Star Formation in Galaxies

1. Star Formation in Galaxies Yuexing Li (Columbia Univ. /AMNH) Mordecai Mac low(AMNH/Columbia) Ralf Klessen (AIP, Germany) John Dubinski (CITA) Zoltan Haiman (Columbia)

2. NASA, Hubble Heritage Team, Nick Scoville and T. Rector NASA/STScI/B.Whitmore Star Forming Galaxies

3. 1. Global Schmidt Law Kennicutt1998 Gao & Solomon 2004

4. 2. Star Formation Thresholds Martin & Kennicutt (2001)

5. Models of the SF laws • Gravitational instability (Kennicutt89, Friedli et al. 94, Kennicutt98, Martin & Kennicutt 01) • Kinematical law (Wyse 86, Silk 87, Hunter, Elmegreen & Baker 98) • Density PDF from turbulence (Elmegreen 02, Kravtsov03, Krumholtz & McKee 05)

6. P1: SF in Isolated Disks • Code: GADGET v1.1 (Springel, Yoshida & White 01) + sink particles (gravitationally bound, convergent flow, n >103 cm-3, represent star clusters) • Galaxy model:  DM halo + disk (stars & isothermal gas) (Mo, Mao, White 98, Springel & White 99, Springel 00) • Initial conditions: • rotational vel.: 50 ≤ Vrot≤ 220 km s-1 • gas fractions: 20 ≤ fg ≤ 90% of Md • effective sound speed cg = 6, 15 km s -1

7. Numerical Criteria • Jeans criterion for mass resolution (Bate & Burkert 97, Truelove et al. 97) • Gravity-hydro balancecriterion for gravitational softening length (Bate & Burkert 97) • Equipartitioncriterion between gas, collisionless particle masses (Steinmetz & White 97)

8. 105 8 x105 106 6.4 x 106 Resolution Study Li, Mac Low & Klessen 2005a

9. How Do Stars Form? LMK 2005b

10. Star Formation Morphology

11. Global Schmidt Law Kennicutt 1998 LMK 2005c

12. Local Schmidt Laws LMK 2005c

13. What Controls SF? Star formation timescale Star Formation Efficiency Gravitational instability Galaxy Model LMK 2005d LMK 2005c

14. P2: SF in Interacting Galaxy Li, Mac Low & Dubinski, in prep

15. Merger vs. Single LMK 2004

16. Mass distribution Age distribution Merger Remnant LMK 2004

17. Connection btw SF and BH Growth • Similarity btw cosmic SFH and quasar evolution (Madau et al. 96, Shaver et al 96) • Starburst – AGN connection (Norman & Scoville 88, Smith, Lonsdale & Lonsdale 98) • MBH –  correlation (Magorrian et al. 98, Ferrarese & Merritt 00, Tremaine et al. 02) • Most starburst gals are mergers (Sanders & Mirable 96, Alexanders et al 2004) • Larger amount of CO in nearby merging galaxies (Scoville 2000) and high-z QSOs (Walter 2002) • QSO lifetimes 106 – 108 yrs (Martini 2004) • Recent simulations (De Mateo, Springel & Hernquist 05, Kazantzidis et al. 05)

18. Simulated MBH -  Relation Li, Haiman & Mac Low, in prep

19. Quasar Lifetimes Li, Haiman & Mac Low, in prep

20. Summary • Our simulations reproduce many obs. of SF in gals -- the Schmidt Laws, SF thresholds… tot gravitational instability, CO SFE • Galaxy interaction trigger starburst. Higher SN of GCs, and bimodal metallicity dist. are natural products of gas-rich major mergers. • Merger also increase BH accretion, and the MBH –  correlation is the fine-tuning of gas removal, in our case regulated by SF. • Quasar lifetime ranges 106 – 108 yrs, depending on the luminosity threshold