Dr Luke Davies
All about the galaxy life cycle
Dr Davies looks at galaxies of all shapes and sizes to compare those that existed in the early Universe to those that formed more recently.
Luke’s big research question at the moment is ‘do galaxies form more stars when they dramatically smash together?’
Research Specialisation: Galaxy evolution by comparing the stellar, dust and molecular gas components of star-forming systems in the early Universe.
the interview below was conducted in 2015
What first got you interested in astronomy/astrophysics, and how old were you?
For as long as I can remember, I have always had a passion to study the unknown. As a child, I wondered about the things that I couldn’t understand, questioning what I saw around me. During many over-dinner conversations and several rained out camping trips, my father would fan the flames of my fascination with the basic human desire to understand the Universe we live in. I remember him asking if I could prove that I wasn’t just a ‘brain in a jar’ somewhere, and that my reality truly existed. After days of pondering, I came to the conclusion that I couldn’t. This realisation bewildered me and I became curious about other questions that as yet had no answers, such as why are we here and where did the Universe come from? With the seed of curiosity well and truly sown, from then on I would look up to the night sky and wonder in amazement at the vast scale of the Universe (and still do), questioning what the small dots of light were, how they got there, and how they work.
What made you decide to take up astronomy as a career?
During my physics undergraduate degree a professor explained to me that the light we observe from distant galaxies was emitted 12 billion years ago and that the galaxy it came from had long since died. I thought about this for a long time and decided that it meant that the light had been traveling through the Universe, unimpeded, for 12 billion years. While the dinosaurs roamed the earth it was flying on its lonely path through space. In fact, since that light left its home, the Sun, the solar system, the Earth, life as we know it and humanity have all come into existence. The fact that humanity, having been around for the blink of an eye in cosmological terms, existing on a tiny little planet, in a seemingly unimportant place in space, can eventually build a telescope to capture that light after its 12 billion year journey and then use it to understand what was going on in a galaxy that ceased to exist billions of years before, was simply mind-blowing for me. So when the opportunity came to do a PhD in Astrophysics and eventually pursue it as a career, I jumped at the chance. I wanted my day-to-day job to be about tackling the unanswered questions about the Universe!
Where and what did you study to become a professional astronomer?
I studied an undergraduate masters level degree in Physics with Astrophysics at the University of Bristol in the UK, and then carried on to do a PhD in galaxy evolution at the same University (entitled – ‘A Multi-Wavelength study of Early Star-forming Galaxies’).
What are some of the observatories you’ve been to? Which one was your favourite and why?
I have observed at the Australia Telescope Compact Array (ATCA) in Narrabri, NSW, the Anglo-Australian Telescope in Siding Spring, NSW, the IRAM 30m telescope in Granada, Spain and the Isaac Newton Telescope (INT) on La Palma, Canary Islands. I think my favourite was probably the INT. At the telescope you are perched on top of a caldera in the middle of the Atlantic Ocean, just off the coast of Africa. You are high above the clouds, which fill the caldera and cover the rest of the island, so it feels like you are floating on a rocky outcrop close to the stars, with only telescope domes for company. The atmosphere is thin up there as well, so the night sky is amazingly beautiful. You can stand outside on a moonless night and see well, just from the light of the stars.
How did you come to be at ICRAR?
While I was working as a post-doctoral researcher at Bristol, a job opening came up in Perth that looked really great. My wife and I had always talked about moving to Australia because it looked like a fantastic place to live (and we weren’t wrong!).
What’s your current research all about?
My current research is in galaxy evolution. I work with large galaxy surveys such as the Galaxy and Mass Assembly (GAMA) survey and the upcoming Wide Area Vista Extragalactic Survey (WAVES), which study the properties of 100,000s to millions of galaxies. Using these surveys I try to understand how these galaxies have changed from those that were formed soon after the Big Bang, right up to the galaxies we see in the Universe at the present day. More specifically, I study the rate at which stars form in galaxies and how this rate is affected by the galaxy’s local environment and its recent history. For example, a question I’m working on at the moment is, do galaxies form more stars when they dramatically smash together?
What astronomical puzzle would you like to crack, or which sort of object would you like to find, and why?
I would like to understand how galaxies grow. Galaxies get bigger by forming new stars or merging together, and the rate at which they grow changes as the Universe evolves over time. So I would like to build a complete picture of how these two competing methods build up galaxies, from the distant early Universe to the present day.
Do you have a hobby telescope? Do you do any night sky observing for fun?
I don’t have a hobby telescope, but I am frequently at events where people do. I always ask them to point out some nearby astronomical object and have a look through. I am pretty amazed at the talents and encyclopaedic knowledge of amateur astronomers, who can normally find anything in the sky I ask to have a look at. I think the night sky observing I do for fun is to simply going out into the middle of nowhere on a dark night and look up. It is very easy to get lost in the specifics of tiny things as a professional astronomer and to never go outside and return to the wonder that you experienced as a child. Now I live in the southern hemisphere this is even more amazing, as I can go out and see the Milky Way galaxy in all its glory.
What’s your favourite astronomical object and why?
I wouldn’t say I have a favourite astronomical object, as I generally work on large surveys of galaxies and not individual sources. However, if I had to choose I would probably say the constellation of Cassiopeia. This was the first thing in the night sky (other than the Moon, Sun and planets) that I learned the name of as a small child. My father pointed out the constellation and told me the story of queen Cassiopeia from Greek mythology. It is also a constellation near to the north pole and is visible all year round in the northern hemisphere, so it always reminds me of my home.