ESA XMM-Newton: Inexplicable signal provides clue about dark matter

A sketch (not to scale) showing axions (blue) streaming out from the Sun, converting in the Earth's magnetic field (red) into X-rays (orange), which are then detected by the XMM-Newton observatory. 

Credit: University of Leicester

Cutting-edge paper by Professor George Fraser, who tragically died in March this year,and colleagues at the University of Leicester provides first potential indication of direct detection of Dark Matter, something that has been a mystery in physics for over 30 years.

Space scientists at the University of Leicester have detected a curious signal in the X-ray sky – one that provides a tantalising insight into the nature of mysterious Dark Matter.

The Leicester team has found what appears to be a signature of 'axions', predicted 'Dark Matter' particle candidates, something that has been a puzzle to science for years.

In a study being published on Monday 20 October in the Monthly Notices of the Royal Astronomical Society, the University of Leicester scientists describe their finding of a signal which has no conventional explanation.

As first author Professor George Fraser, who sadly died in March of this year, wrote: "The direct detection of dark matter has preoccupied physics for over thirty years."

Dark Matter, a kind of invisible mass of unknown origin, cannot be seen directly with telescopes, but is instead inferred from its gravitational effects on ordinary matter and on light.

Dark Matter is believed to make up 85% of the matter of the Universe.

"The X-ray background, the sky, after the bright X-ray sources are removed - appears to be unchanged whenever you look at it," explained Dr. Andy Read, also from the University of Leicester Department of Physics and Astronomy and now leading the paper.

"However, we have discovered a seasonal signal in this X-ray background, which has no conventional explanation, but is consistent with the discovery of axions."

This result was found through an extensive study of almost the entire archive of data from the European Space Agency's X-ray observatory, XMM-Newton, which will celebrate its 15th year in orbit this December.

Previous searches for axions, notably at CERN, and with other spacecraft in Earth orbit, have so far proved unsuccessful.

As Professor Fraser explains in the paper: "It appears plausible that axions, Dark Matter particle candidates, are indeed produced in the core of the Sun and do indeed convert to X-rays in the magnetic field of the Earth."

It is predicted that the X-ray signal due to axions will be greatest when looking through the sunward side of the magnetic field because this is where the field is strongest.

Dr. Read concludes: "These exciting discoveries, in George's final paper, could be truly ground-breaking, potentially opening a window to new physics, and could have huge implications, not only for our understanding of the true X-ray sky, but also for identifying the Dark Matter that dominates the mass content of the cosmos."

President of the Royal Astronomical Society Professor Martin Barstow, who is Pro-Vice-Chancellor, Head of the College of Science & Engineering and Professor of Astrophysics & Space Science at the University of Leicester said: "This is an amazing result. If confirmed, it will be first direct detection and identification of the elusive dark matter particles and will have a fundamental impact on our theories of the Universe."

More information: "Potential solar axion signatures in X-ray observations with the XMM-Newton observatory," G. W. Fraser, A. M. Read, S. Sembay, J. A. Carter, E. Schyns, Accepted (08/09/14) for publication in Monthly Notices of the Royal Astronomical Society (mnras.oxfordjournals.org/), Paper can be found on arXiv : arxiv.org/abs/1403.2436.

NASA Chandra: Signal from Dark Matter

An X-ray image of the hot gas in the central region of the Perseus Cluster of galaxies, taken by the Chandra X-ray Observatory. 

The Perseus Cluster is one of the most massive objects in the Universe with thousands of galaxies immersed in an enormous cloud of superheated gas. 

The image shows enormous bright loops, ripples, and jet-like streaks throughout the cluster. 

Astronomers may have detected an emission line from a form of dark matter, the sterile neutrino, in the spectrum of galaxy clusters like Perseus. 

Credit: Chandra/NASA/ESA

Galaxies are often found in groups or clusters, the largest known aggregations of matter and dark matter.

The Milky Way, for example, is a member of the "Local Group" of about three dozen galaxies, including the Andromeda Galaxy located about 2 million light-years away.

Very large clusters can contain thousands of galaxies, all bound together by gravity.

The closest large cluster of galaxies to us, the Virgo Cluster with about 2000 members, is about 50 million light-years away.

The space between galaxies is not empty. It is filled with hot intergalactic gas whose temperature is of order ten million kelvin, or even higher.

