Ph.D. Project 2023-2026

Theoretical modelling of neutron star mergers: Atomic Theory and Radiation Transport.

Project supervisors: Cathy Ramsbottom, Connor Ballance and Stuart Sim

Background and Motivations:

In August 2017 gravitational wave detectors found their first neutron star merger as part of the LIGO and VIRGO projects. Neutron stars come in pairs and represent ultra-dense collapsed cores of stars, they ultimately collide at 20% of the speed of light and create a radioactive ex- pulsion of heavy elements. This new astrophysical phenomenon is termed a kilonova and was awarded Science’s Breakthrough of the year. These binary neutron star mergers are thought to be the forge in which the heavy r-process elements with atomic number greater the Fe are formed. The first kilonova has provided us with rich and complex spectra and understanding these observations is the basis for understanding the physics of these events. To interpret these observations, it is necessary to simulate the physical conditions of the event via modelling. Two major radiative transfer codes will be utilised for modelling these spectra at QUB (ARTIS and TARDIS). Thus far this has proved very difficult as the vital radiative and collisional atomic data does not currently exist with suitable quality and quantity for inclusion in the modelling codes. Thus this project would aim to rectify this and fill the vacuum in the databases for the low ionization stages (I, II, III) for the r-process elements of interest.

Supervision of this project would involve Cathy Ramsbottom, Connor Ballance and Stuart Sim, who are experts in the relevant atomic theory and radiation transport modelling. Funding of a student for this project is guaranteed as part of a major European Research Council grant, awarded to the project supervisors. The PhD student working on this project will therefore be expected to be part of the HEAVYMETAL international research team, a collaboration between QUB, University College Dublin, GSI Darmstadt and the University of Copenhagen. As such, applicants should expect that this project is likely to involve periods of travel and/or extended visits to our project partners.

https://www.qub.ac.uk/News/Allnews/2022/funding-boost-neutron-star-collision-project. html

https://erc.europa.eu/news-events/news/erc-synergy-grants-2022-project-highlights

Benefits to the Student:

• Excellent collaborative networks in the UK, Europe and the USA have been established to complement this project. The student will get the opportunity to travel and liaise with both theoretical and experimental groups in institutes around the world.
• The student will be trained in complex theoretical quantum physics and radiative transfer modelling and will get the opportunity to run some of the most sophisticated computer codes on some of the largest supercomputers in the world.
• The project is interdisciplinary, involving expertise in mathematics, physics, astronomy, modelling, computer science and experimental techniques. This will give the student the opportunity to gather many varied skills throughout their PhD training.
• The opportunity to travel for collaborative visits, conferences and workshops will be ex- tensive

Required skills:

• Previous experience with programming would be beneficial. A large component of the project shall be computational, and an interest in developing these skills on local parallel computing platforms and/or national/international supercomputers is required.
• A basic understanding of introductory quantum mechanics and atomic structure would also be beneficial.
• An interest in astrophysics and modelling.

For further information, please contact c.ramsbottom@qub.ac.uk, c.ballance@qub.ac.uk and/or s.sim@qub.ac.uk.