Cosmología: Seminarios 1-2-3

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 theoryCte.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
The Balloon Model of Expanding Space
-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.
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
Electron
photons
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%
Electrons
Hydrogen-1
nucleus, 94%
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
P
PHASE 5-6: STRUCTURE FORMATION:
STARS AND GALAXIES
Phase 5: Until 1000-2000 mill yrs:
constant expansion:
dominance of matter.
Phase 6: Until now. Acelerated
expansion:
 dominance of DARK ENERGY (??)
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
BB Nucleosynthesis
• 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.
.
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
• For h=0.72, Omega_b=0.04
• Omega_b=M_b/M_total
(Tytler, O'Meara)
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 antimatter 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
~1010 light
years
Time
Us (t ~ 1010 years)
Distance
Expansion
of an
inflationary
Universe
Note: “~” means
“approximately equals.”
Decoupling:
Atoms (t ~ 2105 years)
Protons, neutrons, nuclei
(t ~ 200 sec)
Electrons (t ~ 1 sec)
Quarks (t ~ 10-6 sec)
Big Bang
Inflation (first ~10-35 sec)
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.
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
V ∝ z ,V ∝d , V = H 0 d
H 0 72 2 km s Mpc
1)Ho 1/T, To=1/H_0 , T. Hubble.
2)Example: Andromeda??

1 Parsec = 3.26 light years
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.
Correccion Ley de Hubble: V= H0 d+ K d^2
Kirshner R P PNAS 2004;101:8-13
Cosmología
11-C: COMPOSICION DEL UNIVERSO
C)COMPOSICION UNIVERSO
• CMB+SNI+OTROS:
rho/rho_crit=1.
•Proporciones:
Dark Matter: 23% ± 4%
Dark Energy: 73% ± 4%
Baryons: 4% ± 0.4%
Neutrinos: 2%
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).
Peak frequency is ~ 150 GH, (6cm)
Blackbody radiation retains a blackbody
spectrum despite the expansion the
universe. But, colder, .
rhoCBR t 0
10
34
g cm3
CMB:ESPECTRO DE POTENCIAS
:Información parametros cosmologicos
caliente
caliente
frío
frío
caliente
COBE/NASA
AJUSTE: H0 , b , DM , , DE, w(z)…
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.
GM
2
r
V2
r
V r
r
12
r R vis
~b / m
Allen, Schmidt & Fabian 2002
EVIDENCE DM:Observations of 9 galaxy clusters
EVIDENCE 2: COMA CLUSTER VELOCITIES.
• Zwicky.ApJ 86, 217 (1937)

Dispersion en velocidades: teorema del Virial.

Luminosity in COMA 
M ~ 1013 Mo
Dispersion en velocities (red shifts):
~ 1200 km s-1 -> M ~ 5x1014 Mo

50 times more mass than expected
<K>=-1/2 <V>,
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
DETECTION DM:Astrophysical experiments
IT IS POSSIBLE THE DIRECT DETECTION OF DM:
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
DM,DE: “oscuras”: no interaccion EM, solo gravitatoria.
APARENTEMENTE NO RELACIONADAS
DARK ENERGY
DARK MATTER
• Problema antiguo: 1930
• Muchas soluciones
(Bien fundadas):
-Particulas,-gravedad
• Gravedad “atractiva” “
(+)”.
•
•
•
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: zd

TIEMPO de HUBBLE (Edad del Universo):

Suponiendo v=cte: (HUBBLE TIME)
t H ≡ 1/ H 0~ 14× 10 años
9

RADIO DE HUBBLE: R_H=c t_H
Evidence of Dark Matter (Detail)
• 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
CANDIDATOS PARA DM EN EL SM?
DM: ALGUNAS PROPIEDADES SON
CONOCIDAS
•
Interaccion
Gravitatoria,I. debil
•
Estables (o casi)
•
No ligeras
(100GeV?)
•
No barionicas
NO SM: Evidencia de nueva fisica: MUCHOS CANDIDATOS!!!
primodial black holes, axions, warm gravitinos,neutralinos, sterile
neutrinos, Kaluza-Klein particles, wimpzillas, superWIMPs,
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
caliente
caliente
frío
frío
caliente
COBE/NASA
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
-7
 anisotropía 10 K: 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
z≥ 0.02 el universo
a una escala mayor
se muestra homogéneo (no parece que
estemos en un lugar especial)‫‏‬
Gamma Ray
The universe in different
spectral regions…
X-Ray
IR
Visible
Microwave
El Modelo Est ándar
• Formación de las primeras estructuras
– Surgen de las fluctuaciones del CMB
CMB
Primeras
Estructuras
NASA/WMAP Science Team
(www.gsfc.nasa.gov)
Primeras
Estrellas
Primeras
Galaxias
Ahora