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

In a Walk in my shoes interview, Tuomas Savolainen, a senior researcher at Metsähovi Radio Observatory, reflects on his path in astronomy a journey that began with a fascination for stars and space as a young boy. He shares insights into his research on black holes and what is like to unravel the mysteries of space.
Tuomas Savolainen presenting telescope research
Tuomas Savolainen specialises in black hole research. Photo: Jaakko Kahilaniemi / Aalto University

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.   

Tuomas Savolainen laskeutui Effelsbergin 100-m radioteleskoopin primäärifokukselle.
Tuomas visited the US Very Large Array antenna in New Mexico in 2016. Photo: Frank Schinzel

What is it like to be a researcher at Metsähovi? 

Before Metsähovi, I worked for more than seven years at the Max Planck Institute for Radio Astronomy in Germany, where one of the world's largest radio telescopes is located. I joined Metsähovi as an Academy Research Fellow in 2014. Working at Metsähovi offers the peace of the countryside in a small and pleasant work community. Few radio observatories are run by such a small and efficient team, which means very diverse tasks for researchers as well. Particularly valuable is the flexible access to the telescope, which enables experimentation and also quick reaction when something interesting happens.   

The commissioning of Metsähovi's new receiver and organizing the VLBI observations with it will play a significant role in my work in the coming years. With the new technology, we can access dimmer objects in the sky and get more information for testing physical models. The new type of VLBI observations made with the new receiver will also require a lot of organization of international research cooperation. This is a very long-term project – the life span of the receiver is decades. 

Tuomas vieraili Roomassa
Tuomas has several pairs of shoes to walk in every day. Photo: Marie Körkkö

What is it like to walk in your shoes? 

My job is mostly sitting at the computer: reading, writing, processing data and making video calls. There are many roles in researcher's work, to name a few – I am a researcher, research leader, student advisor, teacher, telescope operator, evaluator, speaker, and mentor. Recently, I have also taken care of Metsähovi's VLBI operations together with our research engineer and led the procurement project for a new receiver. Various international research projects play a major role in my work, thanks to which I have colleagues all over the world – also in time zones that are inconvenient in terms of communication. You could say that I have several pairs of shoes that I change daily.     

The little birds told me that you enjoy live music, tell me what kind of gigs do you go to? 

My taste in music is quite broad and I listen to all sorts of stuff from jazz to alternative rock or from classical music to extreme metal. I go to gigs quite a lot and festivals in the summer, such as Tuska and Sideways, which are easy to visit as a Helsinki resident. You will continue to see me at festivals in the future. 

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Walk in my shoes

Inspired by the saying that you should walk a mile in someone’s shoes to understand them, the ‘Walk in my shoes’ series aims to share some of the experiences, thoughts, perspectives and challenges faced by members of the Aalto community.

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