The stability of nonrotating supermassive stars (M > 105 M⊙) in the presence of a small dark matter component is examined. We find that the destabilizing effects of first-order nonlinear corrections from general relativity can be neutralized when a significant amount of nonrelativistic dark matter is present. In this case, it is possible for supermassive stars to be stabilized through the hydrogen-burning stage. Significant mass loss in this epoch might result in the ejection of the nucleosynthesis products of hot hydrogen burning. Ultimately, however, the post-Newtonian instability can only be delayed. If this instability occurs after the hydrogen-burning epoch, collapse of the star to a black hole is guaranteed. Subject headings: dark matter - gravitation - instabilities nuclear reactions, nucleosynthesis, abundances - relativity - stars: interiors © 1996. The American Astronomical Society. All rights reserved.

The Mikheyev-Smirnov-Wolfenstein (MSW) resonant neutrino oscillation mechanism is investigated for the Sun using a detailed numerical solar model and a modified version of the Parke-Walker technique for following the neutrino phases through the oscillation resonance. We present overall solar-neutrino spectra and the associated expected neutrino count rates for the Cl37, Ga71, and Kamiokande detectors for ranges of masses and vacuum mixing angles for two neutrino species. We also investigate the effects of uncertainties in the solar model. In particular, we examine the effect of opacity changes on the expected solar-neutrino spectrum and resulting parameter space for the MSW mechanism. We find that plausible uncertainties in the standard solar model, and in particular the opacity, translate into significant expansion in the constraints on neutrino masses and vacuum mixing angles from neutrino experiments. It is shown, however, that forthcoming results from the Kamiokande solar-neutrino experiment could put stringent constraints on even the expanded MSW parameter space. © 1989 The American Physical Society.

We discuss general relativistic effects in the steady state neutrino-driven "wind" that may arise from nascent neutron stars. In particular, we generalize previous analytic estimates of the entropy per baryon S, the mass outflow rate M, and the dynamical expansion timescale τdyn. We show that S increases and τdyn decreases with increasing values of the mass-to-radius ratio describing the supernova core. Both of these trends indicate that a more compact core will lead to a higher number of neutrons per seed nucleus. Such an enhancement in the neutron/seed ratio may be required for successful r-process nucleosynthesis in neutrino-heated supernova ejecta. © 1997. The American Astronomical Society. All rights reserved.

We describe how thermally produced antielectron neutrinos (ν̄e) from the homologously collapsing core of a supermassive star (M ≳ 5 × 104 M⊙) can lead to significant deuterium enrichment in the ejected envelope of such a star. Deuterium-enriched material at high redshift might then serve as a clue to the existence of pregalactic supermassive stars. Conceivably, the ejected deuterium-enriched material could intercept the line of sight to a distant QSO and mimic a Lyman limit absorber. In such a case, the deuterium abundance inferred from absorption lines might not reflect the true primordial abundance of deuterium. We discuss relevant theoretical uncertainties in supermassive star physics as well as potential observational signatures in Lyα absorber clouds for processing by stars of this kind. © 1997. The American Astronomical Society. All rights reserved.

In this brief review we explore the role of neutrino-nucleus interactions in core-collapse supernovae and discuss open questions. In addition implications of neutrino mass and mixings in such environments are summarized.

We briefly review the recent developments in neutrino physics and astrophysics which have import for frontline research in nuclear physics. These developments, we argue, tie nuclear physics to exciting developments in observational cosmology and astrophysics in new ways. Moreover, the behavior of neutrinos in dense matter is itself a fundamental problem in many-body quantum mechanics, in some ways akin to well-known issues in nuclear matter and nuclei, and in some ways radically different, especially because of nonlinearity and quantum de-coherence. The self-interacting neutrino gas is the only many body system driven by the weak interactions. © 2013 Elsevier B.V. All rights reserved.

We explore the implications of imposing the constraint that two neutrino flavors (which for definiteness we take to be ν(μ) and ν(τ)) are similarly coupled to the mass basis in addition to the unitarity constraints. We allow three active and an arbitrary number of sterile neutrinos. We show that in this scheme one of the mass eigenstates decouples from the problem, reducing the dimension of the flavor space by one. This result allows significant simplification in the treatment of matter-enhanced neutrino transformation where multiple flavors and level crossings are involved. (C) 1999 Published by Elsevier Science B.V.

We examine the process of electron neutrino and electron antineutrino capture on nuclei with masses A > 40 in the context of the post-core-bounce supernova environment. We discuss the influence of final-state electron blocking, extended distributions of Gamow-Teller strength, and the Coulomb wave correction factor on neutrino and antineutrino capture rates. We study the effect of discrete state transitions and the thermal population of excited states on these rates. We estimate the strength of forbidden capture channels and discuss their importance in neutrino capture rate estimates. We find that forbidden strength can dominate the anti-neutrino capture rates on neutron-rich nuclei which are blocked and have no allowed transitions. Forbidden weak strength may be important in other cases of neutrino or antineutrino capture as well, depending on the excitation energy distribution of this strength. In addition, the importance of neutrino capture relative to anti-neutrino capture on both heavy nuclei and free nucleons is discussed. Formulae for calculating these rates in the context of the post-core-bounce supernova environment are presented. Tables of rates are provided for some key nuclei. A FORTRAN code for calculating rates is available on request.

We present a detailed numerical study of inhomogeneous big bang nucleosynthesis where, for the first time, nuclear reactions are coupled to all significant fluctuation dissipation processes. These processes include neutrino heat transport, baryon diffusion, photon diffusive heat transport, and hydrodynamic expansion with photon-electron Thomson drag. Light-clement abundance yields are presented for broad ranges of initial amplitudes and length scales for spherically condensed fluctuations. The 2H, 3He, 4He, and 7Li nucleosynthesis yields are found to be inconsistent with observationally inferred primordial abundances for all but very narrow ranges of fluctuation characteristics. Rapid hydrodynamic expansion of fluctuations late in the nucleosynthesis epoch results in significant destruction of 7Li (7Be) only if the baryonic contribution to the closure density (Ωb) is less than or comparable to the upper limit on this quantity from homogeneous big bang nucleosynthesis. This implies that 7Li overproduction will preclude an increase on the upperlimit for Ωb for any inhomogeneous nucleosynthesis scenario employing spherically condensed fluctuations.