What regulates star formation?

Transcription

1 What regulates star formation? N. Bouché (UCSB) A. Dekel (Hebrew), R. Genzel, S. Genel (MPE) M. Murphy (Swinburne), C. Martin (UCSB), T. Contini (Toulouse)

2 Great Success Hopkins Beacom 2008 Bouwens et al. 2009

3 What drives star-formation? a) b) merger scenario motivated by hierarchical merger model: Hernquist, Springel, di Matteo, Hopkins et al (rapid) inflow scenario: Dekel & Birnboim 2003,2006, Keres et al. 2005, Teyssier et al. AMR, Teyssier

4 ULIRGs LIRGs High-z SF galaxies

5 What drives star-formation? c) Gas reservoir sets SFR Kennicutt 1998

6 Continuous flow(s) Primordial fluctuations Biegel et al. 2008,2011 H+ HI H 2

7 Continuous flow(s) Primordial fluctuations Growth/ Accretion

8 Sl op e ~ 2 What is the role of feedback? Behroozi et al. 2009

9 Scaling relations KS Relation ΣSFR ~ Σgas1.5 SFR-Mass SFR ~ M0.8 TF M~V4 See Genzel et al 2010, Daddi 2010

10 Scaling relations KS Relation ΣSFR ~ Σgas1.5 SFR-Mass SFR ~ M*0.8 TF M*~V4 Cresci et al. 2009, also Kassin.

11 Scaling relations KS Relation ΣSFR ~ Σgas1.5 SFR-Mass SFR ~ M0.8 TF M~V4

12 The SFR sequence Z=2 GOODS sbzk K<22.5 Daddi07 Z=1 Elbaz07 Z=0.5-1 SD SS Elbaz 2007, Brinchmann 2004 Z= 0 z=0 blue SDSS Noeske 2007 Z= Also, Damen 09, Zheng 07 S S D S 0

13 The SFR sequence Karim et al (COSMOS 105 galaxies) Genel 2008, Neistein 2007 McBride/Fakhouri

14 Evolution is a challenge Davé 2008 Oliver et al. 2010

15 Evolution at z>4? Gonzales 2010

16 Open Questions Why is there SFR-Mass? Why evolution x20 since z~2? Why is there downsizing? Role of gas inflow vs. impact of feedback?

17 Galaxy Formation: Traditional Hydro Simulation

18 et a R noit er cc A Traditional Approach White & Frenk 1991 Inf al l Ra te Birnboim & Dekel 2003 Keres et al. 2005; Ocvirk +Teyssier et al. o o C te a R g li n

19 Galaxy Formation: Approach 3

20 Galaxy Formation: Approach 3 oit er cca MD EP S dm/dt ~ 35 Mh1.1 (1+z)2.2 Genel Mhalo et al. 08, also Fakhouri, Ma; McBride et al.

21 Scaling relations: Summary KS Relation ΣSFR ~ Σgas1.5 Halo Growth dm/dt ~ M1.1? SFR-Mass SFR ~ M*0.8 TF M*~V4

22 Scaling relations: Summary KS Relation ΣSFR ~ Σgas1.5 Halo Growth dm/dt ~ M1.1 Virial relation M ~ V 3 SFR-Mass SFR ~ M*0.8 TF M*~V4

23 Disclaimer

24 Bathtub model: Solutions dmgas = εin dm/dt SFR - Outflow (1) SFR = εsfr Mgas / torb (2) KS The bathtub NEVER overflows!! Reach a quasi-steady state.

25 Quasi-Steady State: Implications t_sfr << t_acc SFR follows net gas inflow rate

26 Bathtub model dmgas = εin dm/dt SFR - Outflow (1) SFR = εsfr Mgas / torb (2)

27 Option 1: Change SF efficiency SFR sequence TF relation Same for SF threshold!

28 Option 2: Change feedback Dutton et al. 2009,2010 ==> Good for M-Z relation

29 RF S go Option 2: Change feedback Dutton et al. 2009,2010 M vir M star See also Finlator et al. 2011

30 Option 3: Change accretion Mshock Mmin Neistein, E., Weinmann, S Bouché et al. 2010, see also Cattaneo et al. 2010

31 Scaling Relations SFR sequence TF relation Without Minimum Mass

32 Scaling Relations SFR sequence TF relation With Minimum Mass Bouché et al. 2010

33 + Evolution Bouché et al 2010

34 Scaling relations are isochrones Finlator et al. 2011; SPH Bouché et al. 2010

35 Other predictions SFR-Mass; TF ssfr (z) Stellar fractions F_gas (M*) F_gaz (z) SFRD (z) Downsizing

36 Predictions 1: Stellar fraction

37 Predictions 2: Gas fractions Daddi et al High accretion high SFR high f_gas

38 Prediction 3: Evolution SFR(z) Bouché et al. 2010

39 Open Questions Why is there SFR-Mass? Why evolution x20 since z~2? Role of gas inflow vs. impact of feedback? What causes downsizing?

40 Scaling relations: Summary KS Relation Σ SFR ~ Σ 1.4 Halo Growth dm/dt ~ M1.1 Genel et al. 2008, Neistein et al SFR-Mass SFR ~ M0.8 TF: M~V4 Ovcrik et al. 2008, Dekel et al. 2009

41 Toy Model: One Assumption

42 Downsizing Archeological Downsizing

43 Casey's trick

44 Evolution at z>4? Papovich 2010 Power law: tau~200 Myr Rising Exponential: tau ~ 400 Myr!

45 Evolution at z>4? Finlator et al. 2011; SPH Bouché et al. 2010

46 Evolution at z>4? GOODS Stark et al Gonzales et al Bouché et al. 2010

47 Problems at z>4? SFH(t) assumed... Emission lines Dust Schaerer et al. 2010

48 Problems at z>4? SFH(t) assumed... Emission lines No one Not in Gonzalez ssfr underestimated Dust No near-ir in Yabe SSFR overestimated

49 In Summary: Mass accretion Floor What is the physical mechanism? A) Traditional UV heating? Only works in halos <10 km/s Feedback? Re-heating / Mo 2005 / Robertson H2 formation B) Cooling / Cantalupo Globular Clusters can reionize universe... Is there evidence for a mass floor?

50 Cooling Curve! Cantalupo 2010

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52 Evidence from MgII Surveys?

53 Evidence for the accretion floor? 14/21 3/19

54 Implications Metal rich halos came first...

55 Would cold flows be ever observed? 1

56 Galaxy formation with MUSE Giant IFU 1 x1 (optical) AO enhance Great stability, High sensitivity (3e-19 erg/s/cm2, 1e-18cgs/sq ) PI: Bacon (Lyon)

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60 MUSE LBGs LAE