NUCLEOSYNTHESIS. from the Big Bang to Today. Summer School on Nuclear and Particle Astrophysics Connecting Quarks with the Cosmos

Transcription

1 NUCLEOSYNTHESIS also known as from the Big Bang to Today Summer School on Nuclear and Particle Astrophysics Connecting Quarks with the Cosmos II George M. Fuller Department of Physics University of California, San Diego

2 NSE Freeze Out

3 13 N 14 N 11 C 12 C 13 C 8 B 10 B 11 B 12 B 7 Be 8 Be 9 Be 10 Be 11 Be (α,γ) 6 Li 7 Li 8 Li 3 He 4 He (α,γ) p 2 H 3 H n Cococubed.asu.edu/code-pages/net_bigbang.shtml

4 Nuclear Abundance Evolution nuclear reactions Wagoner-Kawano Code for example 2 nd order Runga-Kutta integration many variants with different integrators and weak rate prescriptions See bigbangonline.org hosted and led by Michael Smith at ORNL Where, with a simple 2-to-2 strong interaction, as in the example above,

5 M. Smith, L. Kawano, R. Malaney Full network BBN What NSE and the Saha equation would have given

6 Cococubed.asu.edu/code-pages/net_bigbang.shtml

7 N. Suzuki (Tytler group) (2006)

8 FLRW Universe (S/k~10 10 ) The Bang Temperature Neutrino-Driven Wind (S/k~10 2 ) Outflow from Neutron Star Weak Freeze-Out T= 0.7 MeV T~ 0.9 MeV Weak Freeze-Out n/p<1 n/p>1 Alpha Particle Formation T~ 0.1 MeV T~ 0.75 MeV Alpha Particle Formation PROTON Time NEUTRON

9 very crudely: 4 He yield sensitive to expansion rate 2 H sensitive to baryon density Actually, helium does depend on baryon density, and deuterium does depend on the n/p ratio and the expansion rate.

10 There are two neutrons for every alpha particle, so in the limit where every neutron gets incorporated into an alpha particle the abundance of alpha s will be number density is n A = n b Y A Y α 1 2 Y = 1 and abundance is Y n 2 X A = X A A n where Y α = X α 4 where mass fraction is X A and A is nuclear mass number The alpha mass fraction at the α formation epoch, T ~ 100 kev, is then X α = 4Y α 2Y n ( ) ( ) = ( ) ( ) 2n n ( n n + n p ) = 2 n n n p 1+ n n n p 87 = 2 8 = 0.25 and baryon number density is n b where we have used n n 1 at the time the alpha particles form n p 7 Remember that at Weak Freeze Out, T 0.7 MeV, the neutron to proton ratio for zero lepton number is n n n p 1 6

11 Extra particles or energy density speeds up earlier (hotter) weak freeze out and, hence, expansion rate, leading to more 4 He

12 4 He BBN Mass Fraction Y p He emission lines measured in ionized H II regions in >70 galaxies Systematic errors were underestimated for decades ± Olive, Skillman Steigman to Olive & Skillman ± Izotov & Thuan ± Izotov & Thuan 2004 Flux calibration, reddening, stellar absorption Ionization correction needs T and electron density Spatial variations Extrapolation to zero metallicity After slide in Tytler CIPANP

13 Stellar Absorption can hide He emission Izotov & Thuan Fukugita & Kawasaki corrections astro-ph/ After slide in Tytler CIPANP

14 NSE Freeze-Out for the Deuteron deuteron is very fragile, bound by only B.E. = 2.2 MeV, and stays in equilibrium until the neutrons are locked up in alpha particles at T α ~ 0.07 to 0.1 MeV... n + p <-> d + γ Deuteron abundance at Freeze-Out (where the alphas form): Y d ~ e B.E./T α

15 n + p 2 H + γ Deuteron production reaction deprived of neutrons because of alpha formation: goes out of NSE

16 Primordial Deuterium Abundance From observations of isotope-shifted Lyman lines in the spectra of high redshift QSO s. See for example: J.M. O Meara, D. Tytler, D. Kirkman, N. Suzuki, J.X. Prochaska, D. Lubin, & A.M. Wolfe Astrophys. J. 552, 718 (2001) D. Kirkman, D. Tytler, N. Suzuki, J.M. O Meara, & D. Lubin Astrophys. J. Suppl. Ser. 149, 1 (2003)

17 Tytler & Kirkman

18 M. Petini in Astrophysics in the Far UV: five years of discovery with FUSE ed. G. Sonneborn, H. Moos, B.G. Andersson, ASP Conf. Ser. 348, pg. 19

19 Uncertainty in Primordial Deuterium Abundance arguably ~30% with current data With the advent of 30m class telescopes (hence, many more clean QSO absorption systems), might it be possible to get the uncertainty down to ~5% or lower???

