Nucleosynthesis in the presence of primordial isocurvature baryon fluctuations
- Physics Research Program, Institute for Geophysics and Planetary Physics, University of California, Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)
- Department of Physics, University of California, San Diego, La Jolla, California 92093-0319 (United States)
We study big bang nucleosynthesis in the presence of large mass scale, nonlinear entropy fluctuations. Overdense regions, with masses above the local baryon Jeans mass, are expected to collapse and form condensed objects. Surviving nucleosynthesis products therefore tend to originate from underdense regions. We compute expected survival light-element ({sup 2}H, {sup 3}He, {sup 4}He, and {sup 7}Li) abundance yields for a variety of stochastic fluctuation spectra. In general, we find that spectra with significant power in fluctuations on mass scales below that of the local baryon Jeans mass ({approximately}10{sup 5} {ital M}{sub {circle_dot}}) produce nucleosynthesis yields which are in conflict with observationally inferred primordial abundances. Only when this small-scale structure is absent or suppressed, and the collapse efficiency of overdense regions is high, can there exist a range of fluctuation spectral characteristics which conceivably could meet all primordial abundance constraints. Even then, the primordial abundance of {sup 7}Li would have to be larger than {sup 7}Li/H{approx_equal}3{times}10{sup {minus}10}. In such models, abundance constraints could be met even when the precollapse baryonic fraction of the closure density is {Omega}{sub {ital b}}{approx_equal}0.2 {ital h}{sup {minus}2} ({ital h} is the Hubble parameter in units of 100 kms{sup {minus}1} Mpc{sup {minus}1}). Nucleosynthesis in these models is characterized by high {sup 2}H/H and low {sup 4}He mass fraction relative to a homogeneous big bang at a given value of {Omega}{sub {ital b}} {ital h}{sup 2}. A potentially observable signature of these models is the production of intrinsic primordial abundance variations on baryon mass scales up to 10{sup 10}{minus}10{sup 12} {ital M}{sub {circle_dot}}. {copyright} {ital 1995 The American Astronomical Society.}
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 281997
- Journal Information:
- Astrophysical Journal, Vol. 452, Issue 1; Other Information: PBD: Oct 1995
- Country of Publication:
- United States
- Language:
- English
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