论文标题
磁盘蒸发和状态转换的分析模型在积聚黑洞中
Analytical Model of Disk Evaporation and State Transitions in Accreting Black Holes
论文作者
论文摘要
黑洞X射线二进制文件中的状态转变可能是由于薄胶盘蒸发到热的电晕引起的。我们提出了此过程的高度集成版本，适用于分析和数值研究。将半径$ r $缩放到Schwarzschild单位和冠状质量积聚率$ \ dot {M} _C $到Eddington单位，该模型的结果独立于黑洞质量。因此，在X射线二进制文件和AGN中，状态转变应相似。电晕解决方案由两个幂律片段组成，分别以断裂半径$ r_b \ sim10^3 \，（α/0.3）^{ - 2} $组成，其中$α$是粘度参数。汽油以$ r> r_b $的价格从磁盘蒸发到电晕，并以$ r <r_b $凝结。在$ r_b $，$ \ dot {m} _c $达到其最大值，$ \ dot {m} _ {c，{\ rm max}}} \ oft 0.02 \，（α/0.3）^3 $。如果在$ r \ gg r_b $上，带有$ \ dot {m} _d <\ dot {m} _ {m} _ {c，{\ rm max}} $的薄磁盘积聚，则该磁盘在达到$ r_b $之前完全蒸发，并给予硬状态。否则，磁盘在所有半径上都能生存，从而产生热状态。尽管基本模型仅考虑Bremsstrahung冷却和粘性加热，但我们还讨论了一个更现实的模型，其中包括Compton冷却和通过磁盘的能量传输的直接冠状加热。解决方案再次独立于黑洞质量，$ r_b $保持不变。该型号预测$ r> r_b $的强冠风和a $ t \ sim 5 \ times 10^8 \，{\ rm k} $ compton-compton-cooled corona for $ r <r_b $。两个温度的效应被忽略，但在小半径上可能很重要。
State transitions in black hole X-ray binaries are likely caused by gas evaporation from a thin accretion disk into a hot corona. We present a height-integrated version of this process which is suitable for analytical and numerical studies. With radius $r$ scaled to Schwarzschild units and coronal mass accretion rate $\dot{m}_c$ to Eddington units, the results of the model are independent of black hole mass. State transitions should thus be similar in X-ray binaries and AGN. The corona solution consists of two power-law segments separated at a break radius $r_b \sim10^3 \,(α/0.3)^{-2}$, where $α$ is the viscosity parameter. Gas evaporates from the disk to the corona for $r>r_b$, and condenses back for $r<r_b$. At $r_b$, $\dot{m}_c$ reaches its maximum, $\dot{m}_{c,{\rm max}} \approx 0.02\, (α/0.3)^3$. If at $r\gg r_b$ the thin disk accretes with $\dot{m}_d < \dot{m}_{c,{\rm max}} $, then the disk evaporates fully before reaching $r_b$, giving the hard state. Otherwise, the disk survives at all radii, giving the thermal state. While the basic model considers only bremsstrahlung cooling and viscous heating, we also discuss a more realistic model which includes Compton cooling and direct coronal heating by energy transport from the disk. Solutions are again independent of black hole mass, and $r_b$ remains unchanged. This model predicts strong coronal winds for $r>r_b$, and a $T\sim 5\times 10^8\,{\rm K}$ Compton-cooled corona for $r < r_b$. Two-temperature effects are ignored, but may be important at small radii.
