A new experiment carried out in the underground Gran Sasso Laboratory of the Italian National Institute for Nuclear Physics (INFN) could help scientists uncover the origin of some rare elements in the universe.
Nuclear fusion reactions provide the source of energy that makes stars shine. Like gigantic alchemists of the cosmos, they also create new elements from the hydrogen and helium left over by the Big Bang.
Understanding the complex pattern of reactions that leads to the abundances of elements and isotopes that we observe today requires detailed models of stellar evolution and extensive laboratory experiments on individual nuclear reactions. For some time, astronomers have been puzzled by anomalous abundances of rare isotopes of carbon, nitrogen, and oxygen in the atmospheres of some stars and in tiny grains that reach the Earth inside meteorites. In particular, the amount of oxygen-17 – a rare, heavier form of the oxygen we breathe – observed in some red giants and massive stars can provide important clues on the mixing processes that occur inside these stars and bring to their surfaces the debris of nuclear reactions. By measuring the tiny particles released by the fusion of hydrogen and oxygen-17, the study – published in the journal Physical Review Letters – reveals that oxygen-17 is destroyed twice as fast as previously expected: a result that may help reconcile the puzzling abundances observed in stellar atmospheres and stardust grains.
The experiment, which took place at the LUNA (Laboratory for Underground Nuclear Astrophysics) accelerator of the Gran Sasso Laboratory, detected the feeble signals of the fusion reaction with unprecedented precision. Such studies can only be performed in the absence of radiation from space, and the shielding provided by the 1.4km of rock under the Gran Sasso mountain is ideal to suppress the background induced by cosmic rays.
“This work represents another key milestone in the scientific activity of the LUNA collaboration – says Paolo Prati, spokesperson of LUNA – and provides another crucial input to help us understand the origin of the elements in the universe’’.
LUNA is an international collaboration of about 40 scientists from the INFN (Italy), the Helmholtz-Zentrum Dresden-Rossendorf (Germany), MTA-ATOMKI (Hungary) and the School of Physics and Astronomy of the University of Edinburgh (UK).
The UK team, led by Professor Marialuisa Aliotta, played a key role in the planning and execution of the experiment and provided the detectors and related instrumentation.
“This work provides an important piece in the puzzle of the origin of the elements in the universe – says Professor Aliotta, from the School of Physics and Astronomy of the University of Edinburgh – and represents the culmination of four years of careful planning and intense experimental activity. The successful outcome of this project reflects the contributions of a number of individuals and organisations. In particular, Mr Carlo Bruno (SUPA-funded PhD student and first author of the paper) made outstanding contributions to the extensive data taking campaigns and painstaking data analysis. We would also like to say a huge thank-you to the mechanical workshop of the School of Physics and Astronomy for the design and construction of the purpose-built scattering chamber used for the measurements.”
An international team of astronomers, led by Edinburgh, has gained a new view of the evolution of distant galaxies. Their study focuses on a region of the Universe previously studied using the deepest observations of the Hubble Space Telescope.
The team has traced the previously unknown abundance of star-forming gas and dust over cosmic time. This provides new insights into what is known as the golden age of galaxy formation - approximately 10 billion years ago. The new observations of a well-studied area of sky, known as the Hubble Ultra Deep Field, were taken with the ALMA (Atacama Large Millimetre/submillimetre Array) telescope, located high in the Atacama Desert in Chile. The resulting images are significantly deeper and sharper than those from previous surveys undertaken at these long wavelengths. Astronomers have used their findings to show for the first time how the rate of star formation in young galaxies is closely related to their total mass in stars, which is assembled from previous star-formation events.
The findings will be published in in the Monthly Notices of the Royal Astronomical Society.
The first Hubble Ultra Deep Field images, pioneering deep-field observations at optical wavelengths, were captured with the NASA/ESA Hubble Space Telescope and published in 2004. Hubble was refurbished in 2009 and since then, it has captured near-infrared images. The result is the deepest view of the Universe to achieved date, revealing early galaxies that existed less than a billion years after the Big Bang. However, Hubble cannot reveal the emission from young stars that is absorbed and then re-emitted by clouds of interstellar gas and dust, within which the youngest stars form. To do this, astronomers have had to await the advent of ALMA, which for the first time enables the warm glow of dust-enshrouded star-formation activity to be imaged with a depth and clarity comparable to Hubble imaging. The team, led by the University of Edinburgh, used ALMA to obtain the first deep, homogeneous image of the entire Hubble Ultra Deep Field region. This enabled them to clearly match the galaxies detected by ALMA with objects already known from the Hubble imaging. This showed clearly, for the first time, that the mass of stars already existing within a galaxy is the best indicator of how quickly stars are forming in the very distant Universe. The team was able to detect virtually all of the high-mass galaxies and very little else.
