Astronomers using the NASA/ESA Hubble Space Telescope have studied a giant filament of dark matter in 3D for the first time. Extending 60 million light-years from one of the most massive galaxy clusters known, the filament is part of the cosmic web that constitutes the large-scale structure of the Universe, and is a leftover of the very first moments after the Big Bang. If the high mass measured for the filament is representative of the rest of the Universe, then these structures may contain more than half of all the mass in the Universe. The scientists present their work in a paper in the journal Monthly Notices of the Royal Astronomical Society.

An image of the galaxy cluster MACS J0717.5+3745, with a map of its associated dark matter filament superimposed in blue. Credit: NASA, ESA, Harald Ebeling (University of Hawaii at Manoa) & Jean-Paul Kneib (LAM)The theory of the Big Bang predicts that variations in the density of matter in the very first moments of the Universe led the bulk of the matter in the cosmos to condense into a web of tangled filaments. This view is supported by computer simulations of cosmic evolution, which suggest that the Universe is structured like a web, with long filaments that connect to each other at the locations of massive galaxy clusters. However, these filaments, although vast, are made mainly of dark matter, which is incredibly difficult to observe.

The first convincing identification of a section of one of these filaments was made earlier this year [1]. Now a team of astronomers has gone further by probing a filament's structure in three dimensions. Seeing a filament in 3D eliminates many of the pitfalls that come from studying the flat image of such a structure.

"Filaments of the cosmic web are hugely extended and very diffuse, which makes them extremely difficult to detect, let alone study in 3D," says Mathilde Jauzac (LAM, France and University of KwaZulu-Natal, South Africa), lead author of the study.

The team combined high resolution images of the region around the massive galaxy cluster MACS J0717.5+3745 (or MACS J0717 for short), taken using Hubble, NAOJ's Subaru Telescope and the Canada-France-Hawaii Telescope, with spectroscopic data on the galaxies within it from the WM Keck Observatory and the Gemini Observatory. Analysing these observations together gives a complete view of the shape of the filament as it extends out from the galaxy cluster almost along our line of sight.

The team's recipe for studying the vast but diffuse filament combines several crucial ingredients.

First ingredient: A promising target. Theories of cosmic evolution suggest that galaxy clusters form where filaments of the cosmic web meet, with the filaments slowly funnelling matter into the clusters. "From our earlier work on MACS J0717, we knew that this cluster is actively growing, and thus a prime target for a detailed study of the cosmic web," explains co-author Harald Ebeling (University of Hawaii at Manoa, USA), who leads the team that discovered MACS J0717 almost a decade ago.

Second ingredient: Advanced gravitational lensing techniques. Albert Einstein's famous theory of general relativity says that the path of light is bent when it passes through or near objects with a large mass. Filaments of the cosmic web are largely made up of dark matter [2] which cannot be seen directly, but their mass is enough to bend the light and distort the images of galaxies in the background, in a process called gravitational lensing. The team has developed new tools to convert the image distortions into a mass map.

Third ingredient: High resolution images. Gravitational lensing is a subtle phenomenon, and studying it needs detailed images. Hubble observations let the team study the precise deformation in the shapes of numerous lensed galaxies. This in turn reveals where the hidden dark matter filament is located. "The challenge," explains co-author Jean-Paul Kneib (LAM, France), "was to find a model of the cluster's shape which fitted all the lensing features that we observed."

Finally: Measurements of distances and motions. Hubble's observations of the cluster give the best two-dimensional map yet of a filament, but to see its shape in 3D required additional observations. Colour images [3], as well as galaxy velocities measured with spectrometers [4], using data from the Subaru, CFHT, WM Keck, and Gemini North telescopes (all on Mauna Kea, Hawaii), allowed the team to locate thousands of galaxies within the filament and to detect the motions of many of them.

A model that combined positional and velocity information for all these galaxies was constructed and this then revealed the 3D shape and orientation of the filamentary structure. As a result, the team was able to measure the true properties of this elusive filamentary structure without the uncertainties and biases that come from projecting the structure onto two dimensions, as is common in such analyses.

The results obtained push the limits of predictions made by theoretical work and numerical simulations of the cosmic web. With a length of at least 60 million light-years, the MACS J0717 filament is extreme even on astronomical scales. And if its mass content as measured by the team can be taken to be representative of filaments near giant clusters, then these diffuse links between the nodes of the cosmic web may contain even more mass (in the form of dark matter) than theorists predicted. So much that more than half of all the mass in the Universe may be hidden in these structures.

The forthcoming NASA/ESA/CSA James Webb Space Telescope, scheduled for launch in 2018, will be a powerful tool for detecting filaments in the cosmic web, thanks to its greatly increased sensitivity.

