THE UNIVERSE: FROM PARTICLES TO GALAXIES

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Galaxy Evolution in Clusters
Alfonso Aragón-Salamanca School of Physics and
Astronomy University of Nottingham
MAGPOP, August 2007
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Overview

• Motivation
• Observations
• Low redshift
• High redshift
• EDisCS
• Some Theory
• The future

Warning optical-near IR bias
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MOTIVATION

• Galaxies contain gas stars dust dark matter
  
• ? galaxies must and do evolve
• What do we want to know?
• Epoch of galaxy formation
• When did the stars form?
• When did the galaxy assemble?
• When did the galaxy acquire its morphology?
• When did the metals form?
• ...
• Rate of galaxy evolution
• Star-formation history SFR(t)
• Chemical evolution Z(t)
• Rate of morphological change
• ...
• Rôle of the environment
• Are the properties of a galaxy determined by the
  initial conditions at its birth (nature)?
• Are the properties of a galaxy determined by the
  environment where it lives (nurture)?

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PROCESSES INVOLVED

• Cosmology large-scale structure
• Dynamical processes (internal/external)
• Gas physics
• Gas consumption/infall
• Star formation
• Stellar evolution
• Chemical enrichment
• AGN/Black Holes
• Feedback
• ? COMPLEX!

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MANY PROCESSESMANY TEMPORAL AND SPATIAL SCALES
COMPLEX!
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COMPLEX!
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Clusters as Laboratories of Galaxy Evolution

• Physical processes
• ram-pressure stripping
• of gas halo (Bekki et al. 2002)
• of disk gas (Quilis et al. 2000)
• galaxy-galaxy interactions
• harassment (Moore et al. 1998)
• mergers (Bekki 1998)
• cluster tidal field (Bekki 1999)
• cetera

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Information from z0 galaxies

• Morphology
• Photometry Spectroscopy
• Stellar population properties (e.g., age)
• Chemical composition
• Structure/Kinematics/Dynamics
• Statistical properties (e.g., Luminosity
  Functions)
• Environmental information (e.g.,
  morphology-density relation).

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Morphology

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Multi-wavelength photometry
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• Elliptical galaxies
• at z0
• Old stellar populations
• Very little or no current star formation
• Compact spheroidal
• (r¼ de Vaucouleurs profile)
• Supported by random motions
• (v/s 0.3)
• Tight scaling relations
• Colour-magnitude relation
• Faber-Jackson (L ? s4)
• Fundamental plane

Colour-Magnitude relation
Faber-Jackson relation
Bower, Lucey Ellis (1991)
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Fundamental plane
Jørgensen et al. (1999) Djorgovski Davis
(1987) Dressler et al. (1987)
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• Spiral galaxies
• At z0
• Have young and old stellar populations
• Have significant current star formation
• Have exponential disks
• About 1/3 have bars
• Supported by rotation
• (vs)
• Tight scaling relation
• Tully-Fisher (L ? v4)

Luminosity
Rotation Velocity
Pierce Tully 1992
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Luminosity Function

• Schechter function

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Luminosity Functions at z0

• Jerjen Tammann (1997)
• Sandage, Binggeli, Tammann (1985)

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The effect of the environment at z0

• Coma cluster

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Morphology-Density Relation at z0
Hubble Humason (1931)
Density
Dressler (1980)
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Information from z0 galaxies

• Photometry
• Number counts
• Colours
• Spectroscopy
• Redshifts
• Evolution of the Luminosity Function
• SFR of individual galaxies
• SFR(z)
• Chemical composition
• Morphologies
• Environmental information (e.g.,
  morphology-density relation).

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Galaxy clusters at z0
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Photometry of cluster galaxies at z0 The
ButcherOemler Effect
fB NBlue/NTotal

• Butcher Oemler 1978,1984

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Spectroscopy of cluster galaxies at z0
Emission strong absorption
Strong emission
Emission strong absorption
Absorption strong Balmer lines
Absorption moderate Balmer lines
AGN

• Couch Sharples 1987

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Spectroscopy of cluster galaxies at z0
x Emission line galaxy ? Blue with abs. lines ?
Red with abs. lines

• Couch Sharples 1987

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Photometry of cluster galaxies at z0 Colour
Evolution of red cluster galaxies

• Aragón-Salamanca et al. (1993)

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Photometry of cluster galaxies at z0 Colour
Evolution of E/S0 cluster galaxies

• Stanford, Eisenhardt Dickinson, (1998)

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Photometry of cluster galaxies at z0
Luminosity Evolution of cluster galaxies

• De Propris et al. (1999)

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Morphology and photometry of cluster galaxies at
z0 Evolution of the Colour-Magnitude relation.
Z0.56

• Ellis et al. (1997)

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Morphology, spectroscopy and photometry of
cluster galaxies at z0 Evolution of the
Fundamental Plane.