Professor Jim Dunlop, of the School of Physics and Astronomy, said: “This is a breakthrough result. For the first time we are properly connecting the visible and ultraviolet light view of the distant Universe from Hubble and far-infrared views of the Universe from ALMA.”
According to researchers, the new ALMA results imply a rapidly rising gas content in galaxies as we look back further in time. This is likely the root of a remarkable increase in star formation rates during the peak of galaxy formation some 10 billion years ago. The results are the first in a series of planned observations of the distant Universe using ALMA. Astronomers hope the forthcoming program of surveys will complete their view of the galaxies in the Hubble Ultra Deep Field.
Scientists have refined their search for dark matter with the completion of a sophisticated experiment.
An international team of researchers, including from Edinburgh, has completed a series of tests for dark matter – which is thought to account for more than four-fifths of the Universe – using an underground detector in the US.
Although the experiment did not yield any direct evidence of dark matter, the results have enabled scientists to refine their models for dark matter particles.
It will also inform the next generation of experiments that plan to further the search for the material.
The Large Underground Xenon (LUX) dark matter experiment, at the Sanford Underground Research Facility in the Black Hills of South Dakota, has been operating a series of experiments over the past three years.
The experiment was designed to look for so-called weakly interacting massive particles, or WIMPs, which scientists believe are the most likely fit for a dark matter particle.
Their interaction with ordinary matter is expected to be very faint and difficult to detect.
LUX consists of a large tank of cooled liquid xenon surrounded by powerful sensors.
These are designed to detect the tiny flash of light and electrical charge emitted if a WIMP collides with a xenon atom in the tank.
Radiation that might interfere with a dark matter signal, such as cosmic rays, are kept out by the detector’s location a mile underground.
The detector’s extreme sensitivity ensures that if dark matter particles had interacted with the xenon target, the detector would almost certainly have seen it.
Dark matter is thought to account for more than four-fifths of the mass in the universe.
Scientists are confident of its existence because its effects can be seen in the behaviour of galaxies and in the way light bends as it travels through the universe. However, experiments have yet to find a dark matter particle.
The latest results are from the detector’s final 20-month run, which is one of the largest experiments of its type.
Analysis of nearly a half-million gigabytes of data from the detector made use of advanced computer facilities.
Future experiments will include the LUX-ZEPLIN (LZ) experiment, which will replace LUX at the Sanford Underground Research Facility.
LZ will have a larger liquid xenon capacity than LUX, to help fend off external radiation.
The LUX scientific collaboration, which is supported by the DOE and National Science Foundation (NSF), includes 20 research universities and national laboratories in the US, UK and Portugal.
"These latest findings about what dark matter is, and what it isn’t, are the best yet, and will help improve the next generation of experiments to detect this elusive substance." Prof. Alex Murphy, Professor of Nuclear & Particle Astrophysics, School of Physics & Astronomy
The UK Centre for Astrobiology (UKCA) has concluded its fourth MINAR campaign in the 1.1 km-deep Boulby Mine.
MINAR (Mine Analogue Research), is a programme that was set up by UKCA to test planetary science instrumentation and technology for space missions that might also have technology transfer potential for the mining industry. This year the fourth MINAR campaign focused on addressing the science question of whether ancient biosignatures of life could be detected in the 250-million-year-old Permian salt in which the Boulby mine operates.
Groups from the Spanish Centre for Astrobiology, NASA, The European Science Foundation, the University of Madrid and the University of Leicester joined the campaign which ran for three days. Work included drilling for ancient salts and testing an immunoassay instrument (SOLID) developed by the Spanish Centre for Astrobiology for searching for organics on Mars, as well as new commercially available microscopy methods.
UK Centre for Astrobiology
UKCA's mission is to advance knowledge of molecules and life in extreme environments on the Earth and beyond to further our understanding of planetary habitability. It does this with a combination of theoretical, laboratory, field and mission approaches. We apply this knowledge to improving the quality of life on Earth and developing space exploration as two mutually enhancing objectives. The UK Centre for Astrobiology is based at the University of Edinburgh and is affiliated to the NASA Astrobiology Institute.