Science Contacts

Mathilde Jauzac
University of KwaZulu-Natal, South Africa and
Laboratoire d'Astrophysique de Marseille, France
Tel: +33 6 52 67 15 39 (France)
Tel: +27 76 799 2955 (South Africa)
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Jean-Paul Kneib
Laboratoire d'Astrophysique de Marseille, France
Currently on leave at the Ecole Polytechnique Fédérale de Lausanne
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Eric Jullo
Laboratoire d'Astrophysique de Marseille, France
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Harald Ebeling
Institute of Astronomy, University of Hawaii at Manoa, USA
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Cheng-Jiun Ma
Institute of Astronomy, University of Hawaii and Harvard-Smithsonian
Center for Astrophysics, USA
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Media contact

Oli Usher
Hubble/ESA, Garching, Germany
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Images and captions

Images of the massive galaxy cluster MACS J0717.5+3745 at different resolutions can be downloaded from http://www.spacetelescope.org/images/heic1215a/

This enormous image shows Hubble's view of massive galaxy cluster MACS J0717.5+3745. The large field of view is a combination of 18 separate Hubble images.

Studying the distorting effects of gravity on light from background galaxies, a team of astronomers has uncovered the presence of a filament of dark matter extending from the core of the cluster.

The location of the dark matter is revealed in a map of the mass in the cluster and surrounding region, shown here in blue. The filament visibly extends out and to the left of the cluster core.

Using additional observations from ground-based telescopes, the team was able to map the filament's structure in three dimensions, the first time this has ever been done. The filament was discovered to extend back from the cluster core, meaning we are looking along it.

Credit: NASA, ESA, Harald Ebeling (University of Hawaii at Manoa) & Jean-Paul Kneib (LAM)

Images of Hubble: http://www.spacetelescope.org/images/archive/category/spacecraft/

Further information

The research is presented in a paper entitled "A Weak-Lensing Mass Reconstruction of the Large-Scale Filament Feeding the Massive Galaxy Cluster MACSJ0717.5+3745", to be published in the 1 November 2012 issue of Monthly Notices of the Royal Astronomical Society. The paper will be published online this week.

Research paper

http://www.spacetelescope.org/static/archives/releases/science_papers/heic1215.pdf

Notes for editors

The Hubble Space Telescope is a project of international cooperation between ESA and NASA.

The international team of astronomers in this study consists of Mathilde Jauzac (Laboratoire d'Astrophysique de Marseille, France, and University of KwaZulu-Natal, South Africa), Eric Jullo

(Laboratoire d'Astrophysique de Marseille, France and Jet Propulsion Laboratory, USA), Jean-Paul Kneib (Laboratoire d'Astrophysique de Marseille), Harald Ebeling (University of Hawaii, USA), Alexie

Leauthaud (University of Tokyo, Japan), Cheng-Jiun Ma (University of Hawaii), Marceau Limousin (Laboratoire d'Astrophysique de Marseille and University of Copenhagen, Denmark), Richard Massey (Durham University, UK) and Johan Richard (Lyon Observatory, France)

[1] The first identification of a dark matter filament was published in J. Dietrich et al, "A filament of dark matter between two clusters of galaxies" published in Nature on 4 July 2012.

[2] Dark matter, which makes up around three quarters of all matter in the Universe, cannot be seen directly as it does not emit or reflect any light, and can pass through other matter without friction (it is collisionless). It interacts only by gravity, and its presence must be deduced from its gravitational effects, for example its effect on the rotation rate of galaxies and its ability to deflect light according to the theory of general relativity.

[3] The light captured by telescopes encapsulates information about the object that emitted it. One important application of this is to study the redshift of an object (the extent to which its light is reddened by the expansion of the Universe) which can be used to measure distances. Estimating distances based on the relative brightnesses of colours that galaxies appear in images is done using a technique called photometric redshift. Although the precision of the distance estimate is limited, it is a relatively straightforward technique to use on large numbers of galaxies, and it works well even for faint objects.

[4] Spectrometers analyse the detailed properties of the light coming from an object. In this study, the subset of galaxies observed with spectrometers provided detailed information on the motion of the objects within the filament.

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 3500 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

Scientists at the University of Cambridge have used cutting-edge infrared surveys of the sky to discover a new population of enormous, rapidly growing supermassive black holes in the early Universe. The black holes were previously undetected because they sit cocooned within thick layers of dust. The new study has shown however that they are emitting vast amounts of radiation through violent interactions with their host galaxies. The team publish their results in the journal Monthly Notices of the Royal Astronomical Society.

Infrared colour image of ULASJ1234+0907 located 11 billion light years from Earth and one of the reddest objects in the sky. This red colour is caused by the enormous amounts of dust within this system. The dust preferentially absorbs bluer light and is responsible for obscuring this supermassive black hole in the visible wavelengths. Credit: image created using data from UKIDSS and the Wide-field Infrared Survey Explorer (WISE) observatorThe most extreme object in the study is a supermassive black hole called ULASJ1234+0907. This object, located in the direction of the constellation of Virgo, is so far away that the light from it has taken 11 billion years to reach us, so we see it as it appeared in the early universe. The monster black hole has more than 10 billion times the mass of the Sun and 10,000 times the mass of the supermassive black hole in our own Milky Way, making it one of the most massive black holes ever seen.

