Hilay Shah

I am a PhD student in astrophysics at the Australian National University, working with Naomi McClure-Griffiths, Mark Krumholz, Christoph Federrath, Amit Seta and Freeke van de Voort. My research sits where supercomputer simulation meets radio observation.

I build magnetohydrodynamic models of galaxies — how their gas moves, how their magnetic fields are stretched and tangled, and how cosmic rays travel through them — and then turn those models into the quantities a telescope actually measures, such as Faraday rotation and dispersion measures. Comparing those synthetic observations against real survey data is what makes a simulation testable rather than merely plausible.

Two threads run through most of my work. The first is developing the theory needed to extract magnetic field strengths accurately from rotation measure observations. A rotation measure only gives the field once you also know the dispersion measure along the same sight line, which is rarely available, so I build models that predict it from indirect observables. Testing that requires galaxies whose true answer is known, which is why I have constructed and used detailed simulations of the Large Magellanic Cloud and the Milky Way. The LMC models turned out to be useful beyond magnetic fields as well: they help explain why the galaxy is so faint in gamma rays.

The second is the circumgalactic medium, the diffuse envelope of gas surrounding a galaxy. By releasing passive scalar tracers into it, I follow how gas diffuses and mixes, which properties actually drive that mixing, and how magnetic fields change the answer.

Much of this runs at scale — several million CPU-hours on the NCI Gadi supercomputer and tens of terabytes of output — analysed with a mixture of statistical testing, Markov chain Monte Carlo and symbolic regression.

Before Canberra I read Engineering Physics at IIT Roorkee, and spent a summer at the Indian Space Research Organisation's Space Applications Centre designing a polarimetric synthetic-aperture radar concept for imaging the surface of Venus. I also help run public outreach at the department: school visits, stargazing evenings and public talks. Away from research you will usually find me hiking, bouldering, playing racket sports, or turning scientific data into music.