Bulletin of the American Physical Society
2005 2nd Joint Meeting of the Nuclear Physics Divisions of the APS and The Physical Society of Japan
Sunday–Thursday, September 18–22, 2005; Maui, Hawaii
Session 2WG: Workshop 7B: Neutrino Astrophysics |
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Sponsoring Units: DNP JPS Chair: Baha Balantekin, University of Wisconsin Room: Ritz-Carlton Hotel Plantation 2 |
Sunday, September 18, 2005 2:00PM - 2:30PM |
2WG.00001: Neutrino processes in the Big-Bang and Supernovae Invited Speaker: Recent data of CMB anisotropies have suggested cosmological parameters which may manifest accelerating universal expansion. However, inferred baryonic density does not agree at $1\sigma$ C.L. with that determined from the Big-Bang nucleosynthesis (BBN) which satisfies all light element (D, $^{3,4}He$, and $^7Li$) abundance constraints. BBN is a unique cosmological process to test not only the cosmological theory but also the fundamental theory of particles and nuclei. We firstly discuss recent progress in particle and nuclear physics which may resolve partly the cosmological discrepancy of $\Omega_b$. We emphasize an important consequence of newly measured weak coupling constant in terms of neutron life. Secondly, we discuss astrophysical aspect of the supernova (SN) neutrino-processes which contribute to the production of $^7Li$ and $^{11}Li$. SN neutrino thus plays an essential role in constraining chemical evolutin of the light elements. We discuss that the neutrino-processes help understand the origin of the Spite-plateau of $^7Li$ observed in metal-deficient halo stars, which makes the biggest uncertainties in the determination of $\Omega_b$ from the BBN. Thirdly, we propose a theoretical model of disappearing cold dark matter model of SUSY particles in brane world cosmology, and discuss how the BBN constraints allow this model, satisfying many other observational constraints from CMB anisotropies, Type Ia supernova magnitude-redshift relation, galaxy M/L ratios, and galaxy gas-fractions. We finally discuss other possible improvements in nuclear reaction rates which have common significance both in BBN and SN r-process where the neutrino processes again play the important role. [Preview Abstract] |
Sunday, September 18, 2005 2:30PM - 3:00PM |
2WG.00002: Supernova Neutrinos and Nucleosynthesis of Light Elements Invited Speaker: During supernova explosions, a huge amount of neutrinos are emitted from the proto-neutron star. The neutrinos interact with nuclei in the supernova ejecta and change the compositions. This is called the neutrino-process. The neutrino-process plays an important role for $^{11}$B and $^{7}$Li production in supernovae and the amounts of $^{11}$B and $^{7}$Li strongly depend on the characteristics of supernova neutrinos, such as the total neutrino energy and the neutrino spectra. The continuous $^{11}$B and $^{7}$Li production in supernovae contributes to Galactic chemical evolution of the light elements. In this workshop, we show the dependence of the yields of $^{11}$B and $^{7}$Li in supernovae on the characteristics of supernova neutrinos such as the total neutrino energy and the neutrino energy spectra. Then, we constrain the supernova neutrino spectra from recent Galactic chemical evolution models of light elements. It is known that neutrino oscillation changes the energy spectra of supernova neutrinos during the neutrino propagation in the supernova ejecta. This change would also affect the yields of $^{11}$B and $^{7}$Li in supernovae. We also discuss the effect of the neutrino oscillation on the light element synthesis in supernova explosions. [Preview Abstract] |
Sunday, September 18, 2005 3:00PM - 3:30PM |
2WG.00003: Nucleosynthesis of rare heavy elements in supernova explosions Invited Speaker: The origin of the p-nuclei among heavy elements has been discussed for long years. Analyzing the solar system abundances, we have found the empirical scaling laws concerning the p- and s-nuclei with the same atomic number. The abundance ratio of s- and p- nuclei is almost constant with a wide range of the atomic number. In addition, the ratio of two p-nuclei with the same atomic number is also constant. They are an evidence that twenty-seven p-nuclei are dominantly synthesized by the p-process in SNe. We have calculated the ratios by a Type II SN model and the results have reproduced these scalings. The other eight p-nuclei may be synthesized by different processes such as the $\nu$-process. We have proposed two novel concepts of universality of the p- process and a new nuclear cosmochronometer of the p-process, which are based on the scalings. We also report the experimental study using thermal neutrons provided by nuclear reactors for the $^{187}$Re-$^{187}$Os cosmochronometer of the r-process. Co-authors: Toshiyuki Shizuma, Nobuyuki Iwamoto, Satoshi Chibam, Tuneo Nakagawa, Nobuo Shinohara, Toshitaka Kajino, National Astronomical Observatory; Hideyuki Umeda, Ken'ichi Nomoto, University of Tokyo. [Preview Abstract] |
Sunday, September 18, 2005 3:30PM - 4:00PM |
2WG.00004: Simultaneous Matter-Enhanced Transformation of Neutrinos and Antineutrinos in Astrophysical Environments Invited Speaker: The neutrino flavor evolution problem in supernovae is notoriously difficult. We point out a simple neutrino energy-independent solution in a specific limiting case that corresponds closely to some of the ``synchronization'' solutions seen numerically. Neutrino-neutrino forward scattering produces both flavor diagonal and off-diagonal potentials for neutrinos propagating coherently above the proto-neutron star in supernovae and in the early universe. We show that both the active neutrinos ($\nu_e$,$\nu_\mu$,$\nu_\tau$)and the corresponding antineutrinos can be maximally mixed in medium over broad ranges of neutrino energy when the flavor off-diagonal potential is large compared to the neutrino-matter potential. With this simple criterion we can identify epochs in the evolution of the supernova environment where large neutrino and antineutrino mixing can occur. We discuss the effects of this on shock re-heating and r-process nucleosynthesis models and on the expected neutrino signal. [Preview Abstract] |
Sunday, September 18, 2005 4:00PM - 4:30PM |
2WG.00005: Neutrinos At The Heart Of Gamma Ray Bursts Invited Speaker: The identification of redshifts in the optical afterglows of long-duration gamma-ray bursts (GRB) has settled the dispute of their location in favor of an origin at cosmological distances. Other observational evidence points towards their association with the death throws of massive stars. This has led many to posit that the most plausible model for the GRB central engine is the formation of a stellar mass black hole and an accretion disk at the center of a collapsing massive star. The accretion disk cools by neutrino emission and successful explosions may, in part, rely upon the ability to extract momentum and energy from the large neutrino luminosity. I present calculations for the energy/momentum transfer and discuss their implications for these GRB models. [Preview Abstract] |
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