Geneviève Parmentier

Transcription

1 MPIfR/AIfA Hauptkolloquium, 19 Novembe 2010 Splinte Bonn, 15 Septembe 2010 Fom Molecula Clump Popeties to Galaxy Evolution with Sta Clustes Geneviève Pamentie Agelande-Institut füf Astonomie Rheinische Fiedich-Wilhelms Univesität t Bonn

2 Sta Clustes: at the cossoad between sta fomation and galaxy evolution Geneviève Pamentie - Bonn Agelande-Institut fü Astonomie 2 /

3 Setting the Scene: Sta Clustes (SC) as Poweful Taces of Galaxy Evolution Sta Clustes (SC): Compact goups of coeval stas bound togethe by gavity Identified on a one-by-one basis against the backgound of thei host galaxy Jodan+04 (ACS Vigo Galaxy Cluste Suvey II, fig6) Elliptical galaxy M49 Backgound-subtacted image Geneviève Pamentie - Bonn Agelande-Institut fü Astonomie 3 /

4 Setting the Scene: Sta Clustes (SC) as Poweful Taces of Galaxy Evolution Sta Clustes (SC): Compact goups of coeval stas bound togethe by gavity Identified on a one-by-one basis against the backgound of thei host galaxy Jodan+04 (ACS Vigo Galaxy Cluste Suvey II, fig6) Elliptical galaxy M49 Multi-band imaging of SC systems ( cluste magnitudes, colous) feasible out to Vigo Galaxy Cluste distances ( 20Mpc) combined to Simple Stella Population models estimates of cluste age, mass, metallicity Backgound-subtacted image Geneviève Pamentie - Bonn Agelande-Institut fü Astonomie 4 /

5 Setting the Scene: Sta Clustes (SC) as Poweful Taces of Galaxy Evolution Sta Clustes (SC): Compact goups of coeval stas bound togethe by gavity Identified on a one-by-one basis against the backgound of thei host galaxy Jodan+04 (ACS Vigo Galaxy Cluste Suvey II, fig6) Elliptical galaxy M49 Multi-band imaging of SC systems ( cluste magnitudes, colous) feasible out to Vigo Galaxy Cluste distances ( 20Mpc) combined to Simple Stella Population models estimates of cluste age, mass, metallicity Backgound-subtacted image Compehensive view of galaxy-: chemical enichment histoy, inteaction histoy, sta fomation histoy ove the past Hubble-Time Sta clustes ae at the vey heat of many astophysical topics Geneviève Pamentie - Bonn Agelande-Institut fü Astonomie 5 /

6 The Big Issue: SCs vesus field stas Most stas in ou Galaxy: ae bon in sta clustes young sta clustes tell us about sta fomation but ae obseved as field stas Sta clustes have the potential of tacing galaxy sta fomation histoies povided we get a fim handle on the atio of sta fomation still esiding in (obseved) sta clustes as a function of age log (dn/dt [My -1 ]) SFH Obseved age distibution of LMC sta clustes log ( age [y] ) Geneviève Pamentie - Bonn Agelande-Institut fü Astonomie 6 /

7 Sta Cluste Dynamical Evolution: Fast Facts SCs go though a lifecycle: they evapoate, until complete dissolution Cluste lifecycle includes 2 phases: 1. Violent elaxation: Vey shot (10-50 My) Dynamical esponse of sta clustes to the expulsion of thei esidual sta-foming gas 2. Secula evolution Until cluste dissolution Tidal-stipping of (pefeentially low-mass) stas combined to intenal two-body elaxation Geneviève Pamentie - Bonn Agelande-Institut fü Astonomie 7 /

8 Secula Evolution Modelling: SC Dissolution Time-Scale in the Lage Magellanic Cloud Pamentie & de Gijs 2008 based on the LMC data of de Gijs & Andes 2006 log (dn/dt [My -1 ]) Cluste fomation ate: - Onset of Secula Evolution - End of Violent Relaxation t 4 dis = 1Gy t 4 dis = 8Gy Obseved age distibution log ( age [y] ) Secula evolution modelling + obseved cluste age distibution histoy of the fomation ate of clustes which suvived thei violent elaxation Geneviève Pamentie - Bonn Agelande-Institut fü Astonomie 8 /

