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8.7.2005 Renzini Ringberg 2005 1
The cosmic star formation rate from the FDF and the Goods-S Fields
R.P. Saglia – MPEreporting work of/with R. Bender, N. Drory, G. Feulner,
A. Gabasch, U. Hopp, M. Pannella, M. Salvato
• Introduction • The Fors Deep and Goods-S Fields• Luminosity functions• Star Formation Rates and stellar densities (up to z=5)• Morphologies (up to z=1)• Conclusions
Gabasch et al. 2004, A&A, 421, 41; Drory et al. 2005, ApJL; 619, L131;Gabasch et al. 2004, ApJL, 616, L83; Pannella et al. 2005, ApJL, in prep
8.7.2005 Renzini Ringberg 2005 2
Introduction
Bouwens et al. 2004
“Madau plot”: Star Formation Rate history of the Universe
Open questions:
• Cosmic variance
• Galaxy selection
• Faint-end contribution
• Role of Dust
• Morphology splitHernquist & Springel 2003
8.7.2005 Renzini Ringberg 2005 3
The FDF and Goods-S fields
Heidt et al. 2003, A&A, 398, 49 Salvato et al. 2005, in prep
lim 26.8I lim 27.6B lim 25.4K U…K photometry, >7 times larger field than HDF
8.7.2005 Renzini Ringberg 2005 4
Photometric redshifts
Gabasch et al. 2004, A&A, 421, 41
362 spectra
SED template fittingBender et al. 2005
0.0
0.
56
028 1
zFOR
D
Sz
GOO s
8.7.2005 Renzini Ringberg 2005 5
Luminosity Functionsat 1500
Gabasch et al.2004, A&A,421, 41
Good agreementwith previous LFdown to the maglimit.= -1.07+-0.04 = -1.6 excludedat 2 level
A
z=0.6 z=1.3
z=2.5 z=4.5
8.7.2005 Renzini Ringberg 2005 6
Evolution of the LFs
*
*
slopes similar in UV and u' bands:
= 1.07 0.04,
decreases by 80-90%
1.6 excluded at 2 level
increases from 0.5 to
= 1.25 0.03 in ' and band
5
by
3.
s
1
M z z
mag
g B
Steidel et al. 1999
8.7.2005 Renzini Ringberg 2005 7
The UV-luminosity density and SFR
(no correction for dust)
Schechter Luminosity Function:
( ) exp
( ) (2 )tot
L LL
L L L
L L M dM L
28 1 31500 1.25 10 totSFR L M yr Mpc
The extrapolation to L=0 amounts to 2-20% for the FDFmagnitude limits!
8.7.2005 Renzini Ringberg 2005 8
The SFR in the FDF
Gabasch et al. 2004, ApJL 616, L83
No difference with I or B catalogues
Dust
Adelberger & Steidel 2000
0.3 difference
to 1.6 :
spectroscopic surveys are not de
dex
ep enough
0 2 4 6 0 2 4 6
Factor 5-9correction
At z>3 Bdrop-outs
8.7.2005 Renzini Ringberg 2005 9
The SFR in FDF and GOODS-S
*
Cosmic variance
less than
SFR(>L
)
No difference
for
Complete census
of galaxies
approache
0.
K lower by
0.2 dex
d
1dex
:
/ 3TOTS
L
FR
L
8.7.2005 Renzini Ringberg 2005 10
Stellar masses • Photoz + BC03
• 2 components (main+burst)
• Age, metallicity Dust, component ratio
Errors in log M/L:
0.1<d log M/L<0.2
8.7.2005 Renzini Ringberg 2005 11
Dust and SFRGALEXSchiminovich et al.
