"Galaxy mergers: gas flows, starbursts and active galactic nuclei."

尽管宇宙可能看起来是一个广袤而人烟稀少的地方，但它的动态性质意味着星系之间经常发生碰撞。这些“星系合并”中的恒星很少正面相遇，但引力的影响可能会给整个星系带来壮观的后果。计算机模拟表明，合并导致两股物质流被撕裂，由于强大的扭矩，星系的大量气体被输送到银河系中心。这些模拟导致了对大规模核恒星爆发和中央黑洞点火的预测。因此，星系合并可能是星系演化的主要驱动力之一。这里提出的这项研究旨在从观测上量化星系合并在历史上的程度，从而更好地理解这些合并对塑造现代宇宙的重要性。通过使用有史以来最大的星系合并样本，我们将试图了解恒星形成的触发和黑洞的活动是如何受到调节的。例如，为什么一些合并会导致真正的大规模恒星爆发，而另一些则相对不受影响？气体流是影响整个银盘的恒星形成，还是只影响核心的恒星形成？一旦恒星暴增完成后会发生什么--银河系是回到原来的自己，还是它的燃料供应耗尽了？这些问题将通过将我们史无前例的大样本与跨越光学、亚毫米和无线电系统的新数据以及一些新的观测技术相结合来解决。

Although the universe may seem a vast and sparsely populated place, its dynamic nature means that galaxies regularly collide. The stars in these "galaxy mergers" rarely meet each other head-on, but the effects of gravity can have spectacular consequences for the galaxy as a whole. Computer simulations show that mergers result in both streams of material being ripped away, and large quantities of the galaxies' gas being funneled towards the galactic centre as a result of strong torque forces. These simulations have led to predictions of massive nuclear starbursts and the ignition of the central black hole. Galaxy mergers may therefore be the (or one of the) main drivers of galaxy evolution. The research proposed here aims to observationally quantify the extent of a merger on a galaxy's history and therefore better understand how important these mergers are for shaping the modern universe. By using the largest sample of galaxy mergers ever assembled, we will attempt to understand how the triggering of star formation and the activity of the black hole is regulated. For example - why do some mergers result in truly massive starbursts, yet others are relatively unaffected? Do the gas flows affect star formation throughout the galactic disk, or only in the nucleus? And what happens once the starburst is complete - does the galaxy return to its old self, or is its fuel supply exhausted? These questions will be addressed by combining our unprecedentedly large sample with both new data that will span the optical, sub-millimetre and radio regimes, plus a number of novel observational techniques.