The Evolution of Galaxy Morphologies in Clusters

“New Views of the Universe”KICP, U. Chicago, December 2005

The Evolution of Galaxy Morphologies in Clusters

“New Views of the Universe”KICP, U. Chicago, December 2005

Marc Postman

& collaborators:

Marc Postman

& collaborators:

Frank BartkoTxitxo BenitezJohn BlakesleeNick CrossRicardo Demarco

Frank BartkoTxitxo BenitezJohn BlakesleeNick CrossRicardo Demarco

Holland FordMarijn FranxTomo GotoBrad HoldenNicole Homeier

Holland FordMarijn FranxTomo GotoBrad HoldenNicole Homeier

Garth IllingworthSimona MeiPiero Rosati& the rest of the ACS IDT

Garth IllingworthSimona MeiPiero Rosati& the rest of the ACS IDT

Understanding the Origin of Understanding the Origin of Morphological Differences in GalaxiesMorphological Differences in Galaxies

• Is the morphology - density relation (MDR) a Is the morphology - density relation (MDR) a fundamental relationship or is it a consequence fundamental relationship or is it a consequence of some other underlying correlation (e.g., of some other underlying correlation (e.g., galaxy mass - density relationship)? galaxy mass - density relationship)? – Is the morphological population set mostly by Is the morphological population set mostly by environmental processes or initial conditions? Is environmental processes or initial conditions? Is the answer to this question dependent on galaxy the answer to this question dependent on galaxy mass?mass?

– When does the MDR get established?When does the MDR get established?– How do the morph. populations of galaxies in How do the morph. populations of galaxies in clusters and the field vary with redshift? clusters and the field vary with redshift?

– The evolution in morphological composition as functions The evolution in morphological composition as functions of radius, density, SFR, galaxy mass are powerful of radius, density, SFR, galaxy mass are powerful constraints on galaxy formation models. constraints on galaxy formation models.

– What are the progenitors of current epoch S0 What are the progenitors of current epoch S0 galaxies? Do mergers play an important role in galaxies? Do mergers play an important role in morphological transformation of cluster galaxy morphological transformation of cluster galaxy populations?populations?

– Data suggested there is detectable Data suggested there is detectable evolution in the morphological evolution in the morphological composition of clusters over the composition of clusters over the past ~5 Gyrs: z~0.5 to the present past ~5 Gyrs: z~0.5 to the present epoch (Dressler et al 1997; Fasano epoch (Dressler et al 1997; Fasano et al. 2000; Treu et al. 2003). et al. 2000; Treu et al. 2003).

Goto et al 2003Goto et al 2003• What we knew prior to ACS on HST:What we knew prior to ACS on HST:– The relative fraction of galaxy The relative fraction of galaxy

morphologies depends on density morphologies depends on density (Dressler 1980, Postman & Geller (Dressler 1980, Postman & Geller 1984) and/or on clustocentric 1984) and/or on clustocentric radius (Whitmore & Gilmore 1993)radius (Whitmore & Gilmore 1993)

– Physical processes exist that can Physical processes exist that can alter galaxy morphology on alter galaxy morphology on timescales much less than the timescales much less than the current age of the universe: ram current age of the universe: ram pressure, tidal disruption, pressure, tidal disruption, mergersmergers

Understanding the Origin of Understanding the Origin of Morphological Differences in GalaxiesMorphological Differences in Galaxies

Quilis, Moore, & Bower 2000: Ram pressure induced gas stripping; Timescale ~100 Myr

Poggianti 2000Poggianti 2000

Images of different morph types

z =0.83

20 kpc

EE

Ellipticals Ellipticals Lenticulars (S0)Lenticulars (S0) Spirals + IrregSpirals + Irreg

z =0.84

z =0.90

z =0.92

z =1.10

z =1.24

z =1.27

MDR & MRR Results

Morphology - Density Relation Morphology - Radius Relation

PG84 z~0 E+S0 FractionD80/D97 z~0 E+S0P2005 ACS z~1 E+S0 Smith et al2005 z~1 E+S0

P2005 ACS z ~ 1 EllipticalsPG84 z ~ 0 EllipticalsD80/D97 z ~ 0 Ellipticals

P2005 ACS z ~ 1 S0 FractionPG84 z ~ 0 S0 FractionD80/D97 z ~ 0 S0 Fraction

P2005 ACS z~1 E+S0 Fraction

WG91 z ~ 0 E+S0 Fraction

P2005 ACS z~1 Ellipticals

WG91 z ~ 0 Ellipticals

P2005 ACS z~1 S0 Fraction

WG91 z ~ 0 S0 Fraction

R/R200

Projected Density

Evolution in MDREvolution in MDRThe increase in the early-The increase in the early-type fraction with type fraction with increasing density is less increasing density is less rapid at z~1 than at z~0. rapid at z~1 than at z~0. Consistent with Consistent with environmentally driven environmentally driven transformation of late --> transformation of late --> early types.early types.

