The first quasars and super-massive black holes

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A quasar, the glowing disk of gas around the super-massive black hole at the centre of a galaxy, can be hundreds of times more luminous than its host galaxy, and the brightest quasars are the most powerful non-transient objects in the Universe. Quasars have been discovered when the Universe was just 5% of its current age (of 13.8 billion years) and represent the only way to trace the formation of the first super-massive black holes. The first part of this project would be to use the results from surveys of distant quasars to determine their properties as a population and, in particular, how it is evolving with cosmic time. This will involve a combination of modelling and Bayesian inference to combine the results of very different samples, hence aiding the design of future surveys that aim to push to even greater distances. The second part of this project concerns the black holes themselves: it is very difficult to explain the formation of black holes of > 10^9 Solar masses in less than a billion years, but another possibility is that they are not actually so massive - their mass estimates come from extrapolating an imperfect empirical correlation established from a different population of quasars which, typically, have much lower mass black holes, and the current approaches to this problem tend to ignore the various sources of uncertainty. In this project we will go back to the original data and establish what can really be said about the first super-massive black holes and quasars and their formation mechanisms.