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July 2013

Institute for Computational Cosmology

Cosmology in Crisis:

What is the matter? ICC News

Summer Science RAS Awards

Research

Overview of ICC research themes

Ogden@10 10th Anniversary of the ICC

COSMA V

New installation of Cosmology Machine


Astronomy Picture of the Day 12th October 2012

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. Pan-STARRS and Nebulae Image Credit: PS1 Science Consortium Processing: Nigel Metcalfe, Peter Draper (Durham Univ.), Gene Magnier (IfA Hawaii)

http://apod.nasa.gov/apod/ap121012.html

(NASA APOD)

ICC NEWS July 2013 icc.dur.ac.uk Written and designed by: Carlton Baugh Image, text credits: Mark Lovell, Till Sawala, Richard Bower, Virgo Consortium, Durham University, IBM, Baojiu Li, ITN News, Euclid Consortium, Royal Astronomical Society. “Durham University plays a starring role in computational cosmology� Case Study reproduced with permission from IBM Systems and Technology. Institute for Computational Cosmology. All rights reserved.

Explanation: A single field from the world's most powerful survey instrument captures this spectacular skyview. Looking toward Sagittarius, the scene spans nearly 3 degrees or six times the width of the Full Moon. At bottom, upper right, and lower left it covers the Lagoon Nebula (M8), the Trifid Nebula (M20), and NGC 6559, in the crowded, dusty starfields of the central Milky Way. The adopted color scheme shows dust reddened starlight in red hues and normally red emission from hydrogen atoms in green. Built and operated by the Pan-STARRS project, the instrument featured a 1.4 gigapixel (billion pixel) digital camera and telescope. Pan-STARRS, the Panoramic Survey Telescope & Rapid Response System, is intended to scan the skies for potentially dangerous near-earth asteroids and comets, exploring the Universe with a unique high resolution, wide field view.


ICC NEWS July 2013

Institute for Computational Cosmology Newsletter

Welcome to the first ICC news! To coincide with the Royal Society’s Summer Science Exhibition in July 2013, we are delighted to release the first ever issue of the Institute for Computational Cosmology Newsletter. The past year has been very busy, with events ranging from the 10th Anniversary of the Ogden Centre for Fundamental Physics to the latest installation of the Cosmology Machine supercomputer. ICC News brings you up to date with all the recent activity at the ICC and explains our research and outreach.

“The Ogden Centre is a world-class centre for research into the fundamental mysteries of modern science, from

What is the ICC?

the properties of the

The Institute for Computational Cosmology (ICC) is a leading international centre for research into the origin and evolution of the Universe based at Durham University. We address some of the most fundamental questions in science: What were the first objects in the Universe? How do galaxies form? What is the nature of the dark matter and dark energy? Where does the large-scale structure of the universe come from? What is the fate of the Universe?

smallest elementary

The ICC is housed in the Ogden Centre for Fundamental Physics, named after the benefactor businessman and Durham physics graduate Professor Sir Peter Ogden. The Ogden Centre is also home to the Institute for Particle Physics Phenomenology (IPPP).

- Prof Carlos Frenk, ICC Director

particles to the structure of our Universe as a whole…”

In This Issue

The Ogden Centre and the Cosmology Machine

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ICC news

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Research at the ICC

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Ogden@10

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Cosmology Machine

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A PhD at the ICC


Awards for ICC staff BIERMANN LECTURER Prof Carlos Frenk

A galactic halo simulated with cold dark matter (left) and warm dark matter (right)

ICC at Summer Science 2013 The Royal Society’s annual Summer Science Exhibition showcases the most exciting cutting-edge science and technology research. The Exhibition is the Society's main public event of the year and is open to members of the general public as well as students and teachers, scientists, policymakers and the media.

Cosmology in Crisis: What is the Matter? The ICC, along with collaborators from the Virgo Consortium and Nick Holliman’s Visualisation Lab, was awarded a place at Summer Science 2013 to present our latest research into the identity of the dark matter, which is generally thought to be a “cold”, weakly interacting elementary particle. ICC researchers, working with the Virgo Consortium, have created computer simulations to model how dwarf galaxies formed, testing their assumptions about the nature of the dark matter. The team found that the final results of these simulations did not at all match what we observe. The models showed many more small galaxies in a wide halo around the Milky Way, whereas in reality there are fewer, larger dwarf galaxies.

