On the last 10 billion years of stellar mass growth in star-forming - PowerPoint PPT Presentation

On the last 10 billion years of stellar mass growth in star-forming galaxies z szomoru+11 Log(SFR/M*) Sam Leitner (University of Chicago) Advisor: Andrey Kravtsov Santa Cruz Galaxy Workshop, August 2011

z≈0 A persistent SDSS SFR-M * SFR main sequence log (SFR/M*) Small scatter in SFR at M * : • z≈0 in SDSS (e.g. Brinchmann+04) • z≈0 in local dwarfs (Lee+11) • z≈2 in M * >10 10 (e.g. Rhodighiero+11) Salim+07 log (M*) z≈2 σ =0.24dex z≈0 Dwarfs SFR-M * log (SFR) log (SFR/M*) Rhodighiero+11 log (M*) Lee+11

Main Sequence Integration stellar mass fraction formed

Main Sequence Integration stellar mass fraction formed

Main Sequence Integration stellar mass fraction formed

Main Sequence Integration stellar mass fraction formed

z≈0 A persistent SDSS SFR-M * SFR main sequence log (SFR/M*) Small scatter in SFR at M * : • z≈0 in SDSS (e.g. Brinchmann+04) • z≈0 in local dwarfs (Lee+11) • z≈2 in M * >10 10 (e.g. Rhodighiero+11) Salim+07 log (M*) z≈2 z≈0 Dwarfs SFR-M * log (SFR) σ =0.24dex log (SFR/M*) Rhodighiero+11 log (M*) Lee+11

z≈0 A persistent SDSS SFR-M * SFR main sequence log (SFR/M*) Small scatter in SFR at M * : • z≈0 in SDSS (e.g. Brinchmann+04) • z≈0 in local dwarfs (Lee+11) • z≈2 in M * >10 10 (e.g. Rhodighiero+11) Salim+07 log (M*) z≈2 z≈2 z≈0 z≈0 Dwarfs SFR-M * log (SFR) SFR σ =0.24dex Wuyts+11 log (SFR/M*) Rhodighiero+11 log (M*) Lee+11

Observations: normalization of SFR-M * 10 SFR ( 10 11 M ʘ ,z ) /M * [1/Gyr] 1 0.1 Salim et al. 2007; Noeske et al. 2007b; Elbaz et al. 2007; Pannella et al. 2009; Daddi et al. 2007; Dunne et al. 2009; Oliver et al. 2010; 0.01 Rodighiero et al. 2010a Karim et al. 2011;

Observations: normalization of SFR-M * 10 SFR ( 10 11 M ʘ ,z ) /M * [1/Gyr] 1 0.1 Salim et al. 2007; Noeske et al. 2007b; Elbaz et al. 2007; Pannella et al. 2009; Daddi et al. 2007; Dunne et al. 2009; Oliver et al. 2010; 0.01 Rodighiero et al. 2010a Karim et al. 2011;

β Observations: slope SFR/M * ~M * 0.4 0.2 β 0.0 smaller galaxies -0.2 grow faster (implies -0.4 downsizing) -0.6

β Observations: slope SFR/M * ~M * 0.4 0.2 β 0.0 smaller galaxies -0.2 grow faster (implies -0.4 downsizing) -0.6

Typical stellar mass growth from main sequence integration stellar mass growth star formation histories 10 11 10 10 10 9 10 8 Extrapolated data Unreliable( ρ SFR ≠∆ρ * ) Robust early growth

Quantifying the late formation of star forming galaxies z 15% : M(z)=0.15M * (z=0)

Quantifying the late formation of star forming galaxies z 15% : M(z)=0.15M * (z=0)

Quantifying the late formation of star forming galaxies stellar mass at z=1 z 15% : M(z)=0.15M * (z=0)

Stellar mass growth from spectra Averaged SED-based SFHs of ~50,000 SDSS star-forming galaxies of 10 10.5 -10 11 M ʘ from the VESPA Database stellar mass growth star formation histories <M * >=6x10 10 M ʘ

Mimicking age uncertainty ->Smooth by σ =0.5dex in log-age SSPs with typical SDSS signal-to noise are not distinguished over <0.5dex: Ocvirk+06 Main Sequence Integration Tests show little bias, MSI+age uncertainty but resolution~1dex for non-SSPs with unknown metallicity

Main sequence integration and SEDs <M * >=6x10 10 M ʘ Main Sequence Integration MSI+age uncertainty

Main sequence integration and SEDs <M * >=2x10 10 M ʘ

Main sequence integration and SEDs <M * >=5x10 9 M ʘ

Main sequence integration and SEDs <M * >=2x10 8 M ʘ

Consistency between SEDs and the main sequence <M * >=6x10 10 M ʘ <M * >=2x10 10 M ʘ <M * >=5x10 9 M ʘ <M * >=2x10 8 M ʘ

A transition at low masses?

A transition at low masses? An SED/CMD discrepancy?

Summary and Conclusions • The main sequence of star formation can be integrated to calculate stellar mass growth in star forming galaxies back to 10-20% of current stellar masses. • Less than 15% of stellar mass (median bulge mass) is in place in star forming galaxies of about M * =1-5x10 10 SFGs at z>2. • SED-based star formation histories are consistent with SFR-M * and its evolution after accounting for age uncertainties. • Local CMD-analyzed dwarfs formed early(?) compared to SED and main sequence extrapolations. • Details: merging, ρ SFR ≠∆ρ * , effect of scatter in SFR-M * , other high S/N SED- and CMD-based disk observations. arXiv:1108.0938

Merging and Scatter

The effect of age resolution on mass growth in SED-based SFHs