S0 fraction at z~1 is <50% S0 fraction at z~1 is <50% of its z~0 value but of its z~0 value but consistent with its z~0.5 consistent with its z~0.5 value (e.g., Dressler et value (e.g., Dressler et al. 1997; Fasano et al. al. 1997; Fasano et al. 2000; Treu et al. 2003)2000; Treu et al. 2003)

No significant evolution No significant evolution seen in elliptical seen in elliptical population fraction - population fraction - density relation. density relation. Does not Does not imply cosmic E pop doesn’t imply cosmic E pop doesn’t increase with time, increase with time, however.however.

No significant evolution No significant evolution seen at low-density (Smith seen at low-density (Smith et al. 2005; Mobasher et et al. 2005; Mobasher et al. 2006)al. 2006)

But pop fractions may be But pop fractions may be correlated with Lcorrelated with LXX

Postman et al. 2005

Smith et al. 2005

T - ∑ Relation vs. Galaxy MassT - ∑ Relation vs. Galaxy MassHOLDEN ET AL. 2005, IN PREP.HOLDEN ET AL. 2005, IN PREP.

10.5 < Log(M) < 10.85Log(M) > 10.85

MS1054 + RXJ0152z=0.83

z ~ 1 Cluster Disk Galaxy Samplez ~ 1 Cluster Disk Galaxy SampleSpectroscopically confirmed members with types Sa or laterSpectroscopically confirmed members with types Sa or later

0

5

10

15

20

25

30

-0.2 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

(U-B) Z

N

Field

Cluster

z~1 Cluster Disk & SF Galaxy Propertiesz~1 Cluster Disk & SF Galaxy PropertiesHomeier et al. 2005, Demarco et al. 2005, Homeier et al. 2005, in Homeier et al. 2005, Demarco et al. 2005, Homeier et al. 2005, in

press.press.

•Cluster spirals Cluster spirals are significantly are significantly redder their field redder their field counterparts counterparts •But, their But, their quantitative quantitative morphologies morphologies (C,A,S) are (C,A,S) are indistinguishableindistinguishable•Sizes (RSizes (R1/21/2 or disk or disk scale height) of scale height) of cluster and field cluster and field galaxies are galaxies are similarsimilar

•Blue cluster disk Blue cluster disk galaxies show galaxies show evidence (97% C.L.) evidence (97% C.L.) for enhanced central for enhanced central star formation.star formation.•Star forming cluster Star forming cluster galaxies avoid densest galaxies avoid densest regions. Most (~80%) are regions. Most (~80%) are “normal” spirals. (a la “normal” spirals. (a la Gisler 1978; Lewis et al. Gisler 1978; Lewis et al. 2002; Gómez et al. 2003)2002; Gómez et al. 2003)

CGE = 10xlog (rCGE = 10xlog (rredred/r/rblueblue))

(U-B) < 1.0

0

2

4

6

8

10

12

14

16

-0.925 -0.775 -0.625 -0.475 -0.325 -0.175 -0.025 0.125 0.275 0.425 0.575 0.725 0.875 1.025

Color Gradient Estimate

N

Field

Cluster

Red Centers Blue Centers

Close Pair CandidatesClose Pair CandidatesCL0152

MS1054

MS1054: A significent population MS1054: A significent population of mergersof mergers

(van Dokkum et al. 2003 &Tran et (van Dokkum et al. 2003 &Tran et al. 2005)al. 2005)

We find similar excesses in CL0152-1357 (z=0.83) and RXJ1252-2927 (z=1.24) but not in CL1226+33 (z=0.89) or any of our less massive (< few x 1014 Msol) clusters.

