History of cosmic web of galaxies

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History of cosmic web of galaxies

• Agnieszka Pollo
• Laboratoire d'Astrophysique de Marseille (LAM)
• Marseille, France

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Short History of the Universe (one of)

• Planck Era 10(-43) s. 10(-33) cm regions
  homogeneous and isotropic. izotropowe,
  T10(32)K.
• Inflation. 10(-35) s after BB, T 10(27)
  10(28)K, fast expansion.
• Inflation ends. 10(-33 s), T 10(27)
  10(28)K. Homogeneous regions from Planck era
  have grown to 100 cm (gt 10(35) times). Tiny
  nearly gaussian density fluctuations.

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Short History of the Universe

• Bariogenesis. 100,000,001 protons per 100,000,000
  antiprotons (and 100,000,000 photons).
• Till 100 s after BB Universe grows and cools
  down, T 109K. Protons anihillate with
  antiprotons, later e- and e. H i He are
  created.

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Krótka historia Wszechswiata

• One month after BB processes which transform
  radiation field into black body radiation become
  slower than the velocity of expansion of the
  Universe from now on there is a chance of some
  informations being preserved in CMB 56 000 years
  after BB matter density radiation density. T
  9000 K. Inhomogeneities of (dark) matter start to
  grow

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Short history of the Universe

• 380 000 after BB protons and electrons make
  neutral H. T3000K. The Universe becomes
  transparent - CMB may travel freely (last
  scattering surface). Normal (barionic) matter
  starts to accumulate on the dark matter
  overdensities
• 100-200 mln years after BB first stars shine and
  re-ionize the Universe. First supernovae explode.
  Galaxies and clusters form.
• 4,6 bln years ago Sun shines.
• Today 13.7 bln years after BB. T2.725 K.

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After recombination (WMAP 3-years temperature map)
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Large-scale structure in the local (zlt0.2)
Universe galaxies (Colless, Maddox, Peacock et
al.)
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The Large Scale Structure of the Universe

• Gravitational instability theory
• Density fluctuations (of dark matter) after
  inflation, Gaussian (?) distribution
• Matter gathers around these
• Galaxies, clusters, LSS form
• The smaller scale the more non-linear evolution
• Tests of the model
• Statistics
• Simulations

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From the observational side...

• The main source of our knowledge about the LSS of
  the Universe are catalogs of galaxies (2D
  positions only and 3D redshift surveys)

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Redshift surveys may allow to investigate...

• The history of formation and evolution of
  galaxies
• Evolution of the LSS of the Universe and what
  physical processes may determine it in different
  epochs and timescales
• Formation and evolution of different classes of
  objects (e.g. AGNs)
• Formation and evolution of clusters

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Most of great calalogs today only local
Universe

• Local Universe a few big surveys, like
• SDSS
• 2dF
• gt 1M galaktyk do z 0.3
• Distribution and properties relatively easy to
  examine
• BUT no evolution

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Which means practical problems

• Few objects (until recently not more than a
  few1000 for 0.5ltzlt5)
• Small volumes (-gtbig cosmic variance)
• Different selection criteria for different
  measurements and related biases how to compare?
  How to make a joint analysis?

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Structure evolution we want to see the whole
movie, not only the last slide!
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Recent deep galaxy surveys

• Goalç to measure redshifts of gt 100 000 galaxies,
  to analyse history of LSS and galaxies themselves
• VVDS
• Deep-2
• ostatnio COSMOS

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The origins build a redshift machine for the ESO
VLT targeted to deep, high-surface density galaxy
samples

• 1995 First ideas WFISNIRMOS
• 1996 Feasibility Study
• 1997 VIMOSNIRMOS contract
• VIisible Multi -Object Spectrograph
• Near InfraRed Multi -Object Spectrograph

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Whos Who in the the
Consortium

• Six main nodes Marseille, Bologna,
  Haute-Provence, Milan, Naples, Toulouse
• PIs O. Le Fevre G.Vettolani
• co-Is D. Maccagni (Milano), J.P. Picat
  (Toulouse), D. Mancini (Naples)
• Science Advisory Committee
• 50 people involved in the Hardware/Software
  Team
• 90 people involved in the Science Team for the
  survey preparation and analysis
• See web page, www.oamp.fr/virmos