The gas is enriched with heavy elements that escape from the galaxies and accumulate in the intracluster medium over billions of years of galactic and stellar evolution.

These intracluster gas elements can be detected from their emission lines in X-ray, and include oxygen, neon, magnesium, silicon, sulphur, argon, calcium, iron, nickel, and even chromium and manganese.

The relative abundances of these elements contain valuable information on the rate of supernovae in the different types of galaxies in the clusters since supernovae make and/or disburse them into the gas.

Therefore it came as something of a surprise when CfA astronomers and their colleagues discovered a faint line corresponding to no known element.

Esra Bulbul, Adam Foster, Randall Smith, Scott Randall and their team were studying the averaged X-ray spectrum of a set of seventy-three clusters (including Virgo) looking for emission lines too faint to be seen in any single one when they uncovered a line with no known match in a particular spectral interval not expected to have any features.

The scientists propose a tantalizing suggestion: the line is the result of the decay of a putative, long-sought-after dark matter particle, the so-called sterile neutrino.

It had been suggested that the hot X-ray emitting gas in a galaxy cluster might be a good place to look for dark matter signatures, and if the sterile neutrino result is confirmed it would mark a breakthrough in dark matter research (it is of course possible that it is a statistical or other error).

Recent unpublished results from another group tend to support the detection of this feature; the team suggests that observations with the planned Japanese Astro-H X-ray mission in 2015 will be critical to confirm and resolve the nature of this line.

More information: "Detection of an Unidentified Emission Line in the Stacked X-Ray Spectrum of Galaxy Clusters," Esra Bulbul, Maxim Markevitch, Adam Foster, Randall K. Smith, Michael Loewenstein, and Scott W. Randall, ApJ 789, 13, 2014.

Mysterious X-ray signal intrigues astronomers

Credit: X-ray: NASA/CXC/SAO/E.Bulbul, et al.

A mysterious X-ray signal has been found in a detailed study of galaxy clusters using NASA's Chandra X-ray Observatory and ESA's XMM-Newton.

One intriguing possibility is that the X-rays are produced by the decay of sterile neutrinos, a type of particle that has been proposed as a candidate for dark matter.

While holding exciting potential, these results must be confirmed with additional data to rule out other explanations and determine whether it is plausible that dark matter has been observed.

Astronomers think dark matter constitutes 85% of the matter in the Universe, but does not emit or absorb light like "normal" matter such as protons, neutrons and electrons that make up the familiar elements observed in planets, stars, and galaxies. Because of this, scientists must use indirect methods to search for clues about dark matter.

The latest results from Chandra and XMM-Newton consist of an unidentified X-ray emission line, that is, a spike of intensity at a very specific wavelength of X-ray light.

Astronomers detected this emission line in the Perseus galaxy cluster using both Chandra and XMM-Newton.

They also found the line in a combined study of 73 other galaxy clusters with XMM-Newton.

"We know that the dark matter explanation is a long shot, but the pay-off would be huge if we're right," said Esra Bulbul of the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Mass. who led the study. "So we're going to keep testing this interpretation and see where it takes us."

The authors suggest this emission line could be a signature from the decay of a "sterile neutrino." Sterile neutrinos are a hypothetical type of neutrino that is predicted to interact with normal matter only via gravity. Some scientists have proposed that sterile neutrinos may at least partially explain dark matter.

"We have a lot of work to do before we can claim, with any confidence, that we've found sterile neutrinos," said Maxim Markevitch, a co-author from NASA's Goddard Space Flight Center in Greenbelt, Maryland. "But just the possibility of finding them has us very excited."

One source of uncertainty is that the detection of this emission line is pushing the capabilities of the two observatories in terms of sensitivity. Also, there may be explanations other than sterile neutrinos if this X-ray emission line is deemed to be real.

There are ways that normal matter in the cluster could have produced the line, although the team's analysis suggested that all of these would involve unlikely changes to our understanding of physical conditions in the galaxy cluster or the details of the atomic physics of extremely hot gases.

The authors note that even if the sterile neutrino interpretation is correct, their detection does not necessarily imply that all of dark matter is composed of these particles.

