Beautifully illustrated poems celebrating Space and Science - Joanna Tilsley

“The ideal scientist thinks like a poet and works like a bookkeeper,” the influential biologist E.O. Wilson said in his spectacular recent conversation with the former Poet Laureate Robert Hass, exploring the shared creative wellspring of poetry and science.

A beautiful embodiment of it comes from 30 Days, an unusual and bewitching series of “quantum poetry” by xYz, the pseudonym of British biologist and poet Joanna Tilsley, who began writing poetry at the age of eight and continued, for her own pleasure, until she graduated college with a degree in biology.

In April of 2013, while undergoing an emotional breakdown, Tilsley took a friend up on a dare and decided to participate in NaPoWriMo, an annual creative writing project inviting participants to write a poem a day for a month.

Immersed in cosmology and quantum physics at the time, she found herself enchanted by the scientific poetics of nature as she strolled around her home in North London.

Translating that enchantment in lyrical form, she produced a series of thirty poems on everything from DNA to the exoplanet Keppler-62F, a “super-Earth-sized planet orbiting a star smaller and cooler than the sun,” to holometabolism, the process by which the caterpillar metamorphoses into a butterfly, to the Soviet cosmonaut Yuri Gagarin, the first human being to see Earth from space.

 I had been reading a lot about cosmology and new physics at the time, and as I took my habitual walks across the marshes surrounding my home in North London, I pondered deeply upon the dimensions of space and time through which I was passing, as well as existing euphorically in the moment with the first stirrings of spring. 

The poems followed naturally through; in fact they burst out of me, allowing me to weave a pattern of deep emotion through a weft of scientific fact.

Read more here

Standard Model may account for Dark Matter and it may be massive

A massive cluster of yellowish galaxies, seemingly caught in a red and blue spider web of eerily distorted background galaxies, makes for a spellbinding picture from the new Advanced Camera for Surveys (ACS) aboard NASA's Hubble Space Telescope. 

To make this unprecedented image of the cosmos, Hubble peered straight through the center of one of the most massive galaxy clusters known, called Abell 1689. 

The gravity of the cluster's trillion stars, plus dark matter, acts as a 2-million-light-year-wide lens in space. 

This gravitational lens bends and magnifies the light of the galaxies located far behind it. Some of the faintest objects in the picture are probably over 13 billion light-years away (redshift value 6). 

Strong gravitational lensing as observed by the Hubble Space Telescope in Abell 1689 indicates the presence of dark matter. 

Credit: NASA, N. Benitez (JHU), T. Broadhurst (Racah Institute of Physics/The Hebrew University), H. Ford (JHU), M. Clampin (STScI),G. Hartig (STScI), G. Illingworth (UCO/Lick Observatory), the ACS Science Team and ESA

The physics community has spent three decades searching for and finding no evidence that dark matter is made of tiny exotic particles.

Case Western Reserve University theoretical physicists suggest researchers consider looking for candidates more in the ordinary realm and, well, more massive.

Dark matter is unseen matter, that, combined with normal matter, could create the gravity that, among other things, prevents spinning galaxies from flying apart.

Physicists calculate that dark matter comprises 27 percent of the universe; normal matter 5 percent.

Instead of WIMPS, weakly interacting massive particles, or axions, which are weakly interacting low-mass particles, dark matter may be made of macroscopic objects, anywhere from a few ounces to the size of a good asteroid, and probably as dense as a neutron star, or the nucleus of an atom, the researchers suggest.

Physics professor Glenn Starkman and David Jacobs, who received his PhD in Physics from CWRU in May and is now a fellow at the University of Cape Town, say published observations provide guidance, limiting where to look.

They lay out the possibilities in a paper "Macro Dark Matter"

The Macros, as Starkman and Jacobs call them, would not only dwarf WIMPS and axions, but differ in an important way.

They could potentially be assembled out of particles in the Standard Model of particle physics instead of requiring new physics to explain their existence.

"We've been looking for WIMPs for a long time and haven't seen them," Starkman said. "We expected to make WIMPS in the Large Hadron Collider (LHC), and we haven't."

WIMPS and axions remain possible candidates for dark matter, but there's reason to search elsewhere, the theorists argue.

"The community had kind of turned away from the idea that dark matter could be made of normal-ish stuff in the late '80s," Starkman said.

"We ask, was that completely correct and how do we know dark matter isn't more ordinary stuff— stuff that could be made from quarks and electrons?"

After eliminating most ordinary matter, including failed Jupiters, white dwarfs, neutron stars, stellar black holes, the black holes in centers of galaxies and neutrinos with a lot of mass, as possible candidates, physicists turned their focus on the exotics.

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.

Scientists New Estimate of Dark Matter Half previous estimate

Artist’s impression of the Milky Way and its dark matter halo (shown in blue, but in reality invisible). 

