Post on 17-Dec-2015
massive galaxies massive galaxies at high redshift:at high redshift:models confront observationsmodels confront observations
rachel somervilleSTScI
rachel somervilleSTScI
GIRLS; Leiden, September 2008
z=5.7 (t=1.0 Gyr)z=5.7 (t=1.0 Gyr)
z=1.4 (t=4.7 Gyr)z=1.4 (t=4.7 Gyr)
z=0 (t=13.6 Gyr)z=0 (t=13.6 Gyr)
Springel et al. 2006Springel et al. 2006 Wechsler et al. 2002
shock heating & radiative cooling
photoionization squelching
merging star formation (quiescent & burst)
SN heating & SN-driven winds
chemical evolution
stellar populations & dust
shock heating & radiative cooling
photoionization squelching
merging star formation (quiescent & burst)
SN heating & SN-driven winds
chemical evolution
stellar populations & dust
rss, Hopkins, Cox, Robertson & Hernquist 2008, MN in press
fairly broad consensus: SN-driven winds remove baryons in small-mass halos
some process(es) prevent(s) cooling in large-mass halos (radio jets, clumps, conduction, cosmic ray pressure?)
fairly broad consensus: SN-driven winds remove baryons in small-mass halos
some process(es) prevent(s) cooling in large-mass halos (radio jets, clumps, conduction, cosmic ray pressure?)
quenching of massive galaxies
(note the slope is wrong for low mass galaxies.this is not due to AGN FB, & cannot be easily solved by ‘tweaking’)
rss, Hopkins, Cox, Robertson & Hernquist 2008, MN in press
SS
FR
stellar mass
halos with primarily “cold” vs. “hot” flows separated by a critical mass of few x 1012 Msun at low redshift (e.g. Birnboim & Dekel 2003; Keres et al. 2004);
heating processes only effective when a quasi-static hot gas halo is present (i.e. in large mass halos)
halos with primarily “cold” vs. “hot” flows separated by a critical mass of few x 1012 Msun at low redshift (e.g. Birnboim & Dekel 2003; Keres et al. 2004);
heating processes only effective when a quasi-static hot gas halo is present (i.e. in large mass halos)
hot vs. cold flowshot vs. cold flows
simulations: A. Kravtsov
M*
Mvir [Mʘ]
all hot
1014
1013
1012
1011
1010
109
0 1 2 3 4 5redshift
z
all cold
cold filamentsin hot medium
MshockMshock>>M*
Mshock~M*
Dekel,Birnboim,Zinger, Kravtsov
dense cold filaments can penetrate the hot mediumin large-mass halos at high redshift
associated with optical/X-ray luminous AGN/QSO
triggered/fed by mergers or secular (bar) instabilities
high accretion rates (0.1-1 LEdd), fueled by cold gas via thin accretion disk
may drive winds that can shut off further accretion onto the BH and sweep the ISM out of the galaxy
associated with optical/X-ray luminous AGN/QSO
triggered/fed by mergers or secular (bar) instabilities
high accretion rates (0.1-1 LEdd), fueled by cold gas via thin accretion disk
may drive winds that can shut off further accretion onto the BH and sweep the ISM out of the galaxy
QSO/bright mode
Radio Mode radio galaxies
(classical FR I and FR II type sources); generally no optical emission lines
‘low accretion state’ (low Eddington ratio, <10-3 Bondi accretion or ADAF?)
jets may heat gas in a hydrostatic hot halo, offsetting or quenching cooling flow
radio galaxies (classical FR I and FR II type sources); generally no optical emission lines
‘low accretion state’ (low Eddington ratio, <10-3 Bondi accretion or ADAF?)
jets may heat gas in a hydrostatic hot halo, offsetting or quenching cooling flow
star formation history stellar mass build-up
all stars
star formationin bursts
blue: fiducial model(cLCDM 8=0.9)red: WMAP3orange: no cooling if Mh<1011 Msun
time-dependent IMF?SFR at high-z overestimated?
solid: MORGANAdash: Munich Mill.dot-dash: rss08
stellar mass function evolution
“raw” model predictions with convolved errors
Fontanot, de Lucia, Monaco & rss in prep
stellar mass assemblywithout mass errors with errors (0.25 dex)
solid: MORGANAdash: Munich Mill.dot-dash: rss08
data: red: Conselice et al.blue: composite MF
Fontanot et al. in prep
star formation rate density as function of galaxy mass
green: GOODS; blue: Zheng et al. (COMBO-17)red: Conselice et al.; cyan: Mobasher et al. 2008
solid: MORGANAdash: Munich Mill.dot-dash: rss08
Fontanot et al. in prep
data:red square: Drory et al. 2008blue: Bell et al. 2007cyan: Martin et al. 2007green: Grazian et al. 2006magenta: Noeske et al. 2007red x: Chen et al. 2008blue diamond: Dunne et al. 2008
evolution of the SF ‘main sequence’
Fontanot et al. in prep
archeological downsizingarcheological downsizingdata: Panter et al. 2007 data: Gallazzi et al. 2007
Fontanot et al. in prep
when did the red sequence emerge?when did the red sequence emerge?
