Mapping the Complete Velocity Field of Extragalactic Jets from sub-parsec to kiloparsec Scales

我们现在知道，基本上所有大质量星系的中心都有一个超大质量黑洞（质量是太阳的100万到数十亿倍）。活跃生长的黑洞，也被称为活动星系核，是宇宙中物质和能量的最大“回收者”之一。这些吸积黑洞的规模与我们的太阳系相当，但据观察，它们会喷出热（电离）气体，也就是所谓的喷流，距离可达几百万光年（相当于典型的星系距离）。这些喷流对它们的宿主星系和它们所在的星系团都有重大影响。然而，目前还不清楚这些喷流携带了多少能量，它们是如何从黑洞物理发射出来的，以及组成气体的粒子是如何在远离黑洞引擎的地方加速到非常高的能量的。这个项目的目标是利用超过30年的无线电成像档案与NSF设施以及新的观测结果，在比以往更大的尺度范围内对数十个喷气机进行首次大规模的时间推移观测汇编：从非常接近黑洞（几光年）到数千或数百万光年。因为这些喷流以接近光速的速度运动，我们可以在几年的时间尺度上观察喷流内气体的运动——由于大量的无线电档案覆盖了几十年，所以对大量的喷流来说，这项工作是可能的。绘制喷流的速度结构将使我们最终能够研究喷流中明亮“结”的本质，探测极端粒子加速的机制，并计算喷流携带到银河系和星系外环境的总能量。这不仅对理解喷流现象本身至关重要，而且还将使我们能够改进大规模的计算机模型，以了解宇宙是如何随着时间的推移而形成的。天文学中主要的开放问题是相对论性双极喷流的本质，电离等离子体被认为是从星系中心的超大质量黑洞的一个子集发出的。在过去二十年中发展起来的一个重要工具是利用固有运动（天空运动）来跟踪这些喷流中的等离子体运动，包括超长基线干涉仪（VLBI）和更紧凑的干涉仪，如甚大阵列（VLA）。因为这些喷流中的等离子体是相对论性的（运动速度非常接近光速），并且与我们的视线有一个很小的角度，所以喷流中的运动特征看起来是超光速的（比光速还快）。喷流的速度“场”图，从秒差距尺度（接近黑洞）到数百或数千秒差距尺度（宿主星系外），是喷流模型的一个非常重要的约束条件，它准确地显示了气体是如何加速并将能量沉积到环境中的。此外，超光速的测量使我们能够约束喷流的固有特性，这些特性很难通过任何其他手段（包括理论建模，由于简并）来确定。在这个提议中，我们的目标是通过使用VLA档案，在千秒尺度上显著增加星系外喷流的测量运动。随着使用VLBA的补充工作，总体目标是建立第一个喷射目录，其速度场从黑洞环境的规模映射到喷射的最终终点，因为它影响了星系际介质。这些目标将通过使用标准干涉成像技术和最近开发的小波分解代码来实现。这项工作解决的科学问题包括喷流中明亮的“结”结构的物理性质，这些结异常高x射线通量的起源，形态类型和喷流能量学之间的联系，以及喷流对其环境的影响。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Part 1We now know that essentially all massive galaxies have a super-massive black hole (a million to billion times more massive than the sun) at their centers. Actively growing black holes, also known as active galactic nuclei, are some of the greatest 'recyclers' of matter and energy in the Universe. These accreting black holes are on the scale of our solar system, but have been observed to drive outflows of hot (ionized) gas, known as jets, reaching distances of up to a few million light years (equivalent to typical galaxy separations). These jets have a major impact on both their host galaxies and the clusters of galaxies in which they reside. However, it is still unclear how much energy these jets carry, how they are physically launched from the black hole, and how particles comprising the gas are accelerated to very high energies very far from the black hole engine. The goal of this project is to utilize over 30 years of archival radio imaging with NSF facilities along with new observations, to make the first-ever large compilation of time-lapse observations of dozens of jets over a much larger range of scales than ever before: from very close to the black hole (a few light years) to thousands or millions of light years. Because these jets are moving at nearly the speed of light, we can observe the movement of the gas within the jet on several-year timescales - work that is possible for a large number of jets now that extensive radio archives cover several decades. Mapping the velocity structure of jets will allow us to finally investigate the nature of bright 'knots' in the jet flow, probing regimes of extreme particle acceleration, and to calculate the total energy carried by jets in to the galactic and extra-galactic environment. This is not only critical for understanding the jet phenomenon itself, but will also allow us to improve large-scale computer models of how to Universe was built up over time.Part 2A major open question in Astronomy is the nature of the bipolar jets of relativistic, ionized plasma seen to emanate from a subset of super-massive black holes at the centers of galaxies. An important tool that has been developed over the last two decades is the use of proper motions (motions on the sky) to track the movement of plasma within these jets, both with Very Long Baseline Interferometry (VLBI) and more compact interferometers like the Very Large Array (VLA). Because the plasma in these jets is relativistic (moving very close to the speed of light) and moving with a small angle to our line-of-sight, the motion of features in the jet flow can appear super-luminal (faster than light). A map of the velocity 'field' of a jet, from parsec scales (close to the black hole) to hundreds or thousands of parsecs (outside the host galaxy) is a very important constraint on jet models, showing exactly how gas is accelerated and deposits energy into the environment. Further, measurements of superluminal speeds allow us to constrain intrinsic properties of jets that are very difficult to determine through any other means (including theoretical modeling, due to degeneracies). In this proposal, we aim to dramatically increase the number of extragalactic jets with measured proper motions on the kiloparsec scale, primarily through the use of the VLA archives. Along with complimentary work using the VLBA, the overall goal is to build the first catalog of jets with velocity fields mapped from the scale of the black hole environment to the final terminus of the jet as it impacts the intergalactic medium. These goals will be accomplished by using both standard interferometric imaging techniques and a recently developed wavelet decomposition code. The science questions addressed by this work include the physical nature of the bright 'knot' structures in the jets, the origin of the anomalously high X-ray fluxes from these knots, the connection between morphological type and jet energetics, and the impact of jets on their environment.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.