Credit: ESO/L. Calçada

A new measurement of dark matter in the Milky Way has revealed there is half as much of the mysterious substance as previously thought.

Australian astronomers used a method developed almost 100 years ago to discover that the weight of dark matter in our own galaxy is 800 000 000 000 (or 8 x 1011) times the mass of the Sun.

They probed the edge of the Milky Way, looking closely, for the first time, at the fringes of the galaxy about 5 million billion kilometres from Earth.

Astrophysicist Dr Prajwal Kafle, from The University of Western Australia node of the International Centre for Radio Astronomy Research (ICRAR), said we have known for a while that most of the Universe is hidden.

"Stars, dust, you and me, all the things that we see, only make up about 4 per cent of the entire Universe," he said.

"About 25 per cent is dark matter and the rest is dark energy."

Dr Kafle, who is originally from Nepal, was able to measure the mass of the dark matter in the Milky Way by studying the speed of stars throughout the galaxy, including the edges, which had never been studied to this detail before.

He used a robust technique developed by British astronomer James Jeans in 1915, decades before the discovery of dark matter.

Dr Kafle's measurement helps to solve a mystery that has been haunting theorists for almost two decades.

"The current idea of galaxy formation and evolution, called the Lambda Cold Dark Matter theory, predicts that there should be a handful of big satellite galaxies around the Milky Way that are visible with the naked eye, but we don't see that," Dr Kafle said.



"When you use our measurement of the mass of the dark matter the theory predicts that there should only be three satellite galaxies out there, which is exactly what we see; the Large Magellanic Cloud, the Small Magellanic Cloud and the Sagittarius Dwarf Galaxy."

University of Sydney astrophysicist Professor Geraint Lewis, who was also involved in the research, said the missing satellite problem had been "a thorn in the cosmological side for almost 15 years."

"Dr Kafle's work has shown that it might not be as bad as everyone thought, although there are still problems to overcome," he said.

The study also presented a holistic model of the Milky Way, which allowed the scientists to measure several interesting things such as the speed required to leave the galaxy.

"Be prepared to hit 550 kilometres per second if you want to escape the gravitational clutches of our galaxy," Dr Kafle said.

"A rocket launched from Earth needs just 11 kilometres per second to leave its surface, which is already about 300 times faster than the maximum Australian speed limit in a car!"

More information: 'On the Shoulders of Giants: Properties of the Stellar Halo and the Milky Way Mass Distribution' P. R. Kafle, S. Sharma, G. F. Lewis, and J. Bland-Hawthorn. Published in the Astrophysical Journal October 10th, 2014. Available at: iopscience.iop.org/0004-637X/794/1/59/. arxiv.org/abs/1408.1787

NASA AMS-2 Particle Detector on ISS Finds Dark matter in Cosmic Rays - Update

The Alpha Magnetic Spectrometer attached to the International Space Station.

Credit: NASA

New research published Thursday in the journal Physical Review Letters shows researchers are making important progress in the hunt for dark matter, using the Alpha Magnetic Spectrometer (AMS), a state-of-the-art cosmic ray particle physics detector located on the exterior of the International Space Station.

The results include new detections of anti-matter particles that could provide new clues in the search for dark matter, invisible matter that can't be directly detected but can be inferred. An overview of the latest findings can be found here.

Computer-generated drawing of the Alpha 
Magnetic Spectrometer (AMS). Credit: NASA

The MIT group leads an international collaboration of scientists that analyzed two and a half years' worth of data taken by the Alpha Magnetic Spectrometer (AMS), a large particle detector mounted on the exterior of the International Space Station, that captures incoming cosmic rays from all over the galaxy.

Among 41 billion cosmic ray events, instances of cosmic particles entering the detector, the researchers identified 10 million electrons and positrons, stable antiparticles of electrons.

Positrons can exist in relatively small numbers within the cosmic ray flux.

An excess of these particles has been observed by previous experiments, suggesting that they may not originate from cosmic rays, but come instead from a new source.

In 2013, the AMS collaboration, for the first time, accurately measured the onset of this excess.

The new AMS results may ultimately help scientists narrow in on the origin and features of dark matter, whose collisions may give rise to positrons.

"The AMS results announced today are tremendously provocative, and will drive scientists around the world to continue pursuing one of the biggest mysteries in the cosmos: dark matter," NASA chief scientist Ellen Stofan said at the agency’s headquarters in Washington.

"The clear and definitive data from AMS represent the caliber of scientific discovery enabled by our unique laboratory in space, the International Space Station."

"Today we are one step closer to answering the fundamental questions about how our universe works, and we look forward to many more exciting twists in this developing story."