The research indicates that that there may be as many as 400 such giant black holes in the part of the universe that we can observe. "These results could have a significant impact on studies of supermassive black holes" said Dr Manda Banerji, lead author of the paper. "Most black holes of this kind are seen through the matter they drag in. As the neighbouring material spirals in towards the black holes, it heats up. Astronomers are able to see this radiation and observe these systems."

"Although these black holes have been studied for some time, the new results indicate that some of the most massive ones may have so far been hidden from our view." The newly discovered black holes, devouring the equivalent of several hundred Suns every year, will shed light on the physical processes governing the growth of all supermassive black holes.

Supermassive black holes are now known to reside at the centres of all galaxies. In the most massive galaxies in the Universe, they are predicted to grow through violent collisions with other galaxies, which trigger the formation of stars and provides food for the black holes to devour. These violent collisions also produce dust within the galaxies therefore embedding the black hole in a dusty envelope for a short period of time as it is being fed.

Markarian 231, an example of a galaxy with a dusty rapidly growing supermassive black hole located 600 million light years from Earth. The black hole is the very bright source at the centre of the galaxy. Rings of gas and dust can be seen around it as well as “tidal tails” left over from a recent impact with another galaxy. Credit: hubblesite.orgIn comparison with remote objects like ULASJ1234+0907, the most spectacular example of a dusty, growing black hole in the local Universe is the well-studied galaxy Markarian 231 located a mere 600 million light years away. Detailed studies with the Hubble Space Telescope have shown evidence that Markarian 231 underwent a violent impact with another galaxy in the recent past. ULASJ1234+0907 is a more extreme version of this nearby galaxy, indicating that conditions in the early Universe were much more turbulent and inhospitable than they are today.

In the new study, the team from Cambridge used infrared surveys being carried out on the UK Infrared Telescope (UKIRT) to peer through the dust and locate the giant black holes for the first time. Prof. Richard McMahon, co-author of the study, who is also leading the largest infrared survey of the sky, said: "These results are particularly exciting because they show that our new infrared surveys are finding super massive black holes that are invisible in optical surveys. These new quasars are important because we may be catching them as they are being fed through collisions with other galaxies. Observations with the new Atacama Large Millimeter Array (ALMA) telescope in Chile will allow us to directly test this picture by detecting the microwave frequency radiation emitted by the vast amounts of gas in the colliding galaxies."

Dr. Manda Banerji
Institute of Astronomy
University of Cambridge
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Prof. Richard McMahon
Institute of Astronomy
University of Cambridge
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Dr Robert Massey
Royal Astronomical Society
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Images can be downloaded from http://www.ast.cam.ac.uk/~mbanerji/Press.html

Figure 1: Infrared colour image of ULASJ1234+0907 located 11 billion light years from Earth and one of the reddest objects in the sky. This red colour is caused by the enormous amounts of dust within this system. The dust preferentially absorbs bluer light and is responsible for obscuring this supermassive black hole in the visible wavelengths. Giant dusty black holes have therefore been hidden from view until now when cutting edge surveys at infrared wavelengths are allowing us to peer through the dust and locate them for the first time. Credit: image created using data from UKIDSS and the Wide-field Infrared Survey Explorer (WISE) observatory

Figure 2: Markarian 231, an example of a galaxy with a dusty rapidly growing supermassive black hole located 600 million light years from Earth. The black hole is the very bright source at the centre of the galaxy. Rings of gas and dust can be seen around it as well as "tidal tails" left over from a recent impact with another galaxy. Credit: hubblesite.org

The new work will appear in "Heavily Reddened Quasars at z~2 in the UKIDSS Large Area Survey: A Transition Phase in AGN Evolution" by Banerji, Manda; McMahon, Richard; Hewett, Paul; Alaghband-Zadeh, Susannah; Gonzalez-Solares, Eduardo; Venemans, Bram, Monthly Notices of the Royal Astronomical Society, in press. A preprint of the paper can be seen on ArXiV at http://arxiv.org/abs/1203.5530

The team used the UKIRT Infrared Deep Sky Survey (UKIDSS) to detect the new black holes. UKIDSS began in 2005 and will survey around 7500 square degrees of sky at infrared wavelengths.

UKIDSS
http://www.ukidss.org/

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 3500 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

The deadline for the Winton Capital Awards for postdoctoral researchers has been extended. The RAS invites nominations for these awards until the revised deadline of Friday 19 October 2012.