Bartko et al. 2006, in prepBartko et al. 2006, in prep

• Excess of red galaxy pairs appears to Excess of red galaxy pairs appears to be a common (but not a universal) be a common (but not a universal) phenomenon associated with very dense phenomenon associated with very dense environments at z ~ 1. It is not seen environments at z ~ 1. It is not seen at lower z nor in less massive (<5 x at lower z nor in less massive (<5 x 10101414 solar masses) hi-z clusters. solar masses) hi-z clusters. Caveat: small sample!Caveat: small sample!

• Early type mergers confined to central Early type mergers confined to central regions. Late type merger fraction not regions. Late type merger fraction not strongly dependent on radius once strongly dependent on radius once beyond central 500 kpc or so.beyond central 500 kpc or so.

S0/a S0/a Elliptical S0/ES0/a S0/a Elliptical S0/E

Elliptical Elliptical Elliptical Sb/Sc Elliptical Elliptical Elliptical Sb/Sc

RXJ0152-13 MS1054 CLJ1226+33 CL1604+4304RXJ0152-13 MS1054 CLJ1226+33 CL1604+4304 z = 0.83 z = 0.83 z = 0.89 z = 0.90z = 0.83 z = 0.83 z = 0.89 z = 0.90

CL1604+4321 RXJ0910+54 RXJ1252-29 RXJ0848+54CL1604+4321 RXJ0910+54 RXJ1252-29 RXJ0848+54 z = 0.92 z = 1.10 z = 1.24 z = 1.27z = 0.92 z = 1.10 z = 1.24 z = 1.27

Brightest Cluster GalaxiesBrightest Cluster Galaxies

BCG Luminosity EvolutionBCG Luminosity EvolutionPostman et al. 2006, in prep.Postman et al. 2006, in prep.

z ~ 1 BCG exhibit a z ~ 1 BCG exhibit a broader morphological broader morphological distribution than their distribution than their z=0 counterpartsz=0 counterparts

MM22 - M - M11 in the majority in the majority z~1 clusters is smaller z~1 clusters is smaller (<0.35 mag) than that (<0.35 mag) than that in ~85% of the z~0 rich in ~85% of the z~0 rich Abell clustersAbell clusters

We thus expect many of We thus expect many of these BCGs will undergo these BCGs will undergo a doubling in mass by a doubling in mass by z~0.5 (e.g., RDCS1252-z~0.5 (e.g., RDCS1252-2927)2927)

Implications for the Evolution of Cluster Galaxy Implications for the Evolution of Cluster Galaxy MorphologiesMorphologies

• MDR is a fundamental relationship, not a simply consequence of MDR is a fundamental relationship, not a simply consequence of mass-density relationship. But the formation of the most mass-density relationship. But the formation of the most massive galaxies may be influenced by initial or large scale massive galaxies may be influenced by initial or large scale conditions.conditions.

• E and S0 populations likely have different formation E and S0 populations likely have different formation histories. Up to 50% of S0’s in high density regions could be histories. Up to 50% of S0’s in high density regions could be in place by z~1.in place by z~1. Work done at z ~ 0.5, shows a similar deficit Work done at z ~ 0.5, shows a similar deficit of S0 galaxies (e.g., Dressler et al. 1997; Fasano et al. of S0 galaxies (e.g., Dressler et al. 1997; Fasano et al. 2000).2000). We are witnessing the “recent” build up of about half We are witnessing the “recent” build up of about half the cluster S0 population via the transformation of in-falling the cluster S0 population via the transformation of in-falling spiral galaxies. spiral galaxies.

• z ~ 1 Cluster spirals are not a “pristine” population - i.e., z ~ 1 Cluster spirals are not a “pristine” population - i.e., they already exhibit evidence for environmentally induced they already exhibit evidence for environmentally induced alteration of their stellar populations (relative to field alteration of their stellar populations (relative to field galaxies at similar redshifts).galaxies at similar redshifts).

• However, a typical z=0 S0 is twice as massive as a typical z=1 However, a typical z=0 S0 is twice as massive as a typical z=1 cluster spiral. Additionally, z~1 BCGs show much more cluster spiral. Additionally, z~1 BCGs show much more morphological and photometric variation than those at z=0. morphological and photometric variation than those at z=0. Many cannot be passively evolved to match current epoch BCG Many cannot be passively evolved to match current epoch BCG luminosities. Galaxy merging is likely an important process.luminosities. Galaxy merging is likely an important process.