the red sequence is still clearly identifiable in the field & clusters up to z~1 (Bell et al. 2005; Faber et al. 2007)
recently, a population of massive red galaxies detected in the field at 2<z<3 (Kriek et al. 2008; Taylor et al. 2008)
very red populations discovered in clusters up to z~2, but absent by z~3 (Zirm et al. 2008; Kodama et al. 2008)
the red sequence is still clearly identifiable in the field & clusters up to z~1 (Bell et al. 2005; Faber et al. 2007)
recently, a population of massive red galaxies detected in the field at 2<z<3 (Kriek et al. 2008; Taylor et al. 2008)
very red populations discovered in clusters up to z~2, but absent by z~3 (Zirm et al. 2008; Kodama et al. 2008)
color-magnitude relation for comacolor-magnitude
relation for coma
Trager & rss 2008
black points: SDSSred points: SAM
rest-frame u-r for proto-clusters (M>1014 Msun)
‘field’ RSfrom Tayloret al. ECDFS
z~0 SDSS RS
Millenniumz=2 clusters
Testing physical parameter extraction from broad-band
photometry
Testing physical parameter extraction from broad-band
photometry
created SAM mock catalogs (including dust & IGM) and extracted U-, B-, and V-dropouts using GOODS selection criteria
added photometric errors by bootstrapping from GOODS data
ran a fairly standard BC03-based SED-fitting code on ACS+ISAAC+IRAC photometry (extract stellar mass, stellar population age, and SFR)
created SAM mock catalogs (including dust & IGM) and extracted U-, B-, and V-dropouts using GOODS selection criteria
added photometric errors by bootstrapping from GOODS data
ran a fairly standard BC03-based SED-fitting code on ACS+ISAAC+IRAC photometry (extract stellar mass, stellar population age, and SFR)
S. Lee, R. Idzi, H. Ferguson, rss, T. Wikland, M. Giavalisco
Stringer et al. 2008
z~0.4-1.4DEEP+Palomar photometryfixed redshiftbootstrapped photometric errorsBundy et al. (2006) massestimation method
no significant offset or mass trend--> scatter ~0.15 dex
parameter estimation summary
parameter estimation summary
sources of error: mismatch between assumed “tau” SFHs and SAM predicted SFH
‘hiding’ of mass beneath young stellar population
‘conspiracy’ of overestimated age (--> higher mass estimate) + ‘youth bias’ (lowers mass estimate) actually reduces mass errors
two-component models (with ‘maximally old’ component or secondary burst) produce improved age & SFR estimates, but poorer mass estimates!
sources of error: mismatch between assumed “tau” SFHs and SAM predicted SFH
‘hiding’ of mass beneath young stellar population
‘conspiracy’ of overestimated age (--> higher mass estimate) + ‘youth bias’ (lowers mass estimate) actually reduces mass errors
two-component models (with ‘maximally old’ component or secondary burst) produce improved age & SFR estimates, but poorer mass estimates!
summarysummary differences between observational datasets much larger than differences between models!
number/mass density of massive galaxies is reproduced fairly well by models (when mass errors convolved) to z~2
SFR of massive galaxies at z~1-2 underestimated by factor of ~few in models if observational estimates taken at face value (IMF, AGN contamination, large errors in SED-fit based estimates?)
low mass galaxies form too early in models --> mass assembly “upsizes” rather than “downsizes”
massive galaxies in large mass halos are being quenched too late in models (RS emerges late)
errors in stellar masses, SFR, and ages derived from SED fitting to broad-band photometry at high redshift may be larger than we think...
differences between observational datasets much larger than differences between models!
number/mass density of massive galaxies is reproduced fairly well by models (when mass errors convolved) to z~2
SFR of massive galaxies at z~1-2 underestimated by factor of ~few in models if observational estimates taken at face value (IMF, AGN contamination, large errors in SED-fit based estimates?)
low mass galaxies form too early in models --> mass assembly “upsizes” rather than “downsizes”
massive galaxies in large mass halos are being quenched too late in models (RS emerges late)
errors in stellar masses, SFR, and ages derived from SED fitting to broad-band photometry at high redshift may be larger than we think...
bias in line-strength derived ages
bias in line-strength derived ages
stellar mass
mass weighted age
LS derived age
for 20 realizations ofa Coma-sized halo Trager & rss 2008
star formation histories of early type galaxiesas a function of stellar mass
SF histories of E’s in hierarchical models show qualitatively correct ‘downsizing’ behavior
but, probably not strong enough (new evidence from /Fe ratios -- Arrigoni, Trager & rss in prep)
SF histories of E’s in hierarchical models show qualitatively correct ‘downsizing’ behavior
but, probably not strong enough (new evidence from /Fe ratios -- Arrigoni, Trager & rss in prep)
the many manifestations of
‘downsizing’
the many manifestations of
‘downsizing’ SF history from lookback studies (original Cowie definition): star formation activity shifts to lower mass galaxies over time
mass assembly histories: high mass galaxies assembled early, low mass galaxies assembled later
archeological downsizing: stellar ages are younger in low mass galaxies, indicating a later epoch of SF
chemo-archeological downsizing: higher [/Fe] ratios in more massive galaxies indicate a shorter epoch of formation
SF history from lookback studies (original Cowie definition): star formation activity shifts to lower mass galaxies over time
mass assembly histories: high mass galaxies assembled early, low mass galaxies assembled later
archeological downsizing: stellar ages are younger in low mass galaxies, indicating a later epoch of SF
chemo-archeological downsizing: higher [/Fe] ratios in more massive galaxies indicate a shorter epoch of formation