Cosmología:

Seminarios 1-2-3

11

11. Cosmo:Caracteristicas del Universo

A) INTRODUCCION

B)EVOLUCION Y EXPANSIÓN DEL UNIVERSO:

1.Fases del Universo temprano

2.expansion “actual”: Ley de Hubble, expansion constante?,acelerada?

C) COMPOSICIÓN DEL UNIVERSO: Materia+ Radiacion+Eoscura

-Estrellas, gas y polvo (galaxias, cúmulos,supercumulos).

-Materia oscura ( neutralinos? ,??)‏

-Radiación difusa (CMB, fondo de neutrinos)‏.

-Energía de vacío o energía oscura ( quintaesencia??, …)

D) MAPA DEL UNIVERSO A GRAN ESCALA

isótropia y homogéneidad del Universo (densidades uniformes de galaxias, radiación y energía de vació)‏

A) INTRODUCCION

preguntas fundamentales:

A) De donde venimos?

B) …a donde vamos?

Cosmología

• Cosmología: estudio global del Universo

•

• Estudio del

• -origen,

• -la evolución (expansion)

• -y el posible final del Universo

• Historia: Sistema solar, La Galaxia,..

• Desarrollo: siglo XX,

• teorias relatividad ,cuántica

• Expansion (Hubble,1929),redshift

• CMB: radiacion cosmica de fondo (CMB),1964

• 2000-2012--…..Estudios detallados

Olber’s Paradox

OBSERVATION: the sky is dark at night- BUT, the sky should be uniformly bright.

1610 - Kepler

1823 - Heinrich Olbers proposed paradox

Argument

• Assume universe is infinite and stars are randomly scattered.

– [Isaac Newton argued that no other assumption made sense]

• Then in every direction you will get to a star and the sky will glow

Resolution of the paradox

• Stars are moving away so light is red-shift and not as bright.

• The universe is not infinitely old - so some light hasn't had time to reach us. Or the universe is not infinite

Our best picture of the early universe:CMB

After subtracting out the effect of our motion and the foreground radiation from …The Olbers idea was TRUE: the sky is FULL of isotropic,diffuse light (at 3K, far from the visible) … we’re left with tiny variations of 1 part in 100,000. These are slight variations in the density of the hot gases that filled the early universe!

B) EVOLUCION Y EXPANSION DEL

UNIVERSO.

B1)FASES. Historia del Universo.

Expansion of Space-time

• 1916 - Einstein’s TGR predicts that space-time is dinamic,

expand, contract, rarely stable.

Einstein does not believe this: fix the theoryCte.cosmo.

• 1920s – Others show that ALL versions of the GTR require

either the expansion or contraction of space.

• 1929 - Hubble’s Law. Redshift of galaxies

• 1930 - Eddington explains Hubble’s Law as the expansion of

space-time described by GTR.

• 1930 - Einstein calls his not accepting his original theory “the

greatest blunder of my scientific career.”

• 2012: Now we know that the cosmo cte. Is TRUE

-Clusters of galaxies: pieces of

paper on the balloon.

-As the balloon is blown up its

surface area (4D)

increases with time.

-The clusters of galaxies

do not increase in size. (Why?)

They get further apart but

do not move through

space.

The Balloon Model of Expanding Space

Phases: t= 0, the Big Bang

Universe was extremely hot and dense.

Space was expanding (linearly?,

exponentially?)which cooled the contents of

the Universe.

Initially the temperature was so high that no

structures could exist.

PHASE 1: Inflation

• Very early phase of extremely rapid, exponential, expansion (Guth, Linde, 1980s). t= 10-35 t= 10-24 sec.

• the Universe expands by a factor of 1050

• Universe was an infinitesimally small volume 1050x1050x1050= 10150 times smaller than we would have guessed from extrapolation of the expansion we observe today.

• HOMOGENEITY,ISOTROPY,FLATNESS

PHASE 2:Formation of protons and

neutrons

• t = 10-6 sec ABB, the Universe was cool

enough for quarks to combine to form

protons and neutrons.

Proton

Neutron photons

Electron

PHASE 3:Formation of He nuclei

• t = 3 - 4 minutes ABB, the universe was

cool enough for protons and neutrons to

stick together. N(protons)>>N(neutrons)

Helium-4

nucleus, 6%

Hydrogen-1

nucleus, 94%

Electrons

Photon

PHASE 4: Neutral atoms. CMB.