AMS was constructed, tested and operated by an international team of 56 institutes from 16 countries and organized under the sponsorship of the U.S. Department of Energy's Office of Science.

NASA's Johnson Space Center in Houston manages the AMS Integration Project Office. AMS was launched on space shuttle Endeavour on May 16, 2011.

Operations on the space station began three days later. AMS continues operations aboard the station today.

More Information
"Electron and Positron Fluxes in Primary Cosmic Rays Measured with the Alpha Magnetic Spectrometer on the International Space Station" Phys. Rev. Lett. 113, 121102 – Published 18 September 2014 - 10.1103/PhysRevLett.113.121102

Milky Way's missing satellite galaxies: Interactive dark matter

The simulated distribution of DM in a Milky Way-like galaxies for standard, non-interacting dark matter (top left), warm dark matter (top right) and the new dark matter model that interacts with the photon background (bottom) are shown. 

Smaller structures are erased up to the point where, in the most extreme model (bottom right), the galaxy is completely sterilized. 

Credit: Credit: Durham University

Scientists believe they have found a way to explain why there are not as many galaxies orbiting the Milky Way as expected.

Computer simulations of the formation of our galaxy suggest that there should be many more, smaller galaxies around the Milky Way than are observed through telescopes.

This has thrown doubt on the generally accepted theory of cold dark matter, a substance that scientists predict should allow for more galaxy formation around the Milky Way than is seen.

Now cosmologists and particle physicists at the Institute for Computational Cosmology (ICC) and the Institute for Particle Physics Phenomenology (IPPP), at Durham University, working with colleagues at LAPTh College & University in France, think they have found a potential solution to the problem.

Writing in the journal Monthly Notices of the Royal Astronomical Society (MNRAS), the scientists suggest that dark matter particles, as well as feeling the force of gravity, could have interacted with photons and neutrinos in the young Universe, causing the dark matter to scatter.

Scientists think clumps of dark matter, or halos, that emerged from the early Universe, trapped the intergalactic gas needed to form stars and galaxies.

Scattering the dark matter particles wipes out the structures that can trap gas, stopping more galaxies from forming around the Milky Way and reducing the number that should exist.

Two models of the dark matter distribution in the halo of a galaxy like the Milky Way, separated by the white line are shown. 

The colours represent the density of dark matter, with red indicating high-density and blue indicating low-density. 

On the left is a simulation of how non-interacting cold dark matter produces an abundance of smaller satellite galaxies. 

On the right the simulation shows the situation when the interaction of dark matter with other particles reduces the number of satellite galaxies we expect to observe around the Milky Way. 

Credit: Durham University

Lead author Dr Celine Boehm, in the Institute for Particle Physics Phenomenology, at, Durham University, said: "We don't know how strong these interactions should be, so this is where our simulations come in.

"By tuning the strength of the scattering of particles, we change the number of small galaxies, which lets us learn more about the physics of dark matter and how it might interact with other particles in the Universe.

"This is an example of how a cosmological measurement, in this case the number of galaxies orbiting the Milky Way, is affected by the microscopic scales of particle physics."

There are several theories about why there are not more galaxies orbiting the Milky Way, which include the idea that heat from the Universe's first stars sterilised the gas needed to form stars.

The researchers say their current findings offer an alternative theory and could provide a novel technique to probe interactions between other particles and cold dark matter.

Co-author Professor Carlton Baugh, in the Institute for Computational Cosmology, at Durham University, said: "Astronomers have long since reached the conclusion that most of the matter in the Universe consists of elementary particles known as dark matter.

"This model can explain how most of the Universe looks, except in our own backyard where it fails miserably.

"The model predicts that there should be many more small satellite galaxies around our Milky Way than we can observe.

"However, by using computer simulations to allow the dark matter to become a little more interactive with the rest of the material in the Universe, such as photons, we can give our cosmic neighbourhood a makeover and we see a remarkable reduction in the number of galaxies around us than originally thought."

The calculations were carried out using the COSMA supercomputer at Durham University, which is part of the UK-wide DiRAC super-computing framework.

More information: Monthly Notices of the Royal Astronomical Society , mnrasl.oxfordjournals.org/look… 0.1093/mnrasl/slu115

ESA NASA Hubble Image: Spiral galaxy in Serpens

This new NASA/ESA Hubble Space Telescope image shows a beautiful spiral galaxy known as PGC 54493, located in the constellation of Serpens (The Serpent). 

This galaxy is part of a galaxy cluster that has been studied by astronomers exploring an intriguing phenomenon known as weak gravitational lensing.

This effect, caused by the uneven distribution of matter (including dark matter) throughout the Universe, has been explored via surveys such as the Hubble Medium Deep Survey.

Dark matter is one of the great mysteries in cosmology. It behaves very differently from ordinary matter as it does not emit or absorb light or other forms of electromagnetic energy, hence the term "dark."

