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"From neutrinos....". DK&ER, lecture12 1 Cosmology and Relic Neutrinos Expanding Universe Big Bang Nucleosynthesis Cosmic Microwave Background measurements Relic neutrinos Informations about neutrino mass Leptogenesis

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Galaxies "From neutrinos....". DK&ER, lecture12 2 Photograph courtesy NASA, ESA, and the Hubble Heritage Team (STScI/AURA)-ESA/Hubble Collaboration Antennae galaxies Andromeda galaxy Galaxy Evolution Explorer

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Galaxies "From neutrinos....". DK&ER, lecture12 3 The Andromeda galaxy, also known as Messier 31, is the largest neighboring galaxy to the Milky Way. This photo, a mosaic of ten images captured by the Galaxy Evolution Explorer spacecraft in 2003, shows blue-white regions along the galaxy's arms where new stars are forming and a central orange-white area containing older, cooler stars.

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"From neutrinos....". DK&ER, lecture12 4 Expanding Universe In 1929 Hubble observed redshifts of spectral lines from distant gallaxies and ascribed them to velocities: v =Hr where r is distance to a gallaxy Hubble constant

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"From neutrinos....". DK&ER, lecture12 5 Expanding Universe Expansion of the Universe depends on time. If R(t) is a universal distance scale then: H is time-dependent but today: Universe expansion is described by the solution of Einstein equations: Friedmann equation

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"From neutrinos....". DK&ER, lecture12 6 Critical density For k= Λ =0 and nonrelat. constant M one gets: critical density It is then convenient to define: More precisely: Age of the Universe

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"From neutrinos....". DK&ER, lecture12 7 Cosmological Parameters i.e. for k=0 =1 independent on t For various k and Λ =0 one can define: then

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"From neutrinos....". DK&ER, lecture12 8 Cosmological Parameters For various k and Λ =0 one can define: then It is often convenient to separate a contribution from relat. particles Ω γ and from pressureless matter Ω m and introduce : Then

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"From neutrinos....". DK&ER, lecture12 9 Radiation dominance in early Universe How various densities evolve with time? Matter density: Radiation energy density: because: = photon density x photon energy because wavelength changes with scale R Therefore while now matter dominates the early Universe was dominated by radiative energy. From Friedmann equation and Stefan-Boltzmann law. one gets : temperature: i.e. at the beginning the Universe was very hot: Big Bang

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"From neutrinos....". DK&ER, lecture12 10 Big Bang The earliest moment: Planck mass We would need quantum gravity (which we do not know) for earlier moments. Probably sometimes at this epoch cosmic inflation happened. In one of the models: early enough the cosmological constant dominates Friedmann equation: giving: Next we’ll describe how the Universe cooled down. We assume, that particles for which: are in thermal equilibrium in comparable abundances and reactions can proceed in both directions eg: Cosmic Inflation is necessary in the Big Bang theory to explain the large scale uniformity of the Universe today.

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"From neutrinos....". DK&ER, lecture12 11 Big Bang – whole picture

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"From neutrinos....". DK&ER, lecture12 12 Breaking of the symmetry of interactions GeV GeV 100 GeV 1 GeV 10 meV

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D. Kiełczewska, wykład 14 Big Bang (1) Wielka Unifikacja – wszystkie oddz. nierozróżnialne bozonów X, Y tyle co np. kwarków leptony kwarki { Δ (B-L)=0} Plazma kwarkowo-gluonowa Bozony X, Y znikają Prawd. pojawia się nadmiar materii nad antymaterią wskutek rozpadów ciężkich neutrin N??