• T=300000 yr. Decoupling phase.Neutral atoms

formed (H, He).,

• the Universe went from charged matter to neutral

matter. Photons decouple from matter.

• Those photons are still in the Universe today, with

the same distribution but cooled by the expansion

of Universe.

• T= 3000 K. 2.73 K. Planck distribution

Phase 5: Until 1000-2000 mill yrs: constant expansion: dominance of matter. Phase 6: Until now. Acelerated expansion: dominance of DARK ENERGY (??)

P PHASE 5-6: STRUCTURE FORMATION: STARS AND GALAXIES

Summary: Early History of the Universe

• t= 0 - Big Bang beginning of a hot, dense universe in expanding space.

Expansion cools the universe.

• PHASE1: t = 10-35 s, T= 1027 K - Inflationary period. Matter dominates

antimatter.

Temperature is too hot for any structure to exist. Elementary particles -

leptons (electrons) and quarks in a sea of photons.

• PHASE2: t = 10-6 s, T = 1012 K – protons and neutrons from quarks.

• PHASE3:t = 3-4 min, T = 109 K – He nuclei from protons and neutrons. 94%

protons (H nuclei) and 6% He nuclei. (2H, 3He, 4He, 7Li, also)

• PHASE4:t = 300,000 yrs, T = 3000 K – neutral atoms. Universe becomes

neutral and the background radiation CMB is released. Dark Ages.

• PHASE5:t=200mill yrs. First stars, 400mill yrs: first galaxies

• PHASE6:t=now, epoch of accelerated expansion, dominance of dark energy.

P PHASES: STRUCTURE FORMATION: STARS AND GALAXIES

Major Epochs in the Early Universe

The behaviour of universe has been dominated by

Different “substances” along its history, this determines type of

expansion:

• t=10-35 s: (??)dominated: inflantion

exponential expansion

• t<3x105 years: Universe radiation dominated

• t>3x105 years: Universe matter dominated, constant expansion

• t>2-3 x109 years: Universe DE dominated

accelerated expansion

Predictions of the Big Bang model

NUCLEOSYNTHESIS: only 3 - 4 minutes after BB ,

essentially stopped after helium.

PREDICTION OF ABUNDANCES OF LIGHT ELEMENTS

CMB :Universe filled with a background radiation (T=3K),

When neutral atoms formed (t= 300,000 yrs), FOTONS

stopped interacting with matter.

Expansion cooled the radiation from 3000 K 3K.

Sólo podemos observar las fases posteriores

•Todo lo anterior es imposible de observar directamente

• Almost all the H in the present Universe was formed at the epoch of recombination

• Most of the light elements (He, D, Li, ) were formed shortly thereafter

• The efficiency with which these light elements were formed depends on what the density of protons and neutrons was (baryonic matter).

• Studying the abundance of light elements (relative to hydrogen) is a good way of determining the baryon content of the Universe.

.

BB Nucleosynthesis

Primordial Nucleosynthesis

• First few minutes of Universe

– Reaction rate propto baryon density squared

– He, D, Li tell us physical baryon density

– D/H from quasar absorption lines

• Omega_b h2 =0.02 +/- 0.002 (Tytler, O'Meara)

• For h=0.72, Omega_b=0.04

• Omega_b=M_b/M_total

Big Bang Nucleosynthesis (BBN) (2)

- Helium mass-fraction

- Deuterium and other light elements number-fraction

…

From PDG 2006

What is the solar system made of?

…We need Supernova nucleosynthesis

A problem:Baryon Asymmetry

• Observable Universe is made up of mostly matter (NO anti-matter)

• Implies a slight asymmetry between matter and anti-matter in the very early Universe (a little more matter than antimatter)`BARYON ASYMMETRY

Problem: why there was a little more matter than antimmater at early universe?

