修正引力中碰撞气体的球形吸积I：自相似解和一个新的宇宙学流体动力学代码
Spherical accretion of collisional gas in modified gravity I: self-similar solutions and a new cosmological hydrodynamical code
摘要：
球形坍缩的场景在宇宙学中具有重要意义，因为它捕捉了结构形成的几个关键方面。Einstein-de Sitter（EdS）模型中自相似解的存在极大地简化了其分析，使其成为一个强有力的工具，以获得对涉及星系形成的真实和更复杂的物理过程的有价值的见解。虽然已经有大量的研究将各种额外的物理过程纳入球形坍缩，但在这种情况下，修正的重力（MG）模型的效果仍然没有得到很好的理解，MG模型是$ΛCDM$范式的流行替代品，可以解释宇宙加速。在本文中，我们研究了一个特殊的MG模型中碰撞气体的球形吸积，这是一个罕见的情况下，也承认自相似的解决方案。该模型显示了由重力增强和筛选机制引起的有趣行为。尽管MG的强大的影响，我们发现，其自相似的解决方案，以及同意的EdS模型。这些结果被用来评估一个新的宇宙学流体动力学代码的球形崩溃模拟介绍这里，这是基于双曲型偏微分方程引擎ExaHyPE 2。其良好的协议与理论预测证实了这个程序的可靠性，在模拟天体物理过程中的球形坍缩。我们将使用此代码来研究更现实的MG模型在未来的工作中的气体的演变。
英文摘要：
The spherical collapse scenario has great importance in cosmology since it captures several crucial aspects of structure formation. The presence of self-similar solutions in the Einstein-de Sitter (EdS) model greatly simplifies its analysis, making it a powerful tool to gain valuable insights into the real and more complicated physical processes involved in galaxy formation. While there has been a large body of research to incorporate various additional physical processes into spherical collapse, the effect of modified gravity (MG) models, which are popular alternatives to the $ΛCDM$ paradigm to explain the cosmic acceleration, is still not well understood in this scenario. In this paper, we study the spherical accretion of collisional gas in a particular MG model, which is a rare case that also admits self-similar solutions. The model displays interesting behaviours caused by the enhanced gravity and a screening mechanism. Despite the strong effects of MG, we find that its self-similar solution agrees well with that of the EdS model. These results are used to assess a new cosmological hydrodynamical code for spherical collapse simulations introduced here, which is based on the hyperbolic partial differential equation engine ExaHyPE 2. Its good agreement with the theoretical predictions confirms the reliability of this code in modelling astrophysical processes in spherical collapse. We will use this code to study the evolution of gas in more realistic MG models in future work.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