9 Gas-Embedded Cluste Fomation Histoy: the next step... Violent elaxation Violent elaxation modelling: (Gas-embedded) CFR SFR log (dn/dt [My -1 ]) Secula evolution modelling: (Bound) CFR Obseved age distibution log ( age [y] ) Geneviève Pamentie - Bonn Agelande-Institut fü Astonomie 9 /

10 Inta-Cluste Gas-Expulsion and Violent Relaxation Geye & Buket (2001) time Effects of gas expulsion - VIOLENT RELAXATION Cluste expansion Sta loss (infant weight-loss), o Cluste dissolution (infant motality) 10 Geneviève Pamentie - Bonn Agelande-Institut fü Astonomie 10 /

11 Violent Relaxation (VR): Obsevable Signatues And Pime Paametes Effects of gas expulsion - VIOLENT RELAXATION Cluste expansion Cluste infant weight-loss and infant motality Obsevable Impints upon Sta Cluste Systems : Cluste mass distibution, Cluste age distibution, Cluste adius distibution, Ratio of the total mass in clustes to the total stella mass in gas-embedded clustes Inta-Cluste Gas-Expulsion and Violent Relaxation Pime paametes: (e.g. Baumgadt & Koupa 2007) - SFE in the Cluste Foming-Region () - Gas expulsion time-scale: τ GExp /τ coss - Impact of extenal tidal field (envionment) time See also Adams (2000), Vespeini et al (2009), Geye & Buket (2001) 11 Geneviève Pamentie - Bonn Agelande-Institut fü Astonomie 11 /

12 Violent Relaxation: Cluste Mass Functions Time-Evolution of Cluste Mass Functions: What obseves tell modelles Log [dn/dlog m] CMF 50My ( = -2.0) CMF 3My ( = -2.0) Infant motality/ weight-loss dn dm m 2 dn d logm m 1 log m [M o ] m ( of VR) = F m ( at Gas Exp) cluste end bound cluste 12 Geneviève Pamentie - Bonn Agelande-Institut fü Astonomie 12 /

13 cluste SFE and Cluste Mass Functions m ( end of VR) = F ( SFE) SFE m bound F bound ( SFE ε ) F bound Instantaneous gas emoval, weak tf impact SFE 13 Geneviève Pamentie - Bonn Agelande-Institut fü Astonomie 13 /

14 F bound GExp / coss SFE ε, τ τ and Cluste Mass Functions GExp coss Pamentie, Goodwin et al. (2008) Koupa & Boily (2002) Constant adius: moe massive cluste-foming egions () have - a deepe potential well - a slowe gas-expulsion t-s - can suvive despite a low SFE of, say, 20% coss dn/dlogm log ( m [M o ] ) 14 Geneviève Pamentie - Bonn Agelande-Institut fü Astonomie 14 /

15 Tidal Field Impact and Cluste Mass Functions t τ coss, τ GExp SFE ε,, τ coss half mass tidal Weak t.f. impact Half-mass adius half-mass Cicula velocity of iso-t potential V c Galactocentic distance D gal tidal Embedded cluste mass m ecl Stong t.f. impact Limiting tidal adius : tidal G m = 2V ecl 2 c 1/ 3 D 2 / 3 gal, with m = ecl SFE. m 15 Geneviève Pamentie - Bonn Agelande-Institut fü Astonomie 15 /

16 Tidal Field Impact and Cluste Mass Functions t τ coss, τ GExp SFE ε,, τ coss half mass tidal Weak t.f. impact Half-mass adius half-mass Cicula velocity of iso-t potential V c Galactocentic distance D gal tidal Embedded cluste mass m ecl Stong t.f. impact Limiting tidal adius : tidal G m = 2V ecl 2 c 1/ 3 D 2 / 3 gal, with m = ecl SFE. m 16 Geneviève Pamentie - Bonn Agelande-Institut fü Astonomie 16 /

17 Half-mass adius to tidal adius atio = 0.3 pc 1pc = = m pc M o 1/ 2 = 0.5 g.cm = m pc M o 1/ 3 ( m [M o ] ) half mass m δ = 4100 M o.pc-3 ( m [M o ] ) tidal half mass tidal m δ 1/ 3 17 Geneviève Pamentie - Bonn Agelande-Institut fü Astonomie 17 / m 1/ 3 ecl m 1/ 3

