Four previously unknown galaxy clusters – each potentially containing thousands of individual galaxies – have been discovered some 10 billion light years from Earth.
An international team of astronomers, led by Imperial College London, used a new way of combining data from the two European Space Agency satellites, Planck and Herschel, to identify more distant galaxy clusters than has previously been possible. The researchers believe up to 2000 further clusters could be identified using this technique, helping to build a more detailed timeline of how clusters are formed. They publish their work in a paper in the journal Monthly Notices of the Royal Astronomical Society.
Galaxy clusters are the most massive objects in the universe, containing hundreds to thousands of galaxies, bound together by gravity. While astronomers have identified many nearby clusters, they need to go further back in time to understand how these structures are formed. This means finding clusters at greater distances from the Earth.
The light from the most distant of the four new clusters identified by the team has taken over 10 billion years to reach us. This means the researchers are seeing what the cluster looked like when the universe was just three billion years old.
Lead researcher Dr David Clements, from the Department of Physics at Imperial College London, explains: “Although we’re able to see individual galaxies that go further back in time, up to now, the most distant clusters found by astronomers date back to when the universe was 4.5 billion years old. This equates to around nine billion light years away. Our new approach has already found a cluster in existence much earlier than that, and we believe it has the potential to go even further.”
The clusters can be identified at such distances because they contain galaxies in which huge amounts of dust and gas are being formed into stars. This process emits light that can be picked up by the satellite surveys.
Galaxies are divided into two types: elliptical galaxies that have many stars, but little dust and gas; and spiral galaxies like our own, the Milky Way, which contain lots of dust and gas. Most clusters in the universe today are dominated by giant elliptical galaxies in which the dust and gas has already been formed into stars.
“What we believe we are seeing in these distant clusters are giant elliptical galaxies in the process of being formed,” says Dr Clements.
Observations were recorded by the Spectral and Photometric Imaging Receiver (SPIRE) instrument as part of the Herschel Multi-tiered Extragalactic Survey (HerMES). Prof Seb Oliver, Head of the HerMES survey said: "The fantastic thing about Herschel-SPIRE
is that we are able to scan very large areas of the sky with sufficient
sensitivity and image sharpness that we can find these rare and exotic
things. This result from Dr Clements is exactly the kind of thing we
were hoping to find with the HerMES survey".
The researchers are among the first to combine data from two satellites that ended their operations last year: the Planck satellite, which scanned the whole sky, and the Herschel satellite, which surveyed certain sections in greater detail. The researchers used Planck data to find sources of far-infrared emission in areas covered by the Herschel satellite, then cross referenced with Herschel
data to look at these sources more closely. Of sixteen sources
identified by the researchers, most were confirmed as single, nearby
galaxies that were already known. However, four were shown by Herschel to be formed of multiple, fainter sources, indicating previously unknown galaxy clusters.
The team then used additional existing data and new observations to
estimate the distance of these clusters from Earth and to determine
which of the galaxies within them were forming stars. The researchers
are now looking to identify more galaxy clusters using this technique,
with the aim of looking further back in time to the earliest stage of
cluster formation.
The research involved scientists from the UK, Spain, USA, Canada, Italy and South Africa. It was part funded by the Science and Technology Facilities Research Council and the UK Space Agency.
Media contact
Gail Wilson
Research Media Officer – Faculty of Natural Sciences
Communications and Public Affairs
Imperial College London
gail.wilson@imperial.ac.uk
Tel: +44(0)20 7594 6702
Out of hours duty press officer: +44(0)7803 886 248
Research Media Officer – Faculty of Natural Sciences
Communications and Public Affairs
Imperial College London
gail.wilson@imperial.ac.uk
Tel: +44(0)20 7594 6702
Out of hours duty press officer: +44(0)7803 886 248
Image and caption
An image is available from https://www.ras.org.uk/images/stories/press/Bootes7col_stamp.png
Caption: Three (false) colour Herschel images of the clumps identified by Planck.
Blue, green and red represent infrared light at successively longer
wavelengths, of 250μm, 350μm and 500μm respectively. The green circle
indicates the size of the Planck beam at the position of the source, which Herschel was able to resolve in far greater detail. Credit: D. Clements / ESA / NASA
Further information
The new work appears in ‘HerMES: Clusters of Dusty Galaxies uncovered by Herschel and Planck’,
D. L. Clements, F. G. Braglia, A. Hyde, I. Perez-Fournon, J. Bock, A.
Cava, S. Chapman, A. Conley, A. Cooray, D. Farrah, E. A. Gonzalez
Solares, L. Marchetti, G. Marsden, S. J. Oliver, I. G. Roseboom, B.
