Tuomas Savolainen: In astronomical research we often navigate in uncharted waters

You have a PhD in astronomy from the University of Turku and you are also a docent in astronomy. How did you end up studying astronomy? 

I've been interested in stars and space since I was less than 10 years old. I got my own telescope around that time and joined the local astronomy club. The club had their own observatory built on top of the municipal water tower, where as teenagers, we made observations together with others interested in astronomy. 

I was admitted to the University of Turku to study physics in 1997. The University of Turku offered astronomy studies as part of physical sciences, but back then, it was by no means clear that I would choose astronomy as my major. However, astronomy took over when I participated in Esko Valtaoja’s quasar research course. From that course, I got an opportunity to work at the Tuorla Observatory as a summer intern.  I think that was the beginning of my astronomical path which has led me up to this point. 

You specialize in radio astronomy, astrophysics and black holes. What is it like to study black holes? 

I did my doctoral dissertation on active galactic nuclei jets using very long baseline interferometry (VLBI). In VLBI, radio telescopes located far from each other are combined to function as a single instrument with a resolution of the telescope of the size of the Earth. The idea is that participating telescopes observe the same object in space simultaneously and record the signals they detect, which are then combined afterwards using a phenomenon called interference. The method gives the highest resolution that can currently be achieved in astronomy. 

In my research, I have focused especially on the plasma jets launched from black holes located in the centers of active galaxies. A black hole is a huge gravitational well, where a lot of material falls in active galaxies. However, not all material falling into the hole always dives beyond the event horizon of the black hole, but some of it can be thrown out as two plasma jets. The jets are huge in size and can extend from the centers of galaxies all the way to intergalactic space. We still don’t fully understand how black holes generate these galaxy-splitting jets of plasma. This mystery of space is something I have been trying to unravel since my doctoral dissertation.    

We managed to capture an image of a black hole for the first time in human history in 2019 as part of the Event Horizon Telescope project, in which I was involved. I would compare taking a picture of a black hole to photographing a golf ball on the surface of the moon because the required resolution is about the same. This project also used very long baseline interferometry and telescopes around the globe to achieve sufficient resolution. The project is a major achievement of long-term international research cooperation and the development of radio astronomical technology. With the help of today's technology, we get a glimpse into environments that were not possible to explore, for example, in the early days of my studies.   

In modern astronomical research, we often navigate in uncharted waters. For example, images from the Event Horizon Telescope have allowed us to test Einstein's general theory of relativity in a completely new environment, near a supermassive black hole. We did not find any deviations from the predictions of the theory, which is a significant result in itself. 

What is it like to be a researcher? 

I'm an observing astronomer, and my job differs, for example, from an experimental physicist in that I cannot go to a laboratory and repeat an experiment changing its conditions one by one. I can only observe what reaches us from space, be it light or particles. Thus, technological improvement in instruments is central to the progress of research, but it isn’t the only important thing in the field. In the objects we study, changes are seen on time scales that range from minutes to decades, which means that monitoring the changes is also important for understanding their physics. 

As a researcher, one must constantly tolerate uncertainty. We must continuously question ourselves whether we missed something in our observations or whether we were able to eliminate all disturbances caused by the equipment. Such uncertainty is a normal part of research work and, one might say, a prerequisite for it. First, you always have to convince yourself – I often ask myself if everything was noticed or, for example, if the statement in the article was accurate. You learn to tolerate it, and one also has to remember that there would be no point in doing research if we were always sure of everything. Then there would be nothing to investigate. 

What is the most rewarding part of your job? 

The most rewarding thing is if we manage to discover something new. The black hole image published in 2019 is certainly one of the high points of my career, but in addition to bigger successes, it is also rewarding to for example see a student's completed doctoral dissertation, have a manuscript approved, get a new insight, or see the arrival of Metsähovi's new receiver next year.