Two prizes of £1,000 each, sponsored by Winton Capital, are awarded for research by a postdoctoral researcher in a UK institution whose career has shown the most promising development. Seperate awards are made for research in Astronomy ('A') and Geophysics ('G'). At the time of nomination candidates should, in normal circumstances, have completed their PhD no more than 5 years previously.

For further details see the instructions for nominations.

Astronomers in Germany have developed an artificial intelligence algorithm to help them chart and explain the structure and dynamics of the universe around us with unprecedented accuracy. The team, led by Francisco Kitaura of the Leibniz Institute for Astrophysics in Potsdam, report their results in the journal Monthly Notices of the Royal Astronomical Society.

An image of a slice through the local universe, 370 million light years on each side. The red circles mark the positions of galaxies observed with the 2MRS survey which measured the positions and distances of over 45000 galaxies. The blue circles are random points (galaxies) inserted to smooth the map across the 'zone of avoidance' where nearby gas and dust in our Galaxy blocks the view of more distant objects. These data are superimposed on the light and dark background of the cosmic web of galaxies modelled by Kitaura et al using an artificial intelligence algorithm. Credit: Francisco Kitaura, Leibniz Institute for Astrophysics, Potsdam. Click for a larger version of this imageScientists routinely use large telescopes to scan the sky, mapping the coordinates and estimating the distances of hundreds of thousands of galaxies and so enabling them to create a map of the large-scale structure of the Universe. But the distribution that astronomers see is intriguing and hard to explain, with galaxies forming a complex 'cosmic web' showing clusters, filaments connecting them, and large empty regions in between.

The driving force for such a rich structure is gravitation. This force originates from two components; firstly the 5% of the universe that appears to be made of 'normal' matter that makes up the stars, planets, dust and gas we can see and secondly the 23% made up of invisible 'dark' matter. Alongside these some 72% of the cosmos is made up of a mysterious 'dark energy' that rather than exerting a gravitational pull is thought to be responsible for accelerating the expansion of the universe. Together these three constituents are described in the Lambda Cold Dark Matter (LCDM) model for the cosmos, the starting point for the work of the Potsdam team.

Measurements of the residual heat from the Big Bang – the so-called Cosmic Microwave Background Radiation or CMBR emitted 13700 million years ago – allow astronomers to determine the motion of the Local Group, the cluster of galaxies that includes the Milky Way, the galaxy we live in. Astronomers try to reconcile this motion with that predicted by the distribution of matter around us and its associated gravitational force, but this is compromised by the difficulty of mapping the dark matter in the same region.

"Finding the dark matter distribution corresponding to a galaxy catalogue is like trying to make a geographical map of Europe from a satellite image during the night that only shows the light coming from dense populated areas", says Dr Kitaura.

To try to solve this problem he developed a new algorithm based on artificial intelligence (AI). It starts with the fluctuations in the density of the universe seen in the CMBR, then models the way that matter collapses into today's galaxies over the subsequent 13 billion years. The results of the AI algorithm are a close fit to the observed distribution and motion of galaxies.

Dr Kitaura comments, "Our precise calculations show that the direction of motion and 80% of the speed of the galaxies that make up the Local Group can be explained by the gravitational forces that arise from matter up to 370 million light years away. In comparison the Andromeda Galaxy, the largest member of the Local Group, is a mere 2.5 million light years distant so we are seeing how the distribution of matter at great distances affects galaxies much closer to home.

'Our results are also in close agreement with the predictions of the LCDM model. To explain the rest of the 20% of the speed, we need to consider the influence of matter up to about 460 million light years away, but at the moment the data are less reliable at such a large distance.

'Despite this caveat, our model is a big step forward. With the help of AI, we can now model the universe around us with unprecedented accuracy and study how the largest structures in the cosmos came into being."

Dr Francisco Kitaura
Leibniz Institute for Astrophysics Potsdam
Germany
Tel: +49 331 7499 447
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Dr Gabriele Schönherr / Kerstin Mork
Public Outreach
Leibniz Institute for Astrophysics Potsdam
Germany
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Dr Robert Massey
Royal Astronomical Society
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Images connected with the new research can be downloaded from http://www.aip.de/mitglieder/fkitaura/images and from www.ras.org.uk

Caption for image on RAS page:

An image of a slice through the local universe, 370 million light years on each side. The red circles mark the positions of galaxies observed with the 2MRS survey which measured the positions and distances of over 45000 galaxies. The blue circles are random points (galaxies) inserted to smooth the map across the 'zone of avoidance' where nearby gas and dust in our Galaxy blocks the view of more distant objects. These data are superimposed on the light and dark background of the cosmic web of galaxies modelled by Kitaura et al using an artificial intelligence algorithm. Credit: Francisco Kitaura, Leibniz Institute for Astrophysics, Potsdam.

