[论文解读] The jet-disk symbiosis. I. Radio to X-ray emission models for quasars

H. Falcke, Peter L. Biermann|arXiv (Cornell University)|Nov 23, 1994

Astrophysics and Cosmic Phenomena被引用 8

一句话总结

本文提出了一种统一的喷流-吸积盘共生模型，通过质量与能量守恒将喷流功率与吸积盘亮度联系起来，从而解释类星体中从射电到X射线的辐射，扩展了Blandford & Königl模型。结果表明，高效率射电噪类星体需要‘最大喷流’，即总等效分配状态，意味着最小电子洛伦兹因子γ ≥ 100或存在对产生，这与观测到的能谱分布和喷流能量学一致。

ABSTRACT

Starting from the assumption that radio jets and accretion disks are symbiotic features present in radio loud and radio quiet quasars we scale the bulk power of radio jets with the accretion power by adding mass- and energy conservation of the whole jet-disk system to the standard Blandford \& Königl theory for compact radio cores. The model depends on only few parameters and can be constrained by observations. Thus we are able to show that radio and X-ray fluxes (SSC emission) of cores and lobes and typical dimensions of radio loud quasars are consistent with a jet being produced in the central engine. We present a synthetic broadband spectrum from radio to X-ray for a jet-disk system. The only way to explain the high efficiency of radio loud objects is to postulate that these objects consist of `maximal jets' with `total equipartition' where the magnetic energy flow of the jet is comparable to the kinetic jet power and the total jet power is a large fraction of the disk power. As the number of electrons is limited by the accretion flow, this is only possible when the minimum Lorentz factor of the electron distribution is $γ_{ m e,min}\ga100$ ($E\ga 50 { m MeV}$) or/and a large number of pairs are present. Such an electron/positron population would be a necessary consequence of hadronic interactions and may lead to some interesting effects in the low frequency self-absorbed spectrum. Emission from radio weak quasars can be explained with an initially identical jet. The difference between radio loud and radio weak could be due to a different efficiency in accelerating relativistic electrons on the sub-parsec scale. Finally we demonstrate that in order to appease the ravenous hunger of radio loud jets its production must be somehow linked to the dissipation process in the inner part of the disk.

研究动机与目标

• 通过将喷流-吸积盘系统建模为共生系统，统一解释射电噪类星体与射电噪弱类星体的辐射机制。
• 通过自洽的喷流-吸积盘能量预算，解释类星体中高射电与X射线光度。
• 确定喷流功率可达到显著分数的吸积盘光度的条件，且与观测一致。
• 研究电子能量分布与对产生在实现高喷流效率中的作用。
• 从电子加速效率的角度，阐明射电噪与射电噪弱类星体之间的物理解释差异。

提出的方法

• 利用喷流-吸积盘系统中的质量与能量守恒，将喷流整体功率与吸积盘亮度关联。
• 将Blandford & Königl模型扩展至包含喷流-吸积盘共生关系与自洽的能量流。
• 使用同步辐射与逆康普顿（SSC）辐射机制，建模从射电到X射线的全波段能谱分布。
• 应用‘总等效分配’概念，即磁能通量与喷流动能通量相当。
• 采用最小洛伦兹因子γ_e,min ≥ 100的电子能量分布，以约束喷流效率与对产生。
• 将模型预测与观测到的射电噪类星体喷流核心与外瓣的流量及尺寸进行比较。

实验结果

研究问题

• RQ1 类星体中观测到的从射电到X射线的辐射能否通过单一的喷流-吸积盘共生模型加以解释？
• RQ2 喷流实现高效率并解释射电噪类星体光度所需的条件是什么？
• RQ3 为何一些类星体为射电噪而另一些为射电噪弱，其差异由何决定？
• RQ4 电子能量分布与对产生如何影响低频射电谱与喷流能量学？
• RQ5 内吸积盘耗散在驱动相对论性喷流中的作用是什么？

主要发现

• 喷流-吸积盘共生模型成功再现了类星体核心与外瓣在宽频带范围内的观测射电与X射线流量。
• 射电噪类星体中高喷流效率要求‘最大喷流’状态，即总等效分配，此时磁能与动能通量相当。
• 该模型要求电子最小洛伦兹因子不低于γ_e,min ≥ 100（E ≥ 50 MeV），或存在显著的电子-正电子对，以实现足够的辐射输出。
• 射电噪弱类星体可由相同的喷流-吸积盘系统解释，其差异源于亚秒差距尺度上电子加速效率较低。
• 喷流产生必须与内吸积盘的能量耗散过程内在关联，以维持所需的高功率。
• 该模型预测喷流中的强子相互作用可能自然导致对产生，从而影响低频自吸收谱。