.1 M ⊙ /kpc 2   Δv ISM ~ hundreds km/s   Local SBs, z~1 SFG: v w  v circ Momentum-driven winds?   If so, mass loading factor η  1/v circ   Note: Similar scalings may arise from other physical mechanisms. M82: Spitzer 8μ Martin 2005 100

18.   Correct (early) evolution of cosmic SFR   IGM enriched to match CIV, OVI absorbers   Mass-metallicity with right slope & scaller   High gas fractions in low-M galaxies   DLA kinematics w/enough wide systems   Non-grav entropy in intracluster gas … all from including one simple scaling of outflows with galaxy mass. Such Outflows Yield…

19.   Mass in outflows >> Mass in stars   Winds recycle a lot; recycled wind accretion dominates at z<~1.   Many baryons blown out of even large halos   Outflows keep galaxies gas rich (not poor).   MZR set by balance of inflows and outflows, not gas processing rate … Some Surprising Implications M wind ~ 3 M * Median N recyc ~3 BDO & RD 08

20. Z~M 1/3 The “Equilibrium” MZR Model z=2 Finlator&RD 08   Z ~ y M * /M acc ~ y (1+  ) -1   If v w >v esc, constant   constant Z. For v w <v esc,   0, Z  y. Produces a feature in MZR-- not seen.   For mom-driven winds:  ~M * -1/3 ~v c -1  Z(M * )~M * 1/3   Z gas set by an equilibrium between recent inflow and outflows. 

21. 680 km/s 340 km/s v w ~v circ Recycling sets the GSMF Halo mass function, scaled by b/m. Baldry+ 08 t rec short; Lots of recycled wind mode t rec longer; Less recycled wind mode t rec > t hubble ; No recycled wind mode  t rec irrelevant; Need to quench  star formation! t rec irrelevant; Need to quench  star formation!

22. Galaxies as “Gas Processing Engines”  Obtain gas via cold, smooth accretion  Creates tight evolving M * -SFR relation.  Process into stars (some) or eject into outflows (most) on a short timescale.  SFR, gas content, metallicity set by balance of inflow vs outflow.  Ejected material recycles, moreso in larger galaxies.  Sets shape and evolution of galaxy stellar mass function.

23. SFR-M * : Close but no cigar  Models get right:  Slope  Scatter  General evolution  But amplitude evolution is wrong!  Data has higher SFR at given M*.  But wait… cold accretion sets maximum rate! RD 08 Green: Millenium SAM Red, magenta: SPH sims Blue: Data (  =0.3) ‏

24. Birthrate evolution: Huh?  Discrepant during the peak dusty SF epoch.  Something different? Calibrations? IMF? Gonzalez+ 10 Simulations RD 08

25. Summary   3 regimes of cosmic SFH: Early growth (z>4), rapid phase (1<z<4), late decline (z<1)   Dominated by fairly smooth, filamentary cold accretion. Mergers & bursts subdominant.   Dust embedded SF peaks @ z~2. Before that, less dust; after, SF morphology change?   Generally, trends well explained by   Cold mode accretion, smooth & filamentary   Outflows that eject more mass from small gals.   Mismatch between SFR and M* evolution, both vs. data and theory?

26. Diff recycling governs GSMF   Without wind mode, GSMF~halo MF (scaled).   Wind recycling boosts higher M* galaxies, flattens GSMF.   Once t recyc > t Hubble, reverts to steep slope, modulated by outflows (vzw shallower since  ~1/v circ ).

27. Halo baryon content  Winds drive lots of baryons out of halos.  Big galaxies lose baryons early.  MW-like halo today has lost ~½ baryons  Peak SF “efficiency” @ 10 13 M .  Qualitatively similar to observations.

28. Winds recycle!   M winds >> M stars    wind ~ 0.2  b    ejected ~ 0.5  b   Compare:  * ~ 0.08  b   Median # ejections: 3   Turnaround radius ~100 physical kpc   high-z: Enrich IGM   low-z: Halo fountains   Median t recyc ~ 1 Gyr

29. Constraints from IGM enrichment   Outflows are the only way to enrich IGM   z~2-4 CIV absorbers very constraining; favors momentum-driven wind scalings: v w ~v circ,  ~v circ -1. wind speed mass loading Too few metals in IGM IGM too hot Diffuse IGM unenriched Too few metals produced Momentum-driven wind scalings! Metallicity Overdensity Oppenheimer & RD 2006 Oppenheimer & RD 2008 Oppenheimer & RD 2009a,b

30. Gas content   f gas (M * ) strongly dependent on outflows.   M-D winds keep low- mass galaxies gas rich by suppressing SF.   Strong outflows make galaxies gas rich, not gas poor.   Galaxies are the antithesis of closed boxes: They process gas as supplied.

31. Z~M 1/3 Mass-Metallicity Relation z=2 Finlator&RD 08   Conventional thinking:   Z gas reflects stage of processing   Galaxies lose metals based on .   NO! Why? Outflows are greedy & destructive:   They don’t share their energy -- they blow holes! Analytic3D simulation

32. “Wind mode” accretion

33. Differential Recycling  t recycling goes inversely with mass 680 km/s 340 km/s v w ~v circ

34. Luminosity functions   z~6: Large SF suppression.   Rapid consumption  must eject gas.   M acc = M * +M outflow  SFR  (1+  ) -1   z~2-4:   Const    ~2+    ~ v c -1   ~1.7   z=0: Faint end slope  ~1.3; less steep!   (bright end?…fugly) Data: Bouwens etel 06 Models:  =0.3,  8 =0.9 RD, Finlator, Oppenheimer 06 

35. DLA Kinematics: Outflows?  Wide separation (  v>v rot ) DLAs hard to produce; protogalactic clump infall fails (eg Pontzen etal).  Momentum-drive winds puff out gas, produces wide- separation systems. Prochaska & Wolfe 01 KS test prob no winds, 8e-5 constant winds, 0.037 MD winds, 0.51 No winds Mom-driven windsConstant winds S. Hong, Katz, RD etal, in prep

36. Feedback Tomography  Background sources observe outflows in action.  Tough now, but will become routine at z~2+ in 30m era.  COS enables at z<1  Also possible in emission around galaxies.  The next frontier of observational galaxy formation!