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 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 ~ 2105 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: zd 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