So what does this mean for dark matter? One possible explanation is that Cold Dark Matter (CDM) does not exist, and the predictions of the standard model relating to it are false. Instead of "cold" dark matter that formed within the first one millionth of a second after the Big Bang, the Universe may instead be filled with warm dark matter (WDM). The WDM would have formed later, up to minutes after the Big Bang, and is described as "warm" as the particles would be lighter and more energetic. When simulations of galaxy formation are run with WDM instead of CDM, the halo of dwarf galaxies has the same structure as we observe. Perhaps we need to change our ideas about dark matter at a fundamental level.

The Biermann lectures bring world-class theoretical and computational astrophysicists to Garching. This year's Biermann lecturer is Prof. Carlos Frenk, who has worked closely with scientists at the Max-Planck-Institute for Astrophysics for almost two decades, trying to understand the evolution of cosmic structure.

RAS FOWLER AWARD Dr Mark Swinbank For developing new techniques to study high redshift galaxies, for example coupling integral field spectrographs with adaptive optics and spatial magnification from gravitational lensing to gain extra detail of these distant objects.

RAS WINTON CAPITAL AWARD Dr Baojiu Li Baojiu Li is a world leader in the field of explanations of the accelerating expansion of the universe that are alternatives to the standard LCDM model.


Recreating the Universe with the Cosmology Machine "We have a worldleading research base in

The Rt. Hon. David Willetts (left) , Carlos Frenk (centre) and Simon Pendlebury (IBM; right)

the UK, thanks to excellent institutions like Durham. Today’s visit has provided an insight into the range of exciting projects at the university.” - David Willetts, Minister of State for Universities and Science

David Willetts visits Durham The Minister of State for Universities and Science, David Willetts, visited Durham University to see research projects made possible by government and private investment. He also unveiled a new £3.7 million supercomputer. The computer, which is one of the most powerful in the country, is being used to run simulations of the Big Bang, the birth of the universe, through to the present day. Scientists at the Institute of Computational Cosmology (ICC) hope it will explain how the universe works. Professor Carlos Frenk, Director of the ICC said: "Modern scientific research, from recreating the evolution of the universe to designing life-saving drugs, relies heavily on supercomputing - the ``new mathematics'.' The machine opened today by the Minister of State is one of the most powerful in the UK and will be wholly dedicated to science." (Reproduced from ITN North East News)

Euclid Mission ICC researchers joined 400 scientists and engineers from across Europe and the USA at the recent Euclid Consortium meeting held in Leiden. Euclid is a Medium-class mission of the European Space Agency which aims to measure the properties of dark energy. Although Euclid is scheduled for launch in 2019, there is still a huge amount of work to do beforehand, and Durham is helping to lead the way!


ICC RESEARCH

This image, measuring 50 Mpc across, shows the formation of a cluster of galaxies in the Eagle simulation. The colours show gas at different temperatures from cold 10 000 K (blue), warm (100,000 K, green) to hot (>1,000,000 K) gas. The main structure is created by the gravitational skeleton of dark matter. Galaxies form a knots in these filaments heating the surrounding gas and creating the fluffy appearance. The large, hot bubbles are created by feedback from black holes in the largest galaxies.

BUILDING A UNIVERSE OF GALAXIES The flagship of Durham Galaxy formation simulations is the EAGLE project. It builds on two of our earlier simulations of the universe : the GIMIC simulation (carried out at the ICC, Crain et al. 2009) and OWLS (carried out in collaboration with astronomers at Leiden University, Schaye et al 2010). These simulations showed that it was possible to incorporate the main processes of galaxy formation into a computer simulations, and that it was possible to simultaneously achieve sufficient resolution to create realistic-looking galaxies and to model a sufficiently large cosmological volume that the results were representative of the universe as a whole. The EAGLE (Evolution of Galaxies and their Environment) simulations push the ideas presented in GIMIC and OWLS to the next level.

“The simulations make a remarkably realistic virtual universe. We believe that they are unique in the accuracy with which they describe the universe around us…” - Prof Richard Bower


REDESIGNING GRAVITY

“Understanding gravity is one of the frontiers of physics. Although Einstein’s theory of general relativity has been tested to high accuracy, the tests have so far been restricted to rather small scales, such as the solar system. To apply this theory on cosmological scales is a remarkable extrapolation of what is known” - Dr Baojiu Li The images show the density fields (top panels) in different modified gravity models, called f(R) gravity. The models approach standard gravity moving from left to right. The bottoms panels show the Newtonian potential Φ in the same simulations. The middle panels show the scalaron field which governs the modification to gravity.

