School of Physics and Astronomy

Galaxy mapping data also test how gravity behaves at cosmic scales.

Mapping galaxies

Scientists, including astrophysicists from the University of Edinburgh, used the Dark Energy Spectroscopic Instrument (DESI) to map how nearly six million galaxies cluster across up to 11 billion years of time.

Their complex analysis of DESI’s first year of data provides one of the most stringent tests yet of Einstein’s famous theory of General Relativity and how gravity behaves at cosmic scales.

Looking at galaxies and how they cluster throughout time reveals how the universe’s structure has grown. This allowed DESI’s scientists to test theories of modified gravity – an alternative explanation for our universe’s accelerating expansion typically attributed to dark energy.

They found that the way galaxies cluster is consistent with our standard model of gravity and the predictions made by Einstein.

The result validates the leading model of the universe and limits possible theories of modified gravity, which have been proposed as alternative ways to explain unexpected observations such as the expansion of the universe.

Dr Samuel Brieden, Postdoctoral Research Associate in Observational Cosmology, Institute for Astronomy, University of Edinburgh, said:

The tests used a technique to hide the results from the scientists until the analysis pipeline was frozen, mitigating any unconscious bias. Seeing the final, ‘unblinded’ results was exhilarating. It felt like years of research culminating into that single moment.

Neutrino influence

A further insight DESI has revealed is on the mystery of neutrino mass. Neutrinos are elementary particles with very small masses, but the force of gravity they collectively produce affects how galaxies move and cluster in space. The DESI dataset has made it possible to detect the effect of neutrinos, which is exciting for both cosmologists and particle physicists.

About DESI

DESI can capture light from 5,000 galaxies simultaneously. It sits atop the US National Science Foundation’s Nicholas U Mayall 4-metre Telescope at Kitt Peak National Observatory, in Arizona, USA.

DESI is managed by the US Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab). UK involvement in DESI includes Durham University, University College London and the University of Portsmouth as full member institutions, together with individual researchers at the universities of Cambridge, Edinburgh, St Andrews, Sussex and Warwick. 

The experiment is now in its fourth of five years surveying the sky and plans to collect data on roughly 40 million galaxies and quasars by the time the project ends.

Edinburgh involvement

While mostly members of the research group led by Professor Florian Beutler (including Dr Samuel Brieden, Dr Richard Neveux, and Dr Mike Shengbo Wang) actively contributed to the study released today, also the groups led by Dr Yan-Chuan Cai, Professor Sergei Koposov, Professor John Peacock, and Professor Alkistis Pourtsidou are deeply involved in the DESI collaboration in various aspects, from investigating the structure of the Milky Way up to testing cosmological models on the largest scales.

Award funds will support Dr Wood’s business ventures in utilising scientific advancements to address societal challenges.

Dr Wood is passionate about using the physics of complex fluids to develop new innovations that will help people live more sustainably and in better health. She has received an Innovate UK Women in Innovation award which will further support her business ventures.

Biotech business

She is the co-founder of biotech business Dyneval which works to improve the profitability and sustainability of farming. In 2022, Dyneval launched the Dynescan, the first semen analyser able to measure the lifetime of semen in conditions similar to the reproductive tract. Tiffany and her co-founder, Dr Vincent Martinez developed this technology from the soft matter physics labs at the University of Edinburgh through to market, and it is bringing exciting new data insights to fertilisation capacity through its automated, precise and reproducible measurements.

Innovative technology

Dr Wood is the inventor of DAINTech, an innovative new gel phase formulation chassis technology that offers long-term stability and unique and beneficial flow characteristics without the use of synthetic polymers. It offers an alternative potential solution to formulate otherwise challenging ingredients and is expected to be broadly applicable to a wide range of industry applications.

Complex fluids

She is also the co-founder and former Director of the Edinburgh Complex Fluids Partnership (ECFP), which specialises in understanding the interactions between components in soft materials and complex fluids and how they influence product behaviour. Through this understanding, the group helps companies optimise product performance, solve manufacturing challenges, and switch to more sustainable resources and efficient processes. 

Women in Innovation award

The Innovate UK Women in Innovation award was launched in 2016 to encourage more women to apply to Innovate UK funding opportunities. The programme supports women across the UK to fully realise their vision for their businesses and make a real difference to the world through innovation.

Dr Wood accepted her award plaque from the Innovate UK Business Connect team on the 7 November and afterwards gave an inspiring seminar for students and staff titled 'The power of physics: improving efficiencies and sustainability for a better future'.

Team successfully measure the bound-state beta decay of fully-ionized thallium-205 ions.

How long did it take for our Sun to form within its stellar nursery? An international team of scientists has come closer to finding out.