The new work appears in "Cosmic Structure and Dynamics of the Local Universe", F-S Kitaura et al, Monthly Notices of the Royal Astronomical Society, in press. A preprint of the paper can be downloaded from http://arxiv.org/abs/1205.5560

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 organises 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 3500 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

Leibniz Institute for Astrophysics

The key areas of research at the Leibniz Institute for Astrophysics (Astrophysics Institute Potsdam – AIP) are cosmic magnetic fields and extragalactic astrophysics. A considerable part of the Institute's efforts aim at the development of research technology in the fields of spectroscopy, robotic telescopes, and e-science. The AIP is the successor of the Berlin Observatory founded in 1700 and of the Astrophysical Observatory of Potsdam founded in 1874. The latter was the world's first observatory to emphasize explicitly the research area of astrophysics. The AIP has been a member of the Leibniz Association since 1992.

Dark energy, a mysterious substance thought to be speeding up the expansion of the Universe is really there, according to a team of astronomers at the University of Portsmouth and LMU University Munich.

After a two-year study led by Tommaso Giannantonio and Robert Crittenden, the scientists conclude that the likelihood of its existence stands at 99.996 per cent. Their findings are published in the journal Monthly Notices of the Royal Astronomical Society.

A visual impression of the data used in the study. The relevant extra-galactic maps are represented as shells of increasing distance from Earth from left to right. The closest thing seen is our Milky Way galaxy, which is a potential source of noise for the analysis. After this are six shells containing maps of the millions of distant galaxies used in the study. These maps are produced using different telescopes in different wavelengths and are colour-coded to show denser clumps of galaxies as red and under-dense regions as blue. There are holes in the maps due to data quality cuts. The last, largest shell shows the temperature of the cosmic microwave background from the WMAP satellite (red is hot, blue is cold), which is the most distant image of the Universe seen, some 46 billion light-years away. The team have detected (at 99.996% significance) very small correlations between these foreground maps (on the left) and the cosmic microwave background (on the right). Image credits: Earth: NASA/BlueEarth; Milky Way: ESO/S. Brunier; CMB: NASA/WMAP. Click for a high resolution image.Professor Bob Nichol, a member of the Portsmouth team, said: "Dark energy is one of the great scientific mysteries of our time, so it isn't surprising that so many researchers question its existence.

"But with our new work we're more confident than ever that this exotic component of the Universe is real – even if we still have no idea what it consists of."

Over a decade ago, astronomers observing the brightness of distant supernovae realised that the expansion of the Universe appeared to be accelerating. The acceleration is attributed to the repulsive force associated with dark energy now thought to make up 73 per cent of the content of the cosmos. The researchers who made this discovery received the Nobel Prize for Physics in 2011, but the existence of dark energy remains a topic of hot debate.

Many other techniques have been used to confirm the reality of dark energy but they are either indirect probes of the accelerating Universe or susceptible to their own uncertainties. Clear evidence for dark energy comes from the Integrated Sachs Wolfe effect named after Rainer Sachs and Arthur Wolfe.

The Cosmic Microwave Background, the radiation of the residual heat of the Big Bang, is seen all over the sky. In 1967 Sachs and Wolfe proposed that light from this radiation would become slightly bluer as it passed through the gravitational fields of lumps of matter, an effect known as gravitational redshift.

In 1996, Robert Crittenden and Neil Turok, now at the Perimeter Institute in Canada, took this idea to the next level, suggesting that astronomers could look for these small changes in the energy of the light, or photons, by comparing the temperature of the radiation with maps of galaxies in the local Universe.

In the absence of dark energy, or a large curvature in the Universe, there would be no correspondence between these two maps (the distant cosmic microwave background and relatively closer distribution of galaxies), but the existence of dark energy would lead to the strange, counter-intuitive effect where the cosmic microwave background photons would gain energy as they travelled through large lumps of mass.

The Integrated Sachs Wolfe effect was first detected in 2003 and was immediately seen as corroborative evidence for dark energy, featuring in the 'Discovery of the year' in Science magazine. But the signal is weak as the expected correlation between maps is small and so some scientists suggested it was caused by other sources such as the dust in our galaxy. Since the first Integrated Sachs Wolfe papers, several astronomers have questioned the original detections of the effect and thus called some of the strongest evidence yet for dark energy into question.

In the new paper, the product of nearly two years of work, the team have re-examined all the arguments against the Integrated Sachs Wolfe detection as well as improving the maps used in the original work. In their painstaking analysis, they conclude that there is a 99.996 per cent chance that dark energy is responsible for the hotter parts of the cosmic microwave background maps (or the same level of significance as the recent discovery of the Higgs boson).

"This work also tells us about possible modifications to Einstein's theory of General Relativity", notes Tommaso Giannantonio, lead author of the present study.

"The next generation of cosmic microwave background and galaxy surveys should provide the definitive measurement, either confirming general relativity, including dark energy, or even more intriguingly, demanding a completely new understanding of how gravity works."