Edinburgh hosted the fourth year of the Astrobiology Academy. This continuing professional development event, set up by the UK Centre for Astrobiology, takes astrobiology into secondary schools and uses the subject to teach fundamental science.
Since its foundation, the Astrobiology Academy has produced lesson plans for UK secondary schools that this year were assembled into astrobiology units for year-long teaching blocks. The Academy's lesson plans have been downloaded over 5000 times by teachers and cover subjects from astronomy to biology.
This year 13 teachers came to Edinburgh to listen to astrobiology lectures, write lesson plans and gain expertise in teaching the subject. The academy was supported by the National Space Centre and was attended by Susan Buckle of the UK Space Agency.
Next year the academy will offer one day astrobiology continuing professional development events as well as its residential course, and will extend astrobiology teacher-training to primary school teachers.
Who can attend?
The Astrobiology Academy is open to science teachers and anyone with a science/technology background and good writing skills who are enthusiastic and self-motivated with interests in the fields of chemistry, biology, physics, geology, astronomy or engineering. Applicants are expected to work together to create and edit astrobiology-based lesson plans for secondary schools. If you are excited by the idea of this science opportunity then register your interest for 2017 now!
School staff have taken part in several science outreach events this summer.
Royal Society summer science exhibition
Members of the LHCb group within experimental particle physics helped to organise the “Antimatter matters” exhibit at the Royal Society summer science exhibition from 4-10th July this year.
We know that matter and antimatter were produced in equal amounts during the Big Bang, but now everything we see in the Universe (stars, planets, dust) appears to be made of matter. Understanding where all of the antimatter has gone is one of the key unanswered questions of science. The exhibit aimed to explain how the properties of antimatter are being studied in detail by the LHCb and ALPHA experiments at CERN, the European laboratory for particle physics. Both experiments are making precision measurements to search for differences between matter and antimatter that might help explain the large asymmetry we observe in the Universe.
Dr Greig Cowan, STFC Ernest Rutherford research fellow and member of the LHCb collaboration, edited and produced the exhibit booklet as well as demonstrating at the event, both during the public sessions and at one of the black tie “soirées” for fellows and guests of the Royal Society.
"It was great to see so many people at the event interested in science and particle physics in particular.” Dr Greig Cowan
You can see more details of the exhibit at the website, as well as other photos and videos on Twitter and Facebook. See links below.
Heavy flavours on Islay
Members of the Edinburgh particle physics group took part in a week of physics meetings and public outreach on Islay. From 10-14th July, the Edinburgh group hosted the “Heavy Flavour 2016 - Quo Vadis?” workshop in the Ardbeg distillery on Islay, where the topic of discussion was the future direction of research for heavy flavour physics, so-called as it involves the study of the heavy beauty and charm quarks that are produced in large numbers at the CERN Large Hadron Collider. Around 30 participants attended the workshop.
"With so many new measurements from the Large Hadron Collider and many more expected during the next decade, it is time to reflect. At this workshop speakers were asked to discuss the future of heavy flavour physics and Islay provided an excellent venue for this, as both the topic and the location involved heavy flavours, beauty and charm." Prof Franz Muheim, who currently holds a Senior Experimental Fellowship from the Institute for Particle Physics Phenomenology (IPPP) at Durham University which provided funds for this workshop.
“It has been a long-term goal for us to have a focussed workshop in a remote location to allow us to discuss the latest developments and future directions of heavy flavour physics. Islay was the perfect choice, not least because of it’ own local “heavy flavoured” spirits." Dr Greig Cowan, STFC Ernest Rutherford research fellow.
Particle Physics for Scottish Schools go to Islay
In parallel with the workshop the group organised a series of public outreach events at Islay High School together with Dr Alan Walker, Director of Particle Physics for Scottish Schools (PP4SS), and the local Science teacher, Russell Pollock. This comprised three joint exhibitions: Particle Physics for Scottish Schools Exhibition, From Higgs to Maxwell Exhibition (Royal Society Edinburgh) and I-SAT: Islay Space and Astronomy Tour.
