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Star Formation Rates, Ages and Masses of Massive Galaxies in the FORS Deep and GOODS South fields. R. Bender, A. Bauer, N. Drory, G. Feulner, A. Gabasch, U. Hopp, M. Pannella, R.P. Saglia, M. Salvato

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Star Formation Rates, Ages and Masses

of Massive Galaxies in the

FORS Deep and GOODS South fields

R. Bender, A. Bauer, N. Drory, G. Feulner, A. Gabasch, U. Hopp, M. Pannella, R.P. Saglia, M. Salvato

(Universitäts-Sternwarte München, Max-Planck Institut für Extraterrestrische Physik, University of Texas)

Map out galaxy assembly: Luminosity functions

Stellar mass functions, Star formation rates as a function of mass.


Star Formation Rates, Ages and Masses

of Massive Galaxies in the

FORS Deep and GOODS South fields

  • Study evolution of galaxies with broadband deep U to K surveys.

  • LFs, Mass Functions, SFRs do not require spectroscopy but can

  • be derived with accurate photometric redshifts.

  • Advantage of photo z: no color selection bias, fainter luminosities,

  • larger sample (~10000 galaxies in FDF and GOODS S sub-sample)

  • FORS Deep Field (IAB=26.8): 98% of all galaxies with dz/(1+z)<0.03;

  • GOODS S (KAB=25.4): dz/(1+z)<0.055

  • Deep I-selection misses only a small fraction of deep K selected

  • objects. Surveys to IAB=27 also cover a large fraction of submm gals.

  • Derive masses from broadband SEDs by fitting exponential SFH +

  • bursts (with extinction); exp. SFHs only do NOT work for large

  • l-range (check via comparison with local SDSS+2MASS sample).

  • Further check: compare FDF I-selected with GOODS K-selected.


The FORS Deep Field (FDF, GTO project)

  • FDF goals: evolution of galaxies: their luminosity functions, star formation rates, morphologies, chemical abundances, dark halo properties, Tully-Fisher , FP relations etc...

  • Imaging in U,B,g,R,I,z,J,K (to AB ~ 27 in optical).

  • Depths within 0.5 ... 1 mag of Hubble Deep Fields.

  • Area ~5 times HDFs together (6.8‘ x 6.8‘).

  • 8000 objects with photometric z and type.

  • Spectroscopy available for ~360 galaxies.

  • HST Advanced Camera observations obtained.

  • FORS partners: Observatories in Heidelberg, Göttingen and Munich built two FORS spectrographs for the VLT.

  • FDF science team: Appenzeller, Bender, Böhm, Drory, Gabasch, Heidt, Hopp, Mehlert, Noll, Saglia, Seitz, Ziegler et al.


FDF field selection: DSS image

QSO 0103-260

z=3.36

FDF

Criteria: z>3 QSO in field, minimize foreground of stars and (z<0.2)

galaxies, high Galactic latitude, good accessibility from VLT


FORS Deep Field

FDF BRI real color image

FWHM = 0.45”

QSO 0103-260

z=3.36



HST ACS

FDF BRI

~1’x1’ enlargements



The goods south field
The Goods-South Field (FDF)

  • J, H, K VLT images, 50 arcmin2, (8 tiles),

    seeing 0.4-0.5”

  • K-selected catalog: 3297 galaxies to KAB=25.4

  • U, I: GOODS/EIS public survey

  • B, V, R: Garching/ Bonn deep survey

Salvato et al. 2006,

A&A, submitted

K-band 2.5’x2.5’


Global galaxy parameters from photometric redshifts (FDF)

  • Advantages:

  • - large samples of ‘normal’ galaxies

  • - redshifts for faint objects

  • - full spectral energy distribution

  • - ‘cheap’ in telescope time

  • - modest amount of spectroscopy

  • needed to test reliability

  • Potential problems:

  • - accurate photometry needed

  • - calibrating galaxies are bright

  • - larger errors in redshift

  • - catastrophic failures in z


Observed vs. synthetic color (FDF)-color diagrams of stars used to check photometric calibration


Semi-empirical SEDs (FDF)derived from broad-band fluxes of galaxies with spectroscopic z by fitting them with SEDs of Bruzual&Charlot, Maraston and spectra from FDF, Kinney&Calzetti, Manucci

=> used as templates to determine photometric redshifts




check: (FDF)

photo z

vs.

spec z

180 galaxies used to derive semi- empirical SEDs

180 galaxies in the control sample

QSO

Only ~ 1% catastrophic failures on normal galaxies! (mostly

very blue, faint dwarf objects with almost power-law SEDs)


check: (FDF)

photo z

vs.

spec z

for

MB > -20

Photometric z for faint objects: o.k.!!



FDF redshift distribution: extends to z ~ 6 (similar to HDFs)

another check:

peaks in photometric

z distribution

well consistent

with peaks in

spectroscopic

z distribution

at: 0.22, 0.33,

0.39, 0.45,

0.77, 2.35,

3.38 (QSO)


M HDFs)B distribution in FDF vs z

completeness

limits in FDF:

red massive

galaxies to

z ~ 2

blue star-

forming

galaxies to

z ~ 6

Most luminous

galaxies in

optical bands

tend to have

oldest SEDs

clustering in

redshift space

very obvious!

