arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2408.03375astro-ph.GA
收藏

共同演化的暗物质晕在恒星棒形成中的主动作用

The active role of co-evolving haloes in stellar bar formation

Matthew Frosst, Danail Obreschkow, Aaron D. Ludlow

AI总结:

通过理想化N体模拟,该研究发现暗物质晕与盘的共同演化对边际不稳定盘中恒星棒的形成和长期存活至关重要,并指出静态晕条件下棒无法形成,现有盘稳定性判据需修正。

摘要:

我们利用活动晕与静态晕中平衡盘的理想化N体模拟,研究暗物质共同演化如何影响恒星粒子组装成棒结构以及暗晕的响应。初始条件对应于根据常用盘稳定性判据处于边际不稳定状态的盘,并演化约150个盘动力学时标(100亿年)。广泛的收敛性研究确保了棒形成过程的精确建模。活动晕导致强棒的形成,但同一个盘在静态晕中演化时则不会形成棒。无论是植入的盘不稳定性,还是更长时间(600亿年)的模拟,在晕为静态的情况下均未形成棒。当活动晕在后期被替换为静态等效晕时,先前稳健的棒会缓慢消散,这表明:(1)盘与晕的共同演化对于边际不稳定盘中棒的组装和长期存活至关重要;(2)对于存在活动晕的盘,全局盘稳定性判据必须加以修正。在我们的活动晕模拟中,一个“暗棒”与恒星棒同步增长。抑制晕与盘之间角动量转移的过程可能会使星系对棒的形成保持稳定,并可能导致棒本身的瓦解。这进一步引发了关于观测到的边际不稳定但无棒盘的令人费解的稳定性问题。

英文摘要:

We use idealised N-body simulations of equilibrium discs in live and static haloes to study how dark matter co-evolution impacts the assembly of stellar particles into a bar and the halo response. Initial conditions correspond to a marginally unstable disc according to commonly used disc stability criteria, and are evolved for the equivalent of about 150 disc dynamical times (10Gyr). An extensive convergence study ensures accurate modelling of the bar formation process. Live haloes lead to the formation of a strong bar, but the same disc remains unbarred when evolved in a static halo. Neither seeded disc instabilities, nor longer (60Gyr) simulations result in the formation of a bar when the halo is static. When the live halo is replaced with a static analogue at later times the previously robust bar slowly dissipates, suggesting: (1) the co-evolution of the disc and halo is critical for the assembly and long-term survival of bars in marginally unstable discs; and (2) global disc stability criteria must be modified for discs in the presence of live haloes. In our live halo runs, a "dark bar" grows synchronously with the stellar bar. Processes that inhibit the transfer of angular momentum between the halo and disc may stabilise a galaxy against bar formation, and can lead to the dissolution of the bar itself. This raises further questions about the puzzling stability of observed discs that are marginally unstable, but unbarred.

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。

↑