Radioactive nuclei with lifetimes on the order of millions of years can reveal the formation history of the Sun and active nucleosynthesis occurring at the time and place of its birth. Among such nuclei whose decay signatures are found in the oldest meteorites, lead-205 is a powerful example. However, making accurate abundance predictions for lead-205 has so far been impossible because the weak decay rates are very uncertain at stellar temperatures.

To constrain these decay rates, a team of scientists measured the bound-state beta decay of fully ionized thallium-205 ions, an exotic decay mode that only occurs in highly charged ions. Work took place at the Experimental Storage Ring at the GSI/FAIR facility in Germany.

With new, experimentally backed decay rates, they used stellar models to calculate lead-205 yields. They found positive isolation times that are consistent with the other short-lived radioactive nuclei found in the early Solar System.

The results reaffirm the site of the Sun’s birth as a long-lived, giant molecular cloud and support the use of the lead-205–thallium-205 decay system as a chronometer in the early Solar System.

Dr Ragandeep Singh Sidhu, the study’s second author, who is based in the School’s Nuclear Physics research group said:

This significant result enhances our understanding of how radioactive lead-205 is produced in asymptotic giant branch stars and sheds light on the timescale of the Sun’s formation.

The results have been published in Nature.

Prize funds will be used to carry out research in topological problems in soft matter physics.

The Philip Leverhulme Prize is awarded to researchers at an early stage of their career, whose work has had international impact and whose future research career is exceptionally promising.

Dr Michieletto’s background is in polymer and statistical physics and he has a track record in using both simulations and experiments. His current main line of research is inspired by how the genome in our cells is mechanically and topologically manipulated by proteins, and he is focused on discovering new DNA-based soft materials and complex fluids that can change topology in time.

Dr Michieletto will use funds from the Philip Leverhulme Prize to continue his group’s research on the use of artificial intelligence and machine learning to classify knots. Although mostly focused on understanding the mechanisms through which AI learns mathematical ‘topological invariants’, this research can also have applications to protein folding, genome organisation and even drug design. 

A spacecraft has revealed the first section of what is set to be the largest 3D map of the Universe ever made.

The Euclid space telescope – orbiting one million miles from Earth – has produced a piece of its cosmic map containing some 14 million galaxies and tens of millions of stars in our own Milky Way. Despite its vast scale, the section accounts for just one per cent of the full map that Euclid will produce during its six-year mission.

The mission – launched in July 2023 – is led by the European Space Agency and a consortium of more than 2,000 scientists from 16 countries, including researchers from the University of Edinburgh.

Map section

The newly released map section – 208 gigapixels in size – is composed of 260 observations made by Euclid’s powerful cameras in Spring of this year.

Researchers will use data gathered by the mission to shed light on two of the biggest mysteries in the Universe: dark matter and dark energy. Dark matter – which does not reflect or emit light – is thought to make up around 80 per cent of all the mass in the Universe and binds galaxies together. Dark energy is a mysterious phenomenon that is pushing galaxies away from each other and causing the expansion of the Universe to accelerate. Unlike gravity, which draws objects together, dark energy appears to drive cosmic objects apart at an increasingly rapid rate, experts say.

Edinburgh expertise

Astronomers from the School of Physics and Astronomy are leading on two of the Euclid mission’s key research areas, including analysis of data relating to so-called gravitational lensing. The phenomenon – which occurs when a galaxy causes the path of light to bend around it – produces tiny changes in the images of galaxies, which can be used to map the distribution of dark matter in space and how it has evolved over time. Edinburgh also hosts Euclid’s UK Science Data Centre, which is processing huge amounts of data generated throughout the mission for scientists to analyse worldwide. 

Professor Andy Taylor (School of Physics and Astronomy) who leads the UK’s Euclid data analysis team and the Euclid gravitational lensing data analysis, said:

This map of a large chunk of the sky is amazing, and shows Euclid's unique capacity to make high-resolution images of the Universe over such large areas. This is essential for Euclid's mission to understand dark matter and dark energy, but also provides astronomy, and the public, with an unprecedented clear view of the Universe.

Colleagues are saddened by the loss of physicist Professor Ian Shipsey, who passed away on Monday 7 October.

Members of the School of Physics & Astronomy in Edinburgh are deeply shocked and saddened by the sudden death of our colleague and friend, Professor Ian Shipsey FRS, Head of the Physics department at the University of Oxford.

Professor Shipsey had many connections with the University of Edinburgh.

After studying physics at Queen Mary in his native London, he studied for his PhD at the University of Edinburgh. His thesis title was Measurement of the two gamma decays of neutral K-mesons, using data from the NA31 experiment at CERN.

He then moved to the USA, working at Syracuse and then Purdue before returning to the UK to take up a professorship at Oxford in 2013.