Image and caption

Image available from http://www.icg.port.ac.uk/~nicholb/shells.tiff

Caption: A visual impression of the data used in the study. The relevant extra-galactic maps are represented as shells of increasing distance from Earth from left to right. The closest thing seen is our Milky Way galaxy, which is a potential source of noise for the analysis. After this are six shells containing maps of the millions of distant galaxies used in the study. These maps are produced using different telescopes in different wavelengths and are colour-coded to show denser clumps of galaxies as red and under-dense regions as blue. There are holes in the maps due to data quality cuts. The last, largest shell shows the temperature of the cosmic microwave background from the WMAP satellite (red is hot, blue is cold), which is the most distant image of the Universe seen, some 46 billion light-years away. The team have detected (at 99.996% significance) very small correlations between these foreground maps (on the left) and the cosmic microwave background (on the right). Image credits: Earth: NASA/BlueEarth; Milky Way: ESO/S. Brunier; CMB: NASA/WMAP

Prof. Bob Nichol
Institute of Cosmology
University of Portsmouth
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Twitter: @robertcnichol

Media contacts

Dr Robert Massey
Royal Astronomical Society
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Dr Jen Gupta
Outreach Officer
Institute of Cosmology
University of Portsmouth
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Kate Daniell
Press Officer
University of Portsmouth
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Further information

The new work appears in "The significance of the integrated Sachs-Wolfe effect revisited", T. Ginnantonio, R. Crittenden, R. Nichol, A. Ross, Monthly Notices of the Royal Astronomical Society, in press. A preprint of the paper is available from http://arxiv.org/abs/1209.2125

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 organises 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 3500 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

BBC technology correspondent Katia Moskvitch has won the first European Astronomy Journalism Prize. The award, announced at a reception at the House of Commons,  sees her receive a trip to the inauguration of the Atacama Large Millimeter / Submillimeter Array (ALMA) in Chile in the spring of 2013.

The Science and Technology Facillities Council (STFC) and European Southern Observatory (ESO) ran the competition in association with the Royal Astronomical Society (RAS) and the Association of British Science Writers (ABSW). Entrants were invited to submit written and broadcast material for consideration by a panel of judges from the four organisations.

Prize winner for excellence Robin McKie, overall winner Katia Moskvitch and highly commended Maggie McKee. Credit: ESOKatia won the prize for her series on the ESO Very Large Telescope sited at Paranal in Chile. She said: "As a technology journalist at the BBC, I don't get to write about astronomy very often. That's why I really loved my time in Chile, reporting about the telescopes in ESO's observatories, and learning a lot of new things about space and technology. After I had written my features, I received really good feedback from readers, and a colleague urged me to enter this competition. I was quite surprised but very happy when I found out I won!"

A special prize for excellence also went to Robin McKie from the Observer newspaper for his work on British involvement in the search for gravitational waves.

The judges highly commended Maggie McKee from Boston, Massachusetts, for an article in New Scientist on European involvement in the study of the Transit of Venus.

Robin McKie will take up his prize of a visit to the Very Large Telescope later this year and Maggie McKee's prize is a trip to the UK from the US where she is based – visiting some of the UK's leading science facilities including STFC's Rutherford Appleton Laboratory, The UK Astronomy Technology Centre in Edinburgh and the University of Manchester's Jodrell Bank Discovery Centre.

Paul Roche of the University of Glamorgan and Andy Newsam of Liverpool John Moores University have become the UK's first Professors of Astronomy Education.

Paul and Andy are both long-serving members of the RAS Education Committee and part of the European Space Education Resource Office network of Space Ambassadors. They were (simultaneously but coincidentally) awarded chairs in recognition of the work they do in using astronomy and space science to encourage learners of all ages to study science, technology, engineering and mathematics (STEM) subjects.

Andy is Director of the National Schools' Observatory and Paul is Director of the Faulkes Telescope Project, international projects that give schools access to large robotic telescopes, where the pupils and students can work alongside professional astronomers.

Andy commented "I think these two Chairs say a lot about the excellent work done in the UK in astronomy education, but also about the attitudes of the two universities and the importance they both place on ensuring that the benefits of research are shared as widely as possible".

Paul added "It's great that the work that Andy and I have been doing over the years has been recognised by our universities. STEM subjects are vital to our economy and astronomy is a great way to inspire people to learn more about modern science and how it impacts on almost every aspect of our lives".

Charles Barclay, Chair of the RAS Education Committee, welcomed the news. "Andy and Paul have worked tirelessly over many years to engage the wider public with astronomy, so I'm delighted that their universities have honoured their achievements in this way. With this step the two institutions show how much they value the role of astronomy and how it motivates people to develop a greater interest in science."

The RAS will award two 'RAS Research Fellowships' in 2013.

Details of the fellowships are provided in the terms and conditions, and instructions on how to apply are on the application form. The deadline for applications is 9am, 19th October 2012.

