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The Prospect of Observing the KS Relation at High-z Desika Narayanan Harvard-Smithsonian CfA Chris HaywardT.J. CoxLars Hernquist Harvard Carnegie
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Kennicutt-Schmidt SFR Laws Locally: Bigiel 2008; Krumholz et al. 2009
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Molecular Kennicutt-Schmidt SFR Laws Gao & Solomon 2004 Local: CO J=1-0 SFRSFR Total H 2 Gas Mass z~2: CO (J=3-2) z~2 Bouché et al. 2007
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Theoretical Approach: SPH simulations of galaxies Springel et al. (2003-2005) Prescriptions for multi-phase ISM (McKee-Ostriker) SF (volumetric Schmidt law) BH growth and associated Feedback Halos scaled to z~2 concentration For z~2 study, isolated galaxies M bar ~ 10 11 M , MMW disks SF follows SFR 1, 1.5, 2
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Desika Narayanan SFR@50, Spineto Non-LTE Radiative Transfer (Synthetic Molecular Line Emission) 3D Monte Carlo code developed based on improved Bernes (1979) algorithm Considers full statistical equilibrium with collisional and radiative processes Sub-grid algorithm considering mass spectrum GMCs as SIS; M cloud =10 4 -10 6 M , (Blitz et al. 2006, Rosolowsky 2007, Bolatto et al. 2008) Uniform Galactic CO Abundance, no H 2 at N H < 10 21 cm -2 DN+ 2006,2008
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SUNRISE (dust RT) to ‘Select’ Galaxies GMC Diffuse ISM Physics Included in Monte Carlo IR RT: -IR transfer of stellar and AGN spectrum (starburst 99 for stars and Hopkins+ 07 for AGN) -dust radiative equilibrium -Kroupa IMF, ULIRG/SMG DTG (same as MW DTM) -Stellar Clusters surrounded by HII regions and PDRs (MAPPINGS; Groves et al. 2008) Jonsson, Groves & Cox (2009)
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Does Differential Excitation Matter?: Local Universe Example CO (J=1-0) Gao & Solomon 2004 CO (J=3-2) Index = 1.0 Narayanan et al. 2005 Iono et al. 2008 SFR ~ CO (1-0) 1.5 SFR ~ CO (3-2) 0.9
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Molecular Kennicutt-Schmidt SFR Laws HCN J=1-0 Gao & Solomon (2004) CO J=1-0 Index = 1.5 Index = 1.0 SF follows SFR 1.5
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Molecular Kennicutt-Schmidt SFR Laws CO (J=1-0) Gao & Solomon 2004 CO (J=3-2) Index = 1.0 Narayanan et al. 2005 Iono et al. 2008 SFR ~ CO (1-0) 1.5 SFR ~ CO (3-2) 0.9 SF follows SFR 1.5
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Differential Excitation; Underlying n=1.5 KS Index Krumholz & Thompson 2007 Narayanan et al. 2008 SF follows SFR 1.5 SFR-CO indexSFR-HCN index CO (J=1-0) CO (J=3-2) HCN (J=1-0)
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HCN (HCN (J=3-2) Observational Survey Bussmann, DN, Shirley, Wu, Juneau, Vanden Bout, Solomon et al. (2008)
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HCN (HCN (J=3-2) Observational Survey Bussmann, DN, Shirley, Juneau et al. 2008
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Getting to the KS Relation at z~2 SF follows SFR 1, 1.5, 2
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Getting to the KS Relation at z~2 SF follows SFR 1, 1.5, 2
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Getting to the KS Relation at z~2 SFR-LCO index versus Transition for KS = 2 galaxies SF follows SFR 1, 1.5, 2
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Mapping the CO 3-2 KS relation at z~2 to the underlying volumetric Schmidt Relation Data from Tacconi et al. 2010: SFR ~ L (CO3-2) 0.97 Physical KS index vs. SFR-CO (J=3-2) index
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Conclusions 1. Excitation Matters
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Conclusions 1. Excitation Matters 2. Getting the KS relation at high-z is feasible (now!)
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Desika Narayanan SFR@50, Spineto GADGET SPH Simulations Springel et al. (2003-2005), Prescriptions for multi-phase ISM (McKee-Ostriker), SF, BH growth and associated Feedback (though BH winds turned off) 100 galaxies used: 20 disk Galaxies 80 merger snapshots SF follows SFR 1.5 Assuming the free-fall time argument for SFR ~ 1.5 holds
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Can we Recover the Basic Relations? Narayanan et al. 2008 SF follows SFR 1.5 SFR-CO indexSFR-HCN index CO (J=1-0) CO (J=3-2) HCN (J=1-0) SFR ~ 1.5 (assumed Schmidt Law) SFR ~ L mol (observed) L molecule ~ Then =1.5/ So we need to understand how line luminosity varies with gas density
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Fiducial Disk Galaxy V 200 =115 km/s f gas =0.2 SFR ~ 1.5 (assumed Schmidt Law) SFR ~ L molecule (observed) L molecule ~ Then =1.5/ Narayanan et al. 2008 CO (J=1-0)
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Fiducial Disk Galaxy V 200 =115 km/s f gas =0.2 SFR ~ 1.5 (assumed Schmidt Law) SFR ~ L molecule (observed) L molecule ~ Then =1.5/ Then =1.5/ Narayanan et al. 2008 Increasing density will increase the gas mass, thus increasing the CO (1-0) luminosity proportionally Low n crit
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Fiducial Disk Galaxy V 200 =115 km/s f gas =0.2 SFR ~ 1.5 (assumed Schmidt Law) SFR ~ L molecule (observed) L molecule ~ Then =1.5/ Then =1.5/ Narayanan et al. 2008 High n crit
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Fiducial Disk Galaxy V 200 =115 km/s f gas =0.2 SFR ~ 1.5 (assumed Schmidt Law) SFR ~ L molecule (observed) L molecule ~ Then =1.5/ Then =1.5/ Increasing density will increase the gas mass, thus increasing the CO (1-0) luminosity proportionally >> n crit slope=1.5 << n crit slope < 1.5
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