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"From neutrinos....". DK&ER, lecture12 14 gamma energy drops enough to allow formation of hadrons neutrinos do not have enough energy for they decouple from matter and move freely Big Bang (2) elmgt and weak forces separate all W’s and Z’s decayed not enough energy to produce them Relic neutrinos

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"From neutrinos....". DK&ER, lecture12 15 Big Bang (3) not enough energy to create e+ e- pairs positrons disappear light nuclei are bound Nucleosynthesis electrons bound into atoms photons interact much more slowly („decouple” from matter) and move freely Relic gammas or cosmic microwave bkg

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"From neutrinos....". DK&ER, lecture12 16

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"From neutrinos....". DK&ER, lecture12 17 Nucleosynthesis Let’s take Universe ~1 sec old By now most of heavier particles annihilated with their antiparticles What is left is: 10 9 times more and than baryons The following processes take place: But: Moreover neutrons decay with Effectively after 400 sec one gets: Also a part of neutrons is bound in nuclei and they don’t decay anymore.

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"From neutrinos....". DK&ER, lecture12 18 Nucleosynthesis Nuclei are produced in elmgt processes: Atoms appear only years later. Production of various nuclei strongly depends on the relative density of baryons to photons. It appears, that observed abundances of various isotopes agree with expectations if: Experimental confirmation of BB

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"From neutrinos....". DK&ER, lecture12 19 Number of neutrino species in BB nucleosynthesis Expansion rate depends on energy density, which in turn depends on the number of neutrino flavors: N For faster expansion less neutrons manage to decay and more helium nuclei can be bound. range acceptable for other nuclei consistent wit LEP measurements

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"From neutrinos....". DK&ER, lecture12 20 Cosmic microwave background CMB Another observation consistent with BB model. Remnant of the hot cosmic plasma According to: we may expect that today the temperature of CMB is a few K. CMB photon energy spectrum agrees with the black body frequency distribution. In 1965 r Penzias i Wilson discovered CMB. Its temp.: COBE satellite (1999)

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"From neutrinos....". DK&ER, lecture12 21 CMB anisotropy measured by WMAP Satellite experiment „Wilkinson Microwave Anisotropy Probe.” has collected data since It studies temp. fluctuations with precision of Images Universe years old. Fluctuations may come from inflation era. If eg. inflation was when: then according to Heisenberg principle we may expect „quantum fluctuations” Quantum fluctuations could give rise to matter condensation seeds, from which gallaxies evolved

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"From neutrinos....". DK&ER, lecture12 22 Cosmic Microwave Background - anisotropy measurements (WMAP) WMAP & 2dfGRS,astro-ph/ Autocorrelation function: measures temp. fluctuations around a mean temp. T 0 in the directions m and n. For small angles: curve: CDM model By fitting the model to the data a surprising number of parameters can be determined.

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Models fitted to the data "From neutrinos....". DK&ER, lecture12 23 Springs represent photon pressure and balls represent the effective mass of the fluid. Regions of compression (maxima) represent hot regions and rarefaction (minima) cold regions A baryon-photon liquid in a gravitation potential well. Radiative pressure of photons competes with the gravitation which compresses the liquid. Acoustic oscillations appear in liquid.. WMAP measures maxima and minima of acoustic oscillations and consequently properties of the liquid as well as the potential well.

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Baryon-photon ratio in the CMB "From neutrinos....". DK&ER, lecture12 24 Baryons increase the effective mass of the fluid. This changes the balance between pressure and gravity in the fluid. Gravitational infall now leads to greater compression of the fluid in the potential well. This increases the amplitude of the oscillation.Thus the relative heights of the peaks present one way of measuring the baryon content of the universe.

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Curvature of the Universe "From neutrinos....". DK&ER, lecture12 25 A spatial temperature fluctuation on the last scattering surface appears to us as an anisotropy on the sky. The conversion from physical scale into angular scale depends on the curvature of the universe and the distance to the last scattering surface. Photons free stream to the observer on geodesics analogous to lines of longitude to the pole. Thus the same angular scale represents a smaller physical scale in a closed universe. E.g. in the case of positive curvature

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Curvature and cosmol. constant "From neutrinos....". DK&ER, lecture12 26 The spacing between the peaks provides the most robust test of the curvature. From WMAP measurements:

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Summary of recent measurements "From neutrinos....". DK&ER, lecture Particle Data Group

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Summary of recent results (PDG2008) "From neutrinos....". DK&ER, lecture12 28

