Star formation relations across the CO ladder and redshift Thomas R. Greve (University College London)

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1 Star formation relations across the CO ladder and redshift Thomas R. Greve (University College London) DeMoGas: Manolis Xilouris (NOA) Ioanna Leonid (NOA) Padelis Papadopoulos (Cardiff) Paul van der Werf (Leiden) Axel Weiss (MPIfR) Zhi-Yu Zhang (PMO/ROE) Galaxy Evolution over five decades O Cambridge September 2013

2 Why are star formation relations interesting? IC 342 HI (atomic gas) THINGS 1 kpc

3 Why are star formation relations interesting? IC 342 HI (atomic gas) THINGS 12 CO J=1-0 (molecular gas) NRAO 12m 1 kpc

4 Why are star formation relations interesting? IC 342 HI (atomic gas) THINGS 12 CO J=1-0 (molecular gas) NRAO 12m Spitzer 70um IR emission (star formation) 1 kpc On kpc scales, SFR is related to H2 gas rather than HI

5 Why are star formation relations interesting? Extended ~ 10 pc scales low density ~ cm -3 1% 10 pc 1 kpc Krumholz+10

6 star formation (IR-CO) relations at high redshifts Challenges: Size measurements are difficult CO-to-H2 gas mass conversion dubious Greve+05 (12 SMGs + LIRGs): α = 1.5 ± 0.3 Iono+09 (SMGs+LIRGs, CO(3-2) only): α = 1.10 ± 0.03 Genzel+10 (10 SMGs + LIRGs): α = 1.15 ± 0.12 Bothwell+13 (>30 SMGs + LIRGs): α = 1.20 ± 0.13 Ivison+11 (SMGs+LIRGs, CO(1-0) only): α = 0.89 ± 0.04 Extended ~ 10 pc scales low density ~ cm -3 Heterogenous samples Poorly sampled SEDs / LIR uncertain AGN contamination harder to assess Mixing J-transitions 1 kpc Genzel+10

7 star formation relations in the high density regime 12 CO J=1-0 Extended ~ 10 pc scales low density ~ cm pc 1 kpc

8 star formation relations in the high density regime 20 μm 10 pc 1 kpc

9 star formation relations in the high density regime CS J=2-1 Compact ~ pc scales High density ~ cm pc 1 kpc

10 star formation relations in the high density regime Critical density: CS(2-1) The CO ladder spans the full density regime encountered in the molecular ISM HCO + (1-0)

11 LIR - Lmol models CO(1-0) HCN(1-0) Krumholz & Thompson + 07

12 star formation relations vs. critical density

13 Observing the CO ladder in local (U)LIRGs JCMT Herschel A Ground-Based Multi-Line Survey of local (U)LIRGs 70 sources selected from IRAS BGS: Molecular lines observed in Arp220 CO 1-0, 2-1, 3-2, 4-3 HCN 1-0, 2-1, 3-2, 4-3 HCO CS 2-1, 3-2, 5-4, 7-6 >350hrs of observing time. This is the largest multiline survey to date + literature data. Papadopoulso+12 Full CO rotational ladder, dense+fir lines Comprehensive ISM characterization! Disentangling Starburst vs. AGN Herschel Comprehensive (U)LIRG Emission Survey HERCULES (P.I.: van der Werf). 29 IRAS BGS sources ALMA CO 5-4 to [CI] 369μm and 609μm H2O lines IRAM PdBI Greve et al. (2009) Observed (100hrs). Van der Werf+10

14 Observing the CO ladder in local (U)LIRGs JCMT Herschel A Ground-Based Multi-Line Survey of local (U)LIRGs 70 sources selected from IRAS BGS: CO 1-0, 2-1, 3-2, 4-3 HCN 1-0, 2-1, 3-2, 4-3 HCO CS 2-1, 3-2, 5-4, 7-6 >350hrs of observing time. This is the largest multiline survey to date + literature data. Papadopoulso+12 Full CO rotational ladder, dense+fir lines Comprehensive ISM characterization! Disentangling Starburst vs. AGN Herschel Comprehensive (U)LIRG Emission Survey HERCULES (P.I.: van der Werf). 29 IRAS BGS sources ALMA CO 5-4 to [CI] 369μm and 609μm H2O lines IRAM PdBI Van der Werf et al. (2010) Observed (100hrs). Van der Werf+10

