Pillars of Standard Model. Homogeneity and Isotropy Night Sky is Dark

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Alexia Black
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1 Pillars of Standard Model Homogeneity and Isotropy Night Sky is Dark Linear Expansion Light Element Abundances Microwave Background Radiation [+other large scale structures]

2 Wilkinson Microwave Anisotropy Probe: February 13, 2003

3 Mean temperature: T=2.725 ± K Spectral Deviation: Compton-y parameter (COBE 1992) Energy Density:

4 Angular fluctuation power: δt T θ ( ) = a lm l,m Y lm θ ( ) C = l a 2 lm Dipole: (l=1)

5 v(sun)-v(cmb)=370 ± 10 km/s v(sun)-v(lg) ~ 300 km/s v(lg)-v(cmb) ~ 600 km/s

7 Forthcoming Planck data will have about twice higher angular resolution

8 Observed abundances of light elements Hydrogen 75% Helium 24% Others 1% Helium problem: - stars would fuse He into C, N, O, etc - if universe started from 100% hydrogen, we would expect 75% H, 13% He, 12% others - problem solved if universe starts out with H + He

9 Helium abundance: - measured in stellar spectra (Helium discovered & named after Sun) - He can be produced in stars, too - extrapolate to zero metallicity to subtract He from stellar nucleosynthesis Lithium abundance: - measured in stellar spectra - Li is depleted in stars by mixing - find plateau at high stellar mass (these stars have little mixing)

10 Destroyed easily in stars Must look for gas that has never cycled through a star quasar absorption lines: - low-density gas - far back in time - extra neutron makes electron slightly more tightly bound - possible only with 10m telescopes (Keck) - D/H = 10-5

11 Big Bang Nucleosynthesis (BBNS) - can make precise calculations for relative abundances of light elements - turns out very sensitive to baryon density Current results: - imply 0.2 hydrogen atoms per cubic m - a small fraction (~4 percent) of the so-called critical density: Ω(baryons) ~ 0.04

12 Not if stars are points of light stuck onto a dome Is this a problem? But yes, in post-copernican models - stars are scattered through space - (or galaxies are )

13 Universe infinitely large Uniformly filled with stars Infinitely old

14 Sum over all stars: J is infinitely large Sum up to the mean free path d=1/(nπr 2 ) Still as bright as the disk of an individual star

15 One or more of the assumptions are wrong - recognized to be a problem already in 1576 by Thomas Digges (vs Copernicus 1543) Obscuring stars by dust does not work - proposed as a solution in 1744 by de Chesaux and in 1826 by Heinrich Olbers Infinitely old, infinitely large, Euclidean universe is self-contradictory. - innocuous-looking puzzle lasts into 20 th century! until discovery of the expansion of the universe

16 Finite age / volume Frequencies redshift Galaxies evolve NB: Einstein did not take note problem when trying to maintain static model

17 Pillars of Standard Model Homogeneity and Isotropy Night Sky is Dark Linear Expansion Light Element Abundances Microwave Background Radiation

18 Modern Pillars of Standard Model: based on inhomogeneities Galaxy distribution / power spectrum Baryon Acoustic Oscillations Abundance of nonlinear objects (galaxy clusters) Weak gravitational lensing statistics

19 Number density n(r) of galaxies traces total matter density ρ(r) 2 large recent surveys: 2dF, SDSS SDSS covers 10,000 sq. degrees Approx 1 million redshifts

22 Based on ~50,000 Galaxies in SDSS (Eisenstein et al. 2005)

23 Large X-ray survey with Chandra (Vikhlinin et al. 2009)

24 Abell 1689

25 Forecast by Song & Knox (2006)

26 Baryonic matter (galaxies and IGM) Radiation Backgrounds Other relativistic particles (neutrinos) Dark Matter (several?) Dark Energy (?)

27 Dark Energy Dark Matter Neutrinos Ordinary gas and stars

28 n ν ~110 cm -3 Ω ν =n ν m ν c 2 neutrino mass is not known, but: lower limit: ~0.05 ev from oscillations upper limit: ~1 ev from cosmic structure Ω ν < 0.01

29 Gamma Ray Bursts Ultra-High Energy Cosmic Rays

30 BATSE (watch for SWIFT!) brightest objects on the sky, lasting few seconds extragalactic origin debated until recently optical identifications settled debate ~3 years ago results of implosion of massive star ( hypernova ) could turn out to be an important tracer of earliest stages of structure formation (optical afterglow )

31 Cosmic rays are energetic protons (and other particles) Most are galactic, but distribution extends to ev No mechanism known to reach this energy (~10 events) Magnetic shocks in fast moving jets of AGNs? Probably cosmological, but CMB limits distance to 100 Mpc

Institut für Kern- und Teilchenphysik Neutrinos & Cosmology

Institut für Kern- und Teilchenphysik Neutrinos & Cosmology Neutrinos & Cosmology 1 Cosmology: WHY??? From laboratory experiment limits can be set ONLY in neutrino mass difference No information if neutrino masses are degenerated From kinematic experiment limits