On the morphologies, gas fractions, and star formation rates of small galaxies
On the morphologies, gas fractions, and star formation rates of small galaxies
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关于小星系的形态、气体组分和恒星形成率
DOI：
10.1111/j.1365-2966.2007.12436.x
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发表时间：
2007
影响因子：
4.8
通讯作者：
J. Bullock
中科院分区：
文献类型：
--
作者：
T. Kaufmann;Coral Wheeler;J. Bullock
我们使用一系列的N体/光滑粒子流体动力学模拟和分析参数，以表明在星际介质中的T F 10 4 K的有效温度地板的存在下，自然解释了低质量星系的倾向，更球状，更丰富的气体，和更低的效率转换重子成恒星比大星系。这种趋势的出现是因为在小的暗物质晕中，与角动量支持相比，气体压力支持变得重要。我们认为，矮星系的旋转速度超过40公里s-1不起源于薄盘，而是出生厚，蓬松的系统。如果被吸积到更大的晕上，这种纤细的矮星将比缩小的更大的螺旋更容易受到气体损失或潮汐变化的影响。对于一个恒定的温度地板，压力支持变得不那么重要，在大晕，这产生了一种趋势，大规模的孤立星系有更薄的磁盘和更有效的星星形成比他们的质量较小的同行，观察。
We use a series of N-body/smoothed particle hydrodynamics simulations and analytic arguments to show that the presence of an effective temperature floor in the interstellar medium at T F ∼ 10 4 K naturally explains the tendency for low-mass galaxies to be more spheroidal, more gas rich, and less efficient in converting baryons into stars than larger galaxies. The trend arises because gas pressure support becomes important compared to angular momentum support in small dark matter haloes. We suggest that dwarf galaxies with rotational velocities ∼ 40 km s -1 do not originate as thin discs, but rather are born as thick, puffy systems. If accreted on to larger haloes, tenuous dwarfs of this kind will be more susceptible to gas loss or tidal transformation than scaled-down versions of larger spirals. For a constant temperature floor, pressure support becomes less important in large haloes, and this produces a tendency for massive isolated galaxies to have thinner discs and more efficient star formation than their less-massive counterparts, as observed.