Brito Richard, Ghosh Shrobana, Barausse Enrico, Berti Emanuele, Cardoso Vitor, Dvorkin Irina, Klein Antoine, Pani Paolo
Max Planck Institute for Gravitational Physics (Albert Einstein Institute), Am Mühlenberg 1, Potsdam-Golm 14476, Germany.
Department of Physics and Astronomy, The University of Mississippi, University, Mississippi 38677, USA.
Phys Rev Lett. 2017 Sep 29;119(13):131101. doi: 10.1103/PhysRevLett.119.131101. Epub 2017 Sep 27.
Ultralight scalar fields around spinning black holes can trigger superradiant instabilities, forming a long-lived bosonic condensate outside the horizon. We use numerical solutions of the perturbed field equations and astrophysical models of massive and stellar-mass black hole populations to compute, for the first time, the stochastic gravitational-wave background from these sources. In optimistic scenarios the background is observable by Advanced LIGO and LISA for field masses m_{s} in the range ∼[2×10^{-13},10^{-12}] and ∼5×[10^{-19},10^{-16}] eV, respectively, and it can affect the detectability of resolvable sources. Our estimates suggest that an analysis of the stochastic background limits from LIGO O1 might already be used to marginally exclude axions with mass ∼10^{-12.5} eV. Semicoherent searches with Advanced LIGO (LISA) should detect ∼15(5) to 200(40) resolvable sources for scalar field masses 3×10^{-13} (10^{-17}) eV. LISA measurements of massive BH spins could either rule out bosons in the range ∼[10^{-18},2×10^{-13}] eV, or measure m_{s} with 10% accuracy in the range ∼[10^{-17},10^{-13}] eV.
旋转黑洞周围的超轻标量场会引发超辐射不稳定性，在视界外形成长寿命的玻色凝聚态。我们利用微扰场方程的数值解以及大质量和恒星质量黑洞群体的天体物理模型，首次计算了来自这些源的随机引力波背景。在乐观的情况下，对于场质量(m_{s})分别处于约([2×10^{-13},10^{-12}])和约(5×[10^{-19},10^{-16}])电子伏特的范围，先进激光干涉引力波天文台（Advanced LIGO）和激光干涉空间天线（LISA）可以观测到该背景，并且它会影响可分辨源的可探测性。我们的估计表明，对来自LIGO O1的随机背景极限的分析可能已可用于勉强排除质量约为(10^{-12.5})电子伏特的轴子。对于场质量为(3×10^{-13})（(10^{-17})）电子伏特的情况，使用先进LIGO（LISA）进行的半相干搜索应能探测到约15（5）至200（40）个可分辨源。LISA对大质量黑洞自旋的测量要么可以排除约([10^{-18},2×10^{-13}])电子伏特范围内的玻色子，要么可以在约([10^{-17},10^{-13}])电子伏特范围内以10%的精度测量(m_{s})。
