What Doesn t Quench Galaxy Formation?

Transcription

1 What Doesn t Quench Galaxy Formation? Phil Hopkins Dusan Keres, Claude Faucher-Giguere, Jose Onorbe, Freeke van de Voort, Sasha Muratov, Xiangcheng Ma, Lena Murchikova, Norm Murray, Eliot Quataert, James Bullock

2 Motivation Q: WHY IS STAR FORMATION SO INEFFICIENT? Moster 2009 No Feedback 10% of baryons Log( Stellar/Halo Mass ) Number Density Stellar Feedback SMBH Feedback Observed Log( Halo Mass ) M stars [M ]

3 Stellar Feedback: How Can We Do Better? Ø High-resolution (~1-10 pc), molecular/metal cooling (~10 K), SF at nh > 100 cm -3 Ø Energy/Mass/Metal Injection: Ø Ø SNe (II & Ia) Stellar Winds (O & AGB) Ø Photoionization (HII) & Photoelectric Ø Momentum Flux: Ø Ø Ø Radiation Pressure!! SNe!! P rad L c (1 + IR) P SNe ĖSNe v 1 ejecta Stellar Winds P W Ṁv wind Ø (also MHD, anisotropic conduction, diffusion)

4 The FIRE Project: Cosmological Simulations at 1-10pc resolution

5 Cosmological Simulations NO PARAMETERS ADJUSTED! REALLY! No Feedback PFH, Keres, et al. (arxiv: )

6 Kennicutt-Schmidt relation emerges naturally ISOLATED GALAXIES no feedback gas / dyn 0.02 gas / dyn with feedback PFH, Quataert, & Murray, 2011a

7 (Galactic) Star Formation Rates are INDEPENDENT of how stars form! Efficiency (SF per tdyn) Index (SFR ~ ) SF Density Threshold Ø Set by feedback (SFR) needed to maintain marginal stability Hopkins, Quataert, & Murray 2011 also Saitoh et al. 2008

8 Inflows & Outflows

9 Simplest Sub-Grid Is Not Enough WE NEED TO DO BETTER! PFH, Keres, et al. (arxiv: ) Proto-MW: Gas Temperature: Decoupled Winds (Sub-Grid) Following Explicit Feedback

10 Does Stellar Feedback Explain the Mass Function? HOW EFFICIENT ARE GALACTIC WINDS? PFH, Keres, et al. (arxiv: ) M = f baryon M halo log (M halo /M )

11 But Feedback Does Matter MULTIPLE FEEDBACK MECHANISMS ARE CRITICAL PFH, Keres, et al. (arxiv: )

12 Feedback Determines the Halo Gas Properties NEED TO PREDICT OUTFLOW MASS, VELOCITY, & GAS PHASE Faucher-Giguere, PFH, et al.

13 Quenching: Non-AGN Mechanisms FAIL MORE THAN GRAVITY, COOLING, STARS, & MHD Ø Morphology? (are bulge-dominated) Ø Clumps/Gravity? (resolution ~10^4 M sun ) Ø MHD/Conduction? (new runs included)! Ø Ø Stars? (late-time AGB/SNIa included)! Ø SFR log (M halo /M )

14 Galaxies Just Keep Plugging Along NO QUENCHED TRACK

15 Lesson 1: Don t Trust Models that Don t Do Stars Right SMALL GALAXIES BECOME BIG GALAXIES Oppenheimer & Dave No Feedback Number Density Observed M stars [M ]

16 Lesson 1: Don t Trust Models that Don t Do Stars Right SMALL GALAXIES BECOME BIG GALAXIES Oppenheimer & Dave No Feedback Number Density Observed Observed Stellar, no AGN Feedback M stars [M ]

17 Lesson 1: Don t Trust Models that Don t Do Stars Right SMALL GALAXIES BECOME BIG GALAXIES Decoupled Winds (Sub-Grid) Following Explicit Feedback

18 Lesson 2: Shutting Down Star Formation in the Disk WHY IT S HARD Ø Self-Regulated SF (K-S) Ø Suppressed SF

19 Shutting Down Star Formation: GAS DEPLETION NEEDED ok, let s raise

20 Shutting Down Star Formation: GAS DEPLETION NEEDED M101 can t self shield (T~10 4 K): M83

21 Can Morphology Do It? Morphological/ Toomre /Dynamical Quenching (Martig, Dekel,+)

22 Can Stars Do It? SNIa, AGB (Conroy+, Ostriker, Novak)

23 Can Stars Do It? SNIa, AGB (Conroy+, Ostriker, Novak)

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25 Can Stars Do It? SNIa, AGB (Conroy+, Ostriker, Novak) NO

26 Can Gravitational Heating Do It? IMPORTANT, BUT NO SFR Virial shock-heating, stirring by clumps/substructure keeps 90% of gas hot

27 Gravitational Heating NOT AS MANY CLUMPS THESE DAYS! Keres et al., in prep Density Formulation ( Old GADGET) Pressure-Entropy Formulation (P-GADGET) Not enough clumps, & existing ones are too metal-rich (join the cooling flow)

28 Can MHD & Conduction Do It? NO SFR (whole box) With MHD+! Conduction No MHD/! Conduction Redshift z Ø Conduction doesn t save us: Ø Magnetic Instabilities (HBI; Quataert 08)! Ø Inefficient in halos < MSUN

29 Ø Star formation is Feedback-Regulated: independent of small-scale SF Ø Enough stars to offset gravity = Kennicutt relation, winds, sub-mw galaxies! Ø Something else needed to quench! Ø Deplete disks ( < 10 Msun/pc 2 ) & Prevent Cooling Ø Need to get stars+ism right Ø Old Stars: Not enough energy, and too many metals! Ø Conduction: Not efficient at low-mass halos, suppressed by MHD instabilities Ø Morphology Alone: Can t stop cooling! (in the disk or from the halo) Ø Gravitational Heating: Not enough. Too few clumps, too far out, too many metals.