The Evolution of Galaxy Morphologies in Clusters

“Distant Clusters of Galaxies”Ringberg, October 2005

The Evolution of Galaxy Morphologies in Clusters

“Distant Clusters of Galaxies”Ringberg, October 2005

Marc Postman

with lots of help from:

Marc Postman

with lots of help from:

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 a fundamental Is the morphology - density relation a fundamental relationship or is it a consequence of some other relationship or is it a consequence of some other underlying correlation (e.g., galaxy mass - density underlying correlation (e.g., galaxy mass - density relationship)? When does the MDR get established?relationship)? 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? Does the clusters and the field vary with redshift? Does the MDR evolve? MDR evolve? – The evolution in morphological composition as functions of The evolution in morphological composition as functions of

radius, density, SFR, galaxy mass are powerful constraints radius, density, SFR, galaxy mass are powerful constraints on galaxy formation models. on galaxy formation models. Only HST has the angular Only HST has the angular resolution to study this evolution.resolution to study this evolution.

• 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?

• 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?

– 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. Does not density relation. 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

CL1604+4321

CL1604+4304

RXJ0910+54RXJ0848+44

RXJ1252-29MS1054-0321

RXJ0152-1357

fE+S0 LX(0.33 +/- 0.09)

fE LX(0.15 +/-

0.09)

fS0 LX(0.18 +/- 0.09)

RXJ0152-1357

CL1604+4304

RXJ0848+44RXJ0910+54

RXJ1252-29

MS1054-0321

CL1604+4304

RXJ1252-29

RXJ0152-1357MS1054-0321

CL1604+4321

Galaxy Population Galaxy Population vs. Cluster vs. Cluster PropertiesProperties

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

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.

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

Cluster

Field

AGNAGN

Can we make a Coma S0 from a Can we make a Coma S0 from a single z = 0.83 cluster spiral?single z = 0.83 cluster spiral?

Holden et al. 2005, in prep.Holden et al. 2005, in prep.

z=0.83 E+S0

z=0.83 Spirals

Close Pair CandidatesClose Pair CandidatesCL0152

MS1054

MS1054: Tran et al. MS1054: Tran et al. 20052005

Red Pair Excess

2.81

2.84

3.29

1.01

Jitter ( = 50 kpc)

4.45

Bartkoet al.2006

Red Pair ExcessJitter ( = 50 kpc)

Bartkoet al.2006

Low-z clustersMS1358 (z=0.33) CL0016 (z=0.54)

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

• MS1054 & CL0152 have comparable merger MS1054 & CL0152 have comparable merger fractions. fractions.

• 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.

Brightest Cluster GalaxiesBrightest Cluster GalaxiesCL0152-13 MS1054 CL1604+4304CL0152-13 MS1054 CL1604+4304

CL1604+4321 CL0910+54 CL1252-29CL1604+4321 CL0910+54 CL1252-29

Elliptical Elliptical Sb/ScElliptical Elliptical Sb/Sc

S0/a S0/a EllipticalS0/a S0/a Elliptical

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 all but one in all but one of these z~1 clusters of these z~1 clusters is smaller (<0.13 mag) is smaller (<0.13 mag) than that in ~90% of than that in ~90% of the z~0 rich Abell the z~0 rich Abell clusters [Exception is clusters [Exception is MS1054 which has 0.36 MS1054 which has 0.36 mag contrast]mag contrast]

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

Implications for the Evolution of Implications for the Evolution of Cluster Galaxy MorphologiesCluster Galaxy Morphologies

• 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 massive mass-density relationship. But the formation of the most massive galaxies may be determined by either initial or large scale galaxies may be determined by either initial or large scale conditions.conditions.

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

• z ~ 1 Cluster spirals are not a “pristine” population - i.e., they z ~ 1 Cluster spirals are not a “pristine” population - i.e., they already exhibit evidence for environmentally induced alteration of already exhibit evidence for environmentally induced alteration of their stellar populations (relative to field galaxies at similar their stellar populations (relative to field galaxies at similar redshifts).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. And z~1 BCGs show much more morphological variation cluster spiral. And z~1 BCGs show much more morphological variation than those at z=0. Many cannot simply be passively evolved to match than those at z=0. Many cannot simply be passively evolved to match current epoch BCG luminosities. Merging is likely an important current epoch BCG luminosities. Merging is likely an important process.process.