HIandMIGHTEE: From gas to galaxies with the MIGHTEE survey

星系形成和演化的关键因素之一是星系内恒星之间的空间、周围的气体环境和星系所处的大尺度星系结构之间的气体交换。这种气体的氢原子成分是我们在宇宙中看到的所有物体的组成部分，可以使用无线电波段中21厘米处的发射线来追踪。然而，这是一条非常弱的发射线，而且绝大多数以前的研究都局限于非常局部的宇宙。在这个项目中，我们将首次能够探测和测量氢原子存在的位置，覆盖的时间范围大约是宇宙年龄的一半。因此，我们可以了解这些气体在过去60亿年中是如何演变的，为我们提供了关于气体如何冷却和冷凝以形成我们今天在宇宙中看到的恒星和星系的急需信息。我们将采取的一种新颖方法是使用其他波长的丰富数据来描绘星系演化的完整画面，而且能够深入挖掘包含原子氢信号的噪声数据。我们可以这样做，因为我们从其他数据中知道星系的距离，这使我们能够从无线电数据中的正确位置提取信号，以便获得氢原子线的测量，无论它是否被检测到。通过结合所有这些数据，我们可以使用先进的统计方法重建原子氢的数量。

One of the key elements in the formation and evolution of galaxies is the exchange of gas between the space between the stars within galaxies, their surrounding gaseous environment and the larger-scale filamentary structure in which galaxies are largely embedded. The atomic hydrogen component of this gas, which is the building block of all the objects we see in the Universe, can be traced using an emission line which is found at 21cm in the radio waveband. However, this is a very weak emission line and the vast majority of previous studies have been restricted to the very local Universe.In this project we will, for the first time, be able to detect and measure where this atomic hydrogen exists, covering a time range of around half the age of the Universe. We can therefore understand how where this gas resides has evolved over the past 6 billion years, providing much needed information on how gas cools and condenses to form the stars and galaxies we see in the Universe today.One of the novel approaches we will undertake is to use the wealth of data at other wavelengths in order to paint a complete picture of galaxy evolution, but also to be able to dig deep into the noisy data which contains the atomic hydrogen signal. We can do this as we know the position at distance of the galaxy from other data, which allows us to then extract the signal from the right place in the radio data in order to obtain a measurement of the atomic hydrogen line, regardless of whether it is detected or not. The by combining all these data we can reconstruct how much atomic hydrogen there is using advanced statistical methods.