20 Improved D/H Tytler CIPANP slide Many suitable QSOs z>2.5 (8000 r<18.99, 16,000 r<19.5) we need only the rare QSOs giving best D/H Improved Signal to Noise Key to choosing adequate set of models Have demonstrated flux calibration to 1-2% Monte Carlo modeling Include full range of models and parameters Expect to reach few percent error 1-3% error on D/H or 0.6-2% on η & baryon density Takes years Astronomers do 100+ projects on each telescope Rarely spend > 1 hour/object. We need 24 hours.

21 Lithium evolution is very interesting BBN predicts factor more 7 Li (produced as 7 Be) than observed on the surfaces of old, blue halo stars Problem with BBN, nuclear reaction rates? or Stellar depletion through rotationally-driven turbulent diffusion Standard BBN produces very, very little 6 Li, but VLT observations of isotope-shifted shifted line suggest a 6 Li abundance on the surfaces of old halo stars ~ 1/30 of the Spite-plateau plateau abundance of 7 Li Non-thermal nuclear reactions driven by WIMP decay? (Jedamzik 2007) Or First stars very massive?; cosmic rays? or Physics of BBN itself?

22 Two ways to make 7 Li At low η the primary production channel is 3 H( α,γ) 7 Li At higher η the primary production channel is 3 He( α,γ) 7 Be So in our universe the 7 Li is produced as 7 Be. (Near T ~ 10 ev the 7 Be captures an electron to become 7 Li.)

23 7 Li: 3-4 x too little & too constant Old halo stars show 3-4 x less 7 Li than SBBN+ D/H or WMAP 7 Li/H increases with log Iron abundance [Fe/H] (Ryan et al. 99) At fixed [Fe/H] intrinsic scatter 7 Li/H < 5% since stars differ in mass, expect more variation if stars destroy Li Models of Richard etal 2005 use turbulence and turbulent diffusion to reproduce near constant Li/H Did this destruction happen in stars? After slide in Tytler CIPANP Asplund et al Blue: 6 Li also seen Internal error in T eff from H-alpha only 30K: unlikely stars lack Li I because are 700K hotter than measured

24 6 Li is a Challenging Observation Asplund et al 2006 detect 6 Li/ 7 Li = > 2 sigma in 9/24 stars; >1 sigma in 18/24 stars. overall convincing, but large errors individually 6 Li/ 7 Li = ± Asplund After slide in Tytler CIPANP

25 Were did all the 6 Li come from? 10 3 x 6 Li from SBBN Correcting each star for expected pre-ms depletion more convection higher [Fe/H] More 6 Li than expected in some models of cosmic ray spallation Asplund astro-ph/ Need non-bbn, or non-thermal Production Expect 6 Li from fusion of alphas accelerated by galaxy merger shocks (Suzuki & Inoue 2002, 2004), or massive Pop III stars, or black holes..or from decay of supersymmetric particles (Jedamzik 2000, 04a, 04b ,) After slide in Tytler CIPANP

26 Neutrino Mass/Mixing

27 Neutrino mass physics is a theme common to both Compact Objects (supernovae; neutron stars; holes; etc...) Cosmology (structure formation; dark matter, etc...)

28 Neutrino Mass: what we know and don t t know We know the mass-squared differences: We do not know the absolute masses or the mass hierarchy:

29 Neutrino energy (mass) states are not coincident with the weak interaction (flavor) states The unitary transformation that relates these states in vacuum has 4 parameters (exclusive( of Majorana phases exclusive of Majorana phases) We know 2 of the 4 vacuum 3X3 mixing parameters and we have a good upper limit on a third.

30 4 parameters

31 Atmospheric Neutrinos δm ev 2 23 sin 2 θ Solar /KamLaND Neutrinos δm 2 sol ev 2 sin 2 θ The key mixing angle limit on θ 13 sin 2 θ 13 < ( 2σ)

32 My take on this is as follows: (1) What we already know about neutrino mass/mixing has potentially big implications for astrophysics. (2) Working out those implications may allow new insights into nucleosynthesis and unmeasured neutrino properties: e.g., a supernova neutrino signal could help us get at θ 13 and the neutrino mass hierarchy. And, vice versa, what we know about Neutrino flavor mixing may give us insights into how supernovae work. (3) The FACT that neutrinos have nonzero rest masses begs the question of whether there are right-handed sterile neutrinos. We can map out the regimes of mass and vacuum mixing which are of astrophysical interest, where experimenters/observers should look.