For PP4SS, this is the third visit to the Scottish Highlands and Islands in as many years, after a very successful series of events in Plockton in 2014 and the Orkney International Science Festival in 2015. The PP4SS exhibition, which was mainly developed with funding from a Science and Society Large Award from the former Particle Physics and Astronomy Research Council, includes several hands-on exhibits demonstrating the working of particle accelerators and experimental detectors. It also outlines the key areas in particle physics research and The University of Edinburgh's involvement in these efforts. Assisted by experienced demonstrators, the visitors were able to walk through a Cosmic Ray Doorway, drive the CERN's LHC accelerator, determine experimentally the life-time of the muon a fundamental particles, and observe particle tracks in a cloud chamber and much more.
"We are very pleased to yet again visit a more remote Scottish community and talk to local people about particle physics and how such cutting-edge research affect all our daily lives. We are in particular proud of meeting many young people, who may later on decide to study physics and become researchers themselves. Quite often they say visiting our exhibition was a contributing factor in making such choices." Alan Walker, Director of PP4SS
Islay Space & Astronomy Tour
Islay Space and Astronomy Tour (I-SAT), is a new invited project by Matjaz Vidmar, our school's alumni of and currently a PhD student in Science, Technology and Innovation Studies, also at the University of Edinburgh. Matjaz is often involved in outreach events and for this occasion he developed an interactive display related to his research, which concerns the applications of basic research and innovation partnerships between scientists and local entrepreneurs in the Space Industry in Scotland.
"It was a privilege to be part of the particle physics outreach activities again and I believe these initiatives are absolutely vital for inspiring high school students in remote parts of Scotland to consider science as their future careers." Matjaz Vidmar, who received an Institute of Physics in Scotland Public Engagement Grant to enable his participation
The series of events also included a public session with presentations by Professor Franz Muheim on "Higgs Bosons, Antimatter and all that" and Matjaz Vidmar on "Astrotechnology - and how it changed the World", which was well attended by the local community.
The Particle Physics Experiments (PPE) group and PP4SS project are very grateful for the work put into supporting this outreach event by Brian Cameron of the School of Geosciences and our dedicated volunteers Dr Konstantina Zerva, Alice Morris and Julija Pustovrh, and for the generous hospitality of the Islay High School, Bowmore.
The School's Prof. Richard Kenway has been elected to the council of the Science and Technology Facilities Council.
Professor Kenway was appointed to the Tait Chair of Mathematical Physics at the University of Edinburgh in 1994. His research explores non-perturbative aspects of theories of elementary particles using computer simulation of lattice gauge theories, particularly the strong interactions of quarks and gluons described by Quantum Chromodynamics (QCD). He led UK participation in the QCDOC project to build three 10 teraflop/s computers to simulate QCD, jointly with the USA and Japan, and these machines operated successfully from 2004 to 2011. In 2002, he initiated the International Lattice Data Grid project, which provides a global infrastructure for sharing simulation data.
As Vice-Principal, Professor Kenway is responsible for the University’s provision of UK high-performance computing services and for promoting advanced computing technologies, computational and data science to benefit academia and industry. For ten years, until it closed in 2011, his responsibilities included the UK National e-Science Centre. In the Queen’s 2008 Birthday Honours, Professor Kenway was awarded an OBE for services to science. He led the establishment of the Scientific Steering Committee of the Partnership for Advanced Computing in Europe (PRACE) and chaired it from 2010 to 2012. He is a founder member of the UK e-Infrastructure Leadership Council and a Trustee of the Alan Turing Institute.
Mr Alan Walker, a former lecturer in the School, has been awarded an Honorary Degree in recognition of his services to science education.
Alan first started in 1993 by working with schools and professional bodies on an individual basis but in 2001 he formalised this into the “SCI-FUN” roadshow. Here, a small team, with Alan as scientific advisor, constructed a set of 40-50 hands-on exhibits which could be taken on tour as a mobile science education centre. SCI-FUN has now visited over 600 sites throughout Scotland and the north of England, attracting over 200,000 members of the public.
Building on SCI-FUN’s success, Alan started the PP4SS (Particle Physics for Scottish Schools) project in 2004. His goal was to find a way to create a series of connected exhibits to describe the work being carried out at CERN’s Large Hadron Collider (LHC) and to introduce people to the discovery of particles from space, ‘cosmic rays’. The project developed exhibits to show the basic principles of particle accelerators, including real-time detection of cosmic ray muons. Alan’s innovation was the creation of small hands-on exhibits connected to a story and presented by enthusiastic science students. PP4SS has reached some 20,000 members of the public, including 2,500 school pupils, and there are now plans to take a version of the roadshow to India. He has also been heavily involved in publicly explaining the significance of the discovery of a Higgs-like Boson.
