论文标题

在风向磁盘中的风向放松周期

On the wind-driven relaxation cycle in accretion disks

论文作者

Ganguly, Shalini, Proga, Daniel

论文摘要

磁盘风能通过扩散过程引起整个磁盘传播的扰动。到达内部磁盘后,这些扰动可以改变磁盘光度,从而改变风质量损耗率,$ \ dot {m} _W $。有人认为,这种所谓的“风驱动的放松周期”可能会解释某些磁盘积聚物体中观察到的可变性。在这里,我们研究了最内向的质量积聚率$ \ dot {m} _a $对以不同速率和半径损失的物质的响应。我们允许风启动半径为$ r_l $,用$ \ dot {m} _a $扩展。我们为各种$ \ dot {m} _W $ - $ \ dot {m} _a $和$ r_ {l} $ - $ \ $ \ dot {m} _a _a $依赖项计算了时间依赖的模型网格。我们发现,与“固定$ r_l $”案例相比,“变量$ r_l $”案例的磁盘行为有很大不同。特别是,比后一种情况需要更强的风能使前者的磁盘不稳定。但是,即使在不稳定的情况下,$ \ dot {m} _a $振幅也不会显着增长,因为振荡由于磁盘耗竭而在低水平上饱和,或者是由于在很小的半径或两者下发射的风。该结果意味着磁盘风不太可能负责状态过渡,因为这些磁盘需要内部磁盘上发生巨大变化。尽管在内部磁盘区域发生了适度的变化,但大半径的磁盘表面密度可以随着幅度较大的幅度而变化,即从0到稳态值的几个因素。外磁盘的这种戏剧性变化可能会带来可观察的后果。

A disk wind can cause perturbations that propagate throughout the disk via diffusive processes. On reaching the inner disk, these perturbations can change the disk luminosity, which in turn, can change the wind mass loss rate, $\dot{M}_w$. It has been argued that this so-called "wind driven relaxation cycle" might explain the observed variability in some disk accreting objects. Here, we study the response of the innermost mass accretion rate $\dot{M}_a$ to the loss of matter at different rates and radii. We allow the wind launching radius, $R_L$, to scale with $\dot{M}_a$. We computed a grid of time-dependent models for various $\dot{M}_w$-$\dot{M}_a$ and $R_{L}$-$\dot{M}_a$ dependencies. We find that the disk behaviour significantly differs for the 'variable $R_L$' case compared to the 'fixed $R_L$' case. In particular, much stronger winds are required to destabilize the disk in the former than the latter case. However, the $\dot{M}_a$ amplitude does not grow significantly even for unstable cases because the oscillations saturate at a low level either due to disk depletion or due to the wind being launched at very small radii, or both. This result implies that disk winds are unlikely to be responsible for state transitions as those require large changes in the inner disk. Despite modest changes at the inner disk regions, the disk surface density at large radii can vary with a large amplitude, i.e., from 0 to a few factors of the steady state value. This dramatic variation of the outer disk could have observable consequences.

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