Nucleosynthesis of Light and Heavy Elements in Baryon-Rich Outflows Associated with Gamma-Ray Bursts

Gamma-ray bursts (GRBs) must originate from low baryon load, ultrarelativistic outflows; however, slower, more baryon-rich outflows (BROs) should also arise in connection with GRBs as ``circum-jet winds'' and/or ``failed GRBs''. We study the possibility of nucleosynthesis within such BROs by conducting detailed reaction network calculations in the framework of the fireball model, showing that they can be interesting sites for synthesis of heavy neutron capture elements, as well as of light elements such as deuterium. These products may be observable in the companion stars of black hole binary systems or in extremely metal-poor stars, offering an interesting probe of conditions in the central engine.Comment: 5 pages, 2 figures, slightly modified version of article to be published in Proc. of "GRBs in the Afterglow Era: 3rd Workshop (Rome 2002)

Nucleosynthesis in Baryon-Rich Outflows Associated With Gamma-Ray Bursts

Robust generation of gamma-ray bursts (GRBs) implies the formation of outflows with very low baryon loads and highly relativistic velocities, but more baryon-rich, slower outflows are also likely to occur in most GRB central engine scenarios, either as ``circum-jet winds'' or ``failed GRBs''. Here we study the possibility of nucleosynthesis within such baryon-rich outflows by conducting detailed reaction network calculations in the framework of the basic fireball model. It is shown that high baryon load fireballs attaining mildly relativistic velocities can synthesize appreciable quantities of heavy neutron capture elements with masses up to the platinum peak and beyond. Small but interesting amounts of light elements such as deuterium and boron can also be produced. Depending on the neutron excess and baryon load, the combination of high entropy, rapid initial expansion and gradual expansion at later times can cause the reaction flow to reach the fission regime, and its path can be intermediate between those of the $r$- and $s$-processes (``$n$-process''). The nucleosynthetic signature of these outflows may be observable in the companion stars of black hole binary systems and in the most metal-poor stars, potentially offering an important probe of the inner conditions of the GRB source. Contribution to the solar abundances for some heavy elements may also be possible. The prospects for further developments in various directions are discussed.Comment: ApJ, in press; 11 pages, 3 figure

Intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 cooperatively contribute to the cutaneous Arthus reaction

金沢大学大学院医学系研究科血管分子科学Immune complex (IC)-induced inflammation is mediated by inflammatory cell infiltration, a process that is highly regulated by expression of multiple adhesion molecules. The roles and interactions of ICAM-1 and VCAM-1, the major regulators of leukocyte firm adhesion, were examined in the cutaneous reverse-passive Arthus reaction using ICAM-1-deficient (ICAM-1-/-) mice and blocking mAb against VCAM-1. Within 8 h, IC challenge of wild-type mice induced edema, hemorrhage, interstitial accumulation of neutrophils and mast cells, as well as production of TNF-α and IL-6. All of these inflammatory parameters were reduced significantly in ICAM-1-/- mice. The blockade of VCAM-1 in wild-type mice did not affect any inflammatory parameters. In contrast, ICAM-1-/- mice treated with anti-VCAM-1 mAb had significantly reduced edema, hemorrhage, and neutrophil infiltration. Furthermore, VCAM-1 blockade in ICAM-1-/- mice suppressed cutaneous TNF-α and IL-6 production. Thus, VCAM-1 plays a complementary role to ICAM-1 in the cutaneous Arthus reaction by regulating leukocyte accumulation and proinflammatory cytokine production. © Society for Leukocyte Biology

Cosmolgical Phase Transition and Inhomogeneous Primordial Nucleosynthesis

We study the quark-hadron phase transition in the early Universe and the effect of baryon density inhomogeneities that emerge from this transition on primordial nucleosynthesis. We try to make clear the relation between the QCD parameters and the astronomical observable and to find the observational constraints on these parameters. We calculate the amplitude of baryon-number fluctuations and the mean separation distance between fluctuations using the finite temperature effective theory. We then analyze primordial nucleosynthesis in an environment with these inhomogeneous distribution of baryon density and compare the predicted elemental abundance with observation. Through the comparison of these calculation with the observation, we discuss the sensitivity of elemental abundance to the physical condition of baryon density inhomogeneities. We first estimate the nucleation rate of hadron bubble during the supercooling epoch and study the evolution of baryon-number density at the constant-temperature coexistence epoch. We calculate the baryon permeability through the phase boundary using the chromoelectric flux tube model. In this calculation, we consider the temperature dependence of the constituent quark mass and that of the string tension suggested from lattice QCD simulation. We find that although the flux of baryons evaporating from QGP is strongly depend on the quark mass and string tension at critical temperature, this flux is still sufficiently small, suggesting that the baryon number is no easily transferred from QGP to hadron phase. For realistic value of quark mass and string tension, the resultant amplitude of baryon density fluctuation is very huge and have a significant effect on primordial nucleosynthesis yields. We then study the inhomogeneous primordial nucleosynthesis in order to compare with observational constraints. We consider the effects of fluctuation geometry on primordial nucleosynthesis. For the first time we consider condensed cylinder and cylindrical-shell fluctuation geometries in addition to condensed spheres and spherical shells. We also consider implications of the possible detection of a high D/H abundance in a Lyman-alpha absorption cloud at high redshift and implied chemical evolution effects of a high deuterium abundance. We find that a cylindrical shell geometry allows for an appreciably higher baryonic contribution to be the closure density (Ωb < 0.2) than that allowed in spherical inhomogeneous or standard homogeneous big bang model. We also find that inhomogeneous primordial nucleosynthesis in the cylindrical shell geometry can lead to significant Be and B production. [Be] = 12+log(Be/ H) 〓 -3 is possible while still satisfying all of the usually adopted light-element abundance constraints