The XENON/DARWIN and LUX-ZEPLIN collaborations have now joined forces to work together on the construction of a new xenon observatory to explore dark matter.
Dark matter makes up 85% of the matter in the Universe, but its nature remains a mystery. The direct identification of the dark matter particle is amongst the highest priorities in science and also one of the most challenging.
The XENON/DARWIN and LUX-ZEPLIN collaborations have now joined forces to work together on the design, construction, and operation of a new, single, multi-tonne scale xenon observatory to explore dark matter. The detector will be highly sensitive to a wide range of proposed dark matter particles and their interactions with visible matter.
The goals
The primary science goal of the new joint observatory is to reach a sensitivity for detecting dark matter in our galaxy by at least a factor of 10 beyond that of the current generation of detectors.
The detector’s large mass and unprecedented low background level will also enable world-leading searches for additional signatures of physics beyond the Standard Model of particle physics that would similarly revolutionize our understanding of the universe. In particular, the secondary science goal will be the search for neutrinoless double-beta decay in xenon, shedding light on the nature of the neutrino and the imbalance of matter and antimatter in the universe.
The observatory will also perform searches for other rare processes and particles such as axions, hypothetical particles that might be emitted from the Sun. It will also measure neutrinos created in the Sun, the Earth’s atmosphere, and potentially those from Galactic supernovae.
Experiments
The current xenon-based experiments XENONnT and LUX-ZEPLIN will start their first science runs in 2021, to lead the race to detect the first signs of new particles and interactions. These experiments employ 5.9 and 7.0 tonnes of liquid xenon for the search, respectively.
The LUX-ZEPLIN experiment operates at the Sanford Underground Research Facility (SURF) in the USA. The XENONnT experiment is located at the INFN Gran Sasso Laboratory (LNGS) in Italy. DARWIN is the evolution of the XENON program and includes additional groups, focusing on several R&D aspects required for the much larger detector.
After a very successful first joint workshop in April 2021, 104 research group leaders from 16 countries have signed a memorandum of understanding on July 6, 2021. Scientific cooperation has now begun to realize this next-generation rare event observatory.
Adapted from a press released by the Sanford Underground Research Facility (SURF) and Gran Sasso National Laboratory (LNGS) on behalf of the DARWIN and LZ collaborations
Research and teaching in theoretical physics to be enhanced as centre expands.
New appointments
Seven new appointments have been made this year to significantly strengthen the Higgs Centre’s research power and extend the breadth of its activities.
The new appointments include academic staff and research fellows:
academic staff
- Samuel Abreu
- Sašo Grozdanov
- Anton Ilderton
- Alkistis Pourtsidou
- Mao Zeng
Higgs fellows
- Suddhasattwa Brahma
- Job Feldbrugge
These appointments follow the recruitment of Professor Neil Turok as the inaugural Higgs Chair of Theoretical Physics in 2020.
Higgs Centre for Theoretical Physics
The Higgs Centre for Theoretical Physics was established in 2012 following the discovery of the Higgs boson at CERN. It is built on the legacy of Peter Higgs and Edinburgh’s outstanding tradition, going back to key theoretical physicists including Max Born and Nick Kemmer.
The purpose of the centre is to promote research excellence in theoretical physics, aiming to answer fundamental questions about Nature by developing new ideas and concepts. The Centre’s vision includes creating bridges between disciplines and combining graduate-school education in synergy with cutting-edge research. Accordingly, the Higgs Centre has launched highly successful Masters programmes in theoretical and mathematical physics and strengthened its PhD programme.
In parallel, the Centre runs a diverse programme of workshops and schools, through which it has established itself as a global focal point in theoretical physics.
World-leading vision
Professor James Dunlop, Head of School of Physics and Astronomy, commented:
In this most difficult of years, it is wonderful that the Higgs Centre for Theoretical Physics at Edinburgh has gone from strength to strength. Building on Neil Turok's appointment in 2020, we have now secured the talents of seven exciting world-leading researchers, whose broad interests will enhance and expand our existing strengths in theoretical physics, as well as forging new interdisciplinary links with Mathematics and Astrophysics/Cosmology. This further substantial investment demonstrates the commitment of the School of Physics & Astronomy and the University of Edinburgh to build on the legacy of Peter Higgs, ensuring that the Higgs Centre can deliver on its promise to be a genuinely world-leading centre for research and teaching in theoretical physics.
Professor Einan Gardi, Director of the Higgs Centre for Theoretical Physics, said:
The University of Edinburgh is making here a major strategic investment in theoretical physics. I am delighted to see this dream coming together. I am thrilled to welcome each and every one of the new researchers to the Higgs Centre. We’ll do our best so that you will flourish and realise your potential. With so much talent and creativity around, I am more confident than ever that we can make big things happen in our field and beyond.
