The dark universe SFB – Transregio Bonn – Munich - Heidelberg

What is our universe made of ? quintessence ! fire, air, water, soil ! Basic questions, high public interest !

Ω m + X = 1 Ω m : 30% Ω m : 30% Ω h : 70% Ω h : 70% Dark Energy Dark Energy ? Unification of all interactions Superstrings Higher dimensions Fundamental origin of mass scales

Important predictions of Dark Energy The expansion of the Universe accelerates today ! Structure formation : One primordial fluctuation- spectrum

Baryon - Peak SDSS galaxy – correlation – function

Observing Dark Energy needs understanding of cosmological role of Dark Matter ! central for our TR

Research fields of TR33 Origin of Dark Energy and Dark Matter Dark Matter – Dark Energy connection Time history of Dark Energy

What is Dark Energy ? Cosmological Constant or Quintessence ? Help from observation !

Cosmological Constant - Einstein - Constant λ compatible with all symmetries Constant λ compatible with all symmetries No time variation in contribution to energy density No time variation in contribution to energy density Why so small ? λ/M 4 = Why so small ? λ/M 4 = Why important just today ? Why important just today ?

Cosm. Const. | Quintessence static | dynamical

Cosmological mass scales Only ratios of mass scales are observable ! homogeneous dark energy: ρ h /M 4 = ˉ¹²¹ homogeneous dark energy: ρ h /M 4 = ˉ¹²¹ matter: ρ m /M= ˉ¹²¹ matter: ρ m /M 4 = ˉ¹²¹ ρ m,r /M 4 ~ t -2 ρ m,r /M 4 ~ t -2 For matter : huge age of universe For matter : huge age of universe small ratio small ratio Same explanation for small dark energy ? Same explanation for small dark energy ?

Realization : Scalar field, Quintessence, K-essence,.. New interaction !

The nature of Dark Energy determines the future of the Universe …

Themes of this TR Dark Energy Dark Energy Static or dynamic ? Static or dynamic ? Origin of Dark Energy Origin of Dark Energy Dark Matter – cosmological context Dark Matter – cosmological context Interactions Dark Energy – Dark Matter Interactions Dark Energy – Dark Matter Structure formation – cosmological aspects Structure formation – cosmological aspects

Theory – simulation - observation Complete chain from basic theory to observation Complete chain from basic theory to observation Cosmological expertise from theoretical particle physics and astrophysics : synergy needs effort ! Cosmological expertise from theoretical particle physics and astrophysics : synergy needs effort ! Observational approaches : complementary Observational approaches : complementary Leading role in large surveys: Leading role in large surveys: CMB : Planck satellite CMB : Planck satellite Lensing, Galaxy Power Spectra and Galaxy Clusters : Lensing, Galaxy Power Spectra and Galaxy Clusters : OmegaCam, Virus OmegaCam, Virus Galaxy Clusters : X-rays, APEX, Supernovae surveys Galaxy Clusters : X-rays, APEX, Supernovae surveys

Theory – simulation - observation Theory : basic and phenomenological approaches Theory : basic and phenomenological approaches Includes central areas where new insights and ideas on Dark Energy may come from : Includes central areas where new insights and ideas on Dark Energy may come from : Superstrings, higher dimensions, dilatation symmetry Superstrings, higher dimensions, dilatation symmetry Simulations : leading groups Simulations : leading groups Dynamical Dark Energy not much studied yet Dynamical Dark Energy not much studied yet New numerical challenges for inclusion of Dark Energy – Dark Matter coupling ( fluctuations of scalar field ) New numerical challenges for inclusion of Dark Energy – Dark Matter coupling ( fluctuations of scalar field )

Interface theory-observation milestones Time history of Dark Energy Time history of Dark Energy Determination of Determination of cosmological Dark Matter characteristics and cosmological Dark Matter characteristics and possible coupling to Dark Energy from comparison of possible coupling to Dark Energy from comparison of observation and simulations of dark matter structures observation and simulations of dark matter structures Standard model for cosmology ? ! Standard model for cosmology ? !

Time history of dark energy Measure this curve ! h

TR working groups Time history of dark energy Time history of dark energy Cosmological dark matter properties Cosmological dark matter properties Simulations of the universe Simulations of the universe Cosmological information from structure formation Cosmological information from structure formation Gravitational lensing as probe for cosmology Gravitational lensing as probe for cosmology Cosmology from galaxy distributions Cosmology from galaxy distributions Theory of Dark Energy Theory of Dark Energy Theory of Dark Matter Theory of Dark Matter some well focused – some more vague

Additional strength of TR Close connection with several high level organized graduate schools Close connection with several high level organized graduate schools Bonn International Graduate School Bonn International Graduate School Bonn IMPRS Astronomy Bonn IMPRS Astronomy Heidelberg IMPRS “Astronomy and cosmic physics” Heidelberg IMPRS “Astronomy and cosmic physics” Munich IMPRS “Astrophysics” Munich IMPRS “Astrophysics”

Postdocs and PhD students : central for activity of TR !

Early Dark Energy A few percent in the early Universe Not possible for a cosmological constant M.Doran, CW : B1 1σ and 2σ limits Doran,Karwan,..

Simple parameterization of time-dependent dark energy fraction Dark Energy during structure formation CMB,SN,SDSS Supernovae, Riess et al.

A few percent Early Dark Energy If linear power spectrum fixed today ( σ 8 ) : More Structure at high z ! More Structure at high z ! Bartelmann,Doran,… Early quintessence slows down the growth of structure

Cluster number relative to ΛCDM Two models with 4% Dark Energy during structure formation Fixed σ 8 ( normalization dependence ! ) Little Early Dark Energy can make large effect ! More clusters at high redshift

Challenge : Simple, robust, model- and parameterization- independent statements ! Reliable errors !