Primordial black holes as dark matter and Hawking radiation constraints with BlackHawk

Primordial black holes are central in numerous research since their first proposal. If they have a sufficient amplitude, primordial density inhomogeneities could have collapsed at the end of the inflation period, giving birth to black holes in the primordial universe, namely 'primordial black holes'. Primordial black holes are non-baryonic and non-relativistic. Hence, they appear as a perfect candidate for the 'dark matter', this non-luminous matter which is supposed to be five times more abundant than the ordinary matter in the big structures of the universe. Hawking showed that a black hole in not entirely 'black', but emits a continuous radiation as a black body with a temperature inversely proportional to its mass. This 'Hawking radiation' has two major consequences. The first one is that black holes continuously lose mass because of their 'evaporation' due to Hawking radiation. The second one is that black holes can be seen. The continuous emission has consequences on the medium around the primordial black holes. There exists a narrow window for which primordial black holes are sufficiently massive so that they are stable at the scale of the age of the universe, but sufficiently light so that their only gravitational effect comes from their global density. These are precisely the dark matter candidates mentioned earlier. Hawking radiation could be the only mean of detection of these black holes. It is thus primordial to compute it as precisely as possible, in order to obtain predictions either on the expected signals in astronomical surveys, or on the best design of future instruments to observe them. This is how BlackHawk was born: a public and free code currently at version 2.1. BlackHawk computes the Hawking radiation of a distribution of black holes, which can have different mass, charge and angular momentum. Then, BlackHawk uses particle physics codes to take into account interactions between emitted particles and their possible decay. This thesis manuscript gathers all the work I have done these last years, mostly with BlackHawk. There are two kinds of studies. Firstly, studies that consist in computing the Hawking radiation of a distribution of primordial black holes and in comparing it to astronomical data, in order to deduce a constraint on their abundance. I have performed several studies of that type, in particular concerning black holes with a distribution of mass and spin. I have demonstrated that despite recent progress in theory and observation, the existing constraints suffer from considerable uncertainties. Secondly, studies that deal with the theory of black hole evolution due to evaporation. I studied in particular the evolution of rotating black holes and their lifetime. I have also obtained the formulas that allow to compute the Hawking radiation of a large class of non-standard black holes; constraints are modified. Finally, black holes can produce fields beyond the Standard Model, like particle dark matter, which was the subject of a dedicated study. The release of BlackHawk announces an era of precision in the study of primordial black holes, concomitant with the construction of new instruments. (author)