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“Artists can color the sky redbecause they know it’s blue.Those of us who aren’t artists must colorthings the way they are or people mightthink we’re stupid.”
Jules Feiffer
Red Galaxiesat
High Redshift
Stijn Wuyts, Marijn Franx, Pieter van Dokkum,Ivo Labbé, Natascha Förster Schreiber, Greg Rudnick,TJ Cox, Phil Hopkins, Brant Robertson, Lars Hernquist
• When did the stars in galaxies form?• How was the mass in galaxies assembled?
• When did the stars in galaxies form?• How was the mass in galaxies assembled?
Ingredients & History From colors to physics Evolution
Telescopes
Telescopes
Galaxy interactions
Galaxy interactions-simulations-
Galaxy interactions-simulations-
Holmberg 1941
Galaxy interactions-simulations-
Holmberg 1941 Springel et al.
Quasars&
Black Holes
Richards et al. 2005
Quasars
&
Black Holes
Schmidt 1963
2dF-SDSS LRG and QSO Survey
Genzel et al.
Quasars
&
Black Holes
Schmidt 1963
Häring & Rix 2004
Normal galaxies
Hubble 1926Hubble 1936
• HDFS (5 arcmin2)• MS 1054-03 (25 arcmin2)• CDFS (113 arcmin2)
Labbé et al. 2003
Normal galaxies
Hubble 1926Hubble 1936
• HDFS (5 arcmin2)• MS 1054-03 (25 arcmin2)• CDFS (113 arcmin2)
Stellar population synthesis
Wood 1966
Evolutionary stellar population synthesis
Bruzual & Charlot 2003
Evolutionary stellar population synthesis
Star formation historySSP, exponentially declining (τ300), CSF
Evolutionary stellar population synthesis
Dust screen (Calzetti et al. 2000)
SED modeling - results
Red galaxies at high redshift do not form a uniform population.
Red galaxies at high redshift dominate at the high mass end.
SED modeling - results
Red galaxies dominate the total IR emission at high redshift.
SED modeling - results
Testing SED modeling with simulations
• Wide range of spectral types• Have real universe equivalents
Testing SED modeling with simulations
Mismatch real vs. template SFH→ Impossible to correct for difference light- vs. mass-weighted
Impact of star formation history
Impact of dust
Increased extinction towards young stellar regionsreduces offset light- vs. mass-weighted properties.
Mismatch real vs. template SFH→ Impossible to correct for difference light- vs. mass-weighted→ Less severe in the presence of age-dependent extinction
Impact of dust
Intrinsic Attenuated
Every observer is limited by the light he/she receives.
Impact of dust
Eff
ectiv
e re
dden
ing
Effective extinction
Input: Calzetti, MW or SMC reddening curveEffective reddening: greyer than Calzetti
Impact of dust
Modeling sub-solar stellar populationswith solar-metallicity templates.→ underestimate reddening → underestimate extinction
Impact of metallicity
Real: Stars + AGN → Recovered: younger & dustier stellar pop.
Impact of AGN
Testing SED modeling with simulations: results
An evolutionary scenario
Sanders et al. 1988
ULIRG(L > 1012Lsun)
QSO
An evolutionary scenario
Hopkins et al. 2006
Quasar to galaxy demographics
Hopkins et al. 2006
Quasar to galaxy demographics
Hopkins et al. 2006
Abundance of massive galaxies
Mass function
Colors of massive galaxies
V-J
U-V
Colors of massive galaxies – by type
Colors of massive galaxies – by type
Selecting by specific star formation rate
Abundance of massive galaxies – by type
Pair statistics
Red Galaxiesat
High Redshift
Observations• Diversity at high redshift• Evolutionary scenario involving merger-triggered QSOs• Abundance of massive galaxies OK• Colors of dusty red galaxies not reproduced
Conclusions
Emlen 1967, 1970
After man, the indigo bunting is the best documented example of a speciesthat in its earthly life uses celestial bodies outside the solar system.
• When did the stars in galaxies form?• How was the mass in galaxies assembled?
Ingredients & History From colors to physics Evolution