It seems an obvious fact that galaxies formed through gravitational collapse. And we all know that quasars are powered by accretion onto supermassive black-holes. But perhaps not everyone knows whom we owe this knowledge to. Donald Lynden-Bell passed away in February 2018. Since the beginning of my studies I was intrigued by the notion of an early collapse that would explain why the Milky Way halo contains the most ancient stars and why the metal content increases towards the inner parts of galaxies. The monolithic collapse model of Donald has accompanied my thoughts until I was lucky enough to be part of a Club where I could dine in his company … In front of a rich chocolate pudding I remember a conversation where we shared the puzzling thinking that the biggest galaxies seem to be the oldest. How could we explain this? Did we need another Universe? Perhaps, but first we needed another chocolate … It was always a pleasure to dine in Donald’s company, his radiant optimism and open smile were illuminating the dining room as much as his articles have enlightened generations of astronomers …. As Ruth his wife says ‘Donald loved to attend the Club to be able to meet younger astronomers and see how the world was changing’ … He gave the impression to be happy, and this is how I want to remember him. In admiration and memory of Professor Donald Lynden-Bell, Professor of Theoretical Astrophysics, Gold and Eddington Medal of the Royal Astronomical Society, Director of the Cambridge Institute of Astronomy, Member of the Seven Samurai, and more.
Hedda Gressel and Natalie Hogg, both PhD students with Marco Bruni at ICG, have been awarded a grant by the EU-COST Action CANTATA (Cosmology and Astrophysics Network for Theoretical Advances and Training Actions), a COST Network that Marco has contributed to create. With this funding Hedda is visiting collaborators in Geneva (Switzerland) for a week, and Natalie will visit collaborators in Leiden (Netherlands). In addition, PhD student Simone Peirone from Leiden, collaborating with Natalie and Marco on a common project, has been awarded the same type of grant to visit ICG for a week.
This story has been adapted from a news item that appeared on the University of Portsmouth website.
800 stargazers visited Portsmouth Historic Dockyard two weeks ago to learn about the wonders of the universe and take a tour around the night sky.
Those who turned out for the sixth annual Stargazing at Portsmouth Historic Dockyard event had the chance to chat to cosmologists from the University of Portsmouth’s Institute of Cosmology and Gravitation, listen to fascinating talks and take part in fun activities.
Among the highlights was the chance to “stroll in the cosmos” using a virtual reality headset to experience the universe as it was billions of years ago.
Other popular attractions included a demonstration of the accelerated expansion of the universe using elastic and fairy lights, the chance to classify galaxies online on the Galaxy Zoo citizen science website, sky tours and telescope demonstrations from local amateur astronomers and a constellation trail around HMS Warrior’s main gun deck.
As in previous years, the event was held across two sites at the Historic Dockyard – Action Stations and HMS Warrior 1860. In addition to a variety of hands-on activities provided by the ICG, visitors also had the chance to find out about satellites with Airbus Defence and Space, build a rocket with Action Stations, see where dark skies are in the region with the South Downs National Park, learn about amateur astronomy with Hampshire Astronomical Group, and discover the link between stargazing and navigation with the National Museum of the Royal Navy.
Dr Jen Gupta, astrophysicist and outreach officer at the Institute of Cosmology and Gravitation, said: “Once again the event proved to be really popular and we’re really pleased with how it went. It’s wonderful to see people of all ages engaging with astronomy, showing a fascination with the science of the universe and what they can see in the night sky.”
Photos from the event have been posted on the ICG facebook page. To be the first to know about future public events from the ICG, like us on facebook, follow us on twitter, or sign up to our new mailing list.
BritGrav18 @ Portsmouth
The 18th BritGrav meeting will be hosted by Institute of Cosmology and Gravitation (ICG) at University of Portsmouth. The meeting will span two days, Wednesday 18 April and Thursday 19 April 2018.
The aim is to bring together young researchers working on all aspects of gravitational physics. Following the BritGrav tradition, the meeting will consist of short talks with priority will be given to PhD students and postdocs. Limited funding is provided by the IOP Gravitational Physics Group, to support travel for students.
Deadline for financial support application and abstract submission is 7 March 2018.
At the end of the meeting, we will award The Best Student Talk Prize, sponsored by Classical and Quantum Gravity.
For more information and registration please see the meeting website at https://sites.google.com/port.ac.uk/britgrav18.
Local organisers: Marco Bruni, Emir Gumrukcuoglu, Kazuya Koyama, Andy Lundgren, Chris Pattison, Holly Purslow, David Wands, Bill Wright.
We are delighted to announce that Prof Claudia Maraston has been awarded the 2018 Eddington Medal for Astronomy by the Royal Astronomical Society for ‘investigations of outstanding merit in theoretical astrophysics’.
Claudia has published theoretical models for the expected energy emission and mass of galaxies including innovative prescriptions of stellar evolution, which raised strong interest and a vivid debate, and stimulated further work from international groups.
Previous recipients of the award include Stephen Hawking and Roger Penrose. Claudia is only the second female scientist to receive the award since its inception in 1953.
Research led led by ICG researcher Samantha Penny has found evidence that supermassive black holes prevent stars forming in some smaller galaxies, extending out understanding of how dwarf galaxies evolve.
