An excellent student in math, science and computing, Michael MacDonald was hesitant to pursue a career in any of those fields. It was only after he became actively involved in the discovery process related to astronomical research that he fell in love professionally.
„I think I could have become a programmer in an alternate universe because I excelled at university,” said MacDonald, an associate professor at MIT’s Kavli Institute for Astrophysics and Space Research. „But my first experience with astronomy research, I thought it was something I could do for the rest of my life.”
During his junior year at Queen’s University in Ontario, Canada, McDonald asked a professor named Stéphane Courteau if he could work with him for the summer. That summer changed everything for MacDonald.
„He gave me my first taste of research and took me to Mauna Kea in Hawaii to use a research-grade telescope for the first time,” he says. „It was a life-changing experience, and I immediately got into research and then really didn’t slow down.”
Macdonald received three degrees from Queen’s University: two bachelor’s degrees, one in mathematics and statistics and one in astrophysics, and a master’s degree in astronomy. After earning a doctorate in astrophysics from the University of Maryland, he applied for fellowships and was awarded top Canadian and Australian awards as well as a non-fellowship position at MIT for astrophysics and space research.
Actually wanting a NASA Hubble or Einstein Fellowship, MacDonald learned that he missed Einstein by only one spot—they gave out six awards that year, and he finished seventh. MacDonald says he „debated” what to do with his wife for a long time, then turned down Canadian and Australian fellowships and accepted a position at MIT so he could reapply for Einstein and NASA Hubble fellowships the following year.
„I looked at everyone who was ahead of me on the Hubble/Einstein list, and I identified areas where I was weak,” he says. „I spent that first year at MIT working long hours and fixing distractions as best I could, and between 2011 and 2012 I published seven papers as first author.”
MacDonald accepted a NASA Hubble Fellowship, awarded by both Einstein and Hubble.
McDonald, now an associate professor of physics at MIT’s Kavli Institute for Astrophysics and Space Research, is best known for discovering the Phoenix cluster of galaxies. In the 1980s researchers discovered that galaxy clusters are filled with hot, diffuse gas, and that this gas must eventually cool, triggering the formation of new stars, McDonald says. However, throughout the 1990s and 2000s, no evidence of this cooling or consequent star formation was found, and researchers largely abandoned the idea of cooling flows.
In 2012, McDonald and his team discovered a „bona fide cooling flow” in the Phoenix cluster. To date, he says, „it remains the only system we have discovered that is a valuable laboratory for studying various rare physical phenomena related to the nature and origin of the universe.”
MacDonald was quoted in 2019 as using an analogy, an explanatory technique he excels at, to explain why hot gas in galaxies is expected to cool, why most clusters show no evidence of cooling, and why the Phoenix cluster is different.
Comparing a galaxy cluster to a cup of coffee, he said MIT News „It’s a 10 million degree cup of coffee, but even a 10 million degree cup of coffee gets cold.” However, most constellations behave like a cup of coffee on a warming tray. „The heat is the black hole at the center of the galaxy, and every observed cluster has a hot interior.”
Except for the Phoenix cluster.
The black hole at its center couldn’t completely cool the galaxy’s hot gas, McDonald explained, which was like putting a 10-million-degree cup of coffee on the counter instead of warming it. The plate cools enough to form new stars.
Macdonald’s use of such metaphors is a skill he finds particularly useful, especially when writing news articles or speaking to the general public.
„The vastness and complexity of space is very difficult for all of us to grasp, and simplifying the metaphors goes a long way,” he says. „I do this for myself too, it helps me understand new concepts or discoveries.”
Another strategy Macdonald uses to understand a concept he finds challenging is to let it take over his subconscious. „When I get stuck on something, or don’t fully understand it, I put it aside very quickly and move on to something I can move forward with,” he says. “Usually within 24 hours, whether it’s in bed, in the shower or on the train, I get an improvement, and then I pick up the problem again.
„In computer nerd talk, I run a lot of work in the background.”
The initial discovery of the Phoenix cluster was based on a relatively small, old telescope. As McDonald’s team learned more about this, they used more powerful telescopes, including the Magellan Telescope in Chile and finally the Hubble Space Telescope. MacDonald says the three images representing phases of that observation — the first released in 2012 and the last in 2019 — demonstrate „how you do science.”
„First we got an image of the Phoenix cluster with the telescope, and it was easy to get the timing,” he says. „When we realized it was an amazing system, we moved to an improved facility, and that motivated us to move to a better facility.”
„If we had asked for the Hubble data now, we would have been laughed out of the room because we had no compelling reason at the time to waste astronomy’s most valuable resource. Science sometimes takes a long time.
That process and the discoveries it yields continue to inspire McDonald’s.
„There’s an old book called 'Cosmic Discovery,’ and every time we look at the sky in a new way, with dramatically improved technology (in image quality or wavelength of light), we discover entirely new phenomena,” he said. He says. „That’s what I’m really excited about — there’s a whole new class of objects lurking out there that we don’t even have names for yet.”