Gas
in the EAGLE Simulation, showing hot bubbles (red colours) surrounding
large galaxies, connected by colder filaments (blue and green colours).
Inserts zoom in on the Local Group around the Milky Way and show the
distribution of gas, stars and dark matter. Credit: Richard Bower, John
Helly, Sarah Nixon, Till Sawala, James Trayford, Durham University. Hi-Res Image
The hunt for dark matter has taken another step forward thanks to new supercomputer simulations showing the evolution of our 'local Universe' from the Big Bang to the present day. Physicists at Durham University, UK, who are leading the research, say their simulations could improve understanding of dark matter, a mysterious substance believed to make up 85 per cent of the mass of the Universe. The results will be presented at the National Astronomy Meeting in Portsmouth on Thursday 26 June.
Professor Carlos Frenk, Director of Durham University’s Institute for
Computational Cosmology, said: "I've been losing sleep over this for
the last 30 years. Dark matter is the key to everything we know about
galaxies, but we still don’t know its exact nature. Understanding how
galaxies formed holds the key to the dark matter mystery."
Scientists believe clumps of dark matter – or haloes – that emerged
from the early Universe, trapped intergalactic gas and became the
birthplaces of galaxies. Cosmological theory predicts that our own
cosmic neighbourhood should be teeming with millions of small halos, but
only a few dozen small galaxies have been observed around the Milky
Way.
Prof. Frenk added: "We know there can't be a galaxy in every halo. The question is: why not?"
The Durham researchers believe their simulations answer this
question, showing explicitly how and why millions of haloes around our
galaxy and neighbouring Andromeda failed to produce galaxies and became
barren worlds. They say the gas that would have made the galaxy was
sterilized by the heat from the first stars that formed in the Universe
and was prevented from cooling and turning into stars.
However, a few haloes managed to bypass this cosmic furnace by
growing early and fast enough to hold on to their gas and eventually
form galaxies.
Prof. Frenk, who will also receive the Royal Astronomical Society’s top award, the Gold Medal for Astronomy
on the same day, added: "We have learned that most dark matter haloes
are quite different from the 'chosen few' that are lit up by starlight.
Thanks to our simulations we know that if our theories of dark matter
are correct then the Universe around us should be full of haloes that
failed to make a galaxy. Perhaps astronomers will one day figure out a
way to find them."
Lead researcher Dr Till Sawala, also at the Institute for
Computational Cosmology at Durham University, said the research was the
first to simulate the evolution of our 'Local Group' of galaxies,
including the Milky Way, Andromeda, their satellites and several
isolated small galaxies, in its entirety.
Dr Sawala said: "What we’ve seen in our simulations is a cosmic own
goal. We already knew that the first generation of stars emitted
intense radiation, heating intergalactic gas to temperatures hotter than
the surface of the sun. After that, the gas is so hot that further star
formation gets a lot more difficult, leaving haloes with little chance
to form galaxies. We were able to show that the cosmic heating was not
simply a lottery with a few lucky winners. Instead, it was a rigorous
selection process and only haloes that grew fast enough were fit for
galaxy formation."
The close-up look at the Local Group is part of the larger EAGLE
project currently being undertaken by cosmologists at Durham University
and the University of Leiden in the Netherlands. EAGLE is one of the
first attempts to simulate – right from the start – the formation of
galaxies in a representative volume of the Universe. By peering into the
virtual Universe, the researchers find galaxies that look remarkably
like our own, surrounded by countless dark matter haloes, only a small
fraction of which contain galaxies.
Media contacts
NAM 2014 press office landlines: +44 (0) 02392 845176, +44 (0)2392 845177, +44 (0)2392 845178
Dr Robert Massey
Mob: +44 (0)794 124 8035
rm@ras.org.uk
Anita Heward
Mob: +44 (0)7756 034 243
anitaheward@btinternet.com
Dr Keith Smith
kts@ras.org.uk
Durham University Media Relations Team
+44 (0)191 334 6075
media.relations@durham.ac.uk
Science contacts
Dr Sawala and Prof. Frenk will be at the Royal Astronomical Society’s National Astronomy Meeting at the University of Portsmouth on Wednesday, June 25, and Thursday, June 26, 2014.
An ISDN radio line is available at the National Astronomy Meeting. To request its use please contact Sophie Hall at the University of Portsmouth on sophie.hall@port.ac.uk.
An ISDN radio line is also available at Durham University and bookings can be arranged via the Media Relations Team on the contact details above.
Further information
The work was funded by the UK's Science and Technology Facilities Council (STFC) and the European Research Council.
The Durham-led simulation was carried out on the “Cosmology Machine”,
which is the part of the DiRAC national supercomputing facility for
research in astrophysics and particle physics funded by the Department
for Business, Innovation and Skills through the STFC. The Cosmology
Machine – based at Durham University – has more than 5,000 times the
computing power of typical PCs, and over 10,000 times the amount of
memory.
The research is part of a programme being conducted by the Virgo
Consortium for supercomputer simulations, an international collaboration
led by Durham University with partners in the UK, Germany, Holland,
China and Canada. The new results on the Local Group involve, in
addition to Durham University researchers, collaborators in the
Universities of Victoria (Canada), Leiden (Holland), Antwerp (Belgium)
and the Max Planck Institute for Astrophysics (Germany).
Notes for editors
Durham University is a world
top-100 university with a global reputation and performance in research
and education. The most recent UK league tables place Durham in the
top echelon of British universities academically. Durham is ranked
fifth in the UK in the Complete University Guide 2014 and sixth in the
Times and Sunday Times Good University Guide 2014; it is 26th in the
world for the impact of its research (THE citations ratings) and in the
world top 25 for the employability of its students by blue-chip
companies world-wide (QS World University Rankings 2013/14). It is a
residential Collegiate University: England’s third oldest university and
at its heart is a medieval UNESCO World Heritage Site, of which it is
joint custodians with Durham Cathedral. Durham is a member of the
Russell Group of leading research-intensive UK universities.
Set up in 2007 by the European Union, the European Research Council
(ERC) aims to stimulate scientific excellence in Europe by encouraging
competition for funding between the very best, creative researchers of
any nationality and age based in Europe. Since its launch, the ERC has
awarded grants to over 4,000 researchers performing frontier research in
Europe. The ERC operates according to an "investigator-driven", or
"bottom-up" approach, allowing both early-career and senior scientists
to identify new opportunities in all fields of research (Physical
Sciences and Engineering, Life Sciences and Social Sciences and
Humanities), without predetermined priorities. The ERC has a total
budget of €13.1 billion under Horizon 2020, the new EU research and
innovation programme for 2014 - 2020.
The RAS National Astronomy Meeting
(NAM 2014) will bring together more than 600 astronomers, space
scientists and solar physicists for a conference running from 23 to 26
June in Portsmouth. NAM 2014, the largest regular professional astronomy
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Cosmology (UKCosmo) meetings. The conference is principally sponsored
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