New evidence suggests that hundreds of unseen dwarf galaxies made of dark matter encircle our Milky Way and other large, visible galaxies. Scientists believe that 80 to 90 percent of the universe must be made of this as-yet-undetected matter to account for the observed structure of the universe. According to Einstein, such large concentrations of matter should warp the surrounding space and bend light in much the same way that glass lenses do. With that in mind, astrophysicists at the University of California at San Diego and the Harvard-Smithsonian Center for Astrophysics in Cambridge analyzed how light from distant galaxies was warped by intervening, lensing galaxies in order to indirectly search for dark matter galaxies.
Image: EMILIO FALCO ET AL. Harvard-Smithsonian Center for Astrophysics
This so-called gravitational lensing can split an image of a single galaxy into two or more images. Imagine a rock that partly dams a stream so that water runs around it in two rivulets--a galaxy that lies between a distant light source and Earth can deflect light beams emitted toward our planet into multiple streams in a similar way, yielding numerous images. (For example, the image above depicts the quasar MG 0414+534 showing multiple images due to gravitational lensing by an intervening galaxy.) The number and appearance of these multiple images depends on the distribution of mass inside the intervening galaxies. If the lensing galaxies are surrounded by many smaller galaxies, the brightness of one of these lensed images could be significantly enhanced if it lined up with a dark matter galaxy.
Researchers Neal Dalal and Christopher Kochanek looked at seven different lensing galaxies that each divided the light of a distant galaxy into four images of varying brightness. They determined that about 2 percent of the lensing galaxies masses must be in the form of a halo of invisible, dark matter dwarf galaxies to explain the brightness variations detected among the multiple images of the background galaxies. The scientists remain puzzled as to why these dark matter galaxies contain few or no stars, however, since 10 to 20 percent of their mass should exist as normal matter. "Its difficult to hide that much material," Dalal observes. The findings will appear in the June 10 issue of the Astrophysical Journal.
Charles Choi | Scientific American
Spiral arms: not just in galaxies
30.09.2016 | Max-Planck-Institut für Radioastronomie
Discovery of an Extragalactic Hot Molecular Core
29.09.2016 | National Astronomical Observatory of Japan
Heavy construction machinery is the focus of Oak Ridge National Laboratory’s latest advance in additive manufacturing research. With industry partners and university students, ORNL researchers are designing and producing the world’s first 3D printed excavator, a prototype that will leverage large-scale AM technologies and explore the feasibility of printing with metal alloys.
Increasing the size and speed of metal-based 3D printing techniques, using low-cost alloys like steel and aluminum, could create new industrial applications...
Friction stir welding is a still-young and thus often unfamiliar pressure welding process for joining flat components and semi-finished components made of light metals.
Scientists at the University of Stuttgart have now developed two new process variants that will considerably expand the areas of application for friction stir welding.
Technologie-Lizenz-Büro (TLB) GmbH supports the University of Stuttgart in patenting and marketing its innovations.
Friction stir welding is a still-young and thus often unfamiliar pressure welding process for joining flat components and semi-finished components made of...
Optical quantum computers can revolutionize computer technology. A team of researchers led by scientists from Münster University and KIT now succeeded in putting a quantum optical experimental set-up onto a chip. In doing so, they have met one of the requirements for making it possible to use photonic circuits for optical quantum computers.
Optical quantum computers are what people are pinning their hopes on for tomorrow’s computer technology – whether for tap-proof data encryption, ultrafast...
The Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP has been developing various applications for OLED microdisplays based on organic semiconductors. By integrating the capabilities of an image sensor directly into the microdisplay, eye movements can be recorded by the smart glasses and utilized for guidance and control functions, as one example. The new design will be debuted at Augmented World Expo Europe (AWE) in Berlin at Booth B25, October 18th – 19th.
“Augmented-reality” and “wearables” have become terms we encounter almost daily. Both can make daily life a little simpler and provide valuable assistance for...
With the help of artificial intelligence, chemists from the University of Basel in Switzerland have computed the characteristics of about two million crystals made up of four chemical elements. The researchers were able to identify 90 previously unknown thermodynamically stable crystals that can be regarded as new materials. They report on their findings in the scientific journal Physical Review Letters.
Elpasolite is a glassy, transparent, shiny and soft mineral with a cubic crystal structure. First discovered in El Paso County (Colorado, USA), it can also be...
30.09.2016 | Event News
29.09.2016 | Event News
28.09.2016 | Event News
30.09.2016 | Materials Sciences
30.09.2016 | Earth Sciences
30.09.2016 | Life Sciences