Hydrodynamical N-body simulations of coupled dark energy cosmologies
Hydrodynamical N-body simulations of coupled dark energy cosmologies
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DOI：
10.1111/j.1365-2966.2009.15987.x
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发表时间：
2008-12
影响因子：
4.8
通讯作者：
M. Baldi;V. Pettorino;G. Robbers;V. Springel
中科院分区：
文献类型：
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作者：
M. Baldi;V. Pettorino;G. Robbers;V. Springel
如果宇宙在当前时期的加速膨胀是由暗能量标量场驱动的，那么暗能量和冷暗物质（CDM）流体之间很可能存在非平凡的耦合。这种相互作用在宇宙学结构增长中产生了新的特征，例如CDM粒子之间的额外长程吸引力，或暗物质粒子质量随时间的变化。我们已经实现了这些影响的N体代码GADGET-2，并提出了一系列的高分辨率N体模拟的结果，其中暗能量分量直接与CDM相互作用。作为新物理学的结果，CDM和重子分布在线性和非线性结构形成机制中的演化是不同的。在大尺度上，这两个分量之间已经形成了线性偏差，非线性演变进一步增强了这种偏差。我们还发现，与以前的工作相比，CDM晕的密度分布是不太集中在耦合暗能量宇宙学相比，ACDM，这一功能不依赖于初始条件设置，但耦合引起的额外的物理的一个特定的后果。此外，在耦合模型中的晕重子分数显着降低低于通用重子分数。这些特征缓解了小尺度上观测与ACDM模型之间的紧张关系。我们的方法非常适合探索耦合暗能量模型的预测在完全非线性制度，这可以提供强大的约束，这种情况下的可行的参数空间。
If the accelerated expansion of the Universe at the present epoch is driven by a dark energy scalar field, there may well be a non-trivial coupling between the dark energy and the cold dark matter (CDM) fluid. Such interactions give rise to new features in cosmological structure growth, like an additional long-range attractive force between CDM particles, or variations of the dark matter particle mass with time. We have implemented these effects in the N-body code GADGET-2 and present results of a series of high-resolution N-body simulations where the dark energy component is directly interacting with the CDM. As a consequence of the new physics, CDM and baryon distributions evolve differently both in the linear and in the non-linear regime of structure formation. Already on large scales, a linear bias develops between these two components, which is further enhanced by the non-linear evolution. We also find, in contrast with previous work, that the density profiles of CDM haloes are less concentrated in coupled dark energy cosmologies compared with ACDM, and that this feature does not depend on the initial conditions setup, but is a specific consequence of the extra physics induced by the coupling. Also, the baryon fraction in haloes in the coupled models is significantly reduced below the universal baryon fraction. These features alleviate tensions between observations and the ACDM model on small scales. Our methodology is ideally suited to explore the predictions of coupled dark energy models in the fully non-linear regime, which can provide powerful constraints for the viable parameter space of such scenarios.