Our Ph.D. student, Aishwarya Girdhar was featured as the “Physicist of the week” by The Working Group for Equal Opportunities (AKC) of the German Physical Society (DPG) in the 52nd week of 2020. Aish is a second-year Ph.D. student at the European Southern Observatory (ESO), in Garching, Munich, and is jointly supervised by Dr. Chris Harrison at Newcastle University and Dr. Vincenzo Mainieri at the European Southern Observatory.
Chris Harrison will be taking on a new PhD student in October 2021.
This PhD project is about using cutting-edge astronomical observations to understand the underlying physics of how supermassive black holes impact on the evolution of galaxies. When supermassive black holes grow to become known as “active galactic nuclei” (AGN), it is believed that they drive outflows of gas and consequently regulate the level of star formation inside their host galaxies. However, key questions remain that will be addressed in this studentship: “Through which physical processes do AGN inject energy over galaxy-wide scales?” and “Is there any observational evidence for impact upon star formation by AGN?”.
The student will join the international team of the “Quasar Feedback Survey”, which includes observers and theorists tackling these questions. The student will perform analyses on our multi-wavelength observations of galaxies that host the most powerful AGN (called quasars), including radio observations and integral field spectroscopy. They will extract key physical quantities from the data that will then be compared to theoretical predictions. Due to the extensive data available there is plenty of flexibility in the project depending on which aspects are most appealing to the student. Some programming experience will be required for the project and previous astrophysics education would be desirable.
For more information and to find out how to apply visit findaphd.com
Chris has been awarded public engagement grants from STFC and the Royal Astronomical Society to make a planetarium show and educational resources that are accessible to blind and vision impaired children. This build on a pilot project done last year at the British Science Festival in collaboration with blind astronomer Dr Nic Bonne. Uniquely, the planetarium show will use sounds and narration as the main methods of communication, with visuals acting as a secondary mode of communication. When COVID-19 restrictions are relaxed we will regularly visit our partner schools to also co-develop BVI-accessible classroom based activities around the subject of astronomy that use both sounds and tactile models. Here you can listen to a little taster of the soundtrack below and see a photograph of some of the tactile models.
The 3D models showcased in this montage were created by Nicolas Bonne for A Dark Tour of the Universe, an astronomy show for the blind and visually impaired. Image Credit: ESO/M. Zamani, Nicolas Bonne, S. Brunier, TRAPPIST/ E. Jehin, EHT Collaboration, Sloan Digital Sky Survey, Millennium Simulation Project, NASA/ Goddard/ SDO, WMAP Science Team
The technique of integral field spectroscopy allows us to spatially-resolve the gas properties of individual galaxies. This is because we get a spectrum at every spatial pixel of the galaxy. By measuring the abundance of heavy elements (e.g., Nitrogen) compared to Hydrogen, the so-called “metallicity” we can learn about the star formation processes of the galaxies. Star formation inside a galaxy will enrich the gas with heavy elements (e.g., through supernovae and stellar winds) and will increase the “metallicity”. Strong star formation driven winds and supernova will distribute metals across the galaxy. In contrast, “pristine” material (mostly hydrogen) can also be accreted onto the galaxy through gas inflows. Consequently a lot can be learn by measuring the metallicity gradient inside individual galaxies we can learn about the distribution of star formation and the relevance of gas inflows.
Newcastle’s Chris Harrison is part of a team using extensive integral field spectroscopy from KMOS to study galaxies at the “cosmic noon” i.e., redshift z~1-2 when cosmic star formation was at its highest levels (KROSS, KGES and KURVS surveys). This paper uses these data to measure the galaxy-wide metallicity and metallicity gradients of ~650 star-forming galaxies at z~0.6 – 1.8. We find that for a given stellar mass, more highly star-forming, larger and irregular galaxies have lower gas-phase metallicities, which may be attributable to their lower surface mass densities and the higher gas fractions of irregular systems. Galaxies in our sample exhibit flatter metallicity gradients than local star-forming galaxies, in agreement with numerical models in which stellar feedback plays a crucial role in redistributing metals.
Metallicity gradients – i.e., the spatial gradient of the abundance of heavy elements across each galaxy – as a function of their redshifts (or equivalently, their cosmic time). There is no significant evolution between our two high redshift samples (blue and green circles); however, both samples exhibit slightly flatter gradients than observed locally (square data points). We also show theoretical predictions from two models of disc galaxies from Mott et al. (2013) with radially constant star-formation efficiency (purple dashed line) and variable star formation efficiencies (solid purple line).
We are launching our new research group website! We are a new group, interested in astronomy/astrophysics research topics mostly from an observational perspective. Our group properly started in 2020 with our first intake of PhD students and MRes students.
In this news feed we will post updates on our: research activities (papers, conferences, talks etc.), group membership and outreach/engagement activities.
