Portrait of Katie Bouman by NSF. Portrait of Katie Bouman. Credit: NSF [Public domain].

The electrical engineer

Katie Bouman grew up in Indiana, where she first conducted imaging research as a high school student. The research was conducted at Purdue University. Around this time, she heard about the Event Horizon Telescope Collaboration for the first time.1

She then went to study electrical engineering at the University of Michigan, from where she graduated in 2011 “with highest praise”. She got her master’s and doctoral degrees in electrical engineering and computer science, studying at MIT. She also got awarded for best master’s thesis - as it seems that she excelled in all her studies. She made her doctoral dissertation on the topic of imaging black holes, which laid the foundation for her future endeavors. She also explained her algorithms for black hole imaging at a TED talk:1

TED Talk: How to take a picture of a black hole (Katie Bouman)

The Event Horizon Telescope (EHT) Collaboration

After MIT Bouman became a postdoctoral researcher at Harvard. She joined the Event Horizon Telescope Collaboration, as part of the imaging team.1 The mission was to use an international network of telescopes to to capture the first-ever image of a black hole.2

More specifically, the black hole in question is positioned in far away galaxy; 55 million light-years from Earth.3 The global network of telescopes collected millions of gigabytes of data about the M87 galaxy.2

Using atomic clocks, the network of eight telescopes could combine their data and correct it for time differences and other errors. This technique is called VLBI arrays (Very Long Baseline Interferometry), and allows for the eight telescopes to act as one larger Earth-size telescope, gathering data at mm wavelengths.4

In April 2019, the first ever image of a black hole was released, constructed as an international team effort.2

“We have taken the first picture of a black hole,” said EHT project director Sheperd S. Doeleman of the Harvard-Smithsonian Center for Astrophysics. “This is an extraordinary scientific feat accomplished by a team of more than 200 researchers.”3

First image of a black hole. First image of a black hole. Credit: EHT Collaboration/ESO [CC BY 4.0 (https://www.eso.org/public/outreach/copyright/)]

Katie’s imaging algorithm

Junior team members played a significant role in the black hole imaging project. Especially, Katies imaging algorithm was important to interpret the data that was gathered from the telescopes.2

When using eight telescopes to simulate an earth-sized telescope, there will be data missing in the light collected. Some of this data can be filled by the fact that the earth rotates and thus gives new measurements at new places. However, this will still provide a very limited picture after all the pieces have been assembled.5

This is where Katie’s imaging algorithm comes in, to use the data and form a complete picture. Katie suggests that there is such a thing as a natural image.2 Thus, if we can fill in the gaps in the picture without relying on Einstein’s relativity theory - that is our existing ideas of how black holes should look - we can calculate an image that tells its own truth. 5

“If we bake Einstein’s equations too much into our algorithms, we’ll just end up seeing what we expect to see. In other words, we want to leave the option open for there being a giant elephant at the center of our galaxy.” 5

So to reconstruct the black hole image, Katie used the fact that different types of images have distinct features. The goal is then to let the algorithm reconstruct the image without imposing the characteristics of a specific image set. 5

To solve this, different image sets were used, and the algorithm was then supposed to give similar reconstructions - even though it used different puzzle pieces each time. Thus, a “natural image” can be obtained with more than one image set or more than one technique. 5

“Bouman led the creation of an algorithm that eventually helped capture this first-of-its-kind image: a supermassive black hole and its shadow at the center of a galaxy known as M87.” 2

  1. https://en.wikipedia.org/wiki/Katie_Bouman  2 3

  2. https://www.cnn.com/2019/04/10/us/katie-bouman-mit-black-hole-algorithm-sci-trnd/  2 3 4 5 6

  3. https://eventhorizontelescope.org  2

  4. https://astronomy.fas.harvard.edu/people/shep-doeleman 

  5. https://www.ted.com/talks/katie_bouman_what_does_a_black_hole_look_like/transcript#t-758519  2 3 4 5