Abstract

Supermassive black holes are believed to reside at the centres of galaxies, powering some of themost violent and energetic events in the known Universe. In spite of overwhelming indirect evidence of their existence, until recently black holes had evaded direct observational confirmation. In April 2019, the Event Horizon Telescope Collaboration (EHTC), an international collaboration of over 60 universities and institutes spanning six continents, astonished the world by publishing the first ever picture of a black hole. This picture, of the black hole in the heart of the galaxy Messier 87 (M87), received worldwide media coverage and represents the first time humankind has peered at the literal edge of space and time. To accomplish this unprecedented feat, the EHTC linked radio telescopes around the world, producing a virtual Earth-sized telescope with sufficient resolution to image, from Earth, an orange on the Moon. The EHTC has this year gone a step further, imaging M87 using polarised light, pioneering the measurement of its surrounding magnetic field and unravelling how it consumes and ejects matter so prodigiously.

In this talk I will begin by reviewing the basic properties of black holes and their history in modern science. I will then present an overview of our current understanding of the physics of matter and radiation near the event horizon, outlining how this understanding informed our theoretical calculations of black-hole images which underpinned the EHTC ’s measurement of the image of M87 . I will then explain how the EHTC performed these ground-breaking measurements and produced the first images of a black hole. Finally, I will discuss some of the exciting ongoing efforts and new scientific developments which will be taking place in the near-future.