BRIdging Disciplines of Galactic Chemical Evolution (BRIDGCE): The Rise of the Chemical Elements

The main scientific goal of this consortium is to study the chemical evolution of the universe from the Big Bang up to now by using chemical elements as fingerprints of the processes that took place in stars and galaxies. Although light can travel for billions of years and we can nowadays observe the cosmic microwave background emitted at the epoch of recombination, most of the stars that formed in the early universe are long dead, and larger structures like the first halos have merged or been disrupted. It is therefore not possible to observe them directly. Fortunately, stars and galactic structures leave chemical fingerprints in the stars that formed out of their ashes. Thus, in extremely-metal-poor (EMP) stars that have a low enough mass to live longer than the current age of the universe, we can observe the chemical fingerprints of the processes that took place in the early universe. Moreover, we can constrain their properties by comparing theoretical models of stars with observations of EMP stars in the halo of our galaxy, and by generating models of the chemical evolution of galaxies in cosmologically-valid simulations. Furthermore, by simulating stellar and galactic chemical evolution from the early universe until the present day, we can reproduce the entire chemical history of galaxies and the Milky Way in particular. Our research also addresses other key scientific questions: ``How can we explore and understand the extremes of the universe?'' by studying and constraining the properties of supernova explosions and ``What is the nature of nuclear and hadronic matter? '' by improving our knowledge of nuclear reaction rates. These studies linked to the rise of the chemical elements constitute the main scientific goals of the proposed research.


To answer questions like: "What are the properties of the early universe?, Where were the elements we are made of created?", knowledge in various disciplines of astrophysics and nuclear physics is necessary. Indeed, nuclear data (nuclear reaction rates in particular) are a key input for stellar evolution models since nuclear reactions provide the energy that powers stars. This information determines stellar lifetimes, and the composition of their final ejecta. Stars, in turn, provide important feedback into the galaxies they belong to through the light they radiate, their powerful supernova explosions and all the chemical elements they produce. The outputs of stellar evolution models are therefore key ingredients for galactic chemical evolution models. These models follow successive episodes of star formation and trace the history of the enrichment of the elements in various galaxies. The model predictions can then be compared to observations of EMP stars that carry the chemical fingerprints of the cumulative chemical enrichment that preceded their birth. Comparison to observations can thus constrain both the galactic and stellar properties. Stellar evolution models can also be used as virtual nuclear physics laboratories, in which we can test the impact of uncertainties in certain nuclear reaction rates.


To answer these questions, this consortium will adopt a multidisciplinary approach, gathering expertise from world-leading scientists at five UK universities, and will also further its existing intersectoral links with companies developing and producing particle detectors and high-tech shared-memory computer hardware.


Our research will apply innovative techniques across different disciplines and attack this scientific challenge through 4 projects corresponding to 3 different physical scales:

- Galactic and extra-Galactic scales (Project A)

- Stars and their nucleosynthesis (Project B)

- Micro-physics: sensitivity to nuclear and stellar modelling uncertainties (Project C) and the impact of stellar environments on nuclear reaction rates and stellar evolution (Project D)

The Consortium is cognisant of its role in inspiring and training the next generation of scientists responsible for ensuring the UK's international competitiveness in both the academic and industrial sectors, so our outreach and public engagement activities are a key aspect of our mission. Our investigators and their institutes undertake a spectrum of activities. BRIDGCE will bring a greater breadth and depth to these activities through its interdisciplinary composition.

Application and Exploitation:

Hirschi as part of his ERC project has established a working relation with the Norwegian company Numascale, which develops hardware for shared memory computer clusters. This collaboration opens the door to R&D investments from the private sector and to further European funding. Murphy and the Edinburgh group maintain strong industrial links with partners including the UK company Micron Semiconductor Ltd, in order to develop, for example, silicon strip detectors for advanced implantation detector arrays and for recycling exotic radio-nuclides. Murphy's group is a member of the Nuclear and Plasma Physics theme within SUPA, collaborating towards the creation of the Scottish Centre for the Application of Plasma-Based Accelerators which will develop new scientific and technological advances in accelerator science.

The multi-disciplinary nature of BRIDGCE affords our students and PDRAs broadened training opportunities. They will benefit from our industrial links, particularly in software optimisation alongside experts at Numascale. Designing and optimising advanced simulation codes, and "Big Data" mining as required by our massive datasets, are aligned with UK economic needs, so this training ensures the marketability of our students in diverse career paths. In addition to our postgraduate students and PDRAs staying in academia, others have progressed to highly-skilled jobs in the industrial, financial and public sectors. Our students and PDRAs receive training in data protection and exploitation of intellectual property, in order to maximise and protect current and future exploitation of STFC funded science.

Communications and Public Engagement:

Astrophysicists have unique influence in enthusing the next generation of scientists and building public support for science, and we participate enthusiastically in education and public outreach (EPO). With BRIDGCE science spanning scales from the very small (nuclei) to the very large (stellar and galactic scale), and utilising large scale high-performance computing facilities to generate evolving simulations of astronomical objects like stars (Project B) and galaxies (Project A), our consortium has a unique opportunity to capture the imagination of non-scientists.

All of our institutions have dedicated links with local schools (e.g. Preston Science Partnership, through the Ogden Trust; Bayfordbury Observatory Group Visits at Herts.). One particularly effective dissemination route is via specialised teacher training days which are organised regularly at York, Keele and Herts. in conjunction with their respective science learning centres (SLC), and in Preston at UCLan's Alston Observatory.

Capacity and Involvement:

Alison Laird appeared on BBC Radio 4 to discuss nuclear astrophysics and regularly gives public talks. Gibson employs the outcomes of his STFC-supported research in a wide range of activities. He gives several public lectures per year, most recently as one of the Keynote Speakers at the 2013 European Astrofest, where he shared the stage with Brian Cox and Lucy Hawking.

Keele Observatory and Alston Observatory (Preston) both host weekly events, in addition to special events during Stargazing Live, Transit of Venus, etc. Each observatory accommodates ~1000 people per year, spanning the full spectrum in ages. Herts. runs an open night programme attracting around 2000 public visitors a year at its extensive Bayfordbury Observatory.