Prsentation PowerPoint

Deciphering the CIB12 Oct 2012BanyulsMODELING COUNTS AND CIBA WITH MAIN SEQUENCE AND STARBURST GALAXIESMatthieu Bthermin

CEA Saclay

In collaboration with Mark Sargent, Emanuele Daddi, Georgios Magdis, Olivier Dor, Guilaine Lagache and many others

Material at http://irfu.cea.fr/Sap/Phocea/Page/index.php?id=537INTRODUCTIONStar 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?

OUTLINE2 modes of star formation?

IR SEDs of high-z galaxies.

A new source counts model

Putting IR galaxies into dark matter halos

CIB fluctuation modeling2 star-formation modes (2SFM) MODELING FRAMEWORK

NORMAL STAR-FORMING GALAXIES AND STARBURSTSLocal 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+10A MaiN SEQUENCE OF STAR-FORMING GALAXIESStrong 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)

Distribution of sSFR at fixed M at z~2 (Rodighiero+11):Cross-section through main sequence at fixed MDisTRIBUTION OF SPECIFIC STAR FORMATION RATE AROUND THE MAIN SEQUENCESFR-M relation at z~2 (Rodighiero+11):-> Self similar distribution of sSFRExcess due to starbursts7

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

Sargent+12

Evolution of stellar mass function of star-forming galaxies: constant M* * constant to z = 1; then decliningEvolution of specific SFR (=SFR/M) for main sequence galaxiesEVOLUTION OF THE OTHER INGREDIENTS OF THE MODELSargent+129RECONSTRUCTION OF THE IR LF FROM MASS FUNCTION AND SSFR DISTRIBUTION

Mass functionSFR functionAnimation from Mark Sargent

CONTRIBUTION OF MS AND SB GALAXIES TO THE INFRARED LUMINOSITY FUNCTIONSCombining 3 elements, we reconstruct the IR LF:Mass function of star-forming objectsEvolution of the main sequenceDistribution of sSFR around the MS

Main sequenceStarburstContribution of MS and SB modes to the bolometric infrared luminosity function from z=0 et z=2 (Sargent+12)11EVOLUTION OF SPECTRAL ENERGY DISTRIBUTION OF MAIN-SEQUENCE GALAXIESFew variation OF SEDs of MAIN-sequence galaxies with STELLAR MASS

Mean spectral energy distribution of z~2 star-forming galaxies measured by stacking for several stellar mass bins (Magdis+12, resubmitted)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.FEW VARIATION OF SEDS of MAIN SEQUENCE GALAXIES WITH SSFR

Mean spectral energy distribution of z~2 star-forming galaxies measured by stacking for several sSFR bins (Magdis+12)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.GAZ FRACTION AS A FUNCTION of DISTANCE TO THE MAIN SEQUENCE

Gas fraction as a function of the distance to the main sequence (Magdis+12)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.SED TEMPLATES OF MS AND SB GALAXIES

Plots from Bthermin+12cData from Magdis+12

Evolution of (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 of 0.2 dex.SOURCE COUNTS MODELSED TEMPLATES OF MS AND SB GALAXIESsSFR 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 (Bthermin+12c)MiD-IR to FAR-IR counts from OUR FIDUCIAL MODELNumber 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 (Bthermin+12c) MiD-IR to FAR-IR counts from OUR FIDUCIAL MODELNumber 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 (Bthermin+12c)

PUTTING IR GALAXIES INTO DARK MATTER HALOSPRINCIPLE OF ABUNDANCE MATCHING TECHNIQUE

Number densityLIR = K-1 f(M*) = K-1 h(Mh)

Number densityM* = h(Mh)Number densityMhAssume a monotonic relation between infrared luminosity stellar mass and halo mass22MAIN SEQUENCE RECOVERED BY A SIMPLE ABUNDANCE MATCHING

Relation between specific star formation rate and the stellar mass (Bthermin+12a)LINK BETWEEN SFR AND HALO MASS

Top: Ratio between SFR and halo mass as a function of halo massBottom: Differential contribution to SFR density as a function of halo mass.(Bthermin+12a)CIB FLUCTUATION MODELINGCOMBINING ABUNDANCE MATCHING AND POPULATION MODELSFR-Mstar model for star forming galaxies(Bthermin+12c)Mass function spitted in star-forming and quenched galaxies(adapted from Ilbert+09)Halo mass function including sub-structures(Tinker+08,Tinker+09)Abundance matchingStar formingNeglect the IR outputs of quenched galaxiesQuenchedMain 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 halosPRELIMINARYSFR to HALO MASS RATIO

SFR to halo mass ratio at various redshift used in our CIB model (Bthermin+ in prep)PRELIMINARYCOMPUTATION OF THE POWER SPECTRUM

2 halo term:1 halo term:PRELIMINARYPRELIMINARY RESULTSCIB power spectrum and galaxy counts (Bthermin et al. in prep.)

PRELIMINARYPRELIMINARY RESULTSCIB power spectrum and galaxy counts (Bthermin+ in prep.)

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)-0.4 at z>2.5.Compatible with the observations.

BUT, many other possible explanations

PRELIMINARYSFR to HALO MASS RATIO

SFR to halo mass ratio at various redshift used in our CIB model (Bthermin+ in prep)PRELIMINARYSTAR FORMATION EFFICIENCYSFR to baryonic accretion rate ratio at various redshift used in our CIB model (Bthermin+ in prep)

Salpeter IMFPRELIMINARYBaryon accretion rate deduced from Fakhouri+10STAR FORMATION EFFICIENCY

SFR to baryonic accretion rate ratio at various redshift used in our CIB model (Bthermin+ in prep)Chabrier IMFPRELIMINARYBaryon accretion rate deduced from Fakhouri+10SUMMARYEvidences of two main modes of star-formation (main sequence and starburst). MS dominates the SFR budget at z