33 Relic Neutrinos

34 Contribution to closure of all neutrino species with thermal (black body, BB) energy spectra. A thermal energy spectrum is characterized by a temperature and a degeneracy parameter (chemical potential divided by temperature). ( ) Ω ν tot h T γ K 3 i BB F 2 η ν i 3 ζ 3 2 ( ) () 4 11 T ν i () 1/3 T γ 3 "mν " i 1 ev e.g., a neutrino and antineutrino with mass 2 m ν 3 δm atm ev Ω ν tot ( ) 0.7 h 2 ~ 3% of baryon rest mass

35 Relativistic Fermi Integral of order k For example, and

36 cosmological constraints on neutrino rest mass WMAP+ACBAR+CBI + SDSS + HST: ν Dark Matter assumes that neutrinos have thermal, black body, zero chemical potential energy spectra WMAP+SDSS P g (k) WMAPext+SDSS P g (k) + HST H 0 + SDSS Ly-α K. Abazajian

37 Cosmic Background Relic Neutrinos weak interactions force neutrinos into flavor states α=e,μ,τ A. D. Dolgov et al., Nucl. Phys. B632,363 (2002); N. Bell, R. Volkas, Y. Wong PRD 59, (1999); C. T. Kishimoto & G. M. Fuller, PRD 78, (2008). these neutrinos have black body, Fermi-Dirac energy spectra at decoupling at temperature T weak. Subsequently, these neutrinos simply free fall through spacetime, with their spacelike momenta redshifting with scale factor a along their geodesics, Therefore, post-decoupling neutrino energy spectra are with and implying neutrino temperature

38 Cosmic Background Relic Neutrinos But these flavor states are coherent superpositions of mass/energy states Therefore the energy density in the relic neutrinos seas is The fraction of the closure density contributed by the relic neutrinos is G. M. Fuller & C. T. Kishimoto, Phys. Rev. Lett. 102, (2009) [arxiv:astro-ph/ ]

39 weak lensing possible sensitivity Next generation CMB experiments (e.g., Planck; Polar Bear) will be sensitive to weak lensing and this will provide the best sensitivity to neutrino mass. See for example Kaplinghat, Knox, Song PRL 91, (2003) But the neutrino mass hierarchy will be one of the chief determinants of whether we can infer the absolute neutrino masses G. M. Fuller & C. T. Kishimoto, Phys. Rev. Lett. 102, (2009) [arxiv:astro-ph/ ]

40 Cosmic Background Relic Neutrinos As these neutrinos free fall through spacetime, their higher mass components eventually become nonrelativistic, while their lighter mass components continue at near light speed Coherence scale can be larger than the local spacetime curvature scale (e.g., clusters of galaxies, galaxies) and an appreciable fraction of the causal horizon scale. causal horizon Do tidal stresses induce de-coherence? But unitarity implies that the comoving number density of neutrinos at a given mass is fixed. redshift G. M. Fuller & C. T. Kishimoto, Phys. Rev. Lett. 102, (2009) [arxiv:astro-ph/ ]

41 observed vacuum energy density ρ 3.9 kev h vac cm ( 2.3 mev) 4 h Ω vac 0.73 Ω vac 0.73 neutrino mass scale?

42 Using the Tool

43 Dave Schramm pioneered the use of primordial nucleosynthesis considerations as a probe of particle physics and cosmology. In particular, he and his co-workers pushed to use the observationally-inferred helium abundance to determine the number of flavors of neutrinos. David N. Schramm

44 Experiment tells us that neutrinos have mass. This fact begs the question: Are there other neutrinos, perhaps with higher masses? If there are, the Z 0 width measurement implies that these neutrinos must have interaction strengths which are SMALLER THAN THE WEAK INTERACTION!!! Sterile Neutrinos.?????

45 Sterile neutrinos are not sterile by virtue of their vacuum mixing with active neutrinos Gives effective interaction strength of the sterile neutrino relative to the standard Weak Interaction It is by virtue of these tiny interactions that sterile neutrinos can be produced in the early universe or in supernovae

46

47 A heavy sterile neutrino can decay into a light active neutrino and a photon. The final state light neutrino and the photon equally share the rest mass energy of the initial heavy neutrino.

48 Singlet Neutrino Radiative Decay Rate Γ γ αg 2 F 64π m [ U 1β U 2β F(r β )] 2 β sin 2 2θ s m s kev 5 no GIM suppression for sterile neutrinos F(r β ) r β ( M ) 2 W r β = M β lep

49 m s sterile neutrino rest mass 1 GeV 100 MeV 10 MeV 1 MeV 100 kev 10 kev 1 kev 100 ev GLAST early universe supernova explosion lepton/baryon-genesis Dark Matter (CDM & WDM) X-Ray Astronomy accelerator 30 m telescope (abundances) core collapse physics, supernova explosion, pulsar kicks, etc. large scale structure/lyman alpha forest BBN -Deuterium/Helium electromagnetic decay channels ( decay processes positioned at energy thresholds ) 10 ev 1 ev Phenomenally adiabatic MSW compare gravitational time scale,~ horizon length, to the oscillation length at resonance 30 m telescope (abundances) r-process fission cycling solution accelerator/ reactor ν U e4 2 s interaction strength relative active-sterile to normal vacuum weak interaction mixing

50 C. Kishimoto, G. M. Fuller, C. Smith, PRL 97, (2006)

51 Messes up relationship between lepton numbers and 4 He yield

52 ABFW 05 astro-ph/

53 C. Smith, G. Fuller, C. Kishimoto, K. Abazajian, PRD 74, (2006)

54 C. Smith, G. Fuller, C. Kishimoto, K. Abazajian, PRD 74, (2006)