Gravitational waves and kicks from the merger of unequal mass, highly compact boson stars
Gravitational waves and kicks from the merger of unequal mass, highly compact boson stars
复制标题
DOI：
10.1103/physrevd.105.064067
复制
发表时间：
2022-01
影响因子：
5
通讯作者：
Miguel Bezares;M. Bošković;S. Liebling;C. Palenzuela;P. Pani;E. Barausse
中科院分区：
文献类型：
--
作者：
Miguel Bezares;M. Bošković;S. Liebling;C. Palenzuela;P. Pani;E. Barausse
近几十年来，玻色子星作为致密物体的简单、自洽模型，以及在某些暗物质场景中形成的自引力结构，引起了人们的广泛关注。通过电磁信号直接探测这些假想物体是不可能的，因为它们的玻色子成分预计不会与普通物质和辐射发生显著的相互作用。然而，双玻色子恒星可能会形成并合并，发出可探测的引力波信号，这可能会将它们与含有黑洞和中子星的普通致密天体双星区分开来。我们研究了两个玻色子星的合并，通过数值演化的完全相对论爱因斯坦-克莱因-戈登方程的复杂标量场与孤子势，产生非常紧凑的玻色子星。由于具有陡峭的质量-半径图，我们可以研究质量比高达$q\约x23$的不等质量双玻色子恒星的动力学和引力辐射，而不会遇到演化大质量比双黑洞时遇到的困难。与之前研究的等质量情况类似，我们对合并的数值演化产生了一个非自旋玻色子恒星或一个自旋黑洞，这取决于初始质量和二元角动量。我们没有发现在残余旋转黑洞或残余玻色子恒星周围形成同步标量云的任何证据。有趣的是，与等质量情况相反，角动量耗散的机制之一现在是不对称的，并导致大的踢速（高达$10^4\,{\rm km/s}$），这可能产生流浪残余玻色子星。我们还比较了玻色子双星和黑洞双星预测的引力波信号，并评论了地面干涉仪对差异的可探测性。
Boson stars have attracted much attention in recent decades as simple, self-consistent models of compact objects and also as self-gravitating structures formed in some dark-matter scenarios. Direct detection of these hypothetical objects through electromagnetic signatures would be unlikely because their bosonic constituents are not expected to interact significantly with ordinary matter and radiation. However, binary boson stars might form and coalesce emitting a detectable gravitational wave signal which might distinguish them from ordinary compact object binaries containing black holes and neutron stars. We study the merger of two boson stars by numerically evolving the fully relativistic Einstein-Klein-Gordon equations for a complex scalar field with a solitonic potential that generates very compact boson stars. Owing to the steep mass-radius diagram, we can study the dynamics and gravitational radiation from unequal-mass binary boson stars with mass ratios up to $q\approx23$ without the difficulties encountered when evolving binary black holes with large mass ratios. Similar to the previously-studied equal-mass case, our numerical evolutions of the merger produce either a nonspinning boson star or a spinning black hole, depending on the initial masses and on the binary angular momentum. We do not find any evidence of synchronized scalar clouds forming around either the remnant spinning black hole or around the remnant boson stars. Interestingly, in contrast to the equal-mass case, one of the mechanisms to dissipate angular momentum is now asymmetric, and leads to large kick velocities (up to a few $10^4\,{\rm km/s}$) which could produce wandering remnant boson stars. We also compare the gravitational wave signals predicted from boson star binaries with those from black hole binaries, and comment on the detectability of the differences with ground interferometers.