by Lisa Grossman Fans of dark matter can rest easy. A study published last month raised eyebrows by suggesting that our cosmic neighbourhood is empty of the extra mass needed to hold the galaxy together. But a re-analysis shows that the dark matter was there all along. Dark matter is the mysterious, invisible stuff that makes up 83… [Read more…]
May 24, 2012
Nous ne voyons pas de matière noire dans notre coin de Galaxie, clamait une équipe d’astrophysiciens. Vos travaux sont «incorrects» les tance une autre équipe, dans un article soumis à la critique des pairs sur le site arXiv.org qui vient leur répliquer de manière assez sévère. Dessin: la vision classique de la matière noire dans notre galaxie. L’affaire démarre… [Read more…]
May 11, 2012
Nassim Bozorgnia, Graciela B. Gelmini, Paolo Gondolo The motion of the Earth around the Sun causes an annual change in the magnitude and direction of the arrival velocity of dark matter particles on Earth, in a way analogous to aberration of stellar light. In directional detectors, aberration of weakly interacting massive particles (WIMPs) modulates the… [Read more…]
April 18, 2012
New study finds mysterious lack of dark matter in Sun’s neighbourhood The most accurate study so far of the motions of stars in the Milky Way has found no evidence for dark matter in a large volume around the Sun. According to widely accepted theories, the solar neighbourhood was expected to be filled with dark… [Read more…]
April 17, 2012
A Tentative Gamma-Ray Line from Dark Matter Annihilation at the Fermi Large Area Telescope Christoph Weniger The observation of a gamma-ray line in the cosmic-ray fluxes would be a smoking-gun signature for dark matter annihilation or decay in the Universe. We present an improved search for such signatures in the data of the Fermi Large… [Read more…]
April 9, 2012
Katherine Freese, Christopher Savage We investigate the interactions of Weakly Interacting Massive Particles (WIMPs) with nuclei in the human body. We are motivated by the fact that WIMPs are excellent candidates for the dark matter in the Universe. Our estimates use a 70 kg human and a variety of WIMP masses and cross-sections. The contributions… [Read more…]
April 2, 2012
http://youtu.be/i5ucytz2C7I There’s more to the cosmos than meets the eye. About 80 percent of the matter in the universe is invisible to telescopes, yet its gravitational influence is manifest in the orbital speeds of stars around galaxies and in the motions of clusters of galaxies. Yet, despite decades of effort, no one knows what this… [Read more…]
March 2, 2012
This composite image shows the distribution of dark matter, galaxies, and hot gas in the core of the merging galaxy cluster Abell 520, formed from a violent collision of massive galaxy clusters. The natural-color image of the galaxies was taken with NASA’s Hubble Space Telescope and with the Canada-France-Hawaii Telescope in Hawaii. Superimposed on the… [Read more…]
February 23, 2012
Blame dark matter underdog for mystery missing lithium by David Shiga AN UNDERDOG dark-matter particle could explain why the universe seems strangely low on lithium. If the idea holds up, it will be a boon in the hunt for dark matter, the stuff needed to account for 80 per cent of the universe’s matter. In the… [Read more…]
February 20, 2012
Finding evidence for dark matter – the unknown substance that theoretically makes up 23% of the universe – has been one of the biggest challenges in modern cosmology. Several experiments are underway to detect dark matter candidates known as Weakly Interacting Massive Particles (WIMPs) as they travel through the Earth. And experiments at the Large… [Read more…]
January 18, 2012
by Lisa Grossman If we could don dark matter glasses and look at the universe around us, we might see thousands of miniature galaxies swarming about the luminous spirals that make up the Milky Way and Andromeda. We can’t – but we have the next best thing. A technique known as gravitational lensing has allowed… [Read more…]
December 21, 2011
RECENT hints of a featherweight Higgs boson don’t just take us nearer to a complete standard model of physics. The results affect a possible link between the Higgs and dark matter, the invisible stuff making up 80 per cent of the universe’s matter. The Higgs is the last remaining hole in the standard model, the… [Read more…]
December 10, 2011
Our galaxy could be filled with asteroid-size black holes that presumably formed shortly after the big bang. If they exist in large numbers, these so-called primordial black holes would serve as the dark matter that keeps stars gravitationally glued inside galaxies. None of these primordial black holes have been detected so far, but a new… [Read more…]
December 7, 2011
Dmitry Lyapustin The Axion is a particle arising from the Peccei-Quinn solution to the strong CP problem. Peccei-Quinn symmetry breaking in the early universe could produce a large number of axions which would still be present today, making the axion a compelling dark matter candidate. The goal of the Axion Dark Matter eXperiment (ADMX) is… [Read more…]
November 30, 2011
by Lisa Grossman - newscientist.com Dark matter is slowly running out of places to hide. Two new looks at the gamma-ray sky suggest that if the mysterious matter is a particle, it is heavier than 40 gigaelectronvolts, about 44 times the mass of a proton. That contradicts hints from three experiments on Earth that pointed to a lightweight dark matter… [Read more…]
November 28, 2011
Dragan Slavkov Hajdukovic Abstract Recently, the gravitational polarization of the quantum vacuum was proposed as alternative to the dark matter paradigm. In the present paper we consider four benchmark measurements: the universality of the central surface density of galaxy dark matter haloes, the cored dark matter haloes in dwarf spheroidal galaxies, the nonexistence of dark… [Read more…]
October 20, 2011
by Sean Carroll Lecture One: Introduction to Cosmology http://youtu.be/vUNtO2r_-eo Lecture Two: Dark Matter http://youtu.be/Gq-lGX2PRrc Lecture Three: Dark Energy http://youtu.be/cYVj2RhXxeU Lecture Four: Thermodynamics and the Early Universe http://youtu.be/178mMnGvWs0 Lecture Five: Inflation and Beyond http://youtu.be/M1PeXaMqKto