Professor Neil Turok, Higgs Chair of Theoretical Physics, said:
When we launched our recruitment drive last year, its outcome was somewhat uncertain because of the pandemic. In the event, it greatly exceeded our hopes: we had a wonderful pool of applicants and every offer we made was accepted. We are really excited about the tide of new talent which will be joining the Higgs Centre this September.
Professor Luigi Del Debbio, Head of Particle Physics Theory, said:
I am delighted to see the appointment of seven new theorists in Edinburgh. Building on the award of the Nobel Prize to Peter Higgs in 2013, they will inject new momentum in a long-term strategy to boost our activities, inspire new generations of students and strengthen the commitment to excellence in the School of Physics and Astronomy. The University’s support for its core activities, research and teaching, must be the way forward in these difficult times.
Funding was successfully secured for collaboration with external partners to develop a biofilm model for testing active ingredients for hand hygiene.
Biofilm research
A number of our researchers are involved in work relating to preventing, detecting, managing or engineering biofilms. Biofilms are communities of microbes, and they can have an enormous impact on human life and the health of the planet.
Testing of skin disinfection formulations
There is a need for simple, affordable and effective procedures for screening hand disinfectant products. Dr Susana Direito the lead and Principal Investigator of the project will work with colleagues from the School’s Institute for Condensed Matter and Complex Systems (Aidan Brown, Job Thijssen, Andreia Fonseca da Silva and Paul Hush), and industrial partners Bear Valley Ventures (Walter Gibson) and Aqualution Systems Limited (Nick Meakin and Michelle Lewis), to develop a human skin biofilm model that can be used for high-throughput testing of novel skin disinfection formulations. It is hoped that use of the model will lead to the development of new hand hygiene products to improve health around the world.
Project funding
Funding for this project was received from the National Biofilms Innovation Centre (NBIC) as part of their forth Proof of Concept. A total of 18 biofilm-related projects have been funded by NBIC during this latest round, which cover a wide range of sectors including health, hygiene, industrial processing, food, water, oral care, personal care, anaerobic digestion, waste and wastewater and biotechnology.
Astronomers have shed light on the mystery of why some galaxies look blue while others appear red.
Galaxies exhibit many different features, in terms of size, shape and colour. The most distinguishable separation, known since the time of Edwin Hubble, is into two families: blue star-forming spiral galaxies, and red non-star forming elliptical galaxies. How they end up in this bimodality is, to this day, a major question in galaxy formation.
In general, astronomers believe that red galaxies live in massive dark matter halos, while blue galaxies live in more moderate-mass ones. But recent observations suggest that both types of galaxies can be hosted by even the same halo mass, and blue galaxies have more stars than red ones. Why does this trend exist, and is it telling us something fundamental about the origin of the colour bimodality? Many previous galaxy formation models have failed to reproduce this observed trend. In contrast, the state-of-the-art SIMBA simulation (figure 1), led by the Institute for Astronomy’s Dr Weiguang Cui, is remarkably successful.
Encouraged by this success, Dr Cui and the team of researchers explored how the colour bimodality originates by tracking individual simulated galaxies back in time. It was revealed that this bimodality originates in differences between their host halo mass growth history, called halo assembly bias (left panel on figure 2), and its unexpected interplay with SIMBA’s unique models that quench galaxies using the energy released from black hole growth.
Differences in the way the dark matter halos – a key building block of galaxies – develop over time influence which type of galaxy will form and the number of stars they contain. The team found that halos with the same mass that formed earlier tend to contain blue galaxies while those that formed later usually contain red ones. The team also found that the way energy is released from black holes – which are found at the centre of every galaxy – is crucial. How this happens affects whether a galaxy will be blue or red, researchers say. The findings show that halos formed later will result in their galaxies with less gas, which causes black holes to emit huge amounts of energy that stops the formation of new stars. By contrast, halos that formed earlier contain more gas, which causes black holes to release less energy and does not prevent new stars forming.
SIMBA thus provides a significant step forward in understanding the physical origin of galaxy bimodality, by connecting large-scale structure formation with small-scale processes of black hole growth and feedback.
Prof John A. Peacock said, “We are working with one of the most sophisticated numerical models of galaxy formation, and it’s really encouraging to see that the new details in the simulation produce galaxies that look more and more like those in the real universe”.
Prof Romeel Dave added, "Such increasingly realistic simulations give us confidence that we are moving towards understanding how the billions of galaxies we see in a variety of shapes, sizes, and colours formed out of the primordial soup of the Big Bang."