Alan is a regular participant at the Edinburgh International Science Festival, and has also been involved with an experiment to demonstrate Einstein’s relativistic time-dilation at the top of the Cairngorm mountain railway.
"Alan’s passion is education and through a sustained programme he has inspired an enormous number of people. He conveys excitement, but eschews showmanship. At a time when much science outreach has become superficial entertainment, Alan has remained committed to explanation, responding with unlimited patience to questions from anyone with a genuine desire for an answer." Prof. Arthur Trew, Head of the School of Physics & Astronomy
Dr Alan Walker (School of Physics & Astronomy, University of Edinburgh)
Some galaxies pump out vast amounts of energy from a very small volume of space, typically not much bigger than our own solar system. The cores of these galaxies, so called Active Galactic Nuclei or AGNs, are often hundreds of millions or even billions of light years away, so are difficult to study in any detail. Natural gravitational ‘microlenses’ can provide a way to probe these objects, and now a team of astronomers have seen hints of the extreme AGN brightness changes that hint at their presence. Leading the microlensing work, PhD student Alastair Bruce of the University of Edinburgh presents their work today (Friday 1 July) at the National Astronomy Meeting in Nottingham.
The energy output of an AGN is often equivalent to that of a whole galaxy of stars. This is an output so intense that most astronomers believe only gas falling in towards a supermassive black hole – an object with many millions of times the mass of the Sun - can generate it. As the gas spirals towards the black hole it speeds up and forms a disc, which heats up and releases energy before the gas meets its demise.
Scientists are particularly interested in seeing what happens to the gas as it approaches the black hole. But studying such small objects at such large distances is tricky, as they simply look like points of light in even the best telescopes. Observations with spectroscopy (where light from an object is dispersed into its component colours) show that fast moving clouds of emitting material surround the disc but the true size of the disc and exact location of the clouds are very difficult to pin down.
Bruce will describe how astronomers can make use of cosmic coincidences, and benefit from a phenomenon described by Einstein’s general theory of relativity more than a century ago. In his seminal theory, Einstein described how light travels in curved paths under the influence of a gravitational field. So massive objects like black holes, but also planets and stars, can act to bend light from a more distant object, effectively becoming a lens.
This means that if a planet or star in an intervening galaxy passes directly between the Earth and a more distant AGN, over a few years or so they act as a lens, focusing and intensifying the signal coming from near the black hole. This type of lensing, due to a single star, is termed microlensing. As the lensing object travels across the AGN, emitting regions are amplified to an extent that depends on their size, providing astronomers with valuable clues.
Bruce and his team believe they have already seen evidence for two microlensing events associated with AGN. These are well described by a simple model, displaying a single peak and a tenfold increase in brightness over several years. MIcrolensing in AGNs has been seen before, but only where the presence of the galaxy was already known. Now Bruce and his team are seeing the extreme changes in brightness that signifies the discovery of both previously unknown microlenses and AGNs.
“Every so often, nature lends astronomers a helping hand and we see a very rare event. It’s remarkable that an unpredictable alignment of objects billions of light years away could help us probe the surroundings of black holes. In theory, microlensing could even let us see detail in accretion discs and the clouds in their vicinity. We really need to take advantage of these opportunities whenever they arise.” University of Edinburgh PhD student Alastair Bruce, who leads the microlensing work.
To the depth we can see so far, there are expected to be fewer than 100 active AGN microlensing events on the sky at any one time, but only some will be at or near their peak brightness. The big hope for the future is the Large Synoptic Survey Telescope (LSST), a project the UK recently joined. From 2019 on, it will survey half the sky every few days, so has the potential to watch the characteristic changes in the appearance of the AGNs as the lensing events take place.
RAS National Astronomy Meeting 2016
The RAS National Astronomy Meeting 2016 (NAM 2016, http://nam2016.org) takes place this year at the University of Nottingham from 27 June to 1 July. NAM 2016 brings together more than 550 space scientists and astronomers to discuss the latest research in their respective fields. The conference is principally sponsored by the Royal Astronomical Society and the Science and Technology Facilities Council. Follow the conference on Twitter via @rasnam2016