Evolution of galaxies Evolution of galaxies and clusters in voids and clusters in voids and superclusters and superclusters

Jaan EinastoJaan EinastoMaret Einasto, Enn Saar, Erik Tago, Gert Hütsi, Juhan Maret Einasto, Enn Saar, Erik Tago, Gert Hütsi, Juhan Liivamägi, Ivan Suhhonenko Liivamägi, Ivan Suhhonenko - - Tartu ObservatoryTartu ObservatoryVolker Müller, Alexander Knebe, Volker Müller, Alexander Knebe, Stefan Gottlöber - AIPStefan Gottlöber - AIPDouglas Tucker Douglas Tucker - Fermilab- FermilabAmsterdam 14.12.2006Amsterdam 14.12.2006

OverviewOverview Peebles question: why voids are empty?Peebles question: why voids are empty? Numerical modeling of structure evolution; Numerical modeling of structure evolution;

wavelet decomposition wavelet decomposition Numerical modeling: evolution in void, Numerical modeling: evolution in void,

filament, supercluster environmentfilament, supercluster environment Numerical modeling: the role of perturbations Numerical modeling: the role of perturbations

of different wavelengthof different wavelength SDSS & 2dF data: voids, filaments, SDSS & 2dF data: voids, filaments,

superclusterssuperclusters ConclusionsConclusions

Structure of the Supercluster-void Structure of the Supercluster-void networknetwork

Galaxies are concentrated to long essentially 1-D filaments; rich filaments form superclusters, poor filaments cross low-density regions.Concentration of galaxies to filaments is impossible in a later epoch: galaxies must form in filaments (Einasto, Saar, Joeveer 1977, 1980).

Evolution of under- and over-density regions

Over-densities contract until collapse, the formation time is earlier for higher over-densities. Forming objects have sizes ~ 1 Mpc/h

Under-densities expand, local density decreases, but never reaches zero level – analytic solution bySaar (1979)

Modeling the evolution in Modeling the evolution in various environmentvarious environment

Models: LCDM 256 (200) Mpc/h box, 256^3 particles, z = 10, 5, 2, 1, 0.5, 0Density field found with 2 smoothing lengths

8 Mpc/h – global environment 0.8 Mpc/h – local environment

Assumptions: 1. The mixing between large-scale environment regions is small 2. Galaxies form only there where local density exceeds the mean density 3. Unclustered matter In under-dense regions is primordial

Simulation volume is divided into 4 regions according to global density: 1. Supercluster regions, containing 30 % of matter 2. Rich filament region 30 % 3. Poor filament region 30 % 4. Void region 10 %

z = 5, z = 2z = 1, z = 0

Main structural elements form early at z > 10 as low-density systems, at z = 5 they have well-defined structure.

During the evolution clusters & filaments merge.

Evolution of sizes of cluster particle Evolution of sizes of cluster particle cloudscloudsClusters/groups at the present epoch were found in high-resolution density field (41060).

Positions of cluster particles were located at earlier epochs, and mean radii of particle clouds were found. In SCL core regions the size decreases 5 times (present clusters form via mergers of many subhalos). In void region sizes do not change – groups do not evolve.

Wavelet analysis of the density Wavelet analysis of the density fieldfield

We use the ‘a trous wavelet transform.

The field is decomposed into several frequency bands, each band contains frequencies twice the previous band, in the range ±√2 x main frequency. The sum of these bands restores the original field.

We show the decomposition of

1) The model M256 at present epoch 2) The evolution of waves w6 and w4 from z = 10 to z = 03) The real density field of SDSS around SCL126

LCDM 256 Mpc/h

Evolution of w6 wave: z = 0, z = 1z = 2, z = 5, z = 10

Positions of maxima do not changeAmplitudes increase

Standing wave

LCDM 256 Mpc/hEvolution of w4 wave: z = 0, z = 1z = 2, z = 5, z = 10

Positions of maxima change little. The increase of the amplitude depends on the location in respect to large waves: near maxima increase much, near minima increase little.

Numerical experiment of the role of Numerical experiment of the role of waves of different lengthwaves of different length

Supercluster-void network scale is determined by largest waves present. In the absence of large & medium scale perturbations galaxies & groups form everywhere – there are no superclusters & filaments.

SDSS Original L=500 Mpc w2 w3w4 w5 w6

Density perturbations as an Density perturbations as an

acoustic phenomenonacoustic phenomenon

If there exists a dominating wavelength (tone), then overtones of this wave are amplified, and intermediate waves not.

In the SDSS slice the wave 250 Mpc/h has enhanced amplitude (scale w5), its 1st overtone (scale w4) is also amplified, as well the next 1st overtone (scale w3).

Superclusters form in regions where large density Superclusters form in regions where large density waves combine in similar high-density phaseswaves combine in similar high-density phases Superclusters are the richer the larger is the Superclusters are the richer the larger is the wavelength of phase synchronizationwavelength of phase synchronization

The role of waves of different The role of waves of different wavelengthwavelength

Large waves form superclusters and large voids, medium waves form galaxy chains/filaments, short waves form galaxies and groups/clusters: rich near maxima of large waves, poor near minima of large waves. No galaxy formation takes place near minima of large and medium waves, since the overall density is here below the mean density level.

Evolution of under- and over-density regions

Over-densities contract until collapse, the formation time is earlier for higher over-densities. Forming objects have sizes ~ 1 Mpc/h

Under-densities expand, local density decreases, but never reaches zero level – analytic solution bySaar (1979)

Conclusions IConclusions I

Superclusters form in regions where large Superclusters form in regions where large density waves combine in similar high-density waves combine in similar high-density phasesdensity phases

Superclusters are the richer the larger is the Superclusters are the richer the larger is the wavelength of phase synchronizationwavelength of phase synchronization

Voids form in regions where large density Voids form in regions where large density waves combine in similar low-density phaseswaves combine in similar low-density phases

Conclusions IIConclusions II In supercluster regions the dynamical evolution is In supercluster regions the dynamical evolution is

rapid, the primordial population is consumed rapidly, rapid, the primordial population is consumed rapidly, and the later evolution consists of the transition of and the later evolution consists of the transition of poor galaxy systems to rich clusterspoor galaxy systems to rich clusters

In void regions the mean density decreases In void regions the mean density decreases continuously, DM-halos in poor filaments evolve very continuously, DM-halos in poor filaments evolve very little, and most particles remain primordial (non-little, and most particles remain primordial (non-clustered)clustered)

Galaxy-sized density perturbations in void regions Galaxy-sized density perturbations in void regions between filaments between filaments had always local density below had always local density below the threshold to start galaxy formationthe threshold to start galaxy formation

In filament regions the evolution is intermediate: about In filament regions the evolution is intermediate: about one quarter of matter is still in primordial stage, the one quarter of matter is still in primordial stage, the growth of cluster population is slow, most of matter is growth of cluster population is slow, most of matter is in galaxy populationin galaxy population..

Luminosity & multiplicity Luminosity & multiplicity functions of 2dF, SDSS & Mill functions of 2dF, SDSS & Mill superclusterssuperclusters

Left: Integrated luminosity function of 2df, SDSS & Mill simulation superclusters. Luminosity is expressed in units of the mean luminosity of richness class 1 superclusters.Right: Multiplicity function of observed (2dF+SDSS) superclusters, Abell cluster superclusters & Mill superclusters. Multiplicity is defined as the number of rich clusters of galaxies in the supercluster.The number of very rich superclusters is much larger than model predicts.

LCDM z = 0: original L= 256 Mpc, w2, w3 w4, w5, w6