The research, published in the journal Nature Astronomy, was funded by the European Research Council, Royal Society and Science and Technology Facilities Council.
Image gallery
Puzzles, tours and a play about psychology and quantum physics: some of the School’s events this year.
A packed programme of online and in-person events celebrating the power of science and the importance of connection has been unveiled by the organisers of the citywide festival.
It will feature more than 200 events, tours, exhibitions, workshops for children, young people and adults, of which 70 per cent are available online and free to access to anyone around the world.
The festival – the world’s first and Europe’s biggest – has this year moved away from its usual Easter holiday dates to take place online and in person between 26 June and 11 July.
The School of Physics and Astronomy is involved in a number of activities: solve our science puzzles; take a self-led tour and learn about biofilms; virtually explore the James Clerk Maxwell building to learn about the work we do and meet some of our students and staff.
Congratulations to Dr Cheryl Patrick who has been awarded an Ernest Rutherford Fellowship.
The STFC (Science and Technology Facilities Council) Ernest Rutherford Fellowships enable early career researchers with clear leadership potential to establish a strong, independent research programme. We are pleased that successful candidate Dr Patrick will be starting with us in October.
Dr Patrick will be based in the School’s Institute for Particle & Nuclear Physics. Her research focuses on neutrinos: light, neutral particles with behaviours beyond the Standard Model of particle physics. As we can only learn about neutrinos through their interactions with matter, she’ll be studying how nuclei affect our understanding of neutrinos in various experiments, and how those experiments might be able to help each other.
Congratulations to Dr XinRan Liu who has received a British Science Association Award Lecture for Physical Sciences and Mathematics.
British Science Association Award Lectures
The British Science Association has announced its Award Lectures winners for 2021. Dr XinRan Liu is the Award Lecture winner for Physical Sciences and Mathematics. These awards are given to UK researchers in recognition of their work and commitment to public engagement efforts. Previous Award Lecturers include Brian Cox, Richard Wiseman and Maggie Aderin-Pocock.
All Award Lecturers create a video where they delve into their research and its real-world implications (link below), and take part in a Q&A event as part of the British Science Festival. The 2021 Festival will be held in Chelmsford from Tuesday 7 to Saturday 11 September.
Dark matter experiment
Dr XinRan Liu is currently a Research Fellow at the School of Physics and Astronomy working on the LUX-ZEPLIN dark matter search experiment. The project is in its final stages of construction at the Sanford Mine in South Dakota and is expected to rapidly become world leading. XinRan specialises in ultra-low background radiation detection and has several leadership roles within the LUX-ZEPLIN experiment including on-site cleanliness during the critically important final construction phase. XinRan is also currently the lead scientist for the Boulby XIA, a world-leading surface radiation detector.
Next generation of scientists
Outside of his research, Dr XinRan Liu has huge enthusiasm for public engagement, his most remarkable outreach activity to date being the “Remote3” project which he conceived and currently leads the delivery of. This project enables pupils from schools in the most remote parts of Scotland, otherwise underserved in STEM opportunities, to build, program and operate small robots in the STFC Mars Yard at the Boulby Underground Laboratory.
Dr XinRan commented on his work:
Our aim is to inspire the next generation of students into science and have lots and lots of fun whilst doing it!
Searching for the invisible
Dr XinRan’s work focuses on attempting to detect dark matter, one of the most common, yet most mysterious and hard-to-study substances in the field of physics. During the British Science Festival event, he will discuss the extreme lengths that scientists have gone to, in order to find the answers to some of the Universe's biggest questions. From studying the stars millions of miles above us to delving several kilometres below the surface of the Earth, he explains why dark matter could be the key to our understanding of the Universe.
Congratulations to Dr Rosa Santomartino who has been awarded a Leverhulme Trust Early Career Fellowship. This Fellowship is intended to assist those who are at a relatively early stage of their academic career to undertake a significant piece of publishable work.
Space microbiology
Dr Santomartino is based in the School’s Institute for Condensed Matter and Complex Systems. Her research in space microbiology focuses on the molecular mechanisms that drive microbial interaction with natural and artificial environments in space, to perform space biomanufacturing, recycling and in-situ resource utilization (ISRU), and to promote an efficient and sustainable impact of space exploration and its terrestrial applications.
She performed two microbiology experiments onboard the International Space Station, BioRock and BioAsteroid, launched in space in 2019 and 2020 respectively. Her work provided the first demonstrations of biomining on a space station, and raised considerable scientific interest, growing her reputation as an expert in the field. She is an invited scientific advisor in microbiology for the Italian Space Agency, and collaborates with international scientists for the creation of the NASA Decadel Survay on microbiology.