18 F bound and Tidal Field Impact 1/ 2 m 1pc = = 1 pc M o = 0.5 g.cm-2 = 0.3 pc = m pc M o 1/ 3 ( m [M o ] ) Pamentie & Koupa (2011) axiv: = 4100 M o.pc-3 ( m [M o ] ) 18 Geneviève Pamentie - Bonn Agelande-Institut fü Astonomie 18 /

19 The m - Diagam as a Diagnostic Tool = m pc M o = m pc M o 1 pc = / 2 1/ 3 ( m [M o ] ) Extenal tidal field stength: (V c, D gal ) h/t in [log(),log(m)] h/t < 0.05: tf does not matte (does not necessaily imply weak tf!) h/t > 0.15: cluste suvivability demands long τ GExp /τ coss and high SFE ( [pc] ) tf impact impedes cl. suvivability As if no extenal tf ( m [M o ] ) 19 Geneviève Pamentie - Bonn Agelande-Institut fü Astonomie 19 /

20 Tidal Field Impact and Cluste Mass Functions: Pobing the cluste-foming egion mass-adius elation Cluste infant weight-loss is mass-independent, the shape of the cluste mass function does not evolve duing VR log (dn/dlogm) Ecl.MF CMF F bound log(m) = 4100 M o.pc-3 ( m [M o ] ) Cluste-foming egions with constant mean volume density: mass-independent infant weight-loss = m pc M o 20 Geneviève Pamentie - Bonn Agelande-Institut fü Astonomie 20 / 1/ 3

21 Tidal Field Impact and Cluste Mass Functions Cluste-foming egion MF dn/dlogm SFE=0.40 D gal =5kpc F bound = 0.5 g.cm-2 log ( m [M o ] ) ( m [M o ] ) Cluste-foming egions with constant mean suface density When moe massive means moe vulneable... Σ : 1pc = 0.01 m 1M o 1/ 2 21 Geneviève Pamentie - Bonn Agelande-Institut fü Astonomie 21 /

22 Clump mass-adius elations: obsevations Clump mass-adius diagam: impint of - cluste-fomation physics, o of - measuement method? Lack of high-mass data Does the whole clump fom a sta cluste? Muelle+02 ( clump [pc] ) clump = 0.15 g.cm-2 clump = 0.3 pc Density pofiles: ( clump,m clump 1E4 cm -3 ( m clump [M o ] ) 22 Geneviève Pamentie - Bonn Agelande-Institut fü Astonomie 22 /

23 Cluste-foming egion mass-adius elation: so what...? ( clump [pc] ) Ca GMC (Yonekua+05) Oion B (Aoyama+01) C 18 O - Red cicles: C 18 O clumps showing signs of SF activity ( m clump [M o ] ) 23 Geneviève Pamentie - Bonn Agelande-Institut fü Astonomie 23 /

24 Cluste-foming egion mass-adius elation: so what...? ( clump [pc] ) Ca GMC (Yonekua+05) Oion B (Aoyama+01) ( m clump [M o ] ) C 18 O - Red cicles: C 18 O clumps showing signs of SF activity - Most of them also host a subclump at 1E5 cm -3 (H 13 CO + ) SF takes place in egions whee the density is highe than a theshold, i.e. only in the densest egions of C 18 O clumps 24 Geneviève Pamentie - Bonn Agelande-Institut fü Astonomie 24 /

25 Cluste-foming egion mass-adius elation: so what...? ( clump [pc] ) Ca GMC (Yonekua+05) Oion B (Aoyama+01) ( m clump [M o ] ) C 18 O - Red cicles: C 18 O clumps showing signs of SF activity - Most of them also host a subclump at 1E5 cm -3 (H 13 CO + ) SF takes place in egions whee the density is highe than a theshold, i.e. only in the densest egions of C 18 O clumps Consequence: the local SFE must be measued ove the cluste-foming volume, not ove the whole C 18 O clump Both - H 13 CO + obsevations and - the tidal field impact analysis suggest: cluste-foming egions of constant mean volume density. (Pamentie & Koupa 2011, axiv: ) 25 Geneviève Pamentie - Bonn Agelande-Institut fü Astonomie 25 / * * * * * *

