**A constant energy which fills the space**

**THE DARK ENERGY**

**THE DARK MATTER**

**Strings, monopoles, and domain walls**

**TOPOLOGICAL DEFECTS IN THE UNIVERSE**

**The dark side of the**

A topological defect is created by a symmetry breaking. We can represent it as follows:

How are they formed?

Symmetry breaking without defects

But in the universe the distances between objects are very large...

Symmetry breaking WITH defects

?

?

Goals:

PROPERTIES

COSMIC

STRINGS

DOMAIN

WALLS

MONOPOLES

Dimensions: 0

Dimensions: 1

Dimensions: 2

CLASSIFICATION

Depending on the way a symmetry is broken, the following

topological defects are formed:

They are energy concentrations with cons-tant density, although the Universe expands.

They are infinite or closed on themselves.

They move at relativistic velocities.

They radiate gravitational waves and so they deform the spacetime.

What is a topological defect?

Topological defects

are irregularities in the energy distribution caused by a sudden phase transition.

INTERACTIONS

.

monopole

.

.

Double Y-junction

Initial state

Intercommuting

No interaction

X-junction

Average distance between walls

Average velocity between walls

Parameters we will obtain

The computer solves the differential equations

We can write this mathematicaly...

SIMULATION I

Radiation era

vs.

Matter era

Radiation era

Matter era

Radiation era

Matter era

Compare the evolution of domain walls for different expansion rates

Compare data from the UNIVERSE supercomputer and our computer

Time

Energy density

Time evolution of the energy density

Time evolution of the velocity of the walls

Velocity of the domain walls

Time

Conclusions:

The velocity of the walls remains constant with time

Redshift &

Blueshift

In radiation era the final speed is a bit higher than in matter era

Density is inversely proportional to time

Andromeda Galaxy (M31)

BLUESHIFT

Goals:

SIMULATION II

Behaviour with different interactions

Compare the evolution of domain walls with different types of interaction: forming X-junctions, Y-junctions or not interacting

Time evolution of the energy density of domain walls

Conclusions:

The velocity and the density are lower when Y-junctions are formed

Virgo Galaxy (M61)

REDSHIFT

Time evolution of the average speed of domain walls

Joves i Ciència presents ...

With the support of

Fundació Catalunya Caixa

Starring professors...

Dr. Anastasios (Tasos) Avgoustidis

Dr. Carlos J. A. P. Martins

Dr. Katherine (Katie) Mack

with the students...

Joan Solà Pau Mir

**Carlota Corbella Gerard Orriols**

**Nieves Montes Laia Domingo**

**Aina Márquez Oriol Frigola**

Sara Avila Elena Muñiz

Goals:

SIMULATION III

3D Universe

vs.

4D Universe

Conclusions:

Supernovae

Observe the effect of having extra dimensions on the evolution of walls

Evolution of energy density as a function of time

4D

ΛCDM

3D

The Universe is not expanding at a constant rate

Compare the results of compact and infinite universes

80 x 80 x 80 x ...

Despite changing the size of the fourth dimension (making it compact), domain walls always tend to have a constant velocity and their density also decreases uniformly.

Fritz Zwicky

Vera Rubin

We add Dark Matter to the galaxies

FINAL CONCLUSIONS

It works!

We consider several Universes

Ω

Independently of the initial conditions and the parameters that we choose, domain walls tend to an

attractor solution

.

We need more matter!

Dark matter

Separated by the Asymptotic Velocity

79 Galaxies

9 groups

Likelihood

Applied to a group of galaxies

Parameters

∑ = disk central surface density (M /pc )

o

The and parameters are related to the curvature and the formation of loops and we will find them

with our simulations

rc = Dark Matter core radius (kpc)

ρ = Dark matter core density (M /pc )

o

r = disk scale radius (kpc)

o

Θ

2

3

Θ

The values

of and

are in agreement with

the published ones.

+

Density is always inversely proportional to time, and the velocity becomes a constant in every model.

Possible alternative

explanations

Dades obtingudes de l'article:

Rotation Curves of 967 Spiral Galaxies

Massimo Persic and Paolo Salucci

Keep rockin' delta theta!

The DarkSiders...

A little bit of history...

Universe accelerates with time

t

Dark Matter is necessary to explain the rotation curves of the galaxies.

Galaxies with more total mass have higher rotation curves.

Galaxies are made of a disk with luminous matter and a halo with dark matter.

Conclusions

large distance

Checking probability

**Universe**

The velocity and the density are greater when X-junctions are formed

Evolution of the velocity as a function of time

Evolution of the velocity as a function of time

Evolution of energy density as a function of time

Fitted parameters:

**That strange matter that we cannot see**

Luminous matter

Dark matter

Total matter