Even though we cannot observe dark matter directly, we know it exists. One prominent piece of evidence for the existence of this mysterious matter is known as the "galaxy rotation problem."

Galaxies rotate at such speeds and in such a way that ordinary matter alone, the stuff we see, would not be able to hold them together.

The amount of mass that is "missing" visibly is dark matter, which is thought to make up some 27 percent of the total contents of the Universe, with dark energy and normal matter making up the rest.

PGC 55493 has been studied in connection with an effect known as cosmic shearing. This is a weak gravitational lensing effect that creates tiny distortions in images of distant galaxies.

Credit: European Space Agency

Researcher advances a new model for dark matter, a cosmological enigma

The distribution of dark matter in the universe as computed within the two-component flavor-mixed dark matter paradigm. 

Credit: University of Kansas / KU News Service

Astrophysicists believe that about 80 percent of the substance of our universe is made up of mysterious "dark matter" that can't be perceived by human senses or scientific instruments.

"Dark matter has not yet been detected in a lab. We infer about it from astronomical observations," said Mikhail Medvedev, professor of physics and astronomy at the University of Kansas, who has just published breakthrough research on dark matter that merited the cover of Physical Review Letters, the world's most prestigious journal of physics research.

Medvedev proposes a novel model of dark matter, dubbed "flavour-mixed multicomponent dark matter."

"Dark matter is some unknown matter, most likely a new elementary particle or particles beyond the Standard Model," Medvedev said.

"It has never been observed directly, but it reveals itself via gravity it produces in the universe. There are numerous experiments around the world aimed at finding it directly."

Medvedev's theory rests on the behavior of elementary particles that have been observed or hypothesized. According to today's prevalent Standard Model theory of particle physics, elementary particles, categorized as varieties of quarks, leptons and gauge bosons, are the building blocks of an atom.

The properties, or "flavors," of quarks and leptons are prone to change back and forth, because they can combine with each other in a phenomenon called flavour-mixing.

"In everyday life we've become used to the fact that each and every particle or an atom has a certain mass," Medvedev said.

"A flavour-mixed particle is weird, it has several masses simultaneously—and this leads to fascinating and unusual effects."

Medvedev compared flavor-mixing to white light that contains several colors and can generate a rainbow.

Orange waves and blue rays represent the effect of quantum evaporation. 

Credit: University of Kansas / KU News Service

"If white was a particular flavor, then red, green and blue would be different masses, masses one, two and three, that mix up together to create white," he said.

"By changing proportions of red, green and blue in the mix, one can make different colors, or flavors, other than white."

Medvedev said that dark matter candidates are also theorized to be flavor-mixed—such as neutralinos, axions and sterile neutrinos.

"These are, in fact, the most preferred candidates people speak about all the time," Medvedev said.

"Previously we discovered that flavor-mixed particles can 'quantum evaporate' from a gravitational well if they are 'shaken', meaning they collide with another particle," he said.

"That's a remarkable result, as if a spacecraft made of flavor-mixed matter and hauled along a bumpy road puts itself into space without a rocket or any other means or effort by us."

Medvedev included the physics process of quantum evaporation in a "cosmological numerical code" and performed simulations using supercomputers.

"Each simulation utilized over a 1,000 cores and ran for a week or so," he said. "This yearlong project consumed about 2 million computer hours in total, which is equal to 230 years."

Medvedev said that dark matter may interact with normal matter extremely weakly, which is why it hasn't been revealed already in numerous ongoing direct detection experiments around the world.

So physicists have devised a working model of completely collisionless (noninteracting), cold (that is, having very low thermal velocities) dark matter with a cosmological constant (the perplexing energy density found in the void of outer space), which they term the "Lambda-CDM model."

But the model has hasn't always agreed with observational data, until Medvedev's paper solved the theory's long-standing and troublesome puzzles.

"Our results demonstrated that the flavor-mixed, two-component dark matter model resolved all the most pressing Lambda-CDM problems simultaneously," said the KU researcher.

Medvedev performed the simulations using XSEDE high-performance computation facilities, primarily Trestles at the San Diego Supercomputer Center and Ranger at the Texas Advanced Computing Center.

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.

'Sterile neutrinos' re-ignites and excites Dark Matter debate - video

Astro-physicists remain cautiously excited about an unexpected X-ray signal discovered in a survey of galactic clusters.

Having first put their findings in the public sphere in March, the work has now passed peer review to hit the presses in the prestigious Astrophysical Journal, and re-ignite discussion about whether the rays represent at least a chunk of the missing stuff in the cosmos.

It's the frequency of the signal that's excited the astronomers' imaginations, since spectroscopy even at high energies is sufficiently familiar that something new demands attention.

