Dark radiation in cosmology 2011 4 3 Dark

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Dark radiation in cosmology 张益 重庆邮电大学 2011. 4. 3

Dark radiation in cosmology 张益 重庆邮电大学 2011. 4. 3

 • Dark Energy! • Dark Matter! • What is dark radiation? Observations! Theory!

• Dark Energy! • Dark Matter! • What is dark radiation? Observations! Theory!

不同组分的演化规律 Friedmann Equation Radiation Matter Cosmological constant Curvature term

不同组分的演化规律 Friedmann Equation Radiation Matter Cosmological constant Curvature term

The radiation dominating universe

The radiation dominating universe

Motivation from Observations • WMAP shows: • BBN Observations limit(68% CL) (astro-ph: 0408033) •

Motivation from Observations • WMAP shows: • BBN Observations limit(68% CL) (astro-ph: 0408033) • CMBR (68% CL) ( arxiv: 1001. 4538, 1009. 0866 ) ATACAMA COSMOLOGY TELESCOPE: ACT measures fluctuations at scale 500<l<3000

Possibilities!( astro-ph: 0612150, 1103. 4132) • Motivated by the LSND(Liquid Scintillator Neutrino Detector) oscillation

Possibilities!( astro-ph: 0612150, 1103. 4132) • Motivated by the LSND(Liquid Scintillator Neutrino Detector) oscillation claim,assume a (light) massive sterile neutrino (1006. 5276); • The neutrinos acquire a mass from a broken lepton flavor symmetry(astroph: 0312267, 1009. 4666, 1011. 0911); • Allow for a violation of the spin-statistics theorem; • A Brans-Dicke field with non trivial potential which could mimic the effect of adding extra radiation between the BBN and CMB epochs(astroph: 0510359); • An extra interaction between the dark energy and radiation (or dark matter); • A quintessence with a tracking potential behavior; • Decaying matter(1011. 3501); • Nonstandard thermal history; • ……

Theories • • • Brane Cosmology Hovara-Lifshitz cosmology Electroweak phase transition EDE(Early Dark Energy)

Theories • • • Brane Cosmology Hovara-Lifshitz cosmology Electroweak phase transition EDE(Early Dark Energy) ………. .

Brane Cosmology(astro-ph: 0211285) Dark radiation term arises from the projection of Weyl curvature of

Brane Cosmology(astro-ph: 0211285) Dark radiation term arises from the projection of Weyl curvature of the bulk black hole on the brane and behaves like an additional collisionless and isotropic massless component.

Electroweak phase transition (0902. 4699)

Electroweak phase transition (0902. 4699)

Triple coincidence problem • Coincidence problem: why the cosmological constant and the matter have

Triple coincidence problem • Coincidence problem: why the cosmological constant and the matter have comparable energy density today even through their time evolution is so different • Triple coincidence problem: why the radiation energy density today is only three orders of magnitude smaller than the dark-matter and dark -energy ones, although it also scales very differently

Scalar field dark energy Interaction 1 Interaction 2

Scalar field dark energy Interaction 1 Interaction 2

Phase-space analysis

Phase-space analysis

Quintessence

Quintessence

Phantom

Phantom

Conclusion • “Triple coincidence problem”still need finetunning。 • This model can recover the history

Conclusion • “Triple coincidence problem”still need finetunning。 • This model can recover the history of our universe.

The Future • Data:Planck, BAO, new result on primordial nuclei abundance? • Models: based

The Future • Data:Planck, BAO, new result on primordial nuclei abundance? • Models: based on string theory, particle physics or others?

THANKS ALL !

THANKS ALL !