UNA BREVE HISTORIA DEL UNIVERSO

NASA/WMAP Science Team (www.gsfc.nasa.gov)

BREVE HISTORIA DEL TIEMPO

Time

Distance

Big Bang

Quarks (t ~ 10-6 sec)

Electrons (t ~ 1 sec)

Protons, neutrons, nuclei (t ~ 200 sec)

Decoupling: Atoms (t ~ 2105 years)

Us (t ~ 1010 years) ~1010 light years

Expansion of an

inflationary Universe

Inflation (first ~10-35 sec)

Note: “~” means “approximately equals.”

Book Recommendation

The First Three Minutes, by Steven Weinberg

Where is the universe headed?: Big RIP

Expansion is accelerating. the expansion will continue “forever”.

Galaxies “islands”. (100000 mill yrs)

all stars will burn out, leaving white dwarfs, neutrons stars, and black holes.

Protons (probably unstable) decay into positrons and neutrinos

Electrons and positrons would gradually annihilate into photons that become

ever more redshifted.

black holes would be the only remaining concentrated form of matter.

BH eventually evaporate into photons via Hawking radiation.

BIG RIP

B2) Expansion: Ley de Hubble

*Almost everything in the universe is

moving away from us.

farther away faster is moving away

*Velocity of receding galaxies is

measured via the redshift:the Doppler

Shift applied to light (sXIX)

Slipher ( 1912 ) measure galaxy

velocities

Hubble (1920-1929) derive his law

Galaxy Spectrum Redshift

Redshift cosmológico de galaxias fuera del Grupo Local:

Red-shift as a Doppler Shift

Ley de Hubble. H_0.

V ∝ z ,V ∝d , V = H 0 d

H 0 72 2 km s Mpc

1 Parsec = 3.26 light years

Hubble's Law(Experimental 1929, Theoretical: Lamaitre 1927)

(1) all objects in deep space have a relative velocity to Earth, and to each other; V. This velocity is observable by redshift z, v/c=z .

(2) this velocity is PROPORTIONAL to their distance from the Earth

1)Ho 1/T, To=1/H_0 , T. Hubble.

2)Example: Andromeda??

Expansión del universo: Aceleracion

-Expansión (Acelerada):1998-2006

Perlmutter(Nobel 2011).

Supernovas Ia: luminosidad bien conocida:estandares de distancia. Luminosidad absoluta con pocas variaciones, muy ligada a su curva de luminosidad temporal.

-

The Hubble diagram for type Ia supernovae.

Kirshner R P PNAS 2004;101:8-13

Correccion Ley de Hubble: V= H0 d+ K d^2

Cosmología

11-C: COMPOSICION DEL UNIVERSO

• CMB+SNI+OTROS: rho/rho_crit=1.

•Proporciones:

Dark Matter: 23% ± 4% Dark Energy: 73% ± 4% Baryons: 4% ± 0.4% Neutrinos: 2%

C)COMPOSICION UNIVERSO

C1. MATERIA:Particles in the Universe.

TWO CATEGORIES:

Ultra-RELATIVISTIC PARTICLES: RADIATION (photons), NEUTRINOS

NON-RELATIVISTIC PARTICLES: BARIONS

A)Baryons (2-4%)

Protons and Neutrons in atomic nuclei

Electrons and Leptons

B)Radiation(<1%)

Photons with Energy E=hf

Interact with Baryons via • Thomson Scattering (non-relativistic) • Compton Scattering (relativistic scattering)

C) Neutrinos(<1%)

Weakly interacting particles

Possess non-zero rest mass (?!?)

Still treat them as massless & Relativistic • Electron neutrino • Muon neutrino • Tau neutrino

C1) Composición: Materia Barionica.

MATERIA BARIONICA(p,n's):

EN: Galaxias (estrellas, gas y polvo)‏

~1011 estrellas,

~1012 Msol,

~1011 galaxias en nuestro universo visible

+Polvo intergalactico.

Visible: por emision radiacion electromagnetica

CUANTA MATERIA BARIONICA?:

-Contaje estrellas y galaxias

-argumentos nucleosintesis primordial

Densidad de materia visible hoy (t0) ~Omega_b=2-4%

= 10- 31 g/cm3

C2) P.Relativistas (Radiacion+neutrinos)

Radiación difusa (no agrupada en grumos ligados gravitatoriamente)‏

CMB:espectro cuerpo negro con T=2.725K+-0.001,

evidencia del Big Bang

Otros:neutrinos: T<=2K (M_neu=0).

rhoCBR t0 1034

g cm3

Peak frequency is ~ 150 GH, (6cm)

Blackbody radiation retains a blackbody

spectrum despite the expansion the

universe. But, colder, .