The emission line occurs at an energy of (3.55-3.57)+/-0.03 keV – let's say “between 3.55 and 3.57 kilo-electron-volts.

Perhaps cautious after the recent BICEP-CMB 'Big Bang' controversy, which still hasn't been completely resolved, the news from ESA and NASA has been given a much more muted reception saying that “this will be huge if it's right”.

It will be huge: the missing matter in the universe remains one of astrophysics' biggest puzzles along with the search for dark energy.

The world is host to a number of sophisticated instruments designed to track down dark matter, but without positively identifying the source.

What the analysis of data from NASA's Chandra X-ray observatory and the ESA's XMM-Newton instrument has turned up is an unexpected line in the X-ray spectrum, while looking at the Perseus cluster.

Galactic clusters are among the largest-scale structures in the universe, consisting of galaxies interacting via gravity, along with the hot gas filling the space between them.

They're also one of the reasons we believe in dark matter, since the observable mass of clusters makes up only 20 per cent of the mass needed to provide the necessary gravity. The rest is presumed to be dark matter.

NASA's press release stated: there's a faint X-ray emission line discovered in the analysis of the Perseus cluster, which is matched by the same line in an analysis of another 73 galactic clusters.

ESA's release explains that while a single image of Perseus showed the line, composite images were needed to detect it in the other galactic clusters.

The research has been posted at Arxiv. NASA stated: “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”.

NASA goes on to point out that 55 other papers offering theories about the X-ray line already cite the original work.

Perseus, about 250 million light years away, has sparked a search for an X-ray emission. 

Credit: NASA

Co-author Maxim Markevitch from Goddard Space Flight Center says the mere possibility that a signature of sterile neutrinos is exciting, but cautions: “We have a lot of work to do before we can claim, with any confidence, that we’ve found sterile neutrinos”.

At ESA, lead author Dr Esra Bulbul from the Harvard-Smithsonian Center for Astrophysics in Cambridge explains: “If this strange signal had been caused by a known element present in the gas, it should have left other signals in the X-ray light at other well-known wavelengths, but none of these were recorded.”

Dr Bulbul doesn't say that sterile neutrinos might make up all of the missing matter in the universe, only that they could be part of it.

Check out more information on this story at NASA Chandra site

How much of the universe is black holes?

Supermassive black holes are enormously dense objects buried at the hearts of galaxies. 

Credit: NASA/JPL-Caltech

We all fear black holes, but how many of them are there out there, really?

Between the stellar mass black holes and the supermassive ones, just how much of our Universe is black holes?

There are two kinds of black holes in the Universe that we know of: There's stellar mass black holes, formed from massive stars, and a supermassive black holes which lives at the hearts of galaxies.

About 1 in a 1000 stars have enough mass to become a black hole when they die. Our Milky Way has 100 billion stars, this means it could have up to 100 million stellar mass black holes.

As there are hundreds of billions of galaxies in the observable Universe, there are lots, lots more out there.

In fact, the math suggests there's a new black hole forming every second or so. So just to recap, the entire Universe is about 1/1000th "regular flavor" stellar mass black holes.

Supermassive black holes are a slightly different story. Our central galactic black hole is about 26,000 light years away from us.

Formally, it's called Sagittarius A-star, but for our purposes I'm going to call it Kevin. Just so you know they don't throw that term "supermassive" around for no reason, Kevin contains 4.1 million times the mass of the Sun.

Kevin is gigantic and horrible. We can only imagine what it's like to be in the region of space near Kevin. What percentage of the galaxy do you think Kevin makes up, mass wise?



Kevin, whilst absolutely super-massive, is a tiny, tiny 1/10,000 of a percent of the Milky Way galaxy's mass.

So, to be precise, if we add Kevin's mass to the mass of all the stellar mass black holes aka. "mini-Kevins", we get a very minor 11/10000s of a %.

As it turns out this ratio holds up on a Universal scale and is approximately the same for all the mass in the Universe. So, 11 ten thousandths of a percent is the answer to the question. As far as we know.

Unless… dark matter is black holes. Dark matter accounts for more than ¾ of the mass of the Universe. It doesn't absorb light or interact with matter in any way. We're only aware of its presence through its gravitational influence.

As it turns out, Astronomers think that one explanation for dark matter might be primordial black holes.

These microscopic black holes would have the mass of an asteroid or more and could only form in the high pressure, high temperature conditions after the Big Bang.

Experiments to search for primordial black holes have yet to turn up any evidence, and most scientists don't think they're a viable explanation. But if they were, then the Universe is almost entirely composed of the physics inspired nightmare that are black holes.

HADES: Continues search for Dark Matter Beyond the Standard Model

HADES at the GSI in Darmstadt, Germany searches for dark matter candidates. 

