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MODELING COUNTS AND CIBA WITH MAIN SEQUENCE AND STARBURST GALAXIES

MODELING COUNTS AND CIBA WITH MAIN SEQUENCE AND STARBURST GALAXIES. Material at http :// irfu.cea.fr /Sap/ Phocea /Page/ index.php?id = 537. Deciphering the CIB 12 Oct 2012 Banyuls. Matthieu Béthermin CEA Saclay

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MODELING COUNTS AND CIBA WITH MAIN SEQUENCE AND STARBURST GALAXIES

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  1. MODELING COUNTS AND CIBA WITH MAIN SEQUENCE AND STARBURST GALAXIES Material at http://irfu.cea.fr/Sap/Phocea/Page/index.php?id=537 Deciphering the CIB 12 Oct 2012 Banyuls Matthieu Béthermin CEA Saclay In collaboration with Mark Sargent, EmanueleDaddi, GeorgiosMagdis, Olivier Doré, GuilaineLagacheand many others

  2. INTRODUCTION • Star formation history: when and in which galaxies do stars form in the Universe? • Which are the dominant processes of star formation in the Universe? • In which dark matter halos do stars form?

  3. OUTLINE • 2 modes of star formation? • IR SEDs of high-z galaxies. • A new source counts model • Putting IR galaxies into dark matter halos • CIB fluctuation modeling

  4. 2 star-formation modes (2SFM) MODELING FRAMEWORK

  5. NORMAL STAR-FORMING GALAXIES AND STARBURSTS • Local Universe: most of the star formation in disk galaxies. • However, higher SFR (higher IR luminosity) are mergers-induced starburst. • Two sequences of star-formation for normal and starburst galaxies:star formation efficiency higher in mergers. Daddi+10

  6. A “MaiN SEQUENCE” OF STAR-FORMING GALAXIES • Strong correlation between SFR and stellar mass in star forming galaxies. • Evolution of this correlation with redshift. • Suggest a quiet smooth star formation history in the bulk of the star-forming galaxies. Correlation between stellar mass and SFR at z~2 (Daddi+07)

  7. DisTRIBUTION OF SPECIFIC STAR FORMATION RATE AROUND THE “MAIN SEQUENCE” Distribution of sSFRat fixed M✭ at z~2 (Rodighiero+11): SFR-M✭relation at z~2 (Rodighiero+11): Cross-section through main sequence at fixed M✭ -> Self similar distribution of sSFR Excess due to starbursts

  8. Main sequence-STARBURST DECOMPOSITION Sargent+12 Starburst contribution to SFRD [Msun/yr Mpc-3] at z~2: ~16% (under some assumptions…!)

  9. EVOLUTION OF THE OTHER INGREDIENTS OF THE MODEL • Evolution of stellar mass function of star-forming galaxies: • constant M* • Φ* constant to z = 1; then declining Sargent+12 Evolution of specific SFR (=SFR/M✭) for main sequence galaxies

  10. RECONSTRUCTION OF THE IR LF FROM MASS FUNCTION AND SSFR DISTRIBUTION Animation from Mark Sargent Mass function SFR function

  11. CONTRIBUTION OF MS AND SB GALAXIES TO THE INFRARED LUMINOSITY FUNCTIONS • Combining 3 elements, we reconstruct the IR LF: • Mass function of star-forming objects • Evolution of the main sequence • Distribution of sSFR around the MS Main sequence Starburst Contribution of MS and SB modes to the bolometric infrared luminosity function from z=0 et z=2 (Sargent+12)

  12. EVOLUTION OF SPECTRAL ENERGY DISTRIBUTION OF MAIN-SEQUENCE GALAXIES

  13. Few variation OF SEDs of MAIN-sequence galaxies with STELLAR MASS • Mean SEDs of MS galaxies at z~2 (sample built using a BzK criterion and removing PACS detected starbursts). • We detect few variations of the SED with stellar mass. Mean spectral energy distribution of z~2 star-forming galaxies measured by stacking for several stellar mass bins (Magdis+12, resubmitted)

  14. FEW VARIATION OF SEDS of MAIN SEQUENCE GALAXIES WITH SSFR • Mean SEDs of MS galaxies at z~2 (sample built using a BzK criterion and removing PACS detected starbursts). • We detect few evolution of the SED with stellar mass. • There are also few variations of the SED with sSFR/sSFRMS. Mean spectral energy distribution of z~2 star-forming galaxies measured by stacking for several sSFR bins (Magdis+12)

  15. GAZ FRACTION AS A FUNCTION of DISTANCE TO THE MAIN SEQUENCE • Dust mass can be estimated from Mdust measured from Draine&Li model. • Gas mass estimated from dust mass and gas to dust ratio versus Z relation (Magdis et al. 2011) • Main sequence galaxies above the central relation seems to contain more gas than the galaxies below the sequence. Gas fraction as a function of the distance to the main sequence (Magdis+12)