2005, ApJL 619, L47
SPITZEREgami et al. 2004
ApJS 154, 130
Stellar mass
Factor 2.5-3
• GALEX confirms SFR at z<1• SPITZER shows that ULIRG cannot dominate
8.7.2005 Renzini Ringberg 2005 12
MorphologiesAnalysis of HST ACS images:
FDF: 4 pointings, 1 orbit per pointing in the F814W filter 40 minutes exposures, I(AB, 10 sigma) = 26
Goods-S: 3/2.5/2.5/5 orbits in the BViz filters 100/80/80/160 minutes exposures BViz(AB, 10 sigma) = 27/27.2/26.5/26.5
Visual Classification performed by U. Hopp
Quantitative morphology performed by M. Pannella, fitting the 2D images with PSF convolved with the Gim2D and Galfit packages, I=24/24.5 for FDF (F814W) and Goods (F775W), z<1.15
Sersic Profiles
8.7.2005 Renzini Ringberg 2005 13
Quality Control
Mock catalogueof 4000 objectsfor each of the twofields, with
22.5<I(AB)<Ilim
0.05”<Re<2”
0.5<n<6
0<ellipticity<0.7
8.7.2005 Renzini Ringberg 2005 14
Visual Morphology
Final catalogue with 1647 objects, 90 sq. arcmin area, z<1.15, withMasses, redshifts, luminosities, dimensions, profiles
8.7.2005 Renzini Ringberg 2005 15
Mass completenessAt any redshift objectswith the highest M/L ratioare cut out of the samplebecause of the flux limit.
• SSP from BC03• formation at z=10• no dust• sub-solar metallicity• passively aging
Largest M/L lowest detectable M
8.7.2005 Renzini Ringberg 2005 16
Morphological stellar mass functionsThe mass at whichdisks becomes dominantis increasing with z
Disks dominate at all redshifts the lowmass end of the MF
In good agreement with Bundy et al.(2005) at the same zand Bell et al. (2003)at z=0
“MorphologicalDownsizing” ?
8.7.2005 Renzini Ringberg 2005 17
Stellar mass density evolutionThe total mass density atz=1 is 50% lower than at z=0
The morphological mixevolves dramatically withredshift
Mass density movesfrom disks to bulgesfrom z=1 to z=0
In agreement withBundy et al. 2005,Brinchmann & Ellis 2000
8.7.2005 Renzini Ringberg 2005 18
Two scenarios
Option 1: the 50% “missing stellar mass” at the high mass is provided by in situ star formation. The morphological mass density evolution from disks to bulges is driven by secular evolution.
Option 2: The star formation rate is not high enough to explain the missing stellar mass. Merging of (smaller mass) galaxies must play a key role. Merging of the massive disk systems explains the morphological evolution.
8.7.2005 Renzini Ringberg 2005 19
Specific star formation ratesOnly 2 objects would beable to double their massesto z=0 assuming constantSFR
Almost all the sample wouldbe unable to increase its original mass by more than30% with constant SFR in situ
Option 2 favoured
8.7.2005 Renzini Ringberg 2005 20
Conclusions: the SFR
• SFR estimates from B, I and I+B catalogues agree well and are confirmed by GALEX at z<1• SFR estimate from K catalogue is lower by 0.3 dex because it is missing galaxies with L<L* • Cosmic variance < 0.1 dex• Bright galaxies with L>L* produce 1/3 of the total SFR • Previous estimates of the SFR are too high by a factor of 2 because the faint-end slope of the LF has been overestimated• Dust correction is ~ factor 3• Complete census of galaxies nearly reached: SPITZER• The SFR is roughly constant up to z=4 and declines slowly beyond
8.7.2005 Renzini Ringberg 2005 21
Conclusions: Morphologies
• The morphological mix evolves strongly with redshift
• The stellar mass density moves from disks (at z=1) to bulges (at z=0)
• Merging must have an important role
8.7.2005 Renzini Ringberg 2005 22
The dust correctionUsing a factor 6.5 dust correction (or A28000=2):
8.7.2005 Renzini Ringberg 2005 23
The Sersic profile1/
( ) exp ( ) 1
1: exponen
n=0.5: Gaussi
4 : de Vaucouleu
an
a
r
ti
s
l
n
ee
n
rI r I k n
r
n