Credit: 3-D Rendering: A. Schmah /HADES

Although Dark Energy and Dark Matter appear to constitute over 95 percent of the universe, nobody knows of which particles they are made up.

Astrophysicists now crossed one potential Dark Matter candidate, the Dark Photon or U boson, off the list in top position.

This is the result of recent HADES experiments, where researchers from the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) and from 17 other European institutes try to pin down the nature of Dark Matter.

These negative results, recently published in Physics Letters B, could even lead to challenges of the Standard Model of particle physics.

The interpretation of current astrophysical observations results in the striking mass-energy budget of matter in the universe: 75% Dark Energy and 20% Dark Matter. Only about 5% of the universe consists of "ordinary", baryonic matter.

Many attempts have been made to explain the nature of Dark Matter. Researchers believe that Dark Matter is comprised by hitherto unknown particles which do not fit into the Standard Model of particle physics.

The Standard Model is a theoretically sound quantum field theory with fundamental matter particles, such as quarks (bound in hadrons, e.g., baryons) and leptons (e.g., electrons and neutrinos), which interact via exchange of force-carrier quanta, called gauge bosons (e.g., photons).

Some of these species acquire their masses by the interaction with the Higgs boson.

While evidences for the Higgs boson were found recently at CERN, the Standard Model looks now complete when supplemented by some neutrino masses, and nothing else seems to be needed to understand the wealth of atomic, sub-nuclear and particle physics phenomena.

Nevertheless, Dark Matter appears not to be explained by any of the constituents of the Standard Model.

This status of the affair has initiated worldwide efforts to search for Dark Matter candidates.

Beyond the Standard Model
Searching a needle in the haystack is simpler: one knows both the wanted object (the needle) and the place (the haystack).

In the case of Dark Matter the object is unknown, and the localisation, e.g. in galactic halos, is also not constraining the loci of interest.

To specify the search goal one can envisage diverse hypothetical candidates, such as certain hypothetical particles beyond the Standard Model, which fulfill requirements qualifying them as constituents of Dark Matter.

Dark Energy drives the presently observed accelerated expansion of the universe. Dark Energy is homogeneously distributed and can be attributed to a cosmological constant or vacuum energy.

In extreme cases it may cause, in the future, such a sudden expansion that anything in the universe is disrupted, this would be the Big Rip.

Dark Matter, in contrast, is bumpy and is needed to explain the formation of the observed density distribution of visible matter in the evolving universe, evidenced by the hierarchy of structures from (super)clusters of galaxies, galaxies, stars, planets and other compact objects such as meteorites, etc.

Among the lists of candidates of Dark Matter is a hypothetical particle, often dubbed U boson or Dark Photon.

These nicknames refer to the underlying theory construction: a second unitary ("U") symmetry allows for quanta which are, in one respect, similar to photons, namely gauge bosons, but in another respect different from photons, namely attributing to these quanta a mass, making them to Dark Photons because of a very weak interaction with normal matter.

Very similar to photons the Dark Photons can decay into electron-positron pairs, if they have the proper virtuality.

Combining the chain of hypotheses one arrives at a scenario, where an "ordinary" virtual photon converts into a Dark Photon which decays afterwards into an electron-positron pair.

Background on HADES
HADES is an acronym of High-Acceptance Di-Electron Spectrometer.

It is an optimised detector system operated by a European collaboration of about hundred physicists at GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt.

HADES is aimed at investigating virtual photon signals emitted as electron-positron pairs off compressed nuclear matter to understand the origin of the phenomenon "masses of hadrons" and test it in some detail.

The highly sophisticated apparatus HADES has the capability to select electron-positron pairs, which can be attributed to primary sources, out of a huge background of other particles .

Read the full article here

More information: G. Agakishiev et al. (HADES Collaboration), Phys. Lett. B 731, 265 (2014) dx.doi.org/10.1016/j.physletb.2014.02.035

Dark Matter: Cosmologists weigh cosmic filaments and voids

A zoomed-out view of galaxies identified by the Sloan Digital Sky Survey. 

Filaments and voids are visible at this scale.

Cosmologists have established that much of the stuff of the universe is made of dark matter, a mysterious, invisible substance that can't be directly detected but which exerts a gravitational pull on surrounding objects.

Dark matter is thought to exist in a vast network of filaments throughout the universe, pulling luminous galaxies into an interconnected web of clusters, interspersed with seemingly empty voids.

Researchers at the University of Pennsylvania have measured the "weight" of these cosmic voids and filaments for the first time, showing the former are not as empty as they look.

The studies of voids and filaments are currently available on the ArXiv (arXiv:1402.3302) and were conducted by graduate student Joseph Clampitt and professor Bhuvnesh Jain of the Department of Physics and Astronomy in Penn's School of Arts & Sciences.