• van Dokkum et al. (1998)

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Morphology, spectroscopy and photometry of
cluster galaxies at z0 Evolution of the
Fundamental Plane.

• Treu et al. (2005)

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HST data
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Morphology-Density relation at z0 (Present
time) Many S0s in clusters Few Spirals in
clusters
Morphology-Density relation at 0.36ltzlt0.6 (5
Billion years ago) Many Spirals in clusters Few
S0s in clusters
Dressler et al. (1997) Desai et al. (2007)
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The ESO Distant Cluster Survey (Rudnick et al.
2003, The Messenger, 112 White et al., 2005, AA,
444, 365)
S. White ( MPA-Garching, D )A. Aragón-Salamanca
( Nottingham, UK )R. Bender ( Munich, D )P.
Best ( ROE, Scotland )M. Bremer ( Bristol, UK
)S. Charlot ( MPA, D IAP, F )D. Clowe ( Bonn,
D)J. Dalcanton ( U.Washington, USA )B. Fort (
IAP, F )P. Jablonka ( OPM, F )G. Kauffmann (
MPA, D )Y. Mellier ( IAP, F )R. Pello ( OMP, F
)B. Poggianti ( Padova, I ) H. Rottgering (
Leiden, NL )P. Schneider ( Bonn, D )
D. Zaritsky ( U. Arizona, USA )G. De Lucia (
MPA, D )V. Desai ( Caltech, USA )C. Halliday (
Goettingen, D )B. Milvang-Jensen ( Copenhagen,
Denmark )G. Rudnick ( NOAO, USA )R. Saglia (
Munich, D )L. Simard ( U. Victoria, C )S.
Bamford ( Nottingham, UK ) A. v.d. Linden (MPA, D
) I. Whiley (Nottingham, UK ) O. Johnson (ROE,
Scotland ) J. Moustakas (U. Arizona, USA ) R.
Finn (Siena College, USA )
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EDisCS Science Goals

• Obtain a uniform imaging and spectroscopic
  database for a large and representative sample of
  galaxy clusters covering at least half of the
  Hubble time.
• Characterise the sizes, luminosities,
  morphologies, internal kinematics, star formation
  and stellar populations of cluster galaxies.
• Compare cluster samples at z0.8, 0.5 and 0.1
  (SDSS) to establish trends as a function of
  redshift exploring a large cluster mass range.
• Compare with high-resolution simulations of
  galaxy and galaxy cluster formation to determine
  the role of the relevant physical processes.

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The EDisCS Strategy

• Select 15 bright candidates with z(est)0.5 and
  z(est)0.8 from the Las Campanas Distant Cluster
  Survey
• Image each field in 2 bands for 20min with FORS2
  (3n FORS)
• Select 1010 best cluster fields for deep
  imaging VRIJK at z0.8 BVIK at z0.5
  (11n FORS 20n SOFI)
• 30min spectroscopy of one FORS2 mask of each
  field to confirm reality of clusters (1.5n FORS)
• 3 or 4 FORS2 masks of each confirmed field at
  longer exposure to get spectra of representative
  systems to I23 (20.5n FORS)
• Get HST/ACS imaging for 10 most distant clusters
  (80 orbits)
• Get WFI 3-colour imaging of all 20 fields to
  study large-scale environment of clusters (84h
  WFI)
• other follow-up work X-rays (XMM/Newton), IR
  (Spizer),
• ESO LP allocation 36n VLT/FORS2 20n NTT/SOFI

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Parent Sample LCDCS Gonzalez et al. 2001
Uniform selection in the optical (130 square deg)
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EDisCS Imaging
10 high-z fields in VRIJK, 10 low-z fields in
BVIK
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Spectroscopy
22 nights of FORS2 MXU spectroscopy ? 50
members/cluster

• zs to I23
• Line indices to I22.5
• ?s to I21.5

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Redshifts and Velocities Claire Halliday, Bo
Milvang-Jensen et al.

• Poor cluster
• z0.7043
• ?420 km/s
• Three groups
• 10 members
• ?200 km/s

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Redshifts and Velocities Claire Halliday, Bo
Milvang-Jensen et al.

