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Baryon Acoustic Oscillations

Baryon Acoustic Oscillations. Renée Hlozek. Bruce Bassett Yabebal Fantaye , Jacques Kotze. Baryon Acoustic Oscillations. Eisenstein et al. 2005. Tegmark et al. 2005. Who will detect the BAO in the radio ?. MeerKAT may be the first.

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Baryon Acoustic Oscillations

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  1. Baryon Acoustic Oscillations Renée Hlozek Bruce Bassett YabebalFantaye, Jacques Kotze

  2. Baryon Acoustic Oscillations Eisenstein et al. 2005 Tegmark et al. 2005 Who will detect the BAO in the radio?

  3. MeerKAT may be the first. Need to be ready to do the analyses before the telescope is operational  useful to review the key ideas. It should!

  4. SKA will provide stunning BAO constraints. review the BAO forecasts for the SKA using Fisher4Cast.

  5. The Universe is neutral. • Photons free-stream away • - no longer interact with ions. • Pressure support is removed. • Baryon wave stalls. The Universe is ionized. • Photons and ions interact via Thomson scattering. • Perturbations in the cosmic plasma oscillate as acoustic waves. The Birth of Cosmic Ripples RECOMBINATION Eisenstein

  6. The Birth of Cosmic Ripples Following a pebble in the cosmic pond… PHOTON DENSITY MASS PROFILE BARYON DENSITY White & Eisenstein

  7. The Birth of Cosmic Ripples PHOTON DENSITY MASS PROFILE BARYON DENSITY The dark matter is slow to move – it only interacts gravitationally White & Eisenstein

  8. The Birth of Cosmic Ripples PHOTON DENSITY MASS PROFILE BARYON DENSITY Photons and baryons move outward together, the radius of the shell moving at White

  9. The Birth of Cosmic Ripples z=1081: just before decoupling PHOTON DENSITY MASS PROFILE BARYON DENSITY The dark matter begins to follow the baryons White

  10. The Birth of Cosmic Ripples PHOTON DENSITY MASS PROFILE – PHOTONS and BARYONS only BARYON DENSITY Lack of pressure support `freezes’ the radius of oscillation into baryon density White

  11. The Birth of Cosmic Ripples PHOTON DENSITY MASS PROFILE – PHOTONS and BARYONS only BARYON DENSITY White

  12. The Birth of Cosmic Ripples PHOTON DENSITY MASS PROFILE BARYON DENSITY Dark matter continues to move slowly – towards baryon peak White

  13. The Birth of Cosmic Ripples PHOTON DENSITY MASS PROFILE BARYON DENSITY Dark matter distribution now clusters around baryon peak. White

  14. The Cosmic RULER • Final density profile peaks at r = 0 - with a second peak ata distance that depends on Ωm and h. • This is the baryon acoustic peak

  15. Distance and Expansion transverse radial

  16. Many pebbles in the pond • But in reality there are superimposed rings of power Bassett and RH, 2008

  17. Enemies of the BAO Shot Noise Bassett and RH, 2008

  18. Enemies of the BAO Cosmic Variance Bassett and RH, 2008 We need lots of galaxies (N > 106) and large volume (V > 0.5 h-3Gpc3)

  19. SKA BAO Blake et al. 2005

  20. Intuitive ERROR ELLIPSES Fisher4Cast

  21. SKA DE Constraints Two key questions:  What is the best HI survey for the SKA?  How much would a 50% or 20% SKA lose in terms of dark energy? For e.g. 108vs109 galaxies – how much does that affect dark energy constraints?

  22. www.cosmology.org.za • Open source, modular and battle-tested GUI designed using software engineering principles • Approximately 400 downloads since May 2008 • Planned Extensions: lensing, CMB, direct radio survey support • Encourage Collaboration and Extensions

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