Gravitational lensing, the tiny distortions of distant galaxy images due to intervening matter, allows scientists to weigh galaxies by measuring how much their light bends.

Voids, on the other hand, are enormous, seemingly empty spaces in the universe with scarcely any galaxies visible — an arrangement that makes measuring their contents through lensing more difficult.

While galaxies and filaments have more mass than the average regions of the universe, voids have less mass than average.

This unbalanced distribution causes matter to rapidly move away from voids and towards the concentrations of mass along the cosmic filaments that lie between them.

A depiction of filaments and voids from The Max Planck Institute for Astrophysics’ Millennium Simulation Project.

"This means that voids act like objects with an effectively negative mass," Clampitt said, "such that even light rays bend away from them. They act roughly like concave lenses, the opposite of big galaxies, which act like convex lenses."

Clampitt and Jain detected the tiny distortions produced by voids on the images of nearly 40 million galaxies in the Sloan Digital Sky Survey.

This breakthrough came just a few months after they, along with Masahiro Takada of Tokyo University's Institute for the Physics and Mathematics of the Universe, detected the lensing signal from the dark matter filaments that connect galaxies.

"The measurements came as a wonderful surprise," Jain said. "Theoretical studies had predicted that we'd have to wait for much bigger surveys well into the future to detect void lensing. Joseph's ingenious analysis techniques extracted a subtle signal no one had seen before."

Their results show that voids are not as empty as they appear. Dark matter and other dim structures permeate all the way to the center of the voids.

"Although the density of this matter is far less than average," Clampitt said, "it is somewhat surprising that the voids are not as empty as the galaxy distribution suggests."

"The density at the center of a typical void," Jain said, "is about half the mean density in the universe, but that still leaves the voids with an enormous deficit in mass, about a thousand trillion times the mass of the sun."

FERMI LAT: Data Holds New Clues To Dark Matter

At left is a map of gamma rays with energies between 1 and 3.16 GeV detected in the galactic center by Fermi's LAT; red indicates the greatest number. 

Prominent pulsars are labeled. 

Removing all known gamma-ray sources (right) reveals excess emission that may arise from dark matter annihilations.

Image courtesy T. Linden, Univ. of Chicago.

A new study of gamma-ray light from the center of our galaxy makes the strongest case to date that some of this emission may arise from dark matter, an unknown substance making up most of the material universe.

Using publicly available data from NASA's Fermi Gamma-ray Space Telescope, independent scientists at the Fermi National Accelerator Laboratory (Fermilab), the Harvard-Smithsonian Center for Astrophysics (CfA), the Massachusetts Institute of Technology (MIT) and the University of Chicago have developed new maps showing that the galactic center produces more high-energy gamma rays than can be explained by known sources and that this excess emission is consistent with some forms of dark matter.

Dan Hooper

"The new maps allow us to analyze the excess and test whether more conventional explanations, such as the presence of undiscovered pulsars or cosmic-ray collisions on gas clouds, can account for it," said Dan Hooper, an astrophysicist at Fermilab in Batavia, Ill., and a lead author of the study.

"The signal we find cannot be explained by currently proposed alternatives and is in close agreement with the predictions of very simple dark matter models."

The galactic center teems with gamma-ray sources, from interacting binary systems and isolated pulsars to supernova remnants and particles colliding with interstellar gas.

It's also where astronomers expect to find the galaxy's highest density of dark matter, which only affects normal matter and radiation through its gravity.

Large amounts of dark matter attract normal matter, forming a foundation upon which visible structures, like galaxies, are built.

No one knows the true nature of dark matter, but Weakly Interacting Massive Particles (WIMPs), represent a leading class of candidates.

Theorists have envisioned a wide range of WIMP types, some of which may either mutually annihilate or produce an intermediate, quickly decaying particle when they collide.

Both of these pathways end with the production of gamma rays -- the most energetic form of light -- at energies within the detection range of Fermi's Large Area Telescope (LAT).

When astronomers carefully subtract all known gamma-ray sources from LAT observations of the galactic center, a patch of leftover emission remains.

This excess appears most prominent at energies between 1 and 3 billion electron volts (GeV) -- roughly a billion times greater than that of visible light -- and extends outward at least 5,000 light-years from the galactic center.

Hooper and his colleagues conclude that annihilations of dark matter particles with a mass between 31 and 40 GeV provide a remarkable fit for the excess based on its gamma-ray spectrum, its symmetry around the galactic center, and its overall brightness.

Writing in a paper submitted to the journal Physical Review D, the researchers say that these features are difficult to reconcile with other explanations proposed so far, although they note that plausible alternatives not requiring dark matter may yet materialize.

"Dark matter in this mass range can be probed by direct detection and by the Large Hadron Collider (LHC), so if this is dark matter, we're already learning about its interactions from the lack of detection so far," said co-author Tracy Slatyer, a theoretical physicist at MIT in Cambridge, Mass.

