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BBN, NEUTRINOS, AND THE CBR Gary Steigman (with J. P. Kneller & V. Simha) Center for Cosmology and Astro-Particle Physics Ohio State University PPC 2007, TAMU, May 14 – 18, 2007
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~ 0.1 s after the Big Bang Neutrinos Decouple ~ 380 kyr after the Big Bang Relic Photons (CBR) are free ~ 100 s after the Big Bang Primordial Nucleosynthesis
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BBN (~ 20 Minutes) & The CBR (~ 400 kyr) Provide Complementary Probes Of The Early Evolution Of The Universe Do predictions and observations of the baryon density ( 10 (n B /n γ ) 0 = 274 B h 2 ) and expansion rate ( H ) of the Universe agree at these different epochs? * Neutrinos Play Important Roles At Both Epochs
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As the Universe expands and cools, BBN “begins” at T 70 keV (when n / p 1 / 7) Coulomb barriers and the absence of free neutrons end BBN at T 30 keV t BBN 4 24 min. The Early, Hot, Dense Universe Is A Cosmic Nuclear Reactor
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BBN Abundances of D, 3 He, 7 Li are RATE (Density) LIMITED D, 3 He, 7 Li are potential BARYOMETERS BBN – Predicted Primordial Abundances 7 Li 7 Be 4 He Mass Fraction
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DEUTERIUM --- The Baryometer Of Choice As the Universe evolves, D is only DESTROYED * Anywhere, Anytime : (D/H) t (D/H) P * For Z << Z : (D/H) t (D/H) P (Deuterium Plateau) H and D are seen in Absorption, BUT … * H and D spectra are identical H Interlopers? * Unresolved velocity structure Errors in N(H ) ? (D/H) P is sensitive to the baryon density ( )
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D/H vs. Metallicity Deuterium Plateau ? Real variations, systematic differences, statistical uncertainties ? Low – Z / High – z QSOALS
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10 5 (D/H) P = 2.68 ± 0.27 For Primordial D/H adopt the mean For the error adopt the dispersion around the mean D/H vs. Metallicity
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D + SBBN 10 = 6.0 ± 0.4 SBBN
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CBR
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CBR Temperature Anisotropy Spectrum ( T 2 vs. ) Depends On The Baryon Density The CBR is an early - Universe Baryometer 10 = 4.5, 6.1, 7.5 CBR constrains 10 V. Simha & G.S.
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CBR 10 = 6.1 ± 0.2 V. Simha & G.S. (2007) CBR
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SBBN CBR & SBBN (D) Agree !
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S H/ H ( / ) 1/2 (1 + 7 N / 43) 1/2 The Expansion Rate (H Hubble Parameter) provides a probe of Non-Standard Physics 4 He is sensitive to S while D probes + N and N 3 + N 4 He provides a Chronometer D provides a Baryometer
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SBBN Prediction As O/H 0, Y 0 Do SBBN Predictions of D and 4 He Agree ?
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Likelihoods (SBBN) from D and 4 He AGREE ?
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0.23 0.24 0.25 4.0 3.0 2.0 Y P & y D 10 5 (D/H) D & 4 He Isoabundance Contours Kneller & Steigman (2004)
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BBN (D, 4 He) For N ≈ 2.4 ± 0.4 Y P & y D 10 5 (D/H) 4.03.02.0 0.25 0.24 0.23 D & 4 He Isoabundance Contours Kneller & Steigman (2004)
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NSBBN NSBBN (D & 4 He) 10 = 5.7 ± 0.4
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BBN (20 min) & CBR (380 kyr) AGREE on 10
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NSBBN NSBBN (D & 4 He) N = 2.4 ± 0.4
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CBR Temperature Anisotropy Spectrum Depends on the Radiation Density R (S or N ) The CBR is an early - Universe Chronometer N = 1, 3, 5 V. Simha & G.S. CBR constrains N (S)
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CBR N = 2.3 (1.2 ≤ N ≤ 4.4 @ 68 %)
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CBR BBN BBN (20 min) & CBR (380 kyr) AGREE on N
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BBN (D & 4 He) V. Simha & G.S. BBN Constrains N N < 4 N > 1
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CBR V. Simha & G.S. CBR Constrains 10
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BBN (D & 4 He) & CBR AGREE ! V. Simha & G.S.
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Lithium ( “Spite” ) Plateau (?) [Li] 12 + log(Li/H) 2.1 [Li] 12 + log(Li/H) 2.6 – 2.7 Li too low ? BBN and Primordial (Pop ) Lithium
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4.03.02.0 0.25 0.24 0.23 y Li 10 10 (Li/H) 4.0 Even for N 3 Y + D H Li H 4.0 0.7 x 10 10 log (Li) 2.6 0.1 (vs. log (Li) obs 2.2) Li depleted / diluted in Pop stars ?
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Summary : Baryon Density Determinations N < 3 ? Depleted ? D & 3 He agree with the CBR
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Summary : N Determinations 95% Ranges
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BBN (D & 4 He) and the CBR Agree ! (The Theorist’s Mantra) More & Better Data Are Needed ! SUCCESS CHALLENGE (Lithium ?)
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