Constraining the Properties of Quasars and their Outflows Using Variability

使用变异性约束类星体的属性及其流出

• 批准号: RGPIN-2017-05983
• 负责人: Hall, Patrick
• 金额: $ 1.82万
• 依托单位: York University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=680391
• 关键词: Constraining; Properties; Quasars; their; Outflows

Imagine voyaging out of our solar system and beyond all the stars in our Milky Way galaxy. The faint dots of light visible to you then then wouldn't be stars, but entire distant galaxies. At the centre of any of those galaxies you'll find a swarm of stars and, if the galaxy is big enough, a black hole with a mass of millions or even billions of Suns. Watch as one of the clouds of hydrogen and helium gas and trace elements in that galaxy ventures too close to the black hole. Gravity stretches the gas cloud into a disk of gas bigger than our solar system, orbiting at incredible speeds but slowly spiralling inwards to accrete onto the black hole. In the inner disk, friction makes the gas hotter than the Sun over an area millions of times larger than the Sun's surface. That enormous, glowing disk can be seen all the way across the universe, and we call it a quasar. This turbulent accretion disk of hot, rotating gas often tosses up gas clumps which are pushed outward by the light from the inner disk. The clumps form spiralling streamers of gas which block the inner disk from view in some directions and which race out into the galaxy hosting the quasar. These fast-moving outflows can reverse the inflow of gas clouds supplying the accretion disk, shutting down the accretion process and turning off the quasar. They can even shock-heat and blow out almost all the gas in the galaxy, ending star formation in it and drastically changing its future appearance and environment. My research team and collaborators and I are surveying quasars for outflows, studying their time variability, and comparing them to computer simulations. We are learning how quasars and their outflows work so that we can refine the picture outlined above and improve our models of how galaxies form and develop. We also aim to help determine whether or not we can use the relationship between quasar size and luminosity to trace the history of dark energy farther back in time than we can with the exploding stars known as supernovae. If so, that would be a useful new test of dark energy, a mysterious force accelerating the expansion of our universe and one of the biggest mysteries in science today.

想象一下，在我们的太阳系之外，在银河系的所有恒星之外航行。那时你能看到的微弱光点不是恒星，而是整个遥远的星系。在这些星系的中心，你会发现一群恒星，如果星系足够大，一个黑洞的质量是数百万甚至数十亿个太阳的质量。观察这个星系中由氢气、氦气和微量元素组成的云团，它们会冒险靠近黑洞。重力将气体云拉伸成一个比我们的太阳系还大的气体盘，以令人难以置信的速度绕轨道运行，但缓慢地螺旋向内吸积到黑洞上。在内盘，摩擦使气体在比太阳表面大数百万倍的区域内比太阳还要热。在整个宇宙中都能看到那个巨大的发光圆盘，我们称之为类星体。这个由热的、旋转的气体组成的紊流吸积盘经常抛出气体团块，这些气体团块被来自内盘的光向外推。这些团块形成螺旋状的气体流，在某些方向上阻挡了内盘的视线，并迅速进入类星体所在的星系。这些快速移动的外流可以逆转提供吸积盘的气体云的流入，关闭吸积过程并关闭类星体。它们甚至可以冲击加热并吹灭星系中几乎所有的气体，终止其中的恒星形成，并彻底改变其未来的外观和环境。我的研究团队和合作者和我正在调查类星体的外流，研究它们的时间变化，并将它们与计算机模拟进行比较。我们正在学习类星体及其流出物是如何工作的，这样我们就可以完善上面概述的图片，并改进我们关于星系如何形成和发展的模型。我们的目标是帮助确定我们是否可以利用类星体大小和亮度之间的关系来追溯暗能量的历史，而不是用超新星爆炸的恒星来追溯。如果是这样，这将是对暗能量的一个有用的新测试，暗能量是一种加速宇宙膨胀的神秘力量，也是当今科学界最大的谜团之一。