It is currently believed that at the centre of every massive galaxy in the Universe, there lies a super-massive black hole (SMBH). Some of these SMBH have now been measured to have as much mass as 10 billion Suns, all squeezed into a volume similar to that of our own solar-system. When these monster SMBH grow by eating in matter that has fallen into their surroundings, they can release huge amounts of energy in the process. This makes them the most extreme and energetic objects in our Universe. While extraordinary and fascinating objects in their own right, these SMBH are also believed to play an important role in the evolution of their host galaxies, including those like our own Milky Way. So if we want to completely understand the origins of our galaxy, understanding how these monsters came to form and evolve is crucial. The goal of the HIZRAD project was to help build a complete picture of the early stages of SMBH formation - answering the questions of how, when and where the most extreme objects in our Universe were formed.
The project made use extensive new radio sky survey from the pan-European radio telescope, the Low Frequency Array (LOFAR), to study actively growing black holes, or Active Galactic Nuclei (AGN), throughout cosmic history. The unique power of these new radio observations is that they can peer through the gas and dust that obscure other signs of activity, meaning that LOFAR is able to reveal AGN activity that has previously been hidden from us. However, while LOFAR offers an enormous leap in our ability to discover these new AGN deep into the earliest stages of cosmic history, it cannot provide a complete picture alone. There is crucial information about these AGN that cannot be learned from their radio emission and so we must combine these data with other measurements across the electromagnetic spectrum in order to unlock their full potential.
The overall objective of the HIZRAD project was to answer the question; what was the accretion history of super-massive black holes in the early Universe? Specifically, we sought to discover news samples of the most extreme SMBH right at the very earliest stages of cosmic history and to measure how this population evolved over the early history of the Universe. We aimed to combine the LOFAR surveys with the best available complementary data from optical and infrared telescopes, including a a state-of-the-art optical survey of radio detected galaxies due to start early in the project.