  16. SED TEMPLATES OF MS AND SB GALAXIES Evolution of <U> (radiation field in Draine&Li model) with redshift. • From Magdis+12, we derive an SED library for MS and SB. • We also assume a scatter on <U> of 0.2 dex. Plots from Béthermin+12c Data from Magdis+12

  17. SOURCE COUNTS MODEL

  18. SED TEMPLATES OF MS AND SB GALAXIES • sSFR assumed to be flat at z>2.5. • Evolution of SF mass function extrapolated at z>2. • Simple prescription for AGN contamination in the mid-IR using Mullaney+11 templates and Aird+12 results. • Dust attenuation increasing with stellar mass following Pannella+09. • Take into account the magnification of a small fraction of distant by strong galaxy-galaxy lensing (computed based on Hezaveh+11 lensing model). Evolution of the various parameters of the model with redshift (Béthermin+12c)

  19. MiD-IR to FAR-IR counts from OUR FIDUCIAL MODEL • Number counts are globally well reproduced using fiducial parameters (no fine tuning). • The starburst (dashed line) have a very variable contribution depending on the flux regime and the wavelength. Comparison between the model and the observations(Béthermin+12c)

  20. MiD-IR to FAR-IR counts from OUR FIDUCIAL MODEL • Number counts are globally well reproduced using fiducial parameters (no fine tuning). • The starburst (dashed line) have a very variable contribution depending on the flux regime and the wavelength. • Reproduce also counts per redshift slice. Comparison between the model and the observations(Béthermin+12c)

  21. PUTTING IR GALAXIES INTO DARK MATTER HALOS

  22. PRINCIPLE OF ABUNDANCE MATCHING TECHNIQUE Numberdensity Numberdensity Numberdensity Mh LIR = K-1 f(M*) = K-1h(Mh) M* = h(Mh) Assume a monotonic relation betweeninfraredluminositystellar mass and halo mass

  23. MAIN SEQUENCE RECOVERED BY A SIMPLE ABUNDANCE MATCHING Relation betweenspecific star formation rate and the stellar mass (Béthermin+12a)

  24. LINK BETWEEN SFR AND HALO MASS Top: Ratio between SFR and halo mass as a function of halo mass Bottom: Differential contribution to SFR density as a function of halo mass. (Béthermin+12a)

  25. CIB FLUCTUATION MODELING

  26. COMBINING ABUNDANCE MATCHING AND POPULATION MODEL PRELIMINARY SFR-Mstar model for star forming galaxies(Béthermin+12c) Star forming Mass function spitted in star-forming and quenched galaxies (adapted from Ilbert+09) Abundance matching Halo mass function including sub-structures (Tinker+08,Tinker+09) Neglect the IR outputs of quenched galaxies Quenched Main hypotheses: - same Mstar-Mhalo relation in main and sub-structures - same Mstar-Mhalo relation for SF and quenched galaxies - the probability to be quenched depends only on the halo mass (no environnemental quenching) - starburst and main-sequence lies in the same halos

  27. SFR to HALO MASS RATIO PRELIMINARY SFR to halo mass ratio at various redshift used in our CIB model (Béthermin+ in prep)

  28. COMPUTATION OF THE POWER SPECTRUM 2 halo term: PRELIMINARY 1 halo term:

  29. PRELIMINARY PRELIMINARY RESULTS CIB power spectrum and galaxy counts (Béthermin et al. in prep.)

  30. PRELIMINARY PRELIMINARY RESULTS • Slightly modified evolution model: • sSFR in (1+z) instead of constant at z>2.5 (as suggested by e.g. Starck+12) • compensated by a decrease in density in (1+z)-0.8 instead of (1+z)-0.4at z>2.5. • Compatible with the observations. • BUT, many other possible explanations… CIB power spectrum and galaxy counts (Béthermin+ in prep.)

  31. SFR to HALO MASS RATIO PRELIMINARY SFR to halo mass ratio at various redshift used in our CIB model (Béthermin+ in prep)

  32. STAR FORMATION EFFICIENCY PRELIMINARY Salpeter IMF Baryon accretion rate deduced from Fakhouri+10 SFR to baryonic accretion rate ratio at various redshift used in our CIB model (Béthermin+ in prep)

  33. STAR FORMATION EFFICIENCY PRELIMINARY Chabrier IMF Baryon accretion rate deduced from Fakhouri+10 SFR to baryonic accretion rate ratio at various redshift used in our CIB model (Béthermin+ in prep)

  34. SUMMARY • Evidences of two main modes of star-formation (main sequence and starburst). MS dominates the SFR budget at z<2. • A simple model (2SFM: 2 star formation mode) based on our knowledge about MS and SB galaxies reproduce nicely the IR LF. • If we use SEDs updated with Herschel data with a temperature of MS increasing with redshift, we are also able to nicely reproduce the infrared source counts, showing the predictive power of this simple approach. • From simple prescription based on abundance matching, we can make puzzlingly accurate predictions of CIB fluctuations, reinforcing the clues of a maximum star formation efficiency around a halo mass of 1012Msun. Material at http://irfu.cea.fr/Sap/Phocea/Page/index.php?id=537

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