The purpose of the RAS Research Fellowships is to enable outstanding candidates to pursue research in the UK in the disciplines advanced by the RAS i.e. astronomy, solar-system science, geophysics and closely related branches of these sciences.

• Applicants, of any nationality, must be 'ordinarily resident' in the UK and either:
  • Have a recognized PhD degree (or equivalent) obtained after October 2008, or
  • Have taken the 'viva' examination by the application deadline (9am, 19th October 2012) and expect to be awarded a PhD degree by the 1st October 2013.
• Only one RAS Research Fellowship may be held in the same university (as listed by UCAS) at any one time (see below for details of current Fellows).
• The Research Fellowships will be awarded for up to a period of three years beginning on 1st October 2013 (or within 6 months thereafter).
• The award, in the form of a grant to the institution at which the fellow is based, will be calculated from the Grade 7 range (spine point 29 to 37) of the Single Pay Spine of the UK's HE Framework Agreement, taking into account age and incorporating annual increments. A further £2,000 per annum may be claimed for costs incurred in attending meetings and conferences or for other items related to the research. In addition, the RAS will meet the cost of Employers National Insurance contributions and make an additional payment, where appropriate, to a Fellow's personal pension plan.
• The RAS will fund only directly incurred costs, and not overheads (including bench fees or 'Full Economic Costs'). Applications will need to be certified by an authorised person at the institution at which the fellowship will be held confirming acceptance of this condition.

Details of current RAS Research Fellowship awards

The September and October digest of upcoming space and astronomy events, from the RAS. Highlights include the departure of the Dawn mission from Vesta and a special conference on future UK space missions.

The Dawn mission, a NASA spacecraft in orbit around the asteroid Vesta since July 2011, is set to depart for its next target, the dwarf planet Ceres, on 5 September. Dawn has mapped and studied Vesta in the year since it arrived, sending back the first detailed images of this small world and helping scientists to establish that it has a large metal-rich core.

An image of a 15 km wide crater on Vesta, from the Dawn spacecraft. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDAThe journey to Ceres, a body 975 km across, will take two and a half years, with Dawn expected to enter orbit around the dwarf planet in February 2015. The spacecraft will then study Ceres for the following five months. Dawn was originally scheduled to leave Vesta on 26 August, but departure was delayed when one of the spacecraft's reaction wheels unexpectedly shut down.

Dawn Mission
http://dawn.jpl.nasa.gov/

Contacts

Jia Rui-Cook
Jet Propulsion Laboratory
Tel: +1 818 354 0850
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Dwayne Brown
NASA HQ
Tel: +1 202 358 1726

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At 1 p.m. on Tuesday 9 October, Professor David Southwood, President of the Royal Astronomical Society, will give the next RAS public lecture on the Cassini-Huygens mission to Saturn and Titan. In his talk, Prof. Southwood will describe the highlights of the more than 30 years since the inception of this ESA / NASA spacecraft, including the first landing of a probe on a moon of another planet and a comprehensive survey of Saturn and its larger moons.

RAS public lectures
http://www.ras.org.uk/events-and-meetings/public-lectures

Contact
Robert Massey
(details above)

On Friday 12 October, space scientists will gather at Burlington House for a special meeting to discuss potential future UK space missions. The meeting will consider the recommendations of the 2010 Space Innovation and Growth Strategy, which set the goal of UK scientists and engineers leading at least three new space missions before 2030.

Bona fide members of the media who wish to attend this meeting should present their credentials at the registration desk for free admission.

Future UK Space Science Missions
http://www2.le.ac.uk/departments/physics/news/rasuksm

Contact
Robert Massey
(details above)

Solar physicists will gather at Burlington House on 12 October, for a special conference on the physical processes that characterise our nearest star.

Bona fide members of the media who wish to attend this meeting should present their credentials at the registration desk for free admission.

RAS Specialist Discussion Meetings
http://www.ras.org.uk/events-and-meetings/ras-meetings

Contact
Robert Massey
(details above)

The scheduled launch window for the Soyuz TMA-06M mission to the ISS opens on 15 October. The Soyuz spacecraft will take off from the Baikonur Cosmodrome in Kazakhstan. Soyuz will carry three astronauts to the ISS as part of Expedition 33; Russians Oleg Novitskiy and Evgeny Tarelkin and Kevin Ford from the United States. The spacecraft is expected to remain attached to the Space Station where it will serve as an emergency escape vehicle.

NASA: Expedition 33
http://www.nasa.gov/mission_pages/station/expeditions/expedition33/index.html

Russian Federal Space Agency
http://www.federalspace.ru/?lang=en

The latest launch of the US Orbital Test Vehicle X-37B is set to take place on or after 26 October, when it will be carried aloft from Cape Canaveral Air Force Station in Florida atop an Atlas 5 rocket. Built for the US Air Force, the X-37B is a reusable robotic spaceplane designed to operate in Earth orbit for several months at a time, where it can carry out a variety of missions before making an autonomous landing.

