• No results found

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

N/A
N/A
Protected

Academic year: 2023

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

Copied!
19
0
0

Bezig met laden.... (Bekijk nu de volledige tekst)

Hele tekst

(1)

Evolution of galaxies and Evolution of galaxies and

clusters in voids and clusters in voids and

superclusters superclusters

Jaan Einasto Jaan Einasto

Maret Einasto, Enn Saar, Erik Tago, Gert Hütsi, Juhan Liivamägi, Ivan Maret Einasto, Enn Saar, Erik Tago, Gert Hütsi, Juhan Liivamägi, Ivan Suhhonenko

Suhhonenko - - Tartu ObservatoryTartu Observatory Volker Müller, Alexander Knebe,

Volker Müller, Alexander Knebe, Stefan Gottlöber - AIPStefan Gottlöber - AIP Douglas Tucker

Douglas Tucker - Fermilab- Fermilab Amsterdam 14.12.2006 Amsterdam 14.12.2006

(2)

Overview Overview

Peebles question: why voids are empty? Peebles question: why voids are empty?

Numerical modeling of structure evolution; wavelet Numerical modeling of structure evolution; wavelet decomposition

decomposition

Numerical modeling: evolution in void, filament, Numerical modeling: evolution in void, filament, supercluster environment

supercluster environment

Numerical modeling: the role of perturbations of Numerical modeling: the role of perturbations of different wavelength

different wavelength

SDSS & 2dF data: voids, filaments, superclusters SDSS & 2dF data: voids, filaments, superclusters

Conclusions Conclusions

(3)

Structure of the Supercluster-void network Structure of the Supercluster-void network

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).

(4)

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 by

Saar (1979)

(5)

Modeling the evolution in various Modeling the evolution in various

environment environment

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

(6)

z = 5, z = 2 z = 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.

(7)

Evolution of sizes of cluster particle clouds Evolution of sizes of cluster particle clouds

Clusters/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.

(8)

Wavelet analysis of the density field Wavelet analysis of the density field

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 = 0 3) The real density field of SDSS around SCL126

(9)

LCDM 256 Mpc/h

Evolution of w6 wave:

z = 0, z = 1 z = 2, z = 5, z = 10 Positions of maxima do not change

Amplitudes increase

Standing wave

(10)

LCDM 256 Mpc/h

Evolution of w4 wave:

z = 0, z = 1 z = 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.

(11)

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

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.

(12)

SDSS Original L=500 Mpc w2 w3 w4 w5 w6

 

 

(13)

Density perturbations as an Density perturbations as an

acoustic phenomenon acoustic 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 1

st

overtone (scale w4) is also amplified, as well the next 1

st

overtone (scale w3).

Superclusters form in regions where large density waves Superclusters form in regions where large density waves

combine in similar high-density phases combine in similar high-density phases

Superclusters are the richer the larger is the wavelength of Superclusters are the richer the larger is the wavelength of

phase synchronization

phase synchronization

(14)

The role of waves of different wavelength The role of waves of different wavelength

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.

(15)

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 by

Saar (1979)

(16)

Conclusions I Conclusions I

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

waves 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 synchronization

wavelength of phase synchronization

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

combine in similar low-density phases

(17)

Conclusions II Conclusions II

In supercluster regions the dynamical evolution is rapid, the In supercluster regions the dynamical evolution is rapid, the primordial population is consumed rapidly, and the later

primordial population is consumed rapidly, and the later

evolution consists of the transition of poor galaxy systems to evolution consists of the transition of poor galaxy systems to

rich clusters rich clusters

In void regions the mean density decreases continuously, DM-In void regions the mean density decreases continuously, DM- halos in poor filaments evolve very little, and most particles halos in poor filaments evolve very little, and most particles

remain primordial (non-clustered) remain primordial (non-clustered)

Galaxy-sized density perturbations in void regions between Galaxy-sized density perturbations in void regions between filaments

filaments had always local density below the threshold had always local density below the threshold to start galaxy formation

to start galaxy formation

In filament regions the evolution is intermediate: about one In filament regions the evolution is intermediate: about one quarter of matter is still in primordial stage, the growth of quarter of matter is still in primordial stage, the growth of

cluster population is slow, most of matter is in galaxy cluster population is slow, most of matter is in galaxy

population population..

(18)

Luminosity & multiplicity Luminosity & multiplicity

functions of 2dF, SDSS & Mill functions of 2dF, SDSS & Mill

superclusters superclusters

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.

(19)

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

Referenties

GERELATEERDE DOCUMENTEN

Along with accurately constraining the history of the molecular gas density (e.g. yellow data in Fig. 1, right), large samples of molecular gas detections in the

"   Number of UDGs roughly scales linearly with halo mass?. "   Total stellar mass in UDGs ≈ 0.2% of total cluster

We have tested this hypothesis by re-measuring the surface mass density pro files for a fixed cumulative number density selection (see Figure 1 for the mass assembly history ), and do

At z = 1, the three samples are in reasonable agreement with each other, all having a similar shape with the hot sample show- ing a marginally lower normalization. This change from z

Here, we present the results of our numerical study of the evolution of complex planetary systems (Solar-like Systems) in star clusters, in which we model the effects of nearby

When adding the galaxy distributions to produce a composite cluster, we either applied no scaling of the projected distances, scaling with the core radii of the individual clusters

There is one dominant scientific requirement, as well as two additional scientific motivations, for the acquisition of radial velocities with GAIA: (i) astrometric measure- ments

We studied the properties (color, effective radius, axis ratio, Sérsic index, magnitude and surface brightness) of UDGs compared with other types of galaxies in different