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• Science drive the VIMOS-VLT Deep Survey (VVDS)
• 50 VIMOS guaranteed nights over 3 years on
  ESO-VLT UT3
• 100,000 redshifts to IABlt22 over an area of 16
  sq.deg., 0ltzlt1.3 in 5 fields
• 50,000 redshifts to 22ltIABlt24 over an area of
  1.5 sq.deg., 0ltzlt5
• 1000 redshifts to IAB26 over a 1x1 sq.arcmin
  area using a Integral Field Spectroscopy unit
  (6400 fibres)
• Preparatory IMAGING
• UBVRIJK photometric surveys at CFHT, ESO, CTIO
• RADIO (VLA_at_1.4GHz, 80 mJy) X-ray (XMM, 1014
  erg s-1 cm-2 for extended sources) coverage of
  the F02 field (deep 1 sq.deg. area at RA02h)
• X-ray (XMM) imaging to fx 10-15 erg s-1 cm-2
  over F02

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VIMOS/NIRMOS layout
VLT Nasmith focus flattened separately into 4
channels, fed into 4 CCD cameras (7x8 arcmin
field of view each)
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A redshift machine gt 500 spectra in one shot
FOV 4x56 sq arcmin multiplexing 800 spectral
resolution 200 -5000 IFU 1'x 1', 6400 fibres
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VVDS and structure evolution

• 2-point correlation function in redshift slices
• Clustering per color, luminosity, spectral types
• Bias evolution
• Clustering of particular types of objects (EROS,
  starforming galaxies) as compared to general
  population
• Galaxy mergers how many close pairs in
  different epochs?
• redshift-space CF distortions -gt small-scale
  galaxy dynamics
• Clusters density Xray (XMM) and optical
  (multi-colour, I-K, matched filter, photo-z,)
• and many more...

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First Epoch VVDS Data

• 11564 spectra from 17.5ltIABlt24, fields 0226-04
  and CDFS, area 0.61 sq.deg.
• 10518 galaxies with measured z, 8869 with
  confidence level gt80
• 836 stars
• 85 AGNs
• 125 unidentified objects
• Field coverage 25 - 30

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First epoch VVDS-Deep survey VVDS-02 field
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First VVDS data

• 0ltzlt5
• 1065 galaxies zgt1.4
• Successful measurements on the redshift desert ,
  i.e. 1.5ltzlt2.2
• Problems in 2.2ltzlt2.7 range (because of the
  filter coverage)

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Distribution of secure redshifts (median 0.70)
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2-point correlation function

• Definition probability above random that we
  find a pair of galaxies at a certain distance
  from each other (spatial, angular)
• In practice different estimators, e.g.
  Landy-Szalay
• Problems different densities of different parts
  of the fields because of different number of
  observation runs, bright stars, non-random choice
  of objects for spectroscopy

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Measuring the correlation function
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Biases removal for the redshift-space correlation
function
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Biases removal for the 2D redshift space
correlation function
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Biases removal for the projected (real space)
correlation function
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Evolution of the 2-point correlation function
from the first-epoch VVDS data
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Evolution of a comoving correlation length
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Comparison with DEEP-2
(astro-h/0409135)
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What theory says? Weinberg at al., 2004, LCDM
simulations clustering history of galaxies and
DM differs dramatically
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Similar informations may be extracted directly
from PDF

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Red (old) galaxies and blue (recently star
forming) galaxies

• Now it is well known that red/early type galaxies
  (elipticals, irregulars) are more clustered than
  blue/late type (spiral) ones
• How did it evolve? When did they segregate?
• When did galaxy types appear?
• Meneux et al., 2006, Cucciati et al. 2006

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Correlation length for different galaxy types and
colors
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CF properties vs absolute luminosities

• w_p(r_p) in different luminosity ranges for small
  and large z
• Correlation length r_0
• slope gamma
• Non power-law fit!
• Different relative bias at different scales

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w_p in luminosity ranges

• VVDS-02, M_B
• 2 wide ranges corresponding to 3.5 bld years,
  medians z0.4 and z0.9
• 7 luminosity ranges in each

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w_p(r_p) and the best (r_0, gamma)
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w_p(r_p) power-law fit
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r_0 VVDS vs SDSS and 2dF
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gamma VVDS vs SDSS i 2dF
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Relative bias at 1 Mpc scale
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No power law Argument for Halo Occupation
Distribution Models...
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...non-linear relative relative bias(with
rescpect to gal L)?
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Summary structure evolution in VVDS

• General populationç correlation length almost
  constant between z0.5 and z2, in a survey
  where the only selection criterion is luminosity
  (IABlt24)
• This effects may be understood as a
  superposition of the evolution of structure
  itself,evolution of bias and different dependence
  of clustering on luminosity
• Generaal population in a good agreement with
  hydrodynamical simulations in a model with CMB
  and big cosmological constant
• Galaxies of early spectral types (eliptical and
  early spirals) are more clustered than late
  spirals and irregulars in all epochs
• Red galaxies more correlated than blue ones
• But a tendency to reverse this relation at
  z1.5?

