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arXiv 0901.4104astro-ph.CO
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类星体性质与高红移暗物质晕性质联系的一个简单模型

A simple model to link the properties of quasars to the properties of dark matter halos out to high redshift

Darren J. Croton

摘要:

我们提出了一个简单的模型,如何类星体占据暗物质晕从z=0到z=5使用所观察到的mBH-西格玛关系和类星体的光度函数。这为观测者提供了一种方法,可以单独使用光度和红移来统计推断类星体观测的宿主晕质量。我们的模型故意简单,回避了任何明确描述物理的需要。尽管它很简单,但模型再现了许多关键观测,并具有预测能力:1)模型类星体具有正确的光度函数(按建筑)和空间集群(2)我们预测了在一定光度下的高红移类星体比同样光度的低红移类星体生活在质量较小的暗物质晕中; 3)我们预测在z~2处的10^8.5 Msun黑洞比目前观测到的多5倍:4)我们预测在z=5和现在之间mBH-Mhalo关系的振幅演化是20倍; 5)我们预计类星体的寿命与光度有关,在tQ~10^(7-8)年之间,但对于比L* 亮的类星体,寿命可能短至10^(5-6)年; 6)当z<1时,团簇演化与光度的关系不大,而当z>L* 时,团簇演化随红移的增加而增强。最后两个结果来自于类星体随着宇宙年龄的增长而占据的晕质量的分布变窄。我们还解构了在不同的红移和空间密度的模型预测的“缩小”和“扩大”的趋势。重要的是,这项工作说明了目前的观测无法区分更复杂的物理动机类星体模型和我们简单的现象学方法。它强调了此类方法提供的机会。

英文摘要:

We present a simple model of how quasars occupy dark matter halos from z=0 to z=5 using the observed mBH-sigma relation and quasar luminosity functions. This provides a way for observers to statistically infer host halo masses for quasar observations using luminosity and redshift alone. Our model is deliberately simple and sidesteps any need to explicitly describe the physics. In spite of its simplicity, the model reproduces many key observations and has predictive power: 1) model quasars have the correct luminosity function (by construction) and spatial clustering (by consequence); 2) we predict high redshift quasars of a given luminosity live in less massive dark matter halos than the same luminosity quasars at low redshifts; 3) we predict a factor of ~5 more 10^8.5Msun black holes at z~2 than is currently observed; 4) we predict a factor of ~20 evolution in the amplitude of the mBH-Mhalo relation between z=5 and the present day; 5) we expect luminosity dependent quasar lifetimes of between tQ~10^(7-8)yr, but which may become as short as 10^(5-6)yr for quasars brighter than L*; 6) while little luminosity dependent clustering evolution is expected at z<1, increasingly strong evolution is predicted for L>L* quasars at higher redshifts. These last two results arise from the narrowing distribution of halo masses that quasars occupy as the Universe ages. We also deconstruct both "downsizing" and "upsizing" trends predicted by the model at different redshifts and space densities. Importantly, this work illustrates how current observations cannot distinguish between more complicated physically motivated quasar models and our simple phenomenological approach. It highlights the opportunities such methodologies provide.

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