Graduate Series: An Interview with David Starkey
Hi David, could you introduce yourself to our readers,
Hi I’m David Starkey, I’m a 24 year old PhD candidate at the University of St Andrews and I’m studying Physics.
What is it specifically that you study?
I’m part of a study that searches for active galaxies. These are also known as quasars (although the term can denote a variety of objects). An active galaxy is a galaxy that shines very brightly – due to the presence of a black hole that is consuming enormous amounts of mass.
The material being consumed by the black hole sort of bunches up and forms a spinning disk of matter called an accretion disk.
How exactly do you study these galaxies?
We measure the amount of photon’s we receive from individual galaxies over time. This data is used to produce what is called a light curve. As such I am involved in the more statistical side of astronomy rather than say observational or theoretical.
The galaxies are too far away for telescopes to resolve. In fact scalewise, it’s a bit like trying to read a newspaper headline on the moon from your back yard with a pair of binoculars. Since the region close to the black hole is too remote to make out, we collect all the light from the galaxy at X-ray, UV, optical and IR wavelengths. We notice that the day-to-day variations in brightness tend to happen first at X-ray/UV wavelengths and then later at longer wavelength optical and IR wavelengths. The time lag between these variations allows us to reconstruct a picture of the accretion disk and overcome (to a degree) the resolution problem.
Is it difficult to arrange time on a telescope for things like this?
It certainly can be. It can take anything from 3 months to 9 months to get on a piece of equipment. You have to submit a proposal to a committee that judges the merits of your research. You’re then prioritised into a queue of time for the telescope.
Where does the funding come from?
My supervisor has secured some funding from grant money. We used it to book time on the LCOGT, JWST and swift telescopes.
HST and swift (the optical, UV and X-ray telescopes we used for that particular project) are NASA-funded telescopes. UK contributions tend to be from the Science and Technology Facilities Council (STFC) who also funded my PhD.
Have you been abroad at all as part of your research?
Yes actually I’ve been to Chile to visit the telescopes they have there, high up the in the Andes so as to avoid the light population of urban populations. It was an unusual place – rather like an empty hotel. I was given a car to travel from the accommodation to the telescope higher up the mountain. However, we were not allowed to use our main beam lights so we had to drive up using the light of the side lights or flashing indicators!
Have you encountered anything surprising during your research?
We thought originally there was a hot corona that had a direct relation with x rays emitted from the black hole. However, the X rays appear to be more random than we thought. One interpretation of our results indicates that, rather than a single accretion disc, we may be dealing with a twin disc system where the outer disk is torn apart and realigns with the black holes spin direction at some inner boundary. Like I said that’s just one interpretation of the light curve time lags we measured, there could be others.
What are your future plans?
I want to stay in academia. I’m applying for a post doc in the UK at the moment but I would be open to travelling abroad.
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"Graduate Series: An Interview with David Starkey" First published on Company Connecting November 2016