October 17, 2011
Like all galaxies, our Milky Way is home to a strange substance called dark matter. Dark matter is invisible, betraying its presence only through its gravitational pull. Without dark matter holding them together, our galaxy’s speedy stars would fly off in all directions. The nature of dark matter is a mystery — a mystery that… [Read more…]
October 11, 2011
Earthly skills like handwritten signature verification turn out to be useful on a cosmological scale as well When the Euclid mission lifts off at the end of this decade, it will map galaxy clusters in infrared and visible light, helping to blueprint the large-scale structure of the universe. And a bunch of amateur science geeks… [Read more…]
October 7, 2011
Ryan Hamerly, Alexander Kosovichev Helioseismology can be used to place new constraints on the properties of dark matter, allowing solar observations to complement more conventional dark matter searches currently in operation. During the course of its lifetime, the Sun accretes a sizeable amount of dark matter. This accreted matter affects the heat transport of the… [Read more…]
October 5, 2011
Supernovas — stars in the process of exploding — open a window onto the history of the elements of Earth’s periodic table as well as the history of the universe. All of those heavier than oxygen were formed in nuclear reactions that occurred during these explosions. The most ancient explosions, far enough away that their… [Read more…]
October 4, 2011
Using very distant supernovae as standard candles, one can trace the history of cosmic expansion and try to find out what’s currently speeding it up. Saul Perlmutter For millennia, cosmology has been a theorist’s domain, where elegant theory was only occasionally endangered by inconvenient facts. Early in the 20th century, Albert Einstein gave us new… [Read more…]
September 21, 2011
“We know that about 25% of the matter in the universe is dark matter, but we don’t know what it is,” Michael Kesden tellsPhysOrg.com. “There are a number of different theories about what dark matter could be, but we think one alternative might be very small primordial black holes.” When many of us think about black… [Read more…]
September 17, 2011
Scientists’ predictions about the mysterious dark matter purported to make up most of the mass of the Universe may have to be revised. Research on dwarf galaxies suggests they cannot form in the way they do if dark matter exists in the form that the most common model requires it to. That may mean that… [Read more…]
September 10, 2011
David B. Cline We review the confused situation concerning evidence for low-mass WIMPs. In the past one half year there have been new results concerning the existence of WIMPs at low mass including the new XENON 100, 100-day data, additional CDMS results, the publication of annual variation data from LVD and Borexino and new CoGeNT… [Read more…]
September 7, 2011
A third experiment has detected tantalising signs of dark matter. The finding raises more questions than answers, however, as two other experiments have found no sign of the mysterious stuff, which is thought to create the gravity that holds spinning galaxies together, accounting for about 85 per cent of all matter in the universe. The new… [Read more…]
August 30, 2011
— After nine months of number-crunching on a powerful supercomputer, a beautiful spiral galaxy matching our own Milky Way emerged from a computer simulation of the physics involved in galaxy formation and evolution. The simulation by researchers at the University of California, Santa Cruz, and the Institute for Theoretical Physics in Zurich solves a longstanding… [Read more…]
August 19, 2011
Sascha Vongehr The public repulsion against dark matter and dark energy is really annoying. Rob Knop at scientopia compares it to 17th century catholic church mentality; Ethan picks it up and bangs the dark matter explains everything drum although dark matter does not fit very well to galaxy rotation curves – Modified Newtonian Dynamics (MOND) fits much better: (From: Begeman, Broeils,… [Read more…]
June 29, 2011
Unexplained “filaments” of radio-wave emission close to our galaxy’s centre may hold proof of the existence of dark matter, researchers have said. Dark matter is believed to make up most of the mass of our Universe, but it has yet to be definitively spotted. A report now suggests the filaments’ emission arises from dark matter… [Read more…]
June 21, 2011
If dark matter fills the universe, astronomers should see the gamma rays it produces. That evidence has so far failed to materialise Among the most dramatic events in the universe are the death of stars as they collapse into black holes and the collision of black holes themselves. These events are so violent that they… [Read more…]
June 8, 2011
A dark-matter experiment deep in the Soudan mine of Minnesota now has detected a seasonal signal variation similar to one an Italian experiment has been reporting for more than a decade. The new seasonal variation, recorded by the Coherent Germanium Neutrino Technology (CoGeNT) experiment, is exactly what theoreticians had predicted if dark matter turned out… [Read more…]
May 25, 2011
An Australian science student managed to provide additional evidence that expert Fritz Zwicky was right in its theory on where the missing mass of the Universe may be hiding. The work done by Amelia Fraser-McKelvie, 22, has already been published in a scientific journal. The Monash University aerospace engineering/science student made the discovery during a… [Read more…]
May 3, 2011
…from CoGeNT Dark Matter Experiment “…..The annual modulation is the closest thing to a smoking gun [for dark matter],” says theorist Jonathan Feng at the University of California, Irvine, who is not part of the CoGeNT team. “This is the first evidence we’ve seen it somewhere other than DAMA……” Read more: http://www.newscientist.com/article/dn20434-second-experiment-hints-at-seasonal-dark-matter-signal.html
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May 24, 2012
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