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COSMOLOGY

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International Meeting of Fundamental Physics

(“Winter” meeting)

Santiago de Compostela, 2007

Eduard Massó

UAB/IFAE

Program

The standard cosmological model

The observed universe

Inflation. Neutrinos in cosmology

Emphasis on “Particles”

Science, vol. 315, 2007

lights-years

ago

Our universe is expanding

co-moving

distance

scale

today

redshift

On top: peculiar (real) velocities

Hubble’s law & Cosmological principle

Cosmological principle

Universe homogenous & isotropic

on large scales

Hubble parameter

(today)

Hubble’s discovery

Hubble’s law:

RG

+

CP

Expansion (or contraction) is inevitable

Robertson-Walker metric

(homogeneity & isotropy)

Parameters:

Content

(matter+radiation)

Content too

(cosm. const.)

Parameters

are related

by eqs.

Spatial geometry

Friedmann eqs.

Cosmological equations

1

2a

1+2a -> 2b

Spatial geometry &Light propagation

Open

Closed

FLAT

3D

Spatial geometry &Light propagation

Absolute luminosity

E/time in rest frame

Luminosity distance

Measured flux

(E/time/area)

Luminosity distance

Hubble’s law

Exact:

Small z

Deceleration

parameter

That was kinematics

Cosmological constant contribution

Negative

pressure

+ any other component

Solution to cosmological eqs.

Equation of state

Assume i - dominance and

RD universe

MD universe.

CCD universe

Critical density

Define

Define also

(Today)

Not energy-density contribution

Rewriting Friedmann eqs.

Cosmic sum rule

2a today

Notice signs

EE

EE

R

R

Diff. eq.

The future

+ Initial conditions

taken today

Eternal Expansion OR Recollapse ?

1

2

3

Distance - Redshift

Co-moving distance to source:

Where:

Can neglect

Distance-redshift relation is function of

Age of the universe

look-back time

lifetime

Flat univ.

Our univ.

(Age crisis: Open universe gave too low lifetime)

Which universe ?

nucleosynthesis

The past universe

rad

recombination

mat

cc

equality

today

next

Equilibrium thermodynamics

The hot universe

g= deg. of freedom

number density

energy density

pressure

distribution

rates

Decoupling of species

Expansion:

Interaction:

Phase transitionsSymmetry restoring

2n order

Phase transitions

1st order

Conformal time

It is the physical distance photons can travel until a time t

Particle Horizon

Defines causal distance at a given time t

Program

The standard cosmological model

The observed universe

Inflation. Neutrinos in cosmology