Star Formation in GalaxiesStar Formation in Galaxies

Yuexing Li (Columbia Univ. /AMNH)

Mordecai Mac low (AMNH/Columbia)

Ralf Klessen (AIP, Germany)John Dubinski (CITA)

Zoltan Haiman (Columbia)

NASA, Hubble Heritage Team, Nick Scoville and T. Rector

Star Forming GalaxiesStar Forming Galaxies

NASA/STScI/B.Whitmore

1. Global Schmidt Law1. Global Schmidt Law

Kennicutt1998 Gao & Solomon 2004

2. Star Formation Thresholds2. Star Formation Thresholds

Martin & Kennicutt (2001)

Models of the SF lawsModels 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)

P1: SF in Isolated Disks 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

Numerical CriteriaNumerical Criteria

Jeans criterion for mass resolution (Bate & Burkert 97, Truelove et al. 97)

Gravity-hydro balance criterion for gravitational softening length (Bate & Burkert 97)

Equipartition criterion between gas, collisionless particle masses (Steinmetz & White 97)

Resolution StudyResolution Study

105

6.4 x 106106

8 x105

Li, Mac Low & Klessen 2005a

How Do Stars Form?How Do Stars Form?

LMK 2005b

Star Formation MorphologyStar Formation Morphology

Global Schmidt LawGlobal Schmidt Law

Kennicutt 1998

LMK 2005c

Local Schmidt LawsLocal Schmidt Laws

LMK 2005c

What Controls SF?What Controls SF?S

tar

form

atio

n ti

mes

cale

Gravitational instabilityLMK 2005d

Sta

r F

orm

atio

n E

ffic

ienc

y

Galaxy Model

LMK 2005c

P2: SF in Interacting GalaxyP2: SF in Interacting Galaxy

Li, Mac Low & Dubinski, in prep

Merger vs. SingleMerger vs. Single

LMK 2004

Merger RemnantMerger Remnant

Mass distributionAge distribution

LMK 2004

Connection btw SF and BH GrowthConnection 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)

Simulated MSimulated MBHBH - - Relation Relation

Li, Haiman & Mac Low, in prep

Quasar LifetimesQuasar Lifetimes

Li, Haiman & Mac Low, in prep

SummarySummary 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