Building on the Macroscopic to understand the Microscopic: from Systems of Star Clusters to Individual Star-Forming Regions

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1 ESTEC, Noodwijk, Building on the Macoscopic to undestand the Micoscopic: fom Systems of Sta Clustes to Individual Sta-Foming Regions Geneviève ve Pamentie Olympia-Moata Fellow of Heidelbeg Univesity Astonomisches-Rechen Institut Heidelbeg Zentum fü Astonomie Gemany

2 Setting the Scene: Sta Clustes (SC) as Poweful Taces of Galaxy Evolution NGC1569: iegula galaxy Cedit: ESA, NASA, Andes+ APOD Distance: 2 Mpc Radio: HI bidges M82 NGC3077 Distance: 3.6 Mpc Yun, Ho & Lo 1994 M81 Sta Clustes (SC): Goups of coeval gavity-bound stas Help us pobe the Univese in both space and time The Antennae NGC4038/9: ongoing galaxy mege Whitmoe & Schweize APOD Distance: 18 Mpc Spial NGC 6946 Lasen 2002 Distance: 5 Mpc Elliptical galaxy M49 Jodan+04 Distance: 20Mpc Geneviève Pamentie - Heidelbeg Astonomisches-Rechen Institut 2 /

3 Setting the Scene: Sta Clustes (SC) as Poweful Taces of Galaxy Evolution Sta Clustes (SC): Compact goups of stas identified on a one-by-one basis against the backgound of thei host galaxy Multi-band imaging of SC systems: Cluste magnitudes & colous combined to Stella Population Synthesis Models cluste age, mass, metallicity estimates Compehensive view of galaxy-: chemical enichment histoy, inteaction histoy, sta fomation histoy (SFH) ove the past Hubble-Time Jodan+04 (ACS Vigo Galaxy Cluste Suvey II, fig6) Elliptical galaxy M49 Backgound-subtacted image Geneviève Pamentie - Heidelbeg Astonomisches-Rechen Institut 3 /

4 Luminosity of the bightest sta cluste Setting the Scene: Sta Clustes (SC) as Poweful Taces of Sta Fomation M V max Bight cluste Faint cluste Lasen 2002, fig11a Lasen+02 (fig11a) Low level of sta High level of sta fomation activity Σ SFR fomation activity Suface density of the SFR of the host galaxy But SCs = encoded ecod of the SFH of thei host galaxy Do most stas fom in clustes? O does it exist two modes of sta fomation (diffuse and clusteed) but with some coelation between the two modes? Geneviève Pamentie - Heidelbeg Astonomisches-Rechen Institut 4 /

5 Obseved Young Sta Cluste Mass Functions Macoscopic: galaxy-wide, o multi-kpc scale mass distibution of sta clustes log ( dn / d m ) CMF (α = -2.0) CMF (α = -2.0) Fig7, Chanda+2010 log ( m [M o ] ) dn dm Note: what happens afte 100My emains disputed 2 dn logm 1 What obseves tell us No evolution of the CMF shape ove the fist few 10My Cluste mass-loss is mass-in independent Geneviève Pamentie - Heidelbeg Astonomisches-Rechen Institut 5 / d m m

6 Evolution of Young SC Mass Functions 1/2 - Tidal Field Impact: hm / t Weak t.f. impact half mass tidal = f Cluste envionment env ( ) - 1 / 3 ρ CFRg Baumgadt & Koupa (2007) paametization Fo a given envionment, highe mass-losses due to gas expulsion if highe tidal field impact e.g. smalle CFRg densities Stong t.f. impact Geneviève Pamentie - Heidelbeg Astonomisches-Rechen Institut 6 /

7 The m CFRg - CFRg Diagam as a Diagnostic Tool log ( CFRg [pc] ) half mass tidal = f env 1 3 ( ρ ) - / CFRg h / t =0.05 Σ CFRg 1/ 2 CFRg m CFRg ρ CFRg. Constant mean suface density CFRg Constant mean volume density 1/ 3 CFRg m CFRg constant log ( m CFRg [M o ] ) Geneviève Pamentie - Heidelbeg Astonomisches-Rechen Institut 7 /

8 The m CFRg - CFRg Diagam as a Diagnostic Tool log ( CFRg [pc] ) half mass tidal = f env 1 3 ( ρ ) - / CFRg h / t =0.05 Σ CFRg 1/ 2 CFRg m CFRg ρ CFRg. Constant mean suface density CFRg Constant mean volume density 1/ 3 CFRg m CFRg constant log ( m CFRg [M o ] ) Geneviève Pamentie - Heidelbeg Astonomisches-Rechen Institut 8 /

9 Young SC Mass Functions - Tidal Field Impact dn/dlogm SFE=0.40 D gal =5kpc Σ CFRg Constant Mean Suface Density CFRgs: When moe massive means moe vulneable... log ( m [M o ] ) Constant Mean Volume Density CFRgs: mass-independent infant weight-loss log ( dn / dlogm ) ρ CFRg log (m [M o ]) Geneviève Pamentie - Heidelbeg Astonomisches-Rechen Institut 9 /

10 The cluste cossing-time: you basic time-unit! A sta cluste does not cae about how long it takes fo the eath to evolve aound the sun! The basic time-unit is the cluste initial cossing-time, not the yea o My (Pamentie & Baumgadt 2012) τ ρ coss CFRg τ coss 35 1/ 2 ( ) CFRg m CFRg 3 YSC Exact coefficient depends on density pofile Sun NGC APOD Hubble Heitage Team, A. Riess 10 Geneviève Pamentie - Heidelbeg Astonomisches-Rechen Institut 10 /