US Air Force factsheet on X-37B
http://www.af.mil/information/factsheets/factsheet.asp?fsID=16639

October should see the maiden flight of the Cygnus 1 cargo freighter to the ISS. The freighter spacecraft is due to be carried into orbit on an Antares rocket from the Wallops Island launch facility in Virginia.

Antares and Cygnus are being developed by Orbital Sciences Corporation as part of the NASA Commercial Orbital Transportation Services programme for private companies to supply cargo and carry crew to the space station over the next few years.

Orbital Sciences Corporation
http://www.orbital.com/

Contact
Barron Beneski
Tel: +1 703 406 5000
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Night sky in September and October

Information on stars, planets, comets, meteor showers and other celestial phenomena is available from the British Astronomical Association (BAA), the Society for Popular Astronomy (SPA) and the Jodrell Bank night sky guide.

BAA
http://www.britastro.org

SPA
http://www.popastro.com

The Night Sky: Jodrell Bank
http://www.jb.man.ac.uk/astronomy/nightsky/

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 3500 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

Astronomers at the University of Zürich, the ETH Zurich, the University of Leicester and NAOC Beijing have found large amounts of invisible "dark matter" near the Sun. Their results are consistent with the theory that the Milky Way Galaxy is surrounded by a massive "halo" of dark matter, but this is the first study of its kind to use a method rigorously tested against mock data from high quality simulations. The authors also find tantalising hints of a new dark matter component in our Galaxy. The team's results will be published in the journal Monthly Notices of the Royal Astronomical Society.

The high resolution simulation of the Milky Way used to test the mass-measuring technique. Credit: Dr A. Hobbs. Click for a larger image.Dark matter was first proposed by the Swiss astronomer Fritz Zwicky in the 1930s. He found that clusters of galaxies were filled with a mysterious dark matter that kept them from flying apart. At nearly the same time, Jan Oort in the Netherlands discovered that the density of matter near the Sun was nearly twice what could be explained by the presence of stars and gas alone. In the intervening decades, astronomers developed a theory of dark matter and structure formation that explains the properties of clusters and galaxies in the Universe, but the amount of dark matter in the solar neighbourhood has remained more mysterious. For decades after Oort's measurement, studies found 3-6 times more dark matter than expected. Then last year new data and a new method claimed far less than expected. The community was left puzzled, generally believing that the observations and analyses simply weren't sensitive enough to perform a reliable measurement.

In this latest study, the authors are much more confident in their measurement and its uncertainties. This is because they used a state-of-the-art simulation of our Galaxy to test their mass-measuring technique before applying it to real data. This threw up a number of surprises. They found that standard techniques used over the past 20 years were biased, always tending to underestimate the amount of dark matter. They then devised a new unbiased technique that recovered the correct answer from the simulated data. Applying their technique to the positions and velocities of thousands of orange K dwarf stars near the Sun, they obtained a new measure of the local dark matter density.

Lead author Silvia Garbari says: "We are 99% confident that there is dark matter near the Sun. In fact, our favoured dark matter density is a little high. There is a 10% chance that this is merely a statistical fluke. But with 90% confidence, we find more dark matter than expected. If future data confirms this high value, the implications are exciting. It could be the first evidence for a "disc" of dark matter in our Galaxy, as recently predicted by theory and numerical simulations of galaxy formation. Or it could be that the dark matter halo of our Galaxy is squashed, boosting the local dark matter density."

Many physicists are placing their bets on dark matter being a new fundamental particle that interacts only very weakly with normal matter -- but strongly enough to be detected in experiments deep underground where confusing cosmic ray events are screened by over a kilometre of solid rock.

An accurate measure of the local dark matter density is vital for such experiments as co-author Prof. George Lake explains: "If dark matter is a fundamental particle, billions of these particles will have passed through your body by the time your finish reading this article. Experimental physicists hope to capture just a few of these particles each year in experiments like XENON and CDMS currently in operation. Knowing the local properties of dark matter is the key to revealing just what kind of particle it consists of."

Science contacts

Silvia Garbari
Tel: +41 76 211 05 12
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Prof. Justin Read
Tel: +41 76 200 5394
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Media contact

Robert Massey
Royal Astronomical Society
Mob: +44 (0)794 124 8035
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An image from the simulation can be downloaded from
http://www.astro.phys.ethz.ch/~jread/Press/mw_hr_00260_disk.jpg

Caption: The high resolution simulation of the Milky Way used to test the mass-measuring technique. Credit: Dr A. Hobbs

The new work appears in: "A new determination of the local dark matter density from the kinematics of K dwarfs", Monthly Notices of the Royal Astronomical Society, in press. A preprint of the paper is available from http://arxiv.org/pdf/1206.0015v2.pdf

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 3500 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