Fellowship
The Leverhulme Trust Early Career Fellowship will provide her the opportunity to establish a new interdisciplinary research direction in Edinburgh and worldwide, and to create a strong collaboration with the School of Biological Sciences.
The School welcomes applications from both external and internal scientists interested in applying for personal fellowships. In particular we have an internal deadline on 15 July 2021 for STFC Ernest Rutherford, Royal Society and EPSRC Fellowships.
We are keen to attract outstanding researchers from Edinburgh and across the world to join us as Postdoctoral Fellows. We offer a high quality research environment and support for you in your fellowship application process.
Fellowship opportunities
The School operates an internal review process for the following fellowship opportunities which have a deadline of Thursday 15 July 2021:
- STFC Ernest Rutherford Fellowships
- Royal Society University Research Fellowships
- EPSRC Open and Postdoctoral Fellowships
We also welcome applicants for other fellowships, the full list of which can be found on the weblink below.
Application information
Candidates are expected to have a PhD in Physics, Astronomy or a related discipline, and in most cases a few years research experience, as well as the ability to present clear evidence of their potential to undertake leading research.
The School of Physics and Astronomy is committed to advancing equality and diversity, welcoming applications from everyone irrespective of gender, ethnic group or nationality.
How to apply
Candidates must submit information including a research statement, CV and list of publications. Full application information can be found on the weblink below.
Astronomers have spotted a giant ‘blinking’ star, 100 times the size of the sun, towards the centre of the Milky Way.
Scientists observed that the enormous star, which lies 25,000 light years away, almost disappeared from the sky before slowly returning to its former brightness. Many stars in the Galaxy change in brightness because they pulsate or they are eclipsed by another orbiting star. However, it’s exceptionally rare for a star to become fainter over a period of several months and then brighten again, experts say.
Twinkle twinkle
Researchers believe the star, known as VVV-WIT-08, might belong to a new class of ‘blinking giant’ star system, where a huge star is eclipsed once every few decades by an as-yet unseen orbital companion.
The partner, which may be another star or planet, is surrounded by an opaque disc that covers the giant star, causing it to disappear and reappear in the sky.
As the blinking star is located in a dense region of the Milky Way, scientists considered whether an unknown dark object could have simply drifted in front of the giant star by chance. However, simulations showed that there would have to be an implausibly large number of dark bodies floating around the galaxy for this scenario to be likely.
Researchers from the University’s School of Astronomy and Physics collaborated on the discovery with experts from the University of Cambridge’s Institute of Astronomy, who led the study, the University of Hertfordshire, the University of Warsaw in Poland and Universidad Andres Bello in Chile.
VISTA telescope
VVV-WIT-08 was found by the Via Lactea survey (VVV) – a project using the British-built VISTA telescope in Chile and operated by the European Southern Observatory (ESO). ESO has been observing the same one billion stars for nearly a decade to search for those with varying brightness.
While VVV-WIT-08 was discovered using VVV data, the dimming of the star was observed by the Optical Gravitational Lensing Experiment, a long-running observation campaign run by the University of Warsaw.
Shining brightly
Edinburgh’s astronomers worked on the scientific modelling of the changes in the brightness of the star. Specifically they tried to understand the shape, opacity and velocity of the giant star’s orbital companion, through their analysis of the variations in VVV-WIT-08’s brightness. Scientists hope that future observations of VVV-WIT-08 in different parts of the electromagnetic spectrum may shed some light on the nature of this mysterious companion.
Dr Sergey Koposov, Co-author and Reader in Observational Astronomy, Institute for Astronomy, University of Edinburgh said:
The discovery of this rare star is very exciting, not only because the object itself is a bit of a mystery, but also because it tells us what discoveries can be made when we can access not only one single image of the sky, but when we’re able to observe its evolution with time. Essentially we are able to look at the movies of the sky as opposed to single photographs and this opens up a lot of opportunities for new discoveries.
Professor Philip Lucas, project co-leader, University of Hertfordshire reported:
Occasionally we find variable stars that don’t fit into any established category, which we call ‘what-is-this?’, or ‘WIT’ objects. We really don’t know how these blinking giants came to be. It’s exciting to see such discoveries from VVV after so many years planning and gathering the data.
Dr Leigh Smith, Project lead, University of Cambridge, Institute of Astronomy commented:
There now appear to be around half a dozen potential known star systems of this type, containing giant stars and large opaque discs. There are certainly more to be found, but the challenge now is in figuring out what the hidden companions are, and how they came to be surrounded by discs, despite orbiting so far from the giant star. In doing so, we might learn something new about how these kinds of systems evolve.
The study is published in Monthly Notices of the Royal Astronomical Society.