CMB:ESPECTRO DE POTENCIAS

AJUSTE: H0 ,

b ,

DM , ,

DE, w(z)…

:Información parametros cosmologicos

COBE/NASA

caliente frío

caliente

caliente frío

C3) Composición: Materia oscura.

• Materia oscura (la mayor parte de la materia):

-no emite luz, solo interaccion gravitatoria.

-Tipos: Exotica (la mayor parte),No exotica (Materia Barionica Oscura).

EVIDENCIA ??: (principalmente)

-Curvas rotacion galacticas

-Colision de cumulos de Galaxias

-Fluctuaciones Temperatura CMB

-Velocidades en cumulos, Rayos X en nebulas, Light bending.etc

• Evidencia 1: curvas de rotación de galaxias:

más masa que la masa

Visible.

G M

r2

V2

rV r r

1 2r Rvis

EVIDENCE DM:Observations of 9 galaxy clusters

Alle

n,

Schm

idt

& F

ab

ian 2

002

~b / m

Dispersion en velocidades: teorema del Virial. <K>=-1/2 <V>,

Luminosity in COMA M ~ 1013 Mo

Dispersion en velocities (red shifts):

~ 1200 km s-1 -> M ~ 5x1014 Mo

50 times more mass than expected

EVIDENCE 2: COMA CLUSTER VELOCITIES.

• Zwicky.ApJ 86, 217 (1937)

C) Collision of Galactic Clusters

Collision of galaxy clusters:

” Bullet Cluster(2006)”

- hot gas: seen with the Chandra X-ray Observatory (pink)

-DM: cluster mass as inferred by gravitational lensing (blue),

-Visible

Best evidence for dark matter to date

What is Dark Matter?

Properties of simplest Dark Matter:

-Must be stable (have immutable qualities)

-Neutral

-weak interactions

CANDIDATES:

- NO EXOTIC: barionic dark matter

COLD DARK MATTER: Non relativistic

HOT DARK MATTER: relativistic.

-EXOTIC:

COLD, HOT

CANDIDATES:NON EXOTIC Dark Matter

•HOT DM: neutrinos

•COLD (barionic dark matter):

• Cold hydrogen

• MACHOs (Massive Compact Halo Objects)

– Black holes

– Dense stars, eg. WD, NS

– Large planets

• Constraints from microlensing

– <20% of our galaxy halo is MACHOS

CANDIDATES DM: Exotic dark matter.

• Warm -Sterile neutrinos, gravitino

• Cold

– LSP (Lightest Super-symmetric Particle, eg. neutralino, axino)

SUSY: Supersymmetry

– LKP (Lightest Kaluza-Klein particle)Extra dimensions

– Axions, axion clusters (Rees, Hogan)

– Solitons (Q-balls, B-balls)

– WIMPs, wimpzilla

IT IS POSSIBLE THE DIRECT DETECTION OF DM:

DETECTION DM:Astrophysical experiments

Composición: Energia Oscura

Energía de vacío (energía oscura)75:‏ por ciento del total

-Incluso el espacio vacío puede tener densidad de Energia

-Constante aditiva: no cambia leyes de Newton pero curva ET en RG

EVIDENCIA:

-CMB

-large Scale galaxy distribution

-Expansión (Acelerada):

Perlmutter(2011). Supernovas Ia.

Origen: desconocido.

CONCLUSION: EL UNIVERSO ES OSCURO

DARK MATTER

• Problema antiguo: 1930

• Muchas soluciones

(Bien fundadas):

-Particulas,-gravedad

• Gravedad “atractiva” “

(+)”.

DM,DE: “oscuras”: no interaccion EM, solo gravitatoria.

APARENTEMENTE NO RELACIONADAS

DARK ENERGY

• Problema nuevo: 2000.

• Ninguna solucion

convincente: Lambda,

Energia del vacio. Campos

escalares.

