New analysis shows a “wobble” in the ring around a black hole

Monday, October 26, 2020

Avery Broderick talks about the latest Event Horizon Telescope work!

When the first picture of a black hole, a gravitational well from which no light can escape, was unveiled last year, it was a stunning technological feat.
Black hole image, showing a red and orange circle of light before it has crossed the event horizonThat now-famous image of the black hole known as M87* which is 55 million light years away in the Messier 87 galaxy, was the result of over a decade of work by hundreds of scientists and engineers who are part of the Event Horizon Telescope (EHT) collaboration that created an “earth-sized” telescope out of eight telescope facilities around the world.

Yet the culmination of all that work was just the beginning.

Since then, the collaboration has been moving from black hole portraiture to black hole cinema.

In the most recent work, scientists used the older, archival data sets from observations of M87* that date all the way back to 2009, when there were only three telescope sites in the collaboration.

From that older data, combined with what they learned from the more recent observations, scientists constructed a moving image showing the “wobble” in the orientation of the bright crescent ring of plasma around M87* They are seeing the changes over time as the plasma is pushed and pulled by magnetic and gravitational forces in an extremely turbulent environment.

The work was published in The Astrophysical Journal in September.

We recently interviewed Avery Broderick, a professor at the University of Waterloo and an associate faculty member at Perimeter Institute for Theoretical Physics who has been a member of the EHT collaboration from the very beginning, about the latest work and what is in store for the future:

Q: How is your team at Waterloo involved in the most recent work to show the wobble?

Avery BroderickBroderick: What we do is develop the pipelines that go all the way from the pre-imaging data to the conclusions about the fundamental science questions that have driven the project and keep us all up at night.

Another way of saying it is that our job is to bring the actual detailed observables of the Event Horizon Telescope into direct contact with the science questions that drove its construction.

Towards that end, we've developed a large amount of software, we've developed a large number of models that facilitate this comparison, and then we execute them.

This wobble paper, was enabled by that process. Once we develop the software, we shared it with the collaboration.  Members of the collaboration then got the idea to go and build out this set of analyses of this prior data given what we know now. We're very pleased that they're using the tools we’ve built here in Waterloo and we're very proud that it has succeeded so widely,

A key feature of this toolkit is careful error estimation. It is especially important to be able to assess how well we can make quantitative statements about the size and orientation of the bright ring in this context.  This allows us to extract cutting edge science even when our data volume is very small and our data is incomplete. The software tools, the analysis tools we developed, are really enabling technologies for this kind of historical inspection where the data quality is poor.

Q: Was this wobble a surprise? Was it what you expected?

See the answer to this question, and many more in the full story!