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arXiv 1809.07673astro-ph.GA
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模糊暗物质晕中的弛豫

Relaxation in a Fuzzy Dark Matter Halo

Ben Bar-Or, Jean-Baptiste Fouvry, Scott Tremaine

摘要:

暗物质可能是由轻玻色子组成,${m_b \sim 10^{-22}\, \mathrm{eV}}$,在典型的星系势中具有德布罗意波长$λ\sim 1 \,\mathrm{kpc}$。这种“模糊的”暗物质(FDM)在比德布罗意波长大得多的尺度上表现得像冷暗物质(CDM),但可能解决CDM在解释小尺度星系($\lesssim 10\,\mathrm{kpc}$)性质时所面临的一些挑战。由于它的波动性质,FDM在德布罗意波长尺度上表现出随机密度波动,永不衰减。这些波动产生的引力场会散射恒星和黑洞,导致它们的轨道在相空间中扩散。我们表明,这种弛豫过程可以定量分析与用于分析经典的两体弛豫在$N$体系统中的相同的工具,并可以通过治疗FDM波动作为准粒子,与有效质量$\sim 10^7 M_\odot {(1\,\mathrm{kpc}/r)}^2{(10^{-22}\,\mathrm{eV}/m_b)}^3$在一个星系中的恒定圆周速度$200\,\mathrm{kms}$。这种新的弛豫机制可以使超大质量黑洞或球状星团的内旋在几百pc的半径处由于动力学摩擦而停止,并且可以加热和膨胀星系的中心区域。这些过程可以用来限制可能构成FDM的轻玻色子的质量。

英文摘要:

Dark matter may be composed of light bosons, ${m_b \sim 10^{-22}\, \mathrm{eV}}$, with a de Broglie wavelength $λ\sim 1 \,\mathrm{kpc}$ in typical galactic potentials. Such `fuzzy' dark matter (FDM) behaves like cold dark matter (CDM) on much larger scales than the de Broglie wavelength, but may resolve some of the challenges faced by CDM in explaining the properties of galaxies on small scales ($\lesssim 10\,\mathrm{kpc}$). Because of its wave nature, FDM exhibits stochastic density fluctuations on the scale of the de Broglie wavelength that never damp. The gravitational field from these fluctuations scatters stars and black holes, causing their orbits to diffuse through phase space. We show that this relaxation process can be analyzed quantitatively with the same tools used to analyze classical two-body relaxation in an $N$-body system, and can be described by treating the FDM fluctuations as quasiparticles, with effective mass $\sim 10^7 M_\odot {(1\,\mathrm{kpc}/r)}^2{(10^{-22}\,\mathrm{eV}/m_b)}^3$ in a galaxy with a constant circular speed of $200\,\mathrm{kms}$. This novel relaxation mechanism may stall the inspiral of supermassive black holes or globular clusters due to dynamical friction at radii of a few hundred pc, and can heat and expand the central regions of galaxies. These processes can be used to constrain the mass of the light bosons that might comprise FDM.

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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