Ian was a valued colleague and collaborator to many of us in Edinburgh. He had remarkable energy and a great love for physics, bringing new ideas, strong leadership and valuable advice to every situation. He understood the importance of collegiality in science, always making time for a friendly and personal conversation when we were attending the same meetings.

Ian was a member of the International Advisory Panel for the Higgs Centre in Theoretical Physics. He was an active collaborator with Edinburgh physicists and astronomers, as was a member of research collaborations including the ATLAS experiment at the LHC at CERN and the Rubin LSST project, working with the particle physics groups and Wide-Field Astronomy Unit.

Ian visited Edinburgh on several occasions over the last decade.  

Ian became profoundly deaf in his late-20s as a side effect of medical treatment and later became an early adopter of cochlear ear implants. In 2014, he presented a general interest seminar to the School on the physics and his experience with the implant, a recording of which can be found below.

Our thoughts are especially with his wife, Professor Daniela Bortoletto, also professor in physics at the University of Oxford and a collaborator with Edinburgh physicists, their daughter and family.

PhD students from 31 countries attend training in Peebles, Scotland.

The 2024 European School of High Energy Physics is taking place this autumn at Peebles, Scotland. This event brings together PhD students from across Europe and beyond to study fundamental particle physics through a series of lectures, discussion sessions and group projects.

Participants will have the opportunity to learn from world-leading experts, including Edinburgh physicists Professor Sinead Farrington and Professor Neil Turok. Dr Alan Walker will provide insights into the life and work of Professor Peter Higgs. There are also courses on science communication and outreach, with training designed to support participants in their future studies and research.

The school rotates between different host countries, and is hosted in the United Kingdom this year for the first time since 1998, taking place between 25 September and 8 October.

Organised by the European Organisation for Nuclear Research (CERN), the 2024 school is supported by a local organising committee comprised of representatives from eight UK universities and research institutes, chaired by Dr William Barter from the School of Physics and Astronomy’s Institute of Particle and Nuclear Physics. Sponsorship is provided by the School of Physics and Astronomy at the University of Edinburgh and the Science and Technology Facilities Council (STFC), enabling broader participation from students who might not otherwise be able to attend.

This year the school brings together students from 31 countries, with 47% of attendees women. 

Scientists working on the Short-Baseline Near Detector (SBND) at Fermi National Accelerator Laboratory have identified the detector’s first neutrino interactions.

Edinburgh contribution to neutrino detection

Students and post-doctoral staff at the School of Physics and Astronomy are one of the largest UK groups contributing to the experiment.

The Edinburgh team members have made significant contributions to the construction of the SBND cathode with innovative wavelength-shifting foils to enhance light collections, as well as to the understanding of the cosmic-ray tracking, photon detection and trigger systems of the detector before and after its start. Edinburgh scientists were also responsible for key items of the software infrastructure of the experiment getting it ready for the detector running.

Neutrino Detectors

The SBND collaboration has been planning, prototyping and constructing the detector for nearly a decade. The detector was built by an international collaboration of 250 physicists and engineers from Brazil, Spain, Switzerland, the United Kingdom and the United States. SBND will play a critical role in solving a decades old mystery in particle physics.

SBND is the final element that completes Fermilab’s Short-Baseline Neutrino (SBN) Program which includes the ICARUS and MicroBooNE detectors. All of the detectors are types of liquid-argon time projection chambers, and each contributes to the development of this particle detection technology for the long-baseline Deep Underground Neutrino Experiment (DUNE).

Neutrinos and the Standard Model

The Standard Model is the best theory for how the universe works at its most fundamental level. But despite being a well-tested theory, the Standard Model is incomplete. And over the past 30 years, multiple experiments have observed anomalies that may hint at the existence of a new type of neutrino.

Neutrinos are the second most abundant particle in the universe, but are difficult to study because they only interact through gravity and the weak nuclear force, meaning they hardly ever show up in a detector. Neutrinos come in three types, or flavours: muon, electron and tau. Perhaps the strangest thing about these particles is that they change among these flavours, oscillating from muon to electron to tau.

Scientists have a pretty good idea of how many of each type of neutrino should be present at different distances from a neutrino source. Yet observations from a few previous neutrino experiments disagreed with those predictions, which means there could be more than the three known neutrino flavours.

The Short Baseline Neutrino Program at Fermilab will perform searches for neutrino oscillation and look for evidence that could point to this fourth neutrino.

Beyond the hunt for new neutrinos

In addition to searching for a fourth neutrino, SBND has an exciting physics program on its own.

Because it is located so close to the neutrino beam, SBND will see 7,000 interactions per day, more neutrinos than any other detector of its kind. This large data sample will allow researchers to study neutrino interactions with unprecedented precision. The physics of these interactions is an important element of future experiments that will use liquid argon to detect neutrinos.