• Anti-Gravedad “ (-)”

OTRAS TRANSPARENCIAS

Ley de Hubble. Tiempo de Hubble.

la ley de Hubble no implica que la Vía Láctea (o la tierra) sea el

centro del universo

Para demostrar la Ley de Hubble tenemos que medir velocidades (z)

y distancias de forma independiente.

Una vez conocida la ley de Hubble, Se puede usar para medir las distancias más lejanas: zd

TIEMPO de HUBBLE (Edad del Universo):

Suponiendo v=cte: (HUBBLE TIME)

RADIO DE HUBBLE: R_H=c t_H

t H≡ 1/ H 0~ 14× 109años

• Galactic clusters: need DM to bind them (1930s, Zwicky)

• Galaxy rotation curves: need a diffuse halo of DM (1970s, Rubin &Ford)

• Gravity lensing: strong and weak lensing show DM in universe

• Hot gas in clusters: need DM to bind the hot gas

• CMB: CMB power spectrum show composition of universe (WMAP)

• Large scale structure formation: a universe composed of CDM and DE

• BBN: light elements abundances agree with observation if

nB/n ~ 6 10-10 (imply baryon mass density ~ 4 )

• Supernovae probe: Hubble diagram indicate DM and DE in universe

• Colliding clusters: observation of colliding clusters from bullet cluster

Evidence of Dark Matter (Detail)

DM: ALGUNAS PROPIEDADES SON CONOCIDAS

CANDIDATOS PARA DM EN EL SM?

• No barionicas

NO SM: Evidencia de nueva fisica: MUCHOS CANDIDATOS!!! primodial black holes, axions, warm gravitinos,neutralinos, sterile

neutrinos, Kaluza-Klein particles, wimpzillas, superWIMPs,

• No ligeras (100GeV?)

• Estables (o casi)

• Interaccion Gravitatoria,I. debil

RADIACION DE FONDO (CMB)

GRAN CANTIDAD INFORMACION:

Universo primigenio en eq. Térmico, muy

uniforme e isótropo

expansión uniforme

Fluctuaciones:+200microK

C_max 0.5-1 grado

COBE/NASA

caliente

frío

caliente

caliente frío

11. Cosmo:Caracteristicas del Universo

C) COMPOSICIÓN DEL UNIVERSO: Materia+ Radiacion+Eoscura

-Estrellas, gas y polvo (galaxias, cúmulos,supercumulos).

-Materia oscura ( neutralinos? ,??)‏

-Radiación difusa (CMB, fondo de neutrinos)‏.

-Energía de vacío o energía oscura ( quintaesencia??, …)

Cosmic Coincidence Problem

Why do we see matter and cosmological constant almost equal in amount?

“Why Now” problem Actually a triple coincidence problem

including the radiation If there is a fundamental reason for

rL~((TeV)2/MPl)4, coincidence

natural

Arkani-Hamed, Hall, Kolda, HM

C) Mapas del universo (radiación)‏ Estructura a gran escala:

ISOTROPÍA y HOMOGENEIDAD

Mapas D,T vs posición angular

ISOTROPÍA (mapa de radiación)‏

t ~ 300 000 años: recombinación da materia neutra y transparente (H, He)‏

T~ 3000 K CBR enfriado hoy hasta 2.73 K

COBE, WMAP: la imagen más cercana al Big Bang

anisotropía mK: movimiento del sistema solar respecto del SR en el que la radiación es casi perfectamente isótropa

anisotropía microK: radiación de nuestra propia Galaxia

anisotropía 10-7K: fluctuaciones que hicieron posible la formación de cúmulos y galaxias

Mapas del universo (materia)‏ HOMOGENEIDAD (mapa de galaxias)‏

Rastreos SDSS, 2dF: 3D posición y espectro de muchas galaxias (930000)

Se observa (Práctica 2) estructura de vacíos (voids), filamentos y paredes pero a una escala mayor el universo se muestra homogéneo (no parece que estemos en un lugar especial)‏

z≥ 0.02

Gamma Ray

The universe in different spectral regions…

X-Ray

Visible

IR

Microwave

• Formación de las primeras estructuras– Surgen de las fluctuaciones del CMB

El Modelo Estándar

CMB Primeras Estructuras

Primeras Estrellas

Primeras Galaxias

Ahora

NASA/WMAP Science Team(www.gsfc.nasa.gov)