15 Observing the CO ladder in local (U)LIRGs JCMT Herschel A Ground-Based Multi-Line Survey of local (U)LIRGs 70 sources selected from IRAS BGS: CO 1-0, 2-1, 3-2, 4-3 HCN 1-0, 2-1, 3-2, 4-3 HCO CS 2-1, 3-2, 5-4, 7-6 >350hrs of observing time. This is the largest multiline survey to date + literature data. Papadopoulso+12 Full CO rotational ladder, dense+fir lines Comprehensive ISM characterization! Disentangling Starburst vs. AGN Herschel Comprehensive (U)LIRG Emission Survey HERCULES (P.I.: van der Werf). 29 IRAS BGS sources ALMA CO 5-4 to [CI] 369μm and 609μm H2O lines IRAM PdBI Observed (100hrs). Van der Werf+10

16 Observing the CO ladder in local (U)LIRGs IR luminosities Careful compilation of pan-chromatic continuum data SED fitting performed using a modified CIGALE (Burgarella+05) code, which employs Chary & Elbaz 2001 (CE01) and Dale & Helou 2002 (DH02) templates We adopt FIR (50-300μm) luminosities (clean compared to μm) Example SEDs:

17 Observing the CO ladder in high-z (U)LIRGs Dusty Star Forming Galaxies (DSFGs): A compilation of all (sub)mm-selected z > 1 DSFGs with CO line detections HERMES J z=2.95 Obvious AGN discarded Multiple observations of the same CO transition were averaged, and intrinsic line luminosities recalculated A total of 58 ʻunlensedʼ DSFGs and 25 lensed DSFGs (published as of Sep 2013) CIGALE fits, identical to local (U)LIRG fits Only sources with >3 FIR/submm data points across the dust peak, and with good CIGALE fits were included in the analysis Final sample: 23 unlensed DSFGs and 21 lensed DSFGs Riechers+11

18 Observing the CO ladder in high-z (U)LIRGs Dusty Star Forming Galaxies (DSFGs): A compilation of all (sub)mm-selected z > 1 DSFGs with CO line detections Obvious AGN discarded Multiple observations of the same CO transition were averaged, and intrinsic line luminosities recalculated A total of 58 ʻunlensedʼ DSFGs and 25 lensed DSFGs (published as of Sep 2013) CIGALE fits, identical to local (U)LIRG fits Only sources with >3 FIR/submm data points across the dust peak, and with good CIGALE fits were included in the analysis Final sample: 23 unlensed DSFGs and 21 lensed DSFGs

19 LIR-LCO relations

20 LIR-LCO relations

21 IR-mol slope vs. critical density

22 IR-mol slope vs. critical density

23 Interpretation of results A simple theoretical argument can be made for why α must always be 1 (Wong & Blitz 2002) We have and so slope of the IR HCN(1-0) relation (1.00 ± 0.05; Gao & Solomon 2004) dense gas fraction (expect to be at least as high at large LʼCO as at small LʼCO) α 1

24 IR-mol scatter vs. critical density

25 Caveats AGN contamination DSFGs are probably a mixed bag of objects (Haywardʼs talk) Differential lensing may be an issue for the strongly lensed DSFGs Low-J / High-J ratio increases with n(h2) and Tk Degeneracy between n(h2) and Tk (since ) fixed: Tk = 60K fixed: n(h2) = 10 4 cm -3 Jup Jup

26 CO SLEDs

HerCULES Herschel Comprehensive (U)LIRG Emission Survey

HerCULES Herschel Comprehensive (U)LIRG Emission Survey Paul van der Werf Leiden Observatory ESAC December 17, 2008 Credits! Data processing: Trevor Fulton Kate Isaak Adam Rykala Modeling: Rowin Meijerink