Effects of transient non-thermal particles on the big bang nucleosynthesis

Abstract

The effects of introducing a small amount of non-thermal distribution (NTD) of elements in big bang nucleosynthesis (BBN) are studied by allowing a fraction of the NTD to be time-dependent so that it contributes only during a certain period of the BBN evolution. The fraction is modeled as a Gaussian-shaped function of $\log (T)$, where $T$ is the temperature of the cosmos, and thus the function is specified by three parameters; the central temporal position, the width and the magnitude. The change in the average nuclear reaction rates due to the presence of the NTD is assumed to be proportional to the Maxwellian reaction rates but with temperature $T_{\mathrm{NTD}}\equiv \zeta T$, $\zeta$ being another parameter of our model. By scanning a wide four-dimensional parametric space at about half a million points, we have found about 130 points with ${\chi }^2<1$, at which the predicted primordial abundances of light elements are consistent with the observations. The magnitude parameter ${\epsilon }_0$ of these points turns out to be scattered over a very wide range from ${\epsilon }_0\sim 10^{-19}$ to $\sim 10^{-1}$, and the $\zeta$-parameter is found to be strongly correlated with the magnitude parameter ${\epsilon }_0$. The temperature region with $0.3\times 10^9 \mbox{K} \lesssim T \lesssim 0.4\times 10^9 \mbox{K}$ or the temporal region $t\simeq 10^3$ s seems to play a central role in lowering ${\chi }^2$.

References in corpus (18)

• First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Determination of Cosmological Parameters
• Planck 2013 results. XVI. Cosmological parameters
• Big-Bang Nucleosynthesis
• Big Bang Nucleosynthesis: 2015
• Primordial Nucleosynthesis in the Precision Cosmology Era
• Big Bang nucleosynthesis and physics beyond the Standard Model
• Primordial Nucleosynthesis: from precision cosmology to fundamental physics
• The Primordial Lithium Problem
• Lithium isotopic abundances in metal-poor halo stars
• A Bitter Pill: The Primordial Lithium Problem Worsens
• A probable stellar solution to the cosmological lithium discrepancy
• The metal-poor end of the Spite plateau. 1: Stellar parameters, metallicities and lithium abundances
• Big Bang Nucleosynthesis and Particle Dark Matter
• Reappraising the Spite Lithium Plateau: Extremely Thin and Marginally Consistent with WMAP
• Gravitino Dark Matter and the Cosmic Lithium Abundances
• Modified big bang nucleosynthesis with non-standard neutron sources
• Big Bang nucleosynthesis with a non-Maxwellian distribution
• Cosmic Rays during BBN as Origin of Lithium Problem