More information: The paper describing the new Chandra and XMM-Newton observations appears in the June 20, 2014, issue of The Astrophysical Journal: dx.doi.org/10.1088/0004-637X/789/1/13

Revolutionary New Burn dressing 'lights up' to signal an infection

Scientists have developed a medical dressing that 'lights up' when a burn is infected.

It could be lifesaving in young children with serious burns in whom infections can rapidly become fatal, the Bristol researchers said. 

A prototype is available for demonstration purposes but trials in humans are still some years away.

Fast diagnosis of infection in children with burns, such as those caused by scalds from hot drinks, is a big problem for clinicians, the researchers said.

Current tests for an infected wound can take up to a couple of days but children - especially those of pre-school age - are particularly at risk from the effects of infection due to their relatively poor immunity.

They can quickly develop a condition called toxic shock syndrome, which if left untreated can be fatal in half of cases.

Fluorescent dye 
The dressing developed by scientists at the University of Bath uses nanocapsules containing a dye that burst open in the presence of disease-causing bacteria.

Using a UV light, doctors can quickly check whether there is infection by seeing if the dressing glows.

The nanocapsules are activated when they come into contact with toxins produced by harmful bacteria, so do not release the dye in response to normal bacteria that live on the skin.

So far the dressing has been tested on skin samples in the laboratory.

Dr Toby Jenkins

Dr Toby Jenkins, reader in Biophysical Chemistry at Bath, and project lead said about 5,000 children a year in England and Wales are treated in hospital for burns.

"The big problem for clinicians is the fast diagnosis of infection. Current methods take between 24 and 48 hours to get an answer as to whether the wound is infected.

"However, our burns dressing gives a simple colour change under UV light if a pathogenic, disease-causing bacteria is present in the burn, meaning clinicians can be alerted quickly to a potential infection."


Dr Amber Young, consultant paediatric anaesthetist at the South West Paediatric Burns Centre at Frenchay Hospital in Bristol and clinical adviser to the project said when a child with a small burn develops a high temperature there is no easy way of knowing if the child has a serious bacterial infection, or simply a cough or cold.

Dr Amber Young

"We currently have to remove the dressing to test for infection, which may result in slower healing and potentially life-long scarring and is very distressing for the child.

"This new dressing will mean we will be able to detect the early signs of infection so we can diagnose and treat the child quickly."

Prof Sheila MacNeil

Prof Sheila MacNeil, from Sheffield University, said the technology was based on two clever concepts - that it only reacts in the presence of life-threatening bacteria and that the florescent dye only shows up once the nanocapsules have burst.

"It has been developed for use in paediatrics but it could also be useful in lots of other contexts, such as the management of chronic ulcers in the home," she added.

The birth of a Radio Telescope 30 times larger than Earth

Artist's impression of Spektr-R, the 10-meter space-borne antenna of the RadioAstron project. Credit: Lavochkin Association.

On 15 November 2011, the Effelsberg 100-meter radio telescope, together with three Russian and one Ukrainian telescope, took part in the first interferometric observations with the orbiting 10-meter antenna Spektr-R of the Russian RadioAstron project. 

The observations were made at a wavelength of 18 centimeters, targeting the distant, bright, and very compact quasar 0212+735. 

Interferometric signals have been successfully detected by the RadioAstron team between Spektr-R and the ground antennas, setting a new world record for the size of a radio interferometer and opening a new era in interferometric studies of cosmic radio emission. 

Play-acting orang-utans signal their desires

They might not win any Oscars, but orang-utans can act. They have been caught on camera performing "pantomimes", in which they express their intentions and desires by acting them out. The finding challenges the view that these behaviours are exclusive to humans.

Non-human great apes such as orang-utans and chimpanzees were already known to display meaningful gestures. They might throw an object when angry, for example. But that is a far cry from displaying actions that are intentionally symbolic and referential – the behaviour known as pantomiming.

"Pantomime is considered uniquely human," says Anne Russon from York University in Toronto, Canada. "It is based on imitation, recreating behaviours you have seen somewhere else, which can be considered complex and beyond the grasp of most non-human species."

Yet over years she has worked with great apes, Russon has seen several cases that she thought could be considered pantomiming. So to gather more concrete evidence, she and colleague Kristin Andrews searched through 20 years of data on the behaviour of free-ranging, rehabilitated orang-utans.