Zooming in on feedback in active galaxies: The first high-resolution radio survey

放大活跃星系的反馈：第一次高分辨率射电勘测

• 批准号: MR/Y020405/1
• 负责人: Leah Morabito
• 金额: $ 75.82万
• 依托单位: Durham University
• 依托单位国家: 英国
• 项目类别: Fellowship
• 财政年份: 2024
• 资助国家: 英国
• 起止时间: 2024 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=MR%2FY020405%2F1
• 关键词: Zooming; feedback; active; galaxies; first

A super-massive black hole exists at the centre of almost every massive galaxy, but what role do they play in galaxy evolution? In about 10 percent of all galaxies, we observe energetic phenomena like outflows and jets of plasma that are powered by these black holes. When a galaxy shows these characteristics we call it an active galaxy, and refer to the black hole and its energetic output as an active galactic nucleus (AGN). We know from both observations and cosmological simulations that feedback between an AGN and its host galaxy can have a significant impact on that galaxy's evolution. What we do not know are the details of how this AGN feedback works.Observations of low-frequency radio emission are a powerful tool to pinpoint what is happening in AGN. This emission traces relativistic electrons in jets launched by a super-massive black hole and winds of outflowing material blown out into the galaxy by the super-massive black hole. However, due to their low spatial resolution, current radio surveys have difficulty distinguishing between this activity and radio emission from star formation. My FLF project overcomes this by using ultra-high spatial resolution radio observations, which rely on advanced calibration techniques I developed for the LOw Frequency ARray (LOFAR), a unique array of radio antenna stations spread across Europe. LOFAR can be a smaller or a bigger 'lens' by using only some or all of the stations: the more we use, the higher the resolution that can be achieved, but this requires specialised calibration techniques. LOFAR is unique in that it can achieve high resolution across a field of view more than 20 times larger than any other similar resolution radio telescope, which is critical to build the large samples necessary to understand AGN activity.My ongoing FLF project is to enact the first wide area, high resolution survey. I am doing this by post-processing data from the LOFAR Two-metre Sky Survey (LoTSS). The survey is recorded with all LOFAR antennas, but standard processing only uses those located in the Netherlands, providing lower resolution. Already I have demonstrated that we can make small high-resolution images (>20 times better than the standard processing) across the field of view, and guided the development of wide-field techniques that image the full field of view, although at a high computational cost.Using these exciting new images, my initial scientific results include identifying an entirely new sample of galaxies where star formation and AGN activity have been simultaneously measured using a combination of these high-resolution and standard imaging techniques; this is the largest sample of its kind by two orders of magnitude. From this, we are already learning that the AGN contribution in faint galaxies is higher than previously thought, with implications for our understanding of how galaxies form and evolve, and this project will continue to quantify this to understand the role of AGN in galaxy evolution.Conducting the first high-resolution survey across the entire Northern sky will allow me to build robust samples, the largest of their kind, to study the physical processes by which AGN produce radio emission, what properties govern these processes across large samples of galaxies, and how these processes impact the typical growth of galaxies through star formation. I will drive forward major advances in AGN feedback studies with my UKRI-FLF project, and push the field to new and exciting territory in answering fundamental astrophysical questions.Over the next several years, my work will lay the foundation for future scientific surveys with the SKA, in which the UK has heavily invested. I will continue to develop international collaborations with SKA pathfinder teams in South Africa, the Netherlands, and India, while placing Durham and the UK at the forefront of this exciting new revolution in science.

几乎每个大型银河系的中心都存在一个超级质量的黑洞，但是它们在星系进化中起什么作用？在所有星系中，大约10％，我们观察到了由这些黑洞供电的流出和血浆流出的现象。当银河系显示这些特征时，我们称其为活动星系，并将黑洞及其能量输出称为活跃的银河核（AGN）。从观察结果和宇宙学模拟中，我们知道，AGN及其宿主星系之间的反馈可以对该星系的进化产生重大影响。我们不知道的是这种AGN反馈如何工作的细节。低频无线电排放的观察是一个有力的工具，可以确定AGN中发生的情况。这种发射会追踪喷气式飞机中的相对论电子，该电子被超级质量黑洞和超级质量黑洞吹入银河系的流出材料的风。但是，由于其低空间分辨率，当前的无线电调查很难区分这种活动和无线电发射与恒星形成。我的FLF项目通过使用超高的空间分辨率无线电观测来克服这一问题，该观测依赖于我为低频阵列（Lofar）开发的高级校准技术，这是一个独特的无线电天线电台，遍布欧洲。 Lofar可以仅使用某些或全部站点是较小或更大的“镜头”：我们使用的越多，可以实现的分辨率越高，但这需要专门的校准技术。 Lofar的独特之处在于它可以在一个视野中实现高分辨率的高分辨率，比任何其他类似的分辨率射电望远镜大20倍以上，这对于构建了解AGN活动所需的大型样本至关重要。我正在进行的FLF项目是制定第一个广泛的区域，高分辨率调查。我正在通过从Lofar两米高的Sky Survey（Lots）的后处理数据来做到这一点。该调查记录在所有Lofar天线，但标准处理仅使用位于荷兰的调查，从而提供了较低的分辨率。 Already I have demonstrated that we can make small high-resolution images (>20 times better than the standard processing) across the field of view, and guided the development of wide-field techniques that image the full field of view, although at a high computational cost.Using these exciting new images, my initial scientific results include identifying an entirely new sample of galaxies where star formation and AGN activity have been simultaneously measured using a combination of these high-resolution and standard imaging techniques;这是两个数量级的最大样本。 From this, we are already learning that the AGN contribution in faint galaxies is higher than previously thought, with implications for our understanding of how galaxies form and evolve, and this project will continue to quantify this to understand the role of AGN in galaxy evolution.Conducting the first high-resolution survey across the entire Northern sky will allow me to build robust samples, the largest of their kind, to study the physical processes by which AGN produce radio emission, what properties govern these大型星系样品的过程，以及这些过程如何通过恒星形成影响星系的典型生长。我将通过我的UKRI-FLF项目来推动AGN反馈研究的重大进展，并将该领域推向回答基本天体物理问题的新领域。在接下来的几年中，我的工作将为未来的科学调查与SKA奠定基础，而SKA将为英国投资大量投资。我将继续与南非，荷兰和印度的SKA探路者团队进行国际合作，同时将达勒姆和英国置于这一令人兴奋的科学新革命的最前沿。