I am an astronomer using radio telescopes to answer fundamental questions on how super-massive black holes co-evolve with the galaxies in which they reside. My speciality is high-resolution imaging at low frequencies, using a Square Kilometre Array pathfinder telescope, the Low Frequency Array. I recently won a UKRI Future Leaders Fellowship to carry out a unique high-resolution, low-frequency radio survey using LOFAR to help advance our understanding on how AGN help shape galaxy evolution. I will hold this fellowship from November 2020 at the Centre for Extragalactic Astronomy and the Institute for Computational Cosmology, Durham University, where I am an Assistant Professor. Outside of work, I am an avid reader, I love to sew, and you can often find me in the countryside walking my dogs! Scroll down for more information on my research, qualifications, advocacy, and how to contact me.
Active Galactic Nuclei (AGN)
A super-massive black hole exists at the centre of almost every massive galaxy. The gravitational potential of these black holes can power highly energetic phenomena which are observed on sub-galaxy to galaxy cluster size scales, across the entire electromagnetic spectrum; when we observe these phenomena we know these are active galactic nuclei (AGN). The basic picture of AGN that has emerged is of a black hole surrounded by an accretion disk, with a corona of hot gas, and the entire region is circled by a dusty torus. In some cases, AGN launch relativistic jets that extend far beyond the galaxy itself. But no matter how much energy an AGN outputs, the black hole powering it still remains a tiny part (both in physical size and total mass) of its host galaxy. Yet we see observational evidence for tight correlations between black hole properties and the general properties of galaxies, and we know from cosmological simulations of the Universe that some energy from AGN must help regulate galaxy growth; without it we are unable to reproduce observed galaxy populations. This suggests feedback between AGN and their host galaxies, but the huge range of size scales coupled with a wide range of energy transport options means the true nature of this feedback remains unknown.
Radio emission from AGN
A galaxy with an AGN can produce radio emission in multiple ways. The red/pink emission you see in the image on the left (a galaxy named Cygnus A) is from synchrotron emission which is observed at radio wavelengths. These relativistic jets extend far beyond the host galaxy (the small white blob at the centre) and can interact with their environment. Here you can see that they have tunnelled through the hot gas in the intra-cluster medium, which is traced by X-ray emission in blue. Large scale jets like these were thought to be rare, although recently LOFAR has revealed they may be more prevalent than we think, and they are not well modelled in simulations. While the majority of AGN don't have these kinds of jets, they can still produce fainter, small-scale radio emission in other ways. We know there will be some contribution from star formation, as supernova remnants leftover from the deaths of massive stars are ideal locations for cosmic rays to accelerate and produce synchrotron emission. But there is a portion of the faint radio emission from AGN that cannot be accounted for by star formation: is it small scale jets? Thermal radio emission associated with disk winds? Something we haven't thought about yet? High resolution radio observations for large samples will be crucial for understanding the origin of this extra radio emission.
View full Curriculum Vitae • Search by orcid on ADS • PhD, Leiden University October 2012 - September 2016 "Radio Galaxies at Low Frequencies: high spatial and spectral resolution studies with LOFAR" Supervisor: Huub Rottgering • MSc, University of Oklahoma September 2009 - May 2012 "Active Galactic Nuclei: from Supermassive Black Holes to Rare FeLoBALs" Supervisor: Xinyu Dai • BSc, University of Michigan September 2001 - April 2005 Double major in Physics and Astronomy
I am committed to helping promote gender equality in Physics. As an undergraduate at the University of Michigan, I was one of the three co-founders of the Society of Women in Physics (SWiP). As a fellow at Oxford, I served as the President of the Oxford Women in Physics Society, and served on the department's Equality and Diversity committee. I am also committed to helping promote racial equality in Physics, and am actively learning what steps I can take to make systematic changes in our community. Here is an excellent talk series I recommend for everyone, whether or not they belong to an under-represented group: Astronomy in Colour Talk Series. I am not associated with the AiC organisation, but have attended as many of the talks as I can!