26 Fom the mass function of GMCs/clumps to that of gas-fee sta clustes... Log(dN/dm) = 1.7, molecula clumps and Giant Molecula Clouds dn dm α m = 2 young sta clustes log(m) 26 Geneviève Pamentie - Bonn Agelande-Institut fü Astonomie 26 /

27 Fom the mass function of GMCs/clumps to that of gas-fee sta clustes... Log(dN/dm) = 1.7, molecula clumps and Giant Molecula Clouds dn dm α m Mass-vaying SFE: lowe SFE at highe cloud/clump mass?? = 2 young sta clustes SFE log(m) Embedded -clustes 27 Geneviève Pamentie - Bonn Agelande-Institut fü Astonomie 27 /

28 Fom the mass function of GMCs/clumps to that of gas-fee sta clustes... Log(dN/dm) = 1.7, molecula clumps and Giant Molecula Clouds dn dm α m Mass-vaying SFE: lowe SFE at highe cloud/clump mass?? Steepe than = 2 = 2 young sta clustes SFE But then mass-vaying F bound too?? log(m) F bound Gas-fee sta clustes Embedded -clustes 28 Geneviève Pamentie - Bonn Agelande-Institut fü Astonomie 28 /

29 Fom the mass function of GMCs/clumps to that of gas-fee sta clustes... with a volume density theshold fo sta fomation Cluste-foming egions: constant mean volume density (tidal field impact analysis) GMCs and Molecula clumps with signs of SF activity: Constant mean suface density Lason 1981 Blitz Heye GMCs in - LMC - MW Galactic C 18 O Molec. clumps with SF activity Fig8 in Blitz+06 Fig 10 in Pamentie (2011) axiv: Geneviève Pamentie - Bonn Agelande-Institut fü Astonomie 29 /

30 Cluste-foming egions of constant mean volume density and cloud/clump mass functions log() Mass inceases, deceases clump clump clump 1/ 2 m clump 1/ 3 clump m clump clump 0 clump m clump log(m) - Constant mean suface density clumps a clump of highe mass has a lowe faction of its mass above a given volume density theshold ( ) 0.3 clump 30 Geneviève Pamentie - Bonn Agelande-Institut fü Astonomie 30 / ρ clump m m th clump m -1.9 :

31 Cluste-foming egions of constant mean volume density and cloud/clump mass functions Molecula clump 2-zone model * * * * * * * * * * * * * * * * * * * * ρ clump -1.9 : m m th clump m Muelle+02: density index clump low-density oute envelope: n H2 < n th Pamentie (2011) axiv: High-density of mass m th : n H2 > n th fo a given density pofile clump (), all s have identical mean volume densities (Note: m th = m ) High-density s: = 2 Molecula clumps/clouds of constant mean and = Geneviève Pamentie - Bonn Agelande-Institut fü Astonomie 31 /

32 The sta-foming gas is the dense molecula gas L IR SFR LIRGs/ULIRGs Spials Galaxies: 10 9 < M dense < M o Galactic individual molecula clumps: 10 2 < M dense < 10 4 M o Fig1 in Wu+05 L M HCN dense 32 Geneviève Pamentie - Bonn Agelande-Institut fü Astonomie 32 / ( n H Dense sta-foming gas vs diffuse quiescent molecula gas - Slopes of the cloud and cluste mass functions - Slope of the Kennicutt-Schmidt law 4 cm 3 )

33 Conclusions Popeties of young sta cluste systems shap insights into the clusteed mode of sta fomation sta fomation conditions detemine what mass faction clustes lose as they age infomation needed to econstuct galaxy SFH time-vaiations? (e.g. metallicity) SFH Even a long jouney stats with a one single step Oiental saying Most exciting yeas ae still to come: HERSCHEL, ALMA, log (dn/dt [My -1 ]) Obseved age distibution of LMC sta clustes log ( age [y] ) 33 Geneviève Pamentie - Bonn Agelande-Institut fü Astonomie 33 /