“The work of Durham University ranks at #22 among the 140 institutions comprising the top 1% in the field of Space Science. Durham's current record in this field includes 1,278 papers cited a total of 48,057 times between January 1, 2000 and October 31, 2010. “ —Essential Science Indicators from Thomson Reuters

GALACTIC ARCHEOLOGY Simulations have been carried out to predict which satellite haloes in the Aquarius simulations of Milky Way mass halos (shown here in purple) will host dwarf galaxies. Some of these satellites are pulled apart by tidal forces as they orbit inside the Milky-Way like dark haloes. This image shows (in blue and yellow) the 'debris' of these shredded galaxies, visible in faint clouds and huge 'ghostly' streams. Streams and clouds like these have already been seen around the Milky Way, and our simulations predict that many more are waiting to be discovered. The properties of these streams are a test of the 'lost' population of satellite galaxies, which might not be the same as those that still survive.


GAS BETWEEN GALAXIES

A census of where the baryons are at the present day shows that only a very small fraction is in stars, cold gas that can be detected in absorption or emission, or hot gas in clusters that emits X-rays, meaning that most of it must be in some yet undetected form. Hydrodynamical simulations like the one above show that indeed at the present day the majority of baryons is in a relatively low-density warm-hot phase, called the WHIM. Such low-density ionised gas is very difficult to detect. The image shows the results of one such numerical simulation, in which we compute how strongly the WHIM radiates in Oxygen-VI — the colours show the intensity of the line emission. This UV-emission line traces the filamentary structure of the large-scale matter distribution. We have investigated the surface brightness for a large number of UV and X-ray emission lines, and also qualified how uncertainties in the modelling affect our results. These results can be used to design future space missions that will look for the missing baryons.

LIGHTING UP THE DARK MATTER Modelling the formation and evolution of galaxies is one of the toughest challenges in astrophysics as it requires many nonlinear processes to be followed, such as star formation and heating by AGN, which operate over vast ranges of length, time and mass scales. At the ICC, we pursue complementary routes to study how galaxies are made, which can be divided into gas dynamics simulations and semi-analytical modelling: The ICC is one of the pioneers of the semi-analytical approach to modelling galaxy formation. The current semi-analytical code, GALFORM, makes an ab initio prediction of the star formation, merger and chemical enrichment histories of galaxies. GALFORM is implemented in high-resolution, large-volume N-body simulations of the hierarchical clustering of the dark matter, to predict the spatial distribution of galaxies. Such calculations are used to build mock catalogues for galaxy surveys such as Pan-STARRS and Euclid.

The images show the distribution of dark matter (top) in the Millennium Simulation and the location of the galaxies, (bottom panel) as predicted by GALFORM.


The next generation The ICC has an outstanding track record of training young researchers, offering access to world leading expertise and state of the art resources. Students and postdocs work in a collaborative and supportive environment. Durham provides the opportunity to participate in international collaborations. In addition to the Virgo Consortium for Cosmological Simulations, the ICC plays leading roles in international surveys, including Pan-STARRS, Herschel, GAMA, SCUBA-II and Euclid. We are also the coordinating node of two Marie-Curie funded training programs, CosmoComp and LACEGAL.

Studying for a PhD at the ICC The postgraduate student body at the ICC is truly international (with representatives from China, Crete, Portugal, Ireland, Chile, Mexico, USA, Germany, Switzerland and, of course, the UK). Around half of the places we offer are supported by STFC-funded PhD studentships: the remainder are funded by a range of different sources (e.g. ERC, non-UK government). Students undertake full-time cutting edge astronomical research, in addition to our post-graduate lecture courses in their first year. The STFC-funded PhD studentships cover course fees and living expenses for 3.5 years. Applicants are required to have, or expected to gain, at least a 2.1 in an integrated MPhys or a pass in a Masters degree or a 1st class in a Bachelors degree, in physics, astrophysics or mathematics. Further details and information about how to apply can be found at: http://icc.dur.ac.uk/index.php?content=Postgraduate/Postgraduate

http:// www.youtube.com/ watch? v=w4im7cDkRZg&f eature=player_emb edded Contact Us Postal address: Institute for Computational Cosmology, Ogden Centre for Fundamental Physics, Department of Physics, Durham University, Science Laboratories, South Road, Durham, DH1 3LE. UK.


ICC Newsletter 1  

Find out about the Institute for Computational Cosmology, Durham University.

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