Whenever a neutrino collides with the nucleus of an atom, the interaction sends a spray of particles careening through the detector. Physicists need to account for all the particles produced during that interaction, both those visible and invisible, to infer the properties of the ghostly neutrinos. With the detector located so close to the particle beam, it’s possible that the collaboration could see other surprises.

One of the biggest questions the Standard Model doesn’t have an answer for is dark matter. Although SBND would only be sensitive to lightweight particles, those theoretical particles could provide a first glimpse at a ‘dark sector’.

Prof Andrzej Szelc, SBND physics co-coordinator based at the School of Physics and Astronomy said:

So far ‘direct’ dark matter searches for massive particles haven’t turned anything up. Theorists have devised a whole plethora of dark sector models of lightweight dark particles that could be produced in a neutrino beam and SBND will be able to test whether these models are true.

These neutrino signatures are only the beginning for SBND. The collaboration will continue operating the detector and analysing the many millions of neutrino interactions collected  for the next several years.

The data gathered provides unprecedented insights into the structure and composition of the Milky Way.

The VISTA (Visible and Infrared Survey Telescope for Astronomy), a European Southern Observatory (ESO) facility in Chile, has successfully mapped over 1.5 billion objects in the Milky Way.

Over the course of 13 years, the VISTA Variables in the Vía Láctea (VVV) survey and its extension, the VVV eXtended survey (VVVX), observed the central regions of the Milky Way. Beginning in 2010, these surveys required 420 nights of observation to capture approximately 200,000 images, monitoring over 1.5 billion celestial objects and generating 500 terabytes of scientific data. This represents the largest volume of data ever collected for an ESO observational project.

Notable discoveries

The data gathered provides unprecedented insights into the structure and composition of the Milky Way, the galaxy that contains our own Solar System. Notable discoveries include:

• Globular clusters: the oldest objects in our Galaxy.
• Hypervelocity stars: stars expelled from the Galaxy by the central supermassive black hole.
• Galactic windows: clear views through interstellar dust and gas to the other side of the Galaxy.
• RR Lyrae variable stars: the oldest known population in the centre of the Galaxy.
• Brown dwarf stars and binary floating planets: unique celestial objects that enhance our understanding of stellar and planetary formation.

UK role on VISTA

The University of Edinburgh is one of 18 UK universities which form part of the VISTA Consortium who work closely together with scientists from the Science and Technology Facilities Council through its team at the UK Astronomy Technology Centre (UK ATC) to play a role in the development and delivery of the telescope to the ESO.

Edinburgh involvement

The Wide-Field Astronomy Unit (WFAU) in the University of Edinburgh’s Institute for Astronomy curates and publishes the VVV/VVVX data, along with that from the other public surveys conducted with the VISTA telescope, in its VISTA Science Archive (VSA).

The WFAU Director, Prof Bob Mann said:

Members of the WFAU team – led by Dr Nick Cross – have been working closely with the VVV/VVVX consortium since their survey started. The VSA provides a long-term home for their survey data and many additional data products derived by the consortium, ensuring that their vast, and wonderfully rich, dataset will remain accessible to astronomers. Sky survey data has a scientific longevity, and researchers will be extracting exciting science from the VVV/VVVX dataset for many years to come.

Research could have implications on the emulsification and stability of new materials.

Physicists and mathematicians have turned their attention to a fascinating observation that has intrigued scientists and cocktail enthusiasts alike: the mysterious way ouzo, the anise-flavoured liquor, turns cloudy when water is added.

The research, which involved experts from the University of Edinburgh, Loughborough University and Nottingham Trent University, has resulted in a new mathematical model that offers insights into the spontaneous formation of microscopic droplets and how they can remain suspended in a liquid for a long time.

Revealing the maths taking place in the glass could have far-reaching implications, such as the creation of new materials, especially in fields such as pharmaceuticals, cosmetics, and food products, where the stability and distribution of microscopic particles are critical.

When water is added to ouzo, microscopic droplets form which are a result of the anise oil separating from the alcohol-water mixture. This causes the drink to turn cloudy as the droplets scatter light. The emulsification - the suspension of well-mixed oil droplets in the liquid - is something that requires a lot of energy in other systems and foods, but in the case of ouzo, it happens spontaneously. What’s also surprising is how long these droplets, and the resulting cloudiness, remain stable in the mixture without separating, especially when compared to other food emulsions.

By mixing alcohol, oil, and water in varying proportions, the researchers were able to observe phase separation and measure key properties like surface tension.

They used this data and a statistical mechanical modelling method known as ‘classical density functional theory’ to develop their mathematical model.

This model has been used to calculate a phase diagram that details the stable combinations of the ouzo ingredients.