Ho = 70 km s-1 Mpc-1

Wm= 0.3, WL = 0.7




irregulars HDFs)




Estimating Schechter parameters HDFs)F*, M*, a:

parameter coupling in luminosity function fits

V/Vmax and completeness

corrections applied


The LF faint end slope HDFs)ain the FDF:


FDF HDFs)

constraints

on aand M*between

z ~ 0.6

(low M*)

and

z ~ 3.5

(high M*)

(some low z bins have large errors because

scaling with c2

was applied)

2800 A

1500 A

z

g’

u’


What about Steidel et al. 1999: HDFs)a ~ –1.6 ?

(galaxies selected by drop outtechnique)

FDF

Steidel et al. 1999

FDF

The faint end slope at 1700A:

z~3

z~4.1


FDF HDFs)

FDF

Steidel et al. 1999

FDF:

z ~ 3

z ~ 4

  • cannot be settled definitely yet,

    but a~ –1.6 pretty unlikely


Measured faint end slopes of the LFs in FDF: HDFs)

adopted in

the following:


Evolution of LF HDFs)

in g’ band:

z = 0.3

to

z = 5.5


Evolution of LF HDFs)

at 2800 A:

z = 0.3

to

z = 5.5


1500 A HDFs)

2800 A

F*

vs.

M*

for

z = 0.6

to

z = 4.5

u’

g’


Evolution of HDFs)M* and F* for fixed a

Fits based on FDF alone predict SDSS values reasonably well.


same B-band HDFs)

evolution as

observed for

bright cluster

ellipticals:

DB ~ z

provides

SF history

consistent

with Madau

diagram

a and b values for 1500 A and

2800 A imply SFR ~ constant


The uv luminosity density and sfr
The UV-luminosity density and SFR HDFs)

For the FDF, the extrapolation to L=0 in the calculation

of Ltot amounts to only 2%-20%, depending on redshift.

(no correction for dust)


Adelberger & Steidel (2000) HDFs)

dust corrected

  • Evolution

  • of Star

  • Formation

  • Rate

  • Cosmic variance

  • between FDF and

  • GOODS <0.1dex

  • Luminous galaxies

  • immune to wave-

  • length dependent

  • selection effects.

  • Luminous galaxies

  • (B- to K-selected,

  • L>L*) contribute

  • only ~1/3 to total

  • star formation rate

  • at all redshifts.

  • Gabasch et al. 2004b,

  • ApJ Lett. in press

a= -1.6

a= -1.1

GALEX


Broadband HDFs)galaxy masses from SED-fits: I. check by

application to combined SDSS+2MASS data set (exp.SFH+bursts)

Drory, Bender, & Hopp, ApJL, 616, 103


… and by HDFs)

comparison

with masses

from spectral

analysis of

SDSS data

by Kauffmann

et al. (2003)

(17000 obj.):

o.k.!

Kauffmann + 2003

SDSS spectral feature mass

Mass from SED fitting

Drory + 2004


Residuals of photometric and spectroscopic masses HDFs)

against a dynamical mass indicator: o.k.!


Evolution of HDFs)

the galaxy

mass

function

at low z:

MUNICS

(photo z)

and

K20

(mostly

spectra)


Stellar HDFs)

masses of

galaxies in

FDF and

GOODS S:

red=old

blue=young

at all z,

massive

galaxies

are older

than low

mass

objects!

Drory et al. 2005, ApJL, 619, 131


Evolution of the galaxy stellar mass function HDFs)

with redshift:

Drory et al. 2005, ApJL, 619, 131

See poster by Pannella et al. for MF as function of morphology


Evolution of total stellar mass density. HDFs)

Drory et al. 2005, ApJL, 619, 131


Number density evolution of massive galaxies. HDFs)

Drory et al. 2005, ApJL, 619, 131


Specific star formation rates (from [OII]) to HDFs)z ~ 1.5:

Bauer et al. 2005, ApJL, 621, 89

Bauer et al. 2006

Study star formation as a function of mass and

redshift.


Specific star formation rates (from UV cont.) HDFs)z ~ 4.5:

Feulner et al. 2005, ApJL, 633, 9

Study star formation as a function of mass and

redshift: strong constraints on models of galaxy formation.


Specific star formation rates (from UV cont.) HDFs)z ~ 4.5:

  • More massive galaxies

  • form their stars earlier.

  • Stars are formed by z~2

  • More massive galaxies

  • show a steeper decline

  • in SSFR.


  • Summary: HDFs)

  • faint end slope of luminosity function is shallow at high z

  • LF evolution stronger at shorter wavelength

  • F* decreases, L* increases with redshift in all bands

  • analysis of cosmic SFH not very sensitive to l-selection

  • at all z, L>L* galaxies contribute ~1/3 to total SFR, but less to SSFR

  • at all z, massive galaxies are older than low mass galaxies

  • high mass galaxies form their stars earlier and faster

  • Papers: FDF+GOODS LFs, SFH: Gabasch et al. 2004, 2005

  • FDF+GOODS+MUNICS+SDSS+2MASS masses:

  • Drory et al. 2001, 2003, 2004, 2005


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