The Distributions of Baryons in the Universe and the Warm Hot Intergalactic Medium Baryonic budget at z=0 Overall thermal timeline of baryons from z=1000  0 Three separate redshift intervals in history Conclusions Renyue Cen (Princeton University Observatory) Sept 26, Universe: from microwaves to ultrahigh energies University van Amsterdam

The Bottom 5% in the Standard Model: Komatsu et al (2011) WMAP7 Planck Collaboration (2013)

Warm-Hot Intergalactic Medium (WHIM) z ~ 0 T= Kelvin & Density=(1-300) mean density Cen & Ostriker (1999)

WHIM n=0.96,  8 = 0.8,  x h 2 = 0.126, H 0 = 70 WHIM Power Spectrum in the Standard Model

Cosmolog ical Recom- bination Real Dark Ages Pop III Stars 1 st gen Galaxies 1 st gen Quasars reheating Lya forest Majority of Quasars Ellipticals Majority of Galaxies Clusters LSS  Redshift z= – nd gen Galaxies Quasars Final Reion Temp 10 3 K 10 4 K 10 6 K 10 2 K 10 6 Msun Msun Msun10 9 MsunMass(nonlinear) Budget, Structure, Thermal Timeline: Heating of the Cosmic Baryons by Fusion and Gravitational Energy Baryon budget evolution

z ri ~ SDSS QSOs : z ri ~6.0 SDSS z=6.28 Which translates to z ri = (2σ) (assuming a step function like transition from a totally neutral to totally ionized universe) 2. CMB optical depth  = Fan et al (2002) Epoch of Reionization Observational Data: z ~ 20 to 6 Komatsu et al (2011) WMAP7

z ~ 20 to 6 ab initio theory: the universe can be reionized by stars (mostly Pop II stars), producing optical depth that is consistent with WMAP7, but the process is NOT a step function like and spatially very inhomogeneous Trac, Cen, … (2013)

A list of major observational probes of EoR CMB: probing ionized hydrogen (bubbles) 21cm in radio: probing neutral hydrogen Ground based infrared surveys: probing Ly  emission of galaxies HST & JWST: probing rest-frame optical-UV continuum High-z QSOs: absorption High-z GRBs: absorption as well as SFR IR radiation background

9 Cen et al (1994) z=3 z em  3.6 QSO Womble et al (1996) The standard model + gravitational instability + photoionization + hydrodynamics  A successful model for Ly  observed forest  A powerful method to determine P k on small scales (~1Mpc), complementary to CMB and others Photoionization heated, T ~ 10 4 K Ly  forest: z ~ 6 to 2

Gravitational re-heating of the universe: z ~ 2 to 0 Cen & Ostriker (1999) The process is complex but the essential physics is rather simple: H(z) L(z)  v shock

z ~ 2  0 ab initio theory: the universe is heated by waves breaking due to gravitational collapse of large-scale structure at moderate to low redshift Cen (1999)

Capitalistic development of baryonic universe: z=2 to 0 Cen & Ostriker (1999)

A list of major observational probes of z=2 to 0 IGM QSO absorption lines (H, He, metals) Emission lines (Ly , C IV, OVI, …) X-ray emission from groups/clusters (lines and continuum) SZ effects Soft X-ray background (intensity, correlation function) Cosmic rays produced in shocks  radio emission

 The intergalactic medium in the observable universe have three characteristic redshift ranges  z=100  20: universe expansion cooling  z=20  2: universe being heated by photoionization from star formation (nuclear energy) from 10 to 10 4 K  z=2  0: universe being heated by hydrodynamic shock waves produced by gravitational collapse of large-scale structure from 10 4 to 10 6 K --- IGM “measure” the temperature of the universe Conclusions