• Rich cluster
• z0.7943
• ?1020 km/s
• One group
• z0.2735
• 7 members
• ?350 km/s

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Cluster SubstructureClaire Halliday, Gabriella
De Lucia, et al.
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Redshift histogram for cluster sample
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Cluster velocity dispersions
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Fraction of star-forming galaxies vs. cluster
velocity dispersion
High-z clusters SDSS clusters
EDisCSMORPHS
Poggianti et al. (2006)
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Evolution of the SFfrac vs sclus relation with
redhsift
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Fraction of SF galaxies vs. fraction of passive
spirals
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Model ResultsHigh-z
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Model ResultsLow-z
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Summary and Conclusions

• We have studied how the proportion of
  star-forming galaxies varies between z0.8 and
  z0 as a function of environment in rich
  clusters, groups and the field. Our main findings
  are
• At high redshift (0.4ltzlt0.8) most systems follow
  a broad anticorrelation between the fraction of
  star-forming galaxies and the system velocity
  dispersion scl.
• At high z the star-formation activity in
  star-forming galaxies also varies systematically
  with environment.
• SDSS clusters at z0 have a much lower fraction
  of star-forming galaxies than high z clusters.
• SDSS clusters with sclgt550 km/s show no
  correlation between the fraction of SF galaxies
  and scl.
• The evolution of the star-formation activity
  depends strongly on the mass of the system.
• The non-starforming galaxy population contains a
  mixture of old primordial passive galaxies and
  galaxies whose SF has been quenched. Their
  relative fractions change with redshift and
  cluster mass.
• The changes in star-formation activity in
  clusters between z0.8 and z0 mainly concern
  spiral galaxies evolving into passive S0s.

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The build-up of the colour-magnitude
relationGabriella de Lucia, et al. 2005, 2007
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The build-up of the colour-magnitude
relationGabriella de Lucia, et al. 2005, 2007
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Morphology ? HST
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Ground based and HST images
Cl1037.5-1243
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At z0 (Present time) Many S0s in clusters Few
Spirals in clusters
At 0.36ltzlt0.6 (5 Billion years ago) Many
Spirals in clusters Few S0s in clusters
Morphological evolution
ESO Distant Clusters Survey (EDisCS) Desai et
al. (2007)
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Morphological fractions and cluster velocity
dispersions
Desai et al. (2006)
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EDisCS Summary

• EDisCS has observed 19 homogeneously-selected
  clusters at z0.45-0.8 (plus many groups).
• There is a large homogeneous multi-wavelength
  dataset including ground-based and space-based
  imaging, spectra of 50 members per cluster, plus
  some X-ray, radio and Spitzer data
• We are studying the galaxy morphologies,
  luminosity functions, color-magnitude diagrams,
  stellar populations, chemical abundances,
  kinematics, Tully-Fisher relation, Fundamental
  Plane,...
• We are also analysing cluster properties such as
  velocity distributions, substructure, dynamical
  and lensing masses, X-ray properties,
• Excellent data for field galaxy studies too!

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VLT/FORS2 spectroscopy of high-z cluster Spirals
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HST image FORS2 image with slit
x
?
Example of 2D spectrum
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Rotation Curve of high-z field Spiral
z0.470 R20.8
OII
Hß
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Synthetic rotation curve method
Model rotation curve
data
x
best-fit model
residuals
?
z0.47 Hß
z0.81 OII
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Tully-Fisher relation for high-z Spirals
0.1 ? z ? 1.0 o field and ? cluster spiral
galaxies cluster galaxies 1mag brighter than
field galaxies for same rotation velocity
Luminosity Faint
Bright
Slow
Fast Rotation Velocity
Bamford et al. 2005
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gt3 sigma difference between cluster and field,
with or without redshift evolution
Bamford et al. 2005
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The formation of Large-Scale Structure in the
Universe (Cold Dark Matter Cosmogony)
V. Springel et al. 2005
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Redshift z18.3 (t 0.2 Gyr)
Redshift z5.7 (t 1.0 Gyr)
Redshift z0 (t 13.6 Gyr)
Redshift z1.4 (t 4.7 Gyr)
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Cluster Formation (Cold Dark Matter Cosmogony)
B. Moore
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Galaxy Formation in the field Semi-analytic
models
z5
z3
z2
z0.5
z1
z0
Andrew Benson
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Galaxy Formation in clusters Semi-analytic
models
z2
z1
z0.5
z5
z3
z0
Andrew Benson
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SUMMARY

• The cluster environment has a strong influence on
  galaxy properties (morphologies, star-formation
  histories, )
• Massive cluster ellipticals formed at high
  redshift and evolved mostly passively.
• Low-mass early types became passive at later
  times
• The cluster environment quenches star formation
  in the infalling galaxies
• The morphologies of infalling galaxies are also
  changed by the cluster environment, with spirals
  probably transforming into S0s
• These evolutionary processes happen earlier in
  the most massive clusters

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KMOS
The future

• Innovative instruments
• Larger telescopes
• Larger cluster surveys
• Faster computers
• New better ideas

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Put on your thinking hats!