"This is a very exciting signal, and while the case is not yet closed, in the future we might well look back and say this was where we saw dark matter annihilation for the first time."

More Information: "The Characterization of the Gamma-Ray Signal from the Central Milky Way: A Compelling Case for Annihilating Dark Matter" Authors: Tansu Daylan, Douglas P. Finkbeiner, Dan Hooper, Tim Linden, Stephen K. N. Portillo, Nicholas L. Rodd, Tracy R. Slatyer

Leiden Research: Glimmer of light in the search for dark matter

The Leiden astrophysicist Alexey Boyarsky and his fellow researchers may have identified a trace of dark matter that could signify a new particle: the sterile neutrino. 

Sterile neutrino has mass
The group reported that they have found an indirect signal from dark matter in the spectra of galaxies and clusters of galaxies.

Alexey Boyarsky

They made this discovery: A tiny spike is hidden in the X-ray spectra of the Perseus galaxy cluster, at a frequency that cannot be explained by any known atomic transition.

A Harvard group see the same spike in many other galaxy clusters, while Boyarsky also finds it in the nearby Andromeda galaxy.

The researchers put it down to the decay of a new kind of neutrino, called 'sterile' because it has no interaction with other known neutrinos.

A sterile neutrino does have mass, and so could be responsible for the missing dark matter

Minor expansion of the standard model for elementary particles
The first indications for the existence of dark matter in space were found more than eighty years ago, but there are still many questions surrounding this invisible matter.

Sterile neutrinos are a highly attractive candidate for the dark matter particle, because they only call for a minor extension of the already known and extensively tested standard model for elementary particles.

Boyarsky and his colleagues have already had this extension of the standard model ready for some time, but were waiting for the first observation of the mysterious particle.

Measurements at higher resolution will shed light on the matter, and there is reason to hope that the spectral line just discovered will finally eliminate the problem of the missing mass.

LUX dark matter results confirmed

A new calibration technique fired neutrons directly into the Large Underground Xenon (LUX) dark matter detector, increasing calibration accuracy by a factor of 10. 

Analysis based on the calibration confirms that if "low-mass" dark matter particles had passed through the detector during its initial run, Large Underground Xenon would have seen them. 

Credit: Matt Kapust/Sanford Underground Research Facility

A new high-accuracy calibration of the LUX (Large Underground Xenon) dark matter detector demonstrates the experiment's sensitivity to ultra-low energy events.

The new analysis strongly confirms the result that low-mass dark matter particles were a no-show during the detector's initial run, which concluded last summer.

The first dark matter search results from LUX detector were announced last October.

The detector proved to be exquisitely sensitive, but found no evidence of the dark matter particles during its first 90-day run, ruling out a wide range of possible models for dark matter particles.

Previous experiments had detected potential signatures of dark matter particles with a very low mass, but LUX turned up no such signal.

This latest work was focused on demonstrating the high sensitivity of LUX to potential signals in the search for those low-mass particles.

Rick Gaitskell

"The new calibration improved our calibration accuracy by about a factor of 10," said Rick Gaitskell, professor of physics at Brown University and co-spokesperson for LUX.

"It demonstrates that our first dark matter search result, which showed no sign of low-mass particles, is absolutely robust."

The results of the new analysis were presented Wednesday, Feb. 19, 2014, at the Lake Louise Winter Institute in Alberta, Canada, by James Verbus, a graduate student at Brown who led the new calibration work.

Dark matter is thought to account for about 80 percent of the mass of the universe. Though it has not yet been detected directly, its existence is a near certainty among physicists.

Without the gravitational influence of dark matter, galaxies and galaxy clusters would simply fly apart into the vastness of space.

It's not clear exactly what dark matter is, but the leading idea is that it consists of subatomic particles called weakly interacting massive particles (WIMPs).

WIMPs are thought to be practically ubiquitous in the universe, but because they interact so rarely with other forms of matter, they generally pass right through the earth and everything on it without anyone knowing it.

The LUX is designed to detect those rare occasions when a WIMP does interact with other forms of matter.

The detector consists of a third of a ton of supercooled xenon in a tank festooned with light sensors, each capable of detecting a single photon at a time.

As WIMPs pass through the tank, they should, on very rare occasions, bump into the nucleus of a xenon atom.

Those bumps cause the nucleus to recoil, creating a tiny flash of light and an ion charge, both of which are picked up by LUX sensors.

The detector is more than a mile underground at the Sanford Underground Research Facility in South Dakota, where it is shielded from cosmic rays and radiation that might interfere with a potential dark matter signal.

This latest work was an entirely new way of calibrating the detector to recognize a WIMP signal.