Remember that first picture of a black hole in our galaxy? We took it
How we captured the first image of the supermassive black hole
Looking into darkness
The team observed Sagittarius A* on multiple nights, collecting data for many hours in a row, similar to using a long exposure time on a camera. Although we cannot see the black hole itself, because it is completely dark, glowing gas around it reveals a tell-tale signature: a dark central region (called a “shadow”) surrounded by a bright ring-like structure. The new view captures light bent by the powerful gravity of the black hole, which is four million times more massive than our Sun. The discovery also yields valuable clues about the workings of black holes, which are thought to reside at the center of most galaxies.
The surprising thing about this image is that it looks so similar to the image of M87* we published three years ago – this certainly came as a surprise. The reason for the similarity is that while the M87* black hole is about 1,000 times bigger, the Sagittarius black hole is about 100 times closer. Both of them obey Einstein’s theory of general relativity, showing Einstein was right for a factor of 1,000 in size scale. To aphysicistthis is important. Relativity has been around for a century and it is still proving to be accurate. I think even Einstein himself might have been surprised by that!
The publication of the picture of the Sagittarius A* black hole is a tremendously exciting achievement by the collaboration. When I first saw the image, I thought: this tells us a lot. I couldn’t wait to start writing about it and interpreting the image. We had a lot of meetings to come to a consensus of what it tells us. To begin with, we were meeting face to face in different parts of the world. Then COVID struck and suddenly nobody could go anywhere. So online meetings became the norm, as in every other aspect of life. This definitely slowed us down.
My role was to help write two of thesix papersthat have been released in the Astrophysical Journal Letters: the first one, introducing the observation; and the third one, in which we discuss how we made a picture out of the observations, and how reliable that image is.
In addition, I was a “contributing author” for all six papers. This is an administrative role, in which I handled all correspondence between our team of over 300 astronomers and the academic journal that published our findings. This had its challenges, as I had to deal with every typo and every mistake in the typesetting.
I also had to channel comments from my colleagues. Since the majority of the collaborators are based in either the US or East Asia, it meant that they were working during the night in UK time. Hence, each morning I would come to work to find about 100 overnight emails from colleagues – a daunting start to any day.
Anyway, we got there in the end – and the dazzling result was worth all of the work.
This article byDerek Ward-Thompson, Professor of Astrophysics,University of Central Lancashire,is republished fromThe Conversationunder a Creative Commons license. Read theoriginal article.
Story byThe Conversation
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