Gravitational wave science at the University of Birmingham

我们关于整个宇宙的大部分知识都来自科学家所说的“电磁辐射”--从无线电波到红外辐射和光，再到X射线和伽马射线。2015年9月14日，当我们首次直接探测到被称为引力波的时空涟漪时，这种情况发生了戏剧性的变化。两个黑洞碰撞产生的第一个引力波信号(GW150914)的观测揭开了天文学的新篇章。我们已经发现了双星黑洞，并了解到宇宙中每隔15分钟就有两个质量相当于恒星质量的“重”黑洞发生碰撞。事实上，自2015年9月以来，我们已经观测到了数十次这样的碰撞，其中包括一个质量为太阳150倍的系统，这是天文学家所说的中等质量黑洞的首次观测。2017年8月17日，我们观测到了GW170817，这是第一次双星中子星的合并。两颗中子星碰撞后产生的电磁辐射随后在从伽马射线到无线电波的整个电磁频谱中被探测到，这是天文学史上对单个天体进行的最强烈的观测活动之一。这一首次多信使观测表明，双中子星合并是驱动短硬伽马射线爆发的引擎，也是宇宙中产生金和铂等重元素的重要场所。伯明翰小组在引力波仪器(高级LIGO)的发展中发挥了关键作用，这些仪器使这些发现成为可能，数据分析，震源特性的表征，以及GW170817的后续观测活动。我们现在正在为高级LIGO升级(A+)生产改进的硬件，这将使我们可以探测的宇宙体积增加到原来的十倍，并在未来十年致力于更大胆的技术，进行更彻底的升级和新的设施。在未来几年，我们希望能够每天都能观测到引力波信号。我们正准备利用这些来自黑洞和中子星合并的信号，来更多地了解这些物体、恒星、物质在极端条件下的演化，并测试我们对引力本身的理解。我们正在研究的先进技术将对引力波观测站进行未来的改进，以便能够观察和研究更弱的信号。

Most of our knowledge about the Universe at large has been derived from what scientists refer to as "electromagnetic radiation" - ranging from radio waves through infrared radiation and light, to X-rays and gamma rays. This has changed dramatically on September 14, 2015 when we directly detected for the first time ripples in space-time known as gravitational waves. The observational of the first gravitational-wave signal (GW150914) generated by the collision of two black holes has opened a new chapter in astronomy. We have discovered binary black holes, and learnt that every 15 minutes somewhere in the Universe two `heavy' stellar-mass black holes collide. In fact, since September 2015 we have observed several tens of collisions of this kind, including a system of 150 times the mass of the Sun, the first observation of what astronomers refer to as an intermediate mass black hole.On August 17, 2017 we observed GW170817, the first merger of a binary neutron star. Electro-magnetic radiation generated in the aftermath of the collision of the two neutron stars was then detected across the entire electromagnetic spectrum, from gamma-rays to radio waves, in one of the most intense observational campaigns of a single object in the history of astronomy. This first multi-messenger observation has demonstrated that double neutron star mergers are the engine powering short-hard gamma ray bursts and an important site for production of heavy elements, such as gold and platinum, in the Universe. The Birmingham group has played a key role in the development of the gravitational-wave instruments (Advanced LIGO) that enabled these discoveries, the analysis of the data, the characterisation of the properties of the sources, and the follow-up observational campaign of GW170817. We are now working on producing improved hardware for the Advanced LIGO upgrade (A+) which will increase the volume of the universe we can probe by a factor of ten, and on even more audacious technologies for more radical upgrades and new facilities for the next decade.In the coming years we expect to be able to observe a gravitational-wave signal every day. We are preparing to use these signals from merging black holes and neutron stars to learn more about the evolution of these objects, stars, matter in extreme conditions, and to test our understanding of gravity itself. The advanced technology which we are investigating will make future improvements to gravitational-wave observatories, so that much weaker signals can be observed and studied.