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Summary structure evolution in VVDS

• For different absolute luminosities
• r_0 and gamma rise for LgtL for large z
• non power law fit of CF z -gt argument in favor
  of HOD models?
• Scale-dependent bias?
• Conclusions
• In the z0.9 Universe bright galaxies more
  willingly were closer to other bright galaxies
  than today
• What happened to them? Did they merge? Did they
  get fainter?
• Bias not only evolving, but also non-linear?
• We have to develop models and theory

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First epoch VVDS results (selected)

• Survey description (Le Fevre et al. 2005)
• Two-point correlation function in z slices (Le
  Fevre et al., 2005, Pollo et al., 2005, A A)
• Evolution of LF and B luminosity density (Ilbert
  et al. 2005, Tresse et al. 2005, Zucca et al.
  2005)
• Combined GALEX-VVDS evolution of UV LF and UV
  luminosity density (Arnouts et al. 2005,
  Schiminovich et al 2005)
• Clustering of color-selected classes (Meneux et
  al, 2006. AA, in press)
• Clustering as a function of luminosity (Pollo et
  al., 2006a, AA, in press, Pollo et al., 2006b,
  in prep.)
• Evolution of bias (Marinoni et al., 2005)
• Properties of K-selected galaxies in the
  VVDS-Deep survey (Iovino et al., AA, in press)

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• Effective in isolating galaxies around z3
  (U-dropouts) and z4 (B-dropouts)
• Pioneered by Steidel Hamilton (1992)
• Spectroscopic confirmation only possible thanks
  to the new generation of 10m-telescope
  availability (Keck)
• Selects strongly star-forming galaxies with
  significant Lyman break

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• Correlation length 3-5 h-1 Mpc, i.e. comparable
  to todays normal galaxies!

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Lyman-break galaxies are strongly star-forming
objects, plausibly progenitors of todays
luminous cluster galaxies. Clearly, their
clustering is not representative of general
structure at z3. They are an illustrative
example of a highly biased population of LSS
tracers. Similar examples are provided by very
red galaxies selected using near-infrared bands
around z1 (R-K) and zgt2 (J-K) (e.g. works by
Cimatti et al. and Van Dokkum et al.). ? Need
for larger redshift surveys looking at the global
galaxy population. Two such projects underway
the DEEP2 survey at Keck (Davis et al) and the
VIMOS-VLT Deep Survey (VVDS)
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Two-point correlation function from VVDS
first-epoch data per galaxy morphological types
example for one z slice
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What we expect to find
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2dFGRS Maximum likelihood fit of redshift-space
distortions
A more recent analysis of the 100,000 redshift
public release, with careful treatment of window
function aliases and error correlations finds
?0.16 (Tegmark, Hamilton Xu, 2002,
astro-ph/0111575)
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The VIRMOS survey and the evolution of structure

• Two-point correlation function in z slices
• Clustering of color-selected classes
• Clustering of radio-loud vs. normal population
• Evolution of bias (i.e. the way light traces
  mass)
• Clustering of special classes (e.g. Extremely
  Red Objects, strongly star-forming galaxies) vs.
  general population
• Merging history how many close pairs at
  different redshifts?
• Small-scale dynamics from redshift-space
  distortions
• Evolution of number density of galaxy clusters
  X-ray selection (XMM survey over 2hrs field) vs.
  optical selection (multi-colour, I-K, matched
  filter, photo-z,)
• and much more

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• Effective in isolating galaxies around z3
  (U-dropouts) and z4 (B-dropouts)
• Pioneered by Steidel Hamilton (1992)
• Spectroscopic confirmation only possible thanks
  to the new generation of 10m-telescope
  availability (Keck)
• Selects strongly star-forming galaxies with
  significant Lyman break

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• Correlation length 3-5 h-1 Mpc, i.e. comparable
  to todays normal galaxies!

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Lyman-break galaxies are strongly star-forming
objects, plausibly progenitors of todays
luminous cluster galaxies. Clearly, their
clustering is not representative of general
structure at z3. They are an illustrative
example of a highly biased population of LSS
tracers. Similar examples are provided by very
red galaxies selected using near-infrared bands
around z1 (R-K) and zgt2 (J-K) (e.g. works by
Cimatti et al. and Van Dokkum et al.). ? Need
for larger redshift surveys looking at the global
galaxy population. Two such projects underway
the DEEP2 survey at Keck (Davis et al) and the
VIMOS-VLT Deep Survey (VVDS)
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