A UK-led team of astronomers reports today (August 4th) in Nature that they have tracked down an elusive population of black holes growing rapidly hidden behind clouds of dust. Their results suggest that most black hole growth takes place in dusty galaxies, solving astronomer’s headaches, as until now, the cosmic x-ray background suggested the existence of more growing black holes than they could find.
Growing black holes, known as quasars, are some of the brightest objects in the Universe and are seen by the light emitted as gas and dust spiral into the black hole. Quasars are situated in the inner-most regions of galaxies and can consume the equivalent mass of between ten and a thousand stars in one year! Astronomers believe that all quasars are surrounded by a dusty ring which hides them from sight on Earth in about half of cases.
However, examining the cosmic x-ray background, which is made up primarily of the emissions from quasars, astronomers realised that there should be many more obscured quasars than currently known. Objects surrounded by dust are hard to see with visible light, so the astronomers looked at infrared wavelengths, which are less likely to be reflected away. Using NASA’s Spitzer Space Telescope’s First Look Data, they were able to find a new population of obscured quasars. The new quasars have no spectra that can be seen and are thought to be hidden behind the dust of the galaxy itself rather than just a dust ring. The presence of lots of dust in a galaxy indicates that stars are still forming there. The researchers found 21 examples of these lost quasars in a relatively small patch of sky. All of the objects were confirmed as quasars by the National Radio Astronomy Observatorys Very Large Array radio telescope, New Mexico, and the Particle Physics and Astronomy Research Councils William Hershel Telescope on La Palma.
Purdue cancer identity technology makes it easier