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Measurements of distant supernovae "From neutrinos....". DK&ER, lecture12 29 Supernovae Ia have known luminosity as a function of time so they may serve as „standard candles”. Comparing the expected luminosity with the observed one can determine the SN distance. Measurement of the „redshift” allows to determine the recession velocity

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Supernova measurements (SNIa) Strong indication of Dark Energy

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Cosmological parameters "From neutrinos....". DK&ER, lecture12 31 PDG 2008 However we do not understand the nature of energy represented by Λ We call it Dark Energy

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Matter density slows down expansion Flat geometry

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History of the Universe

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"From neutrinos....". DK&ER, lecture12 34 Neutrino and photon decoupling Then both temperatures decrease with the increasing scale of the Universe as 1/R so eventually now: For nonrelativistic case: Maxwell distribution At decoupling the neutrino temperature is slightly lower than that of photons +1 for neutrinos -1 for photons Because of an effect of „reheating” when slow electr. annihilate

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"From neutrinos....". DK&ER, lecture12 35 What do we know about ? „Visible” matter i.e. stars, gas etc: Baryons visible or invisible calculated from nucleosynthesis: Total matter deduced from gravitational potential energy of gallaxies and gal. clusters: Dark matter: Ciemna energia „flat geometry” k=0

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"From neutrinos....". DK&ER, lecture12 36 The most recent WMAP results (04/2008 ) Energiy balance of the Universe Today years after BB Dark energy contribution rises with time

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"From neutrinos....". DK&ER, lecture12 37 Relic neutrinos Number density from thermodynamic equilibrium Neutrino Dark Matter: - neutrino fraction of the total energy of the Universe for 3 flavors

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"From neutrinos....". DK&ER, lecture12 38 Weighing Neutrinos with Galaxy Surveys Recent results from experiments: Large scale cluster formation is prevented by relativistic neutrinos which stream out of the clusters. This sets a limit on a fraction of energy carried by neutrinos. PDG2008 The line is for Λ CDM model

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"From neutrinos....". DK&ER, lecture12 39 Neutrino contribution to the Universe energy With that one can calculate the neutrino contribution to the total energy in the Universe: which is much more than all the visible matter: From ΛCDM cosmology: On the other hand we have the limit (from tritium decays): From oscillations: which gives for a heaviest state:

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"From neutrinos....". DK&ER, lecture12 40 Current bounds on neutrino masses from cosmol.

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"From neutrinos....". DK&ER, lecture12 41 Matter-antimatter asymmetry We therefore expect that some processes violating CP symmetry gave rise to this matter excess. The observed CP violation in quark sector is not enough to explain the above ratio. A question: maybe CP violation in lepton sector may explain this excess? One would expect that BB produced the same amount of matter and antimatter. However one observes an excess of matter over antimatter

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"From neutrinos....". DK&ER, lecture12 42 Because: so the following decays are possible: Leptogenesis The most attractive explanation of matter-antimatter asymmetry is by Leptogenesis If neutrinos are Majorana particles, then an elegant way to get their masses is via interactions with Higgs of both: known light LH neutrinos as well as very heavy RH neutrinos N with masses of 10 (9-15) GeV. N should be produced in the very early moments of BB. where l +, l - are charged leptons If: then: we get excess of leptons over antileptons” Leptogenesis. Then a baryon excess can be obtained via so called sphalerons.

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"From neutrinos....". DK&ER, lecture12 43 CP violation for Majorana neutrinos One can ask: if then what is the difference between: So the clue to understand matter asymmetry is to look for differences in oscillations: and The difference is that in + decays neutrinos are mostly LH and consequently after oscillations they produce e-: If Leptogenesis hypothesis is true then we all come from heavy neutrinos. while the opposite happens for decays:

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Summary D. Kiełczewska, wykład 14 Cosmology and particle physcics are closely connected Cosmology has become an experimental science Big Bang Model confirmed by: measurements of cosmic microwave background CMB abundances of light nuclei in Universe BUT We don’t know what constitutes more than 90% of Universe energy Dark Matter ? Dark Energy ? We don’t understand how the matter-antimatter symmetry has been broken during the Universe

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