标题： 宇宙流体的随时间变化的绝热指数的Darboux类 显示英文标题

标题： Darboux class of cosmological fluids with time-dependent adiabatic indices

摘要： 引入了一个单参数的随时间变化的绝热指数族，这是通过属于Darboux变换类的数学方法，针对任何给定类型的常数绝热指数宇宙流体。该方法在零宇宙学常数的情况下，需要引入一个与绝热指数的时间依赖性相关的新的常数参数。这些流体可以是宇宙尺度上遇到的真实宇宙流体，它们可以作为对当前加速宇宙的近期实验发现的一种简单而有效的解释。此外，还提出了与这些流体相对应的新类型宇宙标度因子。 显示英文摘要

摘要： A one-parameter family of time dependent adiabatic indices is introduced for any given type of cosmological fluid of constant adiabatic index by a mathematical method belonging to the class of Darboux transformations. The procedure works for zero cosmological constant at the price of introducing a new constant parameter related to the time dependence of the adiabatic index. These fluids can be the real cosmological fluids that are encountered at cosmological scales and they could be used as a simple and efficient explanation for the recent experimental findings regarding the present day accelerating universe. In addition, new types of cosmological scale factors, corresponding to these fluids, are presented