Queen's University Belfast Astronomy Observation and Theory Consolidated Grant 2020-2023

超新星创造了我们在太阳系、银河系和整个可见宇宙中看到的重化学元素。虽然恒星经过数百万年或数十亿年的演化，但超新星爆炸只发生在几秒钟内，发光的残余物持续数年。我们的目标是了解这些爆炸是如何发生的，以及它们是如何在银河系中创造中子星、脉冲星和黑洞的。2017年，发现了第一个与引力波源对应的电磁对应物，这是一项突破性的发现。这被称为千诺瓦，因为它的亮度是新星的1000倍。引力波和千诺瓦来自一对合并的中子星。光学和红外光产生于重元素的放射性衰变，我们称之为r过程元素。它们比元素周期表中的铁还重，这样的中子星合并可能是所有这些重元素的原因。或者，在接下来的几年里，项目会发现更多这样的东西，引力波和电磁信号的结合打开了一扇了解宇宙的新窗口。被用作宇宙尺度并导致诺贝尔奖获得者发现暗能量的热核超新星来自白矮星。但它们究竟是如何爆炸的，以及它们的前身系统是什么，我们仍然不得而知。白矮星是一种比太阳质量大，但和地球一样大的恒星。它们的密度令人难以置信，一茶匙的WD材料重约1万吨。为了了解它们是如何爆炸的，我们将用目前存在的最复杂的三维计算机模型来模拟它们的光谱。超新星中产生的元素形成了我们银河系的行星系统--铁、硅、氧、镁都是形成行星系统的关键。我们银河系中其他恒星(称为系外行星)周围的已知行星系统的多样性令人震惊。我们知道数以千计的系外行星。热木星、多行星系统和超级地球现在经常出现在发现新行星的勘测中。我们可以看到年轻恒星在生命的最初几百万年里，在它们的圆盘中形成了行星。在南半球(ALMA)建造的最新大型设施提供了关于原行星盘的壮观数据，我们在盘化学方面的工作旨在了解它们的起源。我们在这一领域的首要任务是找到另一颗类似地球的行星--合适的大小、年龄和与其母恒星的距离，以支持大气层和液态水。这种搜索需要对提取我们期望的微小信号的方法进行仔细的测试，我们建议开发这一方法，着眼于未来探测地球孪生兄弟的奖赏。我们很快就会在最大的望远镜上安装非常精确的光谱仪来测量恒星的速度，精度可以达到每秒几米。在这个层面上，阻碍我们寻找行星的不再是测量精度的仪器，而是太阳表面像恒星一样的真实活动。我们的项目将致力于了解和缓解这种影响。天体物理学的一个关键部分是把我们在地球上可以测量到的详细的物理学知识整合到我们在遥远的宇宙中只能看到的东西(通过电磁辐射)。这将通过模型原子的计算机计算来完成。这些代码计算电子在原子中是如何激发的，并确保天体物理模型识别导致超新星、超大质量黑洞、星系光谱和恒星中谱线的元素。既然我们已经探测到千诺瓦，我们就必须对最重的元素进行同样的计算。我们还将进行新的实验，使用强大的激光(例如火神激光)来模拟在黑洞双星等吸积源中导致X射线发射的气体的物理。我们将使用这些新颖的实验室数据来测试世界领先的计算机代码，该代码用于模拟靠近黑洞的星系的中心区域。

Supernovae create the heavy chemical elements we see in our solar system, the Galaxy and entire visible Universe. While stars evolve over millions or billions of years, a supernova explosion happens in seconds and the glowing remnant lasts for years. We aim to understand how these explosions happen and how they create the neutron stars, pulsars and black holes in our galaxy. In 2017 a breakthrough discovery was made when the first electromagnetic counterpart to a gravitational wave source was found. This was termed a kilonova because it was 1000 times brighter than a nova. The gravitational waves and the kilonova were from a pair of merging neutron stars. The optical and infrared light arose from the radioactive decay of heavy elements, which we call r-process elements. These are heavier than iron in the periodic table and such neutron star mergers may be responsible for all these heavy elements. Or projects will find more of these in the coming years and the combination of gravitational waves and electromagnetic signals opens up a new window on the Universe. The thermonuclear supernovae that are used as cosmic yardsticks and led to the Nobel Prize winning discovery of dark energy come from white dwarf stars. But exactly how they explode and what the progenitor systems are still eludes us. A white dwarf is a star greater than the mass of the sun, but the size of the earth. They are incredibly dense, one teaspoon of WD material weighs about 10 thousand tonnes. To understand how they explode, we will model their spectra with the most sophisticated 3 dimensional computer models that currently exist. The elements created in supernovae form planetary systems in our galaxy - iron, silicon, oxygen, magnesium are all critical to forming planetary systems. The diversity in the known planetary systems around other stars in our galaxy (called exoplanets) is astounding. We know of thousands of exoplanets. Hot Jupiters, multiple planetary systems and super-earths are now commonly found in surveys to discover new planets. We can see planet formation in the disks of young stars during their first few million years of life. The latest large facility built in the southern hemisphere (ALMA), has provided spectacular data on proto-planetary disks and our work on the chemistry of the disk aims to understand their origins. Our top priority in this area is to find another earth like planet - the right size, age and distance from its parent star to support an atmosphere and liquid water. This search requires careful tests of the methods to extract the tiny signals we expect and we propose to develop this with an eye on the future prize of detecting an earth twin. We will soon have extraordinarily precise spectrometers on the biggest telescopes to measure the velocity of stars down to metres per second. At this level, it is no longer the instrument measuring precision that hinders our planet searching, but the real activity on the surface of Sun like stars. Our project will aim to understand and mitigate this effect. A critical part of astrophysics is pulling together our detailed knowledge of physics that we can measure on earth to what we can only see (through electromagnetic radiation) in the distant Universe. This will be done through computer calculations of model atoms. These codes calculate how electrons are excited in atoms and ensures that astrophysical models identify the elements that cause the spectral lines in supernovae, supermassive black holes, galaxy spectra and stars. Now that we have detected a kilonova we must do the same calculations for the heaviest elements. We will also run novel experiments to use powerful lasers (e.g. the VULCAN laser) to mimic the physics of gas that causes x-ray emission in accreting sources such as black hole binaries. We will use these novel laboratory data to test the world's leading computer code that is used to model the central regions of galaxies close to their black holes.