Echo-mapping of supermassive black holes

Talk by Dr Juan Hernández Santisteban from the University of St Andrews.

We will also have the Sky in November.

In person in Edinburgh or live on our YouTube channel

Supermassive black holes inhabit the cores of every galaxy in our Universe. In many cases, material can reach very close to them forming a flat, thin disc of hot material producing one of the most energetic and bright sources in the sky, observable all the way back to the formation of the first galaxies. As material spirals into the supermassive black hole, it causes changes in the brightness that propagates outwards to the disc. As light travels further away the black hole, it echoes at larger distances in the surrounding disc. From Earth, we observe this “echoes” of the inner parts of the disc at different colours of the electromagnetic spectrum shifted in time. This “echo mapping” of black holes is a fantastic technique that allows us to probe this otherwise inaccessible environment enabling to measure the size of the disc and the mass of the black hole. In this talk I will present what we can learn about the extreme conditions around supermassive black holes and the many puzzles that are left to solve.

Juan did his undergraduate studies in mechanical engineering at UNAM, in Mexico City, Mexico. He the pursued a MSc in Astronomy at UNAM and emigrated to the UK, where he studied a PhD in Astronomy at the University of Southampton focus in the multiwavelength study of accreting white dwarfs and neutron stars. He then worked at the University of Amsterdam and University of St Andrews as a postdoctoral fellow. For the past 3 years, he has worked as a lecturer in Astronomy at St Andrews focusing on observational studies of supermassive black holes.

Image credit: By EHT Collaboration – https://www.eso.org/public/images/eso2208-eht-mwa/ (image link), CC BY 4.0