Seeing Black Holes With An Earth-sized Telescope

SEEING BLACK HOLES WITH AN EARTH-SIZED TELESCOPE

Professor Roger Deane, University of the Witwatersrand

Wednesday 25 January

5.00 pm

COURSE FEES R110

This lecture describes how we take photographs of black holes and the scientific importance thereof. It will include an introduction to black holes and how we are able to see objects from which nothing, including light, can escape. It will describe how a global team and array of antennas are synthesised together to form the single Earth-sized telescope required to capture these images, the so-called Event Horizon Telescope (EHT). We will explore the two black holes that had been imaged so far – one 55 million light years away, the other at the centre of our Milky Way – and how they can be used to test Einstein’s General Theory of Relativity. We will also compare and contrast the EHT with other major observatories like the recently launched James Webb Space Telescope and the Square Kilometre Array, and what they are uncovering about the Universe. The lecture closes with a look at how EHT antennas in carefully selected locations in southern Africa could make unique and critical contributions to this new black hole imaging enterprise, enabling increasingly high precision tests of gravity over the course of the next decade.

Recommended reading and viewing

Thorne, K., 1995. Black holes and Time Warps. New York: WW Norton & Co.

Thorne, K., 2018. The Science of Interstellar. New York: WW Norton & Co.

Overbye, D. 2019. Darkness Visible, Finally: Astronomers Capture First Ever Image of a Black Hole. New York, New York Times. https://www.nytimes.com/2019/04/10/science/black-hole-picture.html

The Event Horizon Telescope Collaboration. 2019. First M87 Event Horizon Telescope results. I. The shadow of the supermassive black hole. The Astrophysical Journal Letters. IOP Publishing, Volume 875, L1.

The Event Horizon Telescope Collaboration. 2022. First Sagittarius A* Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole in the Center of the Milky Way. The Astrophysical Journal Letters. IOP Publishing. Volume 930, L12.

Film documentary: Black Holes, the Edge of All We Know. https://www.blackholefilm.com

Journey to our own black hole, Sagittarius A. Scroll down to this link (there is a download button below the video).

BOOK HERE

Roger Deane is a Professor at the University of the Witwatersrand, Johannesburg, where he holds the SKA Chair in Radio Astronomy and serves as the Director of the Wits Centre for Astrophysics. He also holds an Extraordinary Professorship at the University of Pretoria, where he established the Radio Astronomy Research Group in 2018. He completed his doctorate in 2012 at the University of Oxford. His research interests cover a broad range of energy and spatial scales, from diffuse neutral hydrogen in distant galaxies to the inner accretion disks of supermassive black holes, using the power of next-generation radio telescopes such as South Africa’s MeerKAT radio telescope, a precursor to the Square Kilometre Array, and Very Long Baseline Interferometers, like the Event Horizon Telescope.