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arXiv 1710.08910astro-ph.COhep-ph
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稀密轴子星

Dilute and dense axion stars

Luca Visinelli, Sebastian Baum, Javier Redondo, Katherine Freese, Frank Wilczek

备注：
11 pages, 4 figures. v2: added references, matches published version
发表信息：
Phys.Lett.B 777 (2018) 64-72
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摘要：

轴子星是由轴子形成的假想天体，通过经典运动方程的局部相干振荡解获得。取决于核心$|θ_0| \equiv |θ(r=0)|$处的场振幅的值，系统的平衡来自于动压与自引力或轴子自相互作用的平衡。从广义相对论框架出发，我们得到了一组描述轴子星的配置的方程，我们解决作为一个函数的$|θ_0|$。对于小的$|θ_0| \lesssim 1$，我们重现以前在文献中得到的结果，我们提供的第一原理的参数，这种配置的稳定性。我们比较定性的分析结果与数值计算。对于大振幅的$|θ_0| \gtrsim 1$，轴子场探测到完全的非谐QCD手征势，轴子星进入{ \it稠密}分支。我们的数值解表明，在后一种制度的轴子是相对论的，不应该使用一个单一的频率近似，如以前在文献中应用。我们采用多谐展开来求解恒星中轴子场的相对论方程，并证明了在稠密区域中高阶模是不可忽略的。我们解释的解决方案，在密集的制度作为伪呼吸，并表明，这种配置的寿命比任何宇宙学的时间尺度小得多。

英文摘要：

Axion stars are hypothetical objects formed of axions, obtained as localized and coherently oscillating solutions to their classical equation of motion. Depending on the value of the field amplitude at the core $|θ_0| \equiv |θ(r=0)|$, the equilibrium of the system arises from the balance of the kinetic pressure and either self-gravity or axion self-interactions. Starting from a general relativistic framework, we obtain the set of equations describing the configuration of the axion star, which we solve as a function of $|θ_0|$. For small $|θ_0| \lesssim 1$, we reproduce results previously obtained in the literature, and we provide arguments for the stability of such configurations in terms of first principles. We compare qualitative analytical results with a numerical calculation. For large amplitudes $|θ_0| \gtrsim 1$, the axion field probes the full non-harmonic QCD chiral potential and the axion star enters the {\it dense} branch. Our numerical solutions show that in this latter regime the axions are relativistic, and that one should not use a single frequency approximation, as previously applied in the literature. We employ a multi-harmonic expansion to solve the relativistic equation for the axion field in the star, and demonstrate that higher modes cannot be neglected in the dense regime. We interpret the solutions in the dense regime as pseudo-breathers, and show that the life-time of such configurations is much smaller than any cosmological time scale.

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。

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