GEMS: The Evolution of Disc Galaxies

18/05/2004 Ringberg Workshop: Secular Evolution of Disc Galaxies

GEMS: GEMS: The Evolution of Disc GalaxiesThe Evolution of Disc Galaxies

Marco BardenMarco Barden


Galaxy EvolutionGalaxy Evolution• Archaeology Archaeology Look-back approachLook-back approach• Galaxy evolution Galaxy evolution Population evolutionPopulation evolution• Important because:Important because:

– Even in local universe 60-80% discsEven in local universe 60-80% discs– Most of all stars form in discsMost of all stars form in discs– Most of the stars of the MW formed since z~1Most of the stars of the MW formed since z~1

measure structural parameters of discs measure structural parameters of discs as a function of timeas a function of time


Theoretical ModelsTheoretical Models• Expectation from models (e.g. Mo, Mao, Expectation from models (e.g. Mo, Mao,

White 1998, Bouwens & Silk 2002): White 1998, Bouwens & Silk 2002): Discs in the early universeDiscs in the early universe– were more compactwere more compact– were on average brighterwere on average brighter– had higher surface brightnesshad higher surface brightness– had lower stellar masseshad lower stellar masses

than disc galaxies todaythan disc galaxies today large redshift surveys to constrain modelslarge redshift surveys to constrain models


ObservationsObservations• Several surveys (e.g. Several surveys (e.g.

CFRS, DEEP, GOODS)CFRS, DEEP, GOODS) controversycontroversy

• Strong SB evolution (result Strong SB evolution (result of higher overall SFR, of higher overall SFR, Schade et al. 1996)Schade et al. 1996)

• No evolution in SB No evolution in SB (selection effects, Simard (selection effects, Simard et al. 1999)et al. 1999)

• At z~1 a new class of high At z~1 a new class of high SB galaxies (SB galaxies (0,e0,e<17.7 mag <17.7 mag arcsecarcsec-2-2) appears (Simard ) appears (Simard et al. 1999)et al. 1999)

Ravindranath et al. 2004Ravindranath et al. 2004


ObservationsObservations

• Restricted luminosity rangeRestricted luminosity range interpretation interpretation

• Surface brightness dimming Surface brightness dimming selection effects dominate a high-z selection effects dominate a high-z

• Objects are small Objects are small high spatial resolution needed high spatial resolution needed

• Distribution of surface brightness is wide Distribution of surface brightness is wide large samples large samples


GEMS: Galaxy Evolution from GEMS: Galaxy Evolution from Morphology and SEDsMorphology and SEDs

MPIA:MPIA: Barden, Bell, Borch, Häußler, Barden, Bell, Borch, Häußler, Heymans, Meisenheimer, Rix (P.I.)Heymans, Meisenheimer, Rix (P.I.)

STScI:STScI: Beckwith, Caldwell, Jogee, Beckwith, Caldwell, Jogee, SomervilleSomerville

AIP:AIP: Jahnke, Sanchez, WisotzkiJahnke, Sanchez, Wisotzki

Oxford:Oxford: WolfWolf

UMass:UMass: McIntoshMcIntosh

U. Arizona:U. Arizona: PengPeng



• E-CDFSE-CDFS• Largest HST colour Largest HST colour

mosaic: ~30’x30’, 9x9 mosaic: ~30’x30’, 9x9 ACS tiles, ~150 HDFACS tiles, ~150 HDF

• 125 (GEMS) + 50 125 (GEMS) + 50 (GOODS) orbits(GOODS) orbits

• 2 filters: 2 filters: – F606W (mF606W (mABAB<28.3)<28.3)

– F850LP (mF850LP (mABAB<27.1)<27.1)



• ~10000 ~10000 redshifts from redshifts from COMBO-17 COMBO-17 (Wolf, Meisen-(Wolf, Meisen-heimer et al. heimer et al. 2003)2003)

• 5 broad / 12 5 broad / 12 medium band medium band filtersfilters

z~0.02, z~0.02, 0.1<z<1.3, 0.1<z<1.3, mmrr<24<24

• SEDs (3500-SEDs (3500-92509250Å)Å)

z=1.25z=1.25 z=0.69z=0.69

z=0.46z=0.46 z=0.24z=0.24


The Disc SampleThe Disc Sample• Sersic fits to F850LP Sersic fits to F850LP

images with GALFIT images with GALFIT (Peng et al. 2002)(Peng et al. 2002)

• Selection of discs Selection of discs with n<2.5with n<2.5

• Completeness Completeness simulations (Hsimulations (Häußler äußler et al. 2004)et al. 2004)

• Size correction (de Size correction (de Jong 1996)Jong 1996)


Completeness & Selection EffectsCompleteness & Selection Effects


The Magnitude-Size RelationThe Magnitude-Size Relation



VV (z)=

(20.7

9(z)=

(20.7

9 0

.08

) - (1.05

0.0

8) - (1.0

5 0

.11

) z0

.11

) z



VV (z)=

(20.7

9(z)=

(20.7

9 0

.08

) - (1.05

0.0

8) - (1.0

5 0

.11

) z0

.11

) z

HDF

FIRES

Trujillo et al. 2004



VV (z)=(21

.24

(z)=(21

.24

0.0

8) - (1.7

90

.08

) - (1.79

0.1

1) z

0.1

1) z



Bouwens & Silk 2002Bouwens & Silk 2002


The Mass-Size RelationThe Mass-Size Relation



log log (z) =

8.24(z) =

8.24 0.020.02




ConclusionsConclusions

• The magnitude-size relation of disc galaxies The magnitude-size relation of disc galaxies changes as a function of redshift changes as a function of redshift average SB increasesaverage SB increases

• The appearance of high SB galaxies at high-z is The appearance of high SB galaxies at high-z is a result of the increasing average SBa result of the increasing average SB

• Disc galaxies at different redshifts follow the Disc galaxies at different redshifts follow the same mass-size relation same mass-size relation galaxies form inside-outgalaxies form inside-out

• Mass densities stay roughly constant with Mass densities stay roughly constant with redshiftredshift

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GEMS: The Evolution of Disc Galaxies