RDCS1252 (z = 1.24) C-M Relation with HST/ACS and VLT/ISAAC(Blakeslee et al. 03; Lidman et al. 03; Rosati et al . 04)

Coma at z=1.24

ES0

Late

HST/ACS

The scatter and slope of the red sequence is very similar to low-z clusters, basically frozen over 65% of look-back times !

Lidman et al. 2004

Kodama&Arimoto 97 modelsZF= 2,3,5

VLT/ISAAC

Piero Rosati -- Old galaxies at z=1-1.4

The suburbs of A851: 7/9 are starbursts!

Hypothesis: As gas-rich disk galaxies fall into these rich clusters, either individually or in small groups, they are severely jostled by tidal interactions. Alternate hypothesis: shocks from intracluster medium drive the starbursts.

only 2 k-type and no e(c)’s! 6 are e(a), 1 k+a

Dressler et al. 2004

Alan Dressler -- Starburst galaxies and cluster suburbs

...a remarkable change in the amount and character of star formation in the recent past.

In rich clusters of galaxies, but even in “the field,” the mode of star formation appears to shift to a much greater fraction which are starbursts (20-30%)

E+S0s: cluster induced bursts. GALEX view

• Abundance of NUV detected E/S0 consistent with moderate amounts of recent star formation 10^7-10^8 Gyrs inside the virial radius.

• Consistent with infall scenario and burst of starformation at ~ the virial radius Moran et al. 2006

CL0024

Tommaso Treu:

Also Adam Muzzin; Spitzer starbursts

2-D Family: Age x Extinction

Christian Wolf -- A population of dusty red galaxies

• Fraction of red galaxies depends strongly on density. This is the primary influence of environment on the colour distribution.

• Mean colours depend weakly on environment: transitions between two populations must be rapid (or rare at the present day)

• Trend is not completely absent for fainter galaxies; but never dominant

Balogh et al. 2004

Michael Balogh -- Color trends at low-z

•Simple dependence of “late-type” fraction on environment characterizes much of observed trends (e.g. SFR-density, morphology-density, colour-density etc.).•Interpretation?

1.Two modes of formation. Within each peak is variance due to dust, metallicity (second-order effects).2.Transitions: Where do S0, E+A fit in?

Anja von der Linden -- Local cluster samples from Sloan

Andrea Biviano -- Galaxy orbits

When measured within the physical size of the systems (given by r200

),

the Cluster LF is universal (Popesso et al. 2005)

Paola Popesso -- The LF at low-z

•bimodal behaviour of the cluster LF (steepening at the faint end)

•the cluster LF is universal when measured with the virial radius

•DGR increasing with the clustercentric distance

Vincent Eke -- 2PIGG LF vs mock catalogues from SA

The way to do it! …but models don’t get it right

--- The evolution of the NIR luminosity function of bright galaxies in X-ray luminous clusters at z~1.2 is consistent with passive evolution

--- The redshift evolution of K* up to z=1.2 is compatible with passive evolution of a stellar population formed at z>2

--- The bright end of the LF appears to be dominated by galaxies already evolved both morphologically and spectrophotometrically

Veronica Strazzullo -- The LF at 1.1 < z < 1.3

Also Gabriella De Lucia, LF of red galaxies at z=0.8

Kim –V. Tran -- Red merging pairs

also Marc Postman other high-z clusters: not universal phenomenon, but MS1054 not unique

Hierarchical Assembly: SG1120Ongoing mergers of massive galaxies

• Detection: – Las Campanas Distant Cluster Survey

(Gonzalez et al. 2001)– 4 candidates at z~0.4 within

a 7’ diameter region

• Confirmation:– Chandra + spectroscopy– 6 extended sources within a 13’ diameter region (~4 Mpc)

Groups at z=0.37 (2,3,4,5) Cluster at z=0.48 (1) No redshift yet (6)

• “Supergroup” SG1120-1202

Anthony Gonzales -- Supergroup (or supercluster?)

Morphology - Density 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

Projected Density

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

galaxies show evidence galaxies show evidence (97% C.L.) for (97% C.L.) for “centralized” star “centralized” star formation.formation.

Marc Postman - Morphologies

EDisCS: z = 0.4-0.8 Sloan (Abell): z = 0.04-0.1

Direct link between the star formation activity in galaxies and the history of growth of clusters and groups?

In a scenario in which the passive galaxy population has two components (primordial and quenched galaxies), only two informations needed:

fraction of mass/galaxies already in groups at z=2.5

fraction of mass/galaxies that have experienced the cluster environment for a few Gyr

Bianca Poggianti -- Evolution of the % of starforming galaxies as a function of

environment

Current scenario (common to all of us?)

• In clusters, some galaxies are very old (most massive, Es), both in SF and assembly. A significant % of the cluster galaxies have stopped forming stars at z<1 (from spirals to S0s)

• Morphological evolution and evolution in the SF activity are taking place

• Massive galaxies have on average shorter SF timescales than smaller ones (downsizing)

• Dense environments quench star formation (dense environments?)

• Environmental conditions act in two ways – New concept of “nature” vs “nurture”: “Today’s population is the result of different environments at different epochs”. “Primordial” environment & “proper” environmental effects (when galaxy experiences a “new” environment for the first time) – “Proper environmental effects” are second order effects?

• Starbursts a more common mode of SF in the past than today

• Well sinked in all of us:

clusters as part of a “web” – necessity of “cross-environmental” studies (wide-field studies, importance of the group environment)

history of the “environment” and galaxy history probably closely related

1. Results to be reconciled:

established scenario for Es and S0s form. & evolution

occurrence, consequences & timing of mergers

transformations of galaxy properties and variegated SFHs

apparent “simplicity” of color bimodality

dependence of SF properties on environment at high-z

no apparent dependence at low-z?

starbursts a more common mode of SF at higher z in all envrs.

environmentally-related enhancement of SF?

2. We still don’t know how the “proper” environmental effects really work to quench and/or enhance SF

3. To what extent are we observing “intrinsic” (field) galaxy evolution, and to what extent are field studies looking at environmentally-driven evolution?