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

绘制从亚秒差距到千秒差距尺度的河外喷流的完整速度场

• 批准号: 1814949
• 负责人: Eileen Meyer
• 金额: $ 29.91万
• 依托单位: University of Maryland Baltimore County
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1814949&HistoricalAwards=false
• 关键词: Mapping; Complete; Velocity; Field; Extragalactic

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.

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(质量是太阳的一百万到十亿倍)。活跃生长的黑洞，也被称为活动星系核，是宇宙中最大的物质和能量回收者之一。这些吸积的黑洞的规模与我们的太阳系相当，但已被观察到驱动被称为喷流的热(电离)气体流出，达到数百万光年的距离(相当于典型的星系分离)。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上发射出来的，以及组成气体的粒子如何被加速到离黑洞引擎很远的非常高的能量。该项目的目标是利用美国国家科学基金会设施30多年的无线电成像档案和新的观测，首次对数十架喷气式飞机的延时观测进行大规模汇编，范围比以往任何时候都大得多：从非常接近黑洞(几光年)到数千或数百万光年。由于这些喷气式飞机以接近光速的速度移动，我们可以在几年的时间尺度上观察喷气式飞机内气体的运动--这项工作对于大量喷气式飞机来说是可能的，因为大量的无线电档案涵盖了几十年。绘制喷流的速度结构图将使我们能够最终研究喷流中明亮的“结”的性质，探索极端粒子加速的区域，并计算喷流携带到银河系和银河系外环境的总能量。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如何随着时间的推移而建立的如何宇宙的大规模计算机模型。天文学的第2A部分主要悬而未决的问题是相对论、电离等离子体的双极喷流的性质，这些喷流被认为是从星系中心的超大质量黑洞的子集发出的。在过去二十年中开发的一个重要工具是使用自行(空中运动)来跟踪这些喷流中的等离子体运动，既有非常长的基线干涉测量(VLBI)，也有像甚大阵列(VLA)这样更紧凑的干涉仪。由于这些喷流中的等离子体是相对论的(移动速度非常接近光速)，并且以小角度移动到我们的视线，喷流中的特征运动可能会出现超光速(比光速更快)。喷流速度场的地图，从微秒尺度(接近黑洞)到数百或数千微秒(在主星系之外)，对喷流模型来说是一个非常重要的约束，它准确地显示了气体是如何被加速并将能量储存到环境中的。此外，对超光速的测量使我们能够限制喷流的固有性质，这些性质很难通过任何其他方法来确定(包括由于简并而建立的理论模型)。在这项提议中，我们的目标是主要通过使用VLA档案，大幅增加在千帕秒尺度上测量到自行运动的河外喷流的数量。除了使用VLBA的补充工作，总体目标是建立第一个喷流目录，速度场从黑洞环境的规模映射到喷流的最终终点，因为它影响星际介质。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。这项工作涉及的科学问题包括喷流中明亮的“结”结构的物理性质，来自这些结的异常高的X射线通量的来源，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。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。