Mass and spin co-evolution during the alignment of a black hole in a warped accretion disc
Mass and spin co-evolution during the alignment of a black hole in a warped accretion disc
复制标题
DOI：
10.1111/j.1365-2966.2009.15427.x
复制
发表时间：
2009-07
影响因子：
4.8
通讯作者：
A. Perego;M. Dotti;M. Colpi;M. Volonteri
中科院分区：
文献类型：
--
作者：
A. Perego;M. Dotti;M. Colpi;M. Volonteri
在本文中，我们探索了黑洞（BH）与未对准的吸积盘的磁引力相互作用，以研究 BH 自旋进动和对准以及 BH 质量 M BH 和自旋参数 a 的演化，假设吸积盘在其外部区域由具有固定在给定方向 Ĵ 盘,out 上的角动量的物质持续馈送。我们开发了一种基于绝热近似的迭代方案来研究 BH 盘协同演化：在这种方法中，吸积盘通过一系列准稳态扭曲态（巴丁-佩特森效应）并与 BH 相互作用，直到自旋 J BH 与 Ĵ 盘，out 对齐。对于与同转圆盘对齐的 BH，质量的分数增加通常小于百分之几，而自旋模量可增加高达百分之几十。对于以爱丁顿速率吸积的最大旋转 BH，对准时间尺度 t al ∝ a 5/7 M -32/35 为 ∼ 10 5 -10 6 yr。由于克尔度量中的不对称性，最初反向旋转盘的 BH 盘对准往往比镜面同向旋转情况更有效：反向旋转物质在穿过最内层稳定轨道时携带更大且相反的角动量，因此自旋模量下降得更快，因此相对倾角下降得更快。
In this paper, we explore the gravitomagnetic interaction of a black hole (BH) with a misaligned accretion disc to study BH spin precession and alignment jointly with BH mass M BH and spin parameter a evolution, under the assumption that the disc is continually fed, in its outer region, by matter with angular momentum fixed on a given direction Ĵ disc,out . We develop an iterative scheme based on the adiabatic approximation to study the BH-disc co-evolution: in this approach, the accretion disc transits through a sequence of quasi-steady warped states (Bardeen-Petterson effect) and interacts with the BH until the spin J BH aligns with Ĵ disc,out . For a BH aligning with a corotating disc, the fractional increase in mass is typically less than a few per cent, while the spin modulus can increase up to a few tens of per cent. The alignment time-scale t al ∝ a 5/7 M -32/35 is of ∼ 10 5 -10 6 yr for a maximally rotating BH accreting at the Eddington rate. BH-disc alignment from an initially counter-rotating disc tends to be more efficient compared to the specular corotating case due to the asymmetry seeded in the Kerr metric: counter-rotating matter carries a larger and opposite angular momentum when crossing the innermost stable orbit, so that the spin modulus decreases faster and so the relative inclination angle.