We extend the model of a 5D Brans–Dicke gravity theory reduced to 4D through the presence of a hypersurface-orthogonal space-like killing vector field in the underlying 5D spacetime by including a varying speed of light. The resulting model is characterized by the presence of two scalar fields. We focus on late-time power law solutions which emerge in general when scalar fields couple to spacetime curvature and do not contradict the SNIa astrophysical data. Analytic solutions in 4-dimensions are derived and late-time accelerated expansion was found. The universe is dominated by dark energy, free from phantom field and is characterized by a decaying energy matter density, decaying scalar fields, and a decreasing celerity of light. The model is confronted with astrophysical observations and is found to fit these data.

中文翻译：

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由不同光速支配的五维布兰斯-迪克致密化宇宙

我们通过包含变化的光速，通过在底层 5D 时空中存在超表面正交类空间杀伤矢量场，将 5D Brans-Dicke 引力理论模型扩展为 4D。所得模型的特点是存在两个标量场。我们专注于当标量场与时空曲率耦合并且与 SNIa 天体物理数据不矛盾时通常出现的后期幂律解决方案。导出了4维解析解，发现了后期加速膨胀。宇宙以暗能量为主，没有幻象场，其特征是能量物质密度衰减，标量场衰减，光速下降。该模型面临天体物理观测，并被发现适合这些数据。