Schulz, A. J. Smith, M. Vaccari, J. Vieira, M. Viero, L. Wang, J.
Wardlow, M. Zemcov and G. de Zotti, Monthly Notices of the Royal Astronomical Society, Oxford University Press, in press.
Notes for editors
About Planck and Herschel
Planck was an ESA science mission with instruments and contributions directly funded by ESA Member States, NASA & Canada. Planck
was launched on May 14 2009 and was Europe’s first space mission to
study the relic radiation from the Big Bang. It was named after the
German physicist Max Planck, whose work on the behaviour of radiation
won the Nobel Prize in 1918. Planck is an all sky survey
mission and its main goal is to study the cosmic microwave background
(CMB), but as a by-product it is producing all sky surveys in all its
observational bands. Planck was deactivated in October 2013 when the tank of liquid helium used to cool the instruments finally ran dry.
Herschel was an ESA space observatory with science
instruments provided by European-led Principal Investigator consortia
and with important participation from NASA. Herschel was launched in tandem with Planck and its observations finished on April 29 2014. Scientific work on the data collected by Herschel will continue for many years. With its larger primary mirror and larger detector arrays, Herschel can reach higher angular resolutions and higher sensitivities than Planck, but it is not an all sky survey instrument, with its areal coverage limited to less than 10% of the extragalactic sky.
STFC
The Science and Technology Facilities Council (STFC) is keeping the
UK at the forefront of international science and tackling some of the
most significant challenges facing society such as meeting our future
energy needs, monitoring and understanding climate change, and global
security.
The Council has a broad science portfolio and works with the academic
and industrial communities to share its expertise in materials science,
space and ground-based astronomy technologies, laser science,
microelectronics, wafer scale manufacturing, particle and nuclear
physics, alternative energy production, radio communications and radar.
STFC's Astronomy and Space Science programme provides support for a
wide range of facilities, research groups and individuals in order to
investigate some of the highest priority questions in astrophysics,
cosmology and solar system science
STFC operates or hosts world class experimental facilities including:
- in the UK; ISIS pulsed neutron source, the Central Laser Facility, and LOFAR. STFC is also the majority shareholder in Diamond Light Source Ltd.
- overseas; telescopes on La Palma and Hawaii
It enables UK researchers to access leading international science
facilities by funding membership of international bodies including
European Laboratory for Particle Physics (CERN), the Institut Laue
Langevin (ILL), European Synchrotron Radiation Facility (ESRF) and the
European Southern Observatory (ESO).
STFC is one of seven publicly-funded research councils. It is an
independent, non-departmental public body of the Department for
Business, Innovation and Skills (BIS).
Follow us on Twitter @STFC_Matters
About Imperial College London
Consistently rated amongst the world's best universities, Imperial
College London is a science-based institution with a reputation for
excellence in teaching and research that attracts 14,000 students and
6,000 staff of the highest international quality. Innovative research at
the College explores the interface between science, medicine,
engineering and business, delivering practical solutions that improve
quality of life and the environment - underpinned by a dynamic
enterprise culture.
Since its foundation in 1907, Imperial's contributions to society
have included the discovery of penicillin, the development of holography
and the foundations of fibre optics. This commitment to the application
of research for the benefit of all continues today, with current
focuses including interdisciplinary collaborations to improve global
health, tackle climate change, develop sustainable sources of energy and
address security challenges.
In 2007, Imperial College London and Imperial College Healthcare NHS
Trust formed the UK's first Academic Health Science Centre. This unique
partnership aims to improve the quality of life of patients and
populations by taking new discoveries and translating them into new
therapies as quickly as possible.
The Royal Astronomical Society
The Royal Astronomical Society (RAS, www.ras.org.uk) , founded in 1820, encourages and promotes the study of astronomy,
solar-system science, geophysics and closely related branches of
science. The RAS organizes scientific meetings, publishes international
research and review journals, recognizes outstanding achievements by the
award of medals and prizes, maintains an extensive library, supports
education through grants and outreach activities and represents UK
astronomy nationally and internationally. Its more than 3800 members
(Fellows), a third based overseas, include scientific researchers in
universities, observatories and laboratories as well as historians of
astronomy and others.
Follow the RAS on Twitter via @royalastrosoc
