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arXiv 1008.0348astro-ph.CO
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暗星和增强的暗物质湮灭率

Dark Stars and Boosted Dark Matter Annihilation Rates

Cosmin Ilie, Katherine Freese, Douglas Spolyar

摘要:

暗星(DS)可能构成了恒星演化的第一阶段,由暗物质(DM)湮灭提供动力。假设DM粒子具有解释PAMELA和FERMI卫星探测到的宇宙射线中过量正电子和负电子信号所需的性质,我们将在这里研究DS的性质。这些信号的任何可能的DM解释都需要外来DM候选者,其湮没截面比弱相互作用暗物质的正确热遗迹丰度所需的规范值高几个数量级;此外,在大多数模型中,湮没必须优先于轻子。其次,我们研究了第一批恒星形成的晕的初始DM密度分布的浓度参数对DS性质的依赖关系。我们限制我们的研究DM在恒星由于简单的(与扩展)绝热收缩和最小的(与扩展)捕获,这个简单的研究足以说明依赖的截面和浓度参数。我们的基本结果是,当恒星进入主序时,无论增强湮灭或浓度参数在c=2和c=5之间的值如何,最终的恒星性质总是大致相同的:恒星质量~ 1000 M \odot,光度~ 10^7 L \odot,寿命~ 10^6年(对于这里考虑的最小DM模型;额外的DM将导致更大质量的暗星)。然而,寿命,最终质量和最终亮度的DS表现出一定的依赖性的助推因子和浓度参数的文件中讨论的。

英文摘要:

Dark Stars (DS) may constitute the first phase of stellar evolution, powered by dark matter (DM) annihilation. We will investigate here the properties of DS assuming the DM particle has the required properties to explain the excess positron and elec- tron signals in the cosmic rays detected by the PAMELA and FERMI satellites. Any possible DM interpretation of these signals requires exotic DM candidates, with an- nihilation cross sections a few orders of magnitude higher than the canonical value required for correct thermal relic abundance for Weakly Interacting Dark Matter can- didates; additionally in most models the annihilation must be preferentially to lep- tons. Secondly, we study the dependence of DS properties on the concentration pa- rameter of the initial DM density profile of the halos where the first stars are formed. We restrict our study to the DM in the star due to simple (vs. extended) adiabatic contraction and minimal (vs. extended) capture; this simple study is sufficient to illustrate dependence on the cross section and concentration parameter. Our basic results are that the final stellar properties, once the star enters the main sequence, are always roughly the same, regardless of the value of boosted annihilation or concentration parameter in the range between c=2 and c=5: stellar mass ~ 1000M\odot, luminosity ~ 10^7 L\odot, lifetime ~ 10^6 yrs (for the minimal DM models considered here; additional DM would lead to more massive dark stars). However, the lifetime, final mass, and final luminosity of the DS show some dependence on boost factor and concentration parameter as discussed in the paper.

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