11 Evolution of Young SC Mass Functions 2/2 Cluste Evolutionay Rate Simulations of sta clustes with the most massive clustes the densest ones (constant adius) highe mass objects evolve at a quicke ate. Pamentie & Baumgadt (2012) log ( dn / d m ) dn/dlogm log ( m [M o ] ) Obsevations of sta clustes in the Lage Magellanic Cloud (Chanda+ 2010) log ( m [M o ] ) 11 Geneviève Pamentie - Heidelbeg Astonomisches-Rechen Institut 11 /

12 A Volume Density Theshold fo the SF Gas? ρ CFRg = constant : povides the most obust solution to the time-invaiant shape of the cluste mass function Inteesting since: SFR and dense molecula gas mapping in: Entie galaxies. Gao & Solomon 2004 Galactic molecula clumps... Wu SFR scales as the mass of dense molecula gas: n H2 > 10 4 cm -3 CFRgs of about constant mean volume density (n H2 = few n th ) 12 Geneviève Pamentie - Heidelbeg Astonomisches-Rechen Institut 12 /

13 A Volume Density Theshold fo the SF Gas ρ CFRg = constant : povides the most obust solution to the time-invaiant shape of the cluste mass function Inteesting since: SFR and dense molecula gas mapping in: Entie galaxies. Gao & Solomon 2004 Galactic molecula clumps... Wu SFR scales as the mass of dense molecula gas: n H2 > 10 4 cm -3 CFRgs of about constant mean volume density (n H2 = few n th ) Same scaling (constant mean volume density) as fom: - the tidal field impact analysis (Pamentie & Koupa 2011) - the cossing-time analysis (Pamentie & Baumgadt 2012) 13 Geneviève Pamentie - Heidelbeg Astonomisches-Rechen Institut 13 /

14 cannot be the only explanation But what fo the sta-foming egions of the Sola Neighbouhood? Spitze-telescope obsevations: sta fomation can poceed in low-density envionments too (Allen et al. 2007, Evans et al. 2009, ) 14 Geneviève Pamentie - Heidelbeg Astonomisches-Rechen Institut 14 /

15 Sta Fomation Efficiency pe Fee-Fall Time: ε ff Sta Fomation Efficiency ε ff pe Fee-Fall Time τ ff τ ff = 3π 32 G ρ g Kumholz & McKee 2005 Fo any given time-span afte the onset of sta fomation: molecula-gas egions of highe density achieve highe SFEs On the scale of individual molecula clumps volume density gadients SFE cente >> SFE outskits Consequences? Fig 9 - Wu+2010 Dense Faste HCN3-2 Highe SFE 15 Geneviève Pamentie - Heidelbeg Astonomisches-Rechen Institut 15 /

16 Immediate consequences of the ε ff concept ρ Clump cente Conseq.1 stas gas Clump outskits Density pofiles: ρ * () steepe thanρ g () Local SFE Clump cente Radially-dependent local SFE Cluste suvival! Adams (2000) Clump outskits 16 Geneviève Pamentie - Heidelbeg Astonomisches-Rechen Institut 16 /

17 Immediate consequences of the ε ff concept Fig9, Gutemuth+ (2011) Conseq.2 Σ * ~ Σ g 2 Σ * Density pofiles: ρ * () steepe thanρ g () Σ gas Radially-dependent local SFE Local sta fomation law 17 Geneviève Pamentie - Heidelbeg Astonomisches-Rechen Institut 17 /

18 Sta and Gas Volume Density Pofiles [Conseq.1] ρ g p0 ( t = 0, ) - ε = 0. 1 ff Fig1, Gutemuth+ (2011) MonR2 cloud M tot =25,800M 0 R = 6 pc M =1E4M 0 Density pofiles: ρ * (t,) steepe thanρ g (t,) ρ g (t,) shallowe thanρ g (t=0,) 18 Geneviève Pamentie - Heidelbeg Astonomisches-Rechen Institut 18 /

19 Local Sta Fomation Law [Conseq. 2] ε ff = 0.1 Clump cente Fig9, Gutemuth+ (2011) Σ * ~ Σ g 2 Σ * Σ * Clump outskits Σ g Relation between the local suface densities of YSOs and of the esidual gas: Σ * 10-3 Σ g2 at t = 2My Σ * fo the adopted M, R, ε ff (Pamentie & Pfalzne 2013) Σ g 19 Geneviève Pamentie - Heidelbeg Astonomisches-Rechen Institut 19 /

20 Cluste Suvival Made Easie [Conseq. 1b] Clump cente ε 3D () adially-vaying: clustes suvive despite low global SFE Clump outskits Adams (2000) Local SFE = ε = 3D ( t, ) ρ* ( t, ) ρ ( t, ) + ρ ( t, ) g Pamentie & Pfalzne 2013 * Unifom ε 3D ε 3D adially constant: ε 3D = SFE (local global) Cluste suvival equies global SFE > Geneviève Pamentie - Heidelbeg Astonomisches-Rechen Institut 20 /

21 Conclusions: Fom the Cluste Mass Function to the Local Sta Fomation Law log ( dn / d m ) Macoscopic: galaxy-wide, o multi-kpc scale mass distibution of sta clustes Fig7, Chanda+2010 Σ * Clump outskits Micoscopic: sta-foming egion few-pc scale local sta fomation law ε ff = 0.1 Σ g Clump cente log ( m [M o ] ) Contact Details Talk slides at: wwwstaff.ai.uni-heidelbeg.de/mitabeite/gpam/talks.html gpam AT ai.uni-heidelbeg.de 21 Geneviève Pamentie - Heidelbeg Astonomisches-Rechen Institut 21 /