arXiv 2006.162492020-06astro-ph.COgr-qchep-ph

宇宙弦尖点坍缩的原初黑洞

Primordial black holes from cusp collapse on cosmic strings

Alexander C. Jenkins, Mairi Sakellariadou

备注：: 20 pages, 9 figures; corrections made to the PBH mass spectrum and associated GW constraints, main results unaffected

摘要：

原初黑洞是宇宙学和天体物理学的重要研究对象，作为暗物质候选者和引力波的潜在来源，受到了广泛的关注。一种可能的PBH形成机制是宇宙弦的引力坍缩。到目前为止，关于宇宙弦产生PBH的全部文献都集中在（准）圆形宇宙弦环的坍缩上，这只占宇宙环总数的一小部分。在这里，我们证明了一种新的PBH形成机制：崩溃的一小部分宇宙弦附近的尖点。使用箍猜想，我们表明，崩溃是不可避免的，每当一个尖点出现在一个宏观大的循环，形成一个PBH的静止质量小于质量的循环的一个因素的无量纲弦张力的平方，$(Gμ)^2$。由于尖点是宇宙弦环的一般特征，并且不依赖于像圆形坍缩这样的精细调谐的环结构，这意味着宇宙弦产生的PBH比以前认识到的要多得多。由此产生的PBH是高度旋转的，并被提升到超相对论速度;它们占据了BH质量自旋参数空间的一个独特区域，因此是宇宙弦的“吸烟枪”观测特征。我们推导出新的约束$Gμ$从尖点塌陷PBH的蒸发，并更新现有的约束$Gμ$从引力波搜索。

英文摘要：

Primordial black holes (PBHs) are of fundamental interest in cosmology and astrophysics, and have received much attention as a dark matter candidate and as a potential source of gravitational waves. One possible PBH formation mechanism is the gravitational collapse of cosmic strings. Thus far, the entirety of the literature on PBH production from cosmic strings has focused on the collapse of (quasi)circular cosmic string loops, which make up only a tiny fraction of the cosmic loop population. We demonstrate here a novel PBH formation mechanism: the collapse of a small segment of cosmic string in the neighbourhood of a cusp. Using the hoop conjecture, we show that collapse is inevitable whenever a cusp appears on a macroscopically-large loop, forming a PBH whose rest mass is smaller than the mass of the loop by a factor of the dimensionless string tension squared, $(Gμ)^2$. Since cusps are generic features of cosmic string loops, and do not rely on finely-tuned loop configurations like circular collapse, this implies that cosmic strings produce PBHs in far greater numbers than has previously been recognised. The resulting PBHs are highly spinning and boosted to ultrarelativistic velocities; they populate a unique region of the BH mass-spin parameter space, and are therefore a "smoking gun" observational signature of cosmic strings. We derive new constraints on $Gμ$ from the evaporation of cusp-collapse PBHs, and update existing constraints on $Gμ$ from gravitational-wave searches.

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。

摘要：

英文摘要：

相关论文