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arXiv 1106.0499astro-ph.COastro-ph.GA
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超新星反馈如何将暗物质尖点变成核心

How supernova feedback turns dark matter cusps into cores

Andrew Pontzen, Fabio Governato

备注：
9 pages, 6 figures, accepted by MNRAS. No change in results. Expanded discussion and more references
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摘要：

我们提出并成功地测试对新的宇宙学模拟的物理过程与核心暗物质密度分布的起源一种新的分析描述。在模拟中，中心千秒差距内的势能在红移区间4 > z > 2内的亚动力学时间尺度上发生变化，因为重复的能量反馈会从恒星形成的中心集中爆发中产生膨胀气体的大的低密度气泡。该模型演示了中心势的波动如何不可逆地将能量转移到无碰撞粒子中，从而产生一个暗物质核心。因此，经历崩溃和快速膨胀的天然气供应是必不可少的成分。该框架，基于一种新的脉冲近似，打破了依赖绝热近似，这是不适当的快速变化的限制。它表明，外流和星系喷泉都可以引起尖点平坦化，即使只有百分之几的重子形成恒星。矮星系的核心一直保持到现在。该模型表明，恒定密度的暗物质核心将产生在一个广泛的质量范围内的系统，如果中央星暴或活动星系核阶段是足够频繁和充满活力。

英文摘要：

We propose and successfully test against new cosmological simulations a novel analytical description of the physical processes associated with the origin of cored dark matter density profiles. In the simulations, the potential in the central kiloparsec changes on sub-dynamical timescales over the redshift interval 4 > z > 2 as repeated, energetic feedback generates large underdense bubbles of expanding gas from centrally-concentrated bursts of star formation. The model demonstrates how fluctuations in the central potential irreversibly transfer energy into collisionless particles, thus generating a dark matter core. A supply of gas undergoing collapse and rapid expansion is therefore the essential ingredient. The framework, based on a novel impulsive approximation, breaks with the reliance on adiabatic approximations which are inappropriate in the rapidly-changing limit. It shows that both outflows and galactic fountains can give rise to cusp-flattening, even when only a few per cent of the baryons form stars. Dwarf galaxies maintain their core to the present time. The model suggests that constant density dark matter cores will be generated in systems of a wide mass range if central starbursts or AGN phases are sufficiently frequent and energetic.

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