The results, presented at the 231st meeting of the American Astronomical Society, are particularly important because dwarf galaxies (those composed of a few million to several billion stars) are the most numerous galaxies in the Universe, far outnumbering bigger like the Milky Way. The physical processes affecting these small systems gives a more typical picture of the galaxy evolution.
In any galaxy stars are born when clouds of gas collapse under the force of their own gravity. But stars don’t keep being born forever- star formation in galaxies can shut off. The reason for this differs between galaxies, but sometimes, the galaxy’s own central black hole is the culprit.
Supermassive black holes can regulate their host galaxy’s ability to form new stars through a heating process. The black hole drives energy through powerful winds. When this wind hits the giant molecular clouds in which stars would form, it heats the gas, preventing its collapse into new stars.
Previous research has shown that this process can prevent star formation in larger galaxies containing hundreds of billions of stars – but it was believed a different process could be responsible for dwarf galaxies ceasing to produce stars. Scientists previously thought that the larger galaxies could have been interacting gravitationally with the dwarf systems and pulling the star-making gas away.
The researchers showed that a number of the dwarf galaxies under observation were still hosting gas which should result in star formation, but wasn’t. This led the team to the supermassive black hole discovery. To their great surprise, Penny and her team found these supermassive black holes in about ten percent of the dwarf galaxies they saw in the MaNGA survey.
This research was made possible by the Sloan Digital Sky Survey’s Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) instrument. Whereas most prior surveys had looked at each galaxy as a single entity, MaNGA uses more than 1,000 optical fibres to make detailed maps of seventeen galaxies at a time, seeing each galaxy in detail all the way from its centre to its outskirts.
Using MaNGA, the team were able to map the processes acting on the dwarf galaxies through the star systems’ heated gas, which could be detected. The heated gas revealed the presence of a central supermassive black hole, or active galactic nucleus (AGN), and through MaNGA the team were able to observe the effect that the AGN had on their host dwarf galaxies.
While active black holes had been seen in dwarf galaxies before, their effect on their host galaxy had never been observed. MaNGA allowed us to map the effects of the central supermassive black hole across a whole galaxy. This discovery shows that even isolated dwarf galaxies can stop forming stars if they host an active supermassive black hole.
That’s not what’s written in textbooks, and these results potentially impact how we understand galaxy evolution. This discovery would not have been possible without the data from the MaNGA survey- both in its incredible detail and in its ability to see so many galaxies in such a short time.
ICG today celebrated the Prof David Matravers’ 80th birthday with talks from Prof Roy Maartens (University of Portsmouth and the University of the Western Cape) and Dr Karim Malik (Queen Mary, University of London) about David and his work.
David Matravers is the founding father of cosmology research at Portsmouth. He came to Portsmouth as head of the School of Mathematical Sciences in 1990 shortly before the polytechnic became a university, and began a research group in relativity and cosmology. That research group eventually became the Institute of Cosmology and Gravitation in 2002, building a worldwide reputation for research in astrophysics and cosmology.
Roy Maartens (the founding director of the ICG) spoke about David’s work on establishing the key properties necessary to prove the homogeneity and isotropy of the Universe, while Karim Malik (a Portsmouth PhD graduate) spoke about his work with David studying cosmological perturbations and the generation of vorticity.
On Wednesday 29th of November, ICG researchers enjoyed a very successful night at the annual SEPnet Public Engagement Awards
The awards, and the evening ceremony, are a great opportunity to showcase the amazing work we all do in promoting our research and engaging with the public. Often this work requires much dedication and hard-work, and these awards are part of our recognition of the key roles such people play in our departments.
ICG achieved success in three of the six categories on the night!
Innovation Project Award
Winner – Tactile Universe, ICG Portsmouth
Winner – Karen Masters, ICG Portsmouth
Highly Commended – Lucy Newnham, ICG Portsmouth
Well done all, and more to come next year!
Astronomers from the University of Portsmouth will be on hand to answer a galaxy of cosmic questions at Winchester Science Centre and Planetarium this weekend.
Scientists from the University’s Institute of Cosmology and Gravitation (ICG) will offer their expertise at Night Sky Live – a two-day festival focusing on galaxies, stars, planets and other celestial bodies.
The Institute has partnered with the Science Centre to offer fun family events this Saturday and Sunday. Dr Jen Gupta, of ICG, will present interactive shows on the science of the night sky and shed more light on the planets in our solar system and other wonders of the universe.
Experts from the ICG will also run hands-on space and night sky activities, including a chance to check out their Tactile Universe – a project to engage blind and visually impaired people with astrophysics research by using 3D images of galaxies.
“Night Sky Live is a great opportunity for members of the public to learn about space in a fun, laid-back setting,’ said Dr Gupta. “At the ICG, we love the opportunity to share our cosmology research with people of all ages and introduce them to complex subjects in a way that is interactive, engaging and easy to understand.”
The event also offers stargazing talks and planetarium shows. There is the chance to find the North Star and learn more about astro-navigation, create your own planisphere and constellation and hunt for the Solar System’s ninth planet.
Night Sky Live runs at the Science Centre in Telegraph Way, Winchester between 10am and 9pm on Saturday and 10am and 8.30pm on Sunday. Events run at various times. For general ticket prices and tickets for Dr Gupta’s live shows and the Planetarium shows, and for event times and further details, visit the centre website here.