Alexander Hill

Intro

Graduation from Durham University, June 2016.

Born in Leeds, UK, I completed my Master's degree in Physics and Astronomy at Durham University. My dissertation was on the properties of disk galaxies at the universe's star forming heyday. Check out my current work.

Outside Astronomy

Collingwood College, Floodlit Cup Champions 2016!

In my time away from the computer screen, I like to explore the wilder parts of the country and to travel abroad. I have recently taken up bouldering, which I do alongside playing rugby, football, tennis and mountain biking. I enjoy reading history, literature

LIVDAT

Members of LIVDAT at the CDT National Kick-Off Event in Cardiff, October 2017

I am a member of the Liverpool Big Data Science (LIVDAT) Centre for Doctoral Training (CDT) initiative, a collaboration between Liverpool John Moores University and the University of Liverpool aimed at training students in managing, analysing and interpreting large datasets.

Research

Jodrell Bank, STFC Introductory Summer School in Astronomy 2017

Introduction

I use the EAGLE (Evolution and Assembly of GaLaxies and their Environments) suite of simulations to understand how galaxies formed and evolved over cosmic history. The physics is modelled with nearly 7 billion particles within a box of length 100 Megaparsecs.

Currently I am using EAGLE to investigate the systematics that may affect future radio weak lensing surveys, such as the SKA (Square Kilometer Array). Gravitational lensing occurs when light from a background source is distorted by the matter along its path to an observer. As lensing is sensitive to all types of matter, it is a highly useful tool in understanding the distribution of dark matter in the universe. Weak lensing causes the images of galaxies to be stretched and rotated with respect to their true selves, so understanding the degree of distortion tells you a lot about what the light encountered on its way to us. So far so good, however other physical phenomena can make it seem like lensing has occurred to a greater extent than it has.

Examples of galaxies taken from EAGLE illustrating the z = 0 Hubble sequence of galaxy morphologies (Schaye et al. 2015).

Hill et al. 2021

Figures of the best fitting functions to histograms of star-forming gas - DM misalignment anlge may be found here. Values in the legend refer to the median values of the input distribution and the best fitting profile.

Current Work

The shapes and orientations of galaxies are dependent on many environmental factors, including the properties of their neighbours and their location with respect to the Cosmic Web . Background galaxies can be lensed by a common cluster to appear to be aligned, equally neighbouring galaxies can be aligned by their common local density field. I am in the process of using EAGLE to characterise the shapes, orientations and alignments of gas, stars and dark matter within galaxies, as well as the alignments between neighbouring galaxies and satellites.

Videos of shape error convergence for different tensors: star-forming gas, dark matter, stars

EAGLE catalogue data created by Jon Davies for the purposes of cosmic web extraction may be found here: here

TNG300-1 catalogue data created the purposes of cosmic web extraction may be found here: here

TNG300-1-Dark catalogue data created the purposes of cosmic web extraction may be found here: here

Future Work

In the future I will work to bridge the gap between simulations and real-world observations by creating ’synthetic skies’, investigating how the universe within the simulation would appear to an internal observer.

Seminars

July 2020 - Seminar on my industrial placement at IBM Research UK. Slides here and blog post here.

January 2020 - Seminar at Virgo 2020, Durham, on the predicted Intrinsic Alignment of radio galaxies. [Slides].

July 2019 - Seminar at National Astronomy Meeting, Lancaster. [Slides].

In 2018 I gave a talk to residents of the Liverpool Science Park on the work of the High Performance Computing Group at the ARI [Slids.]

Posters

My poster at the SKA General Science Meeting was on the intrinsic alignment of radio galaxies in the EAGLE Simulation.

Public Engagement

October 2020 - Public engagement lecture on all things astronomy and simulations, in co-operation with the University of Liverpool and the Bolton Council of Mosques. Video and slides.

In 2018 I gave a talk to residents of the Liverpool Science Park on the work of the High Performance Computing Group at the ARI [slides].

Augmented Reality

Between October 2019 and January 2020, I undertook an industrial secondment at imagin3d, with a remit to explore augemnted reality (AR) applications in science education and outreach. One product produced explored the EAGLE universe and featured in my pitch for the IoP's 'Three Minute Wonder' competition.

Tutorials

Download answers and recordings for Galaxies Tutorial II.

Download answers and recordings for Cosmology Tutorial I.

Contact

Please contact me via Email, Twitter or LinkedIn using the below links. My publically available code can be found on my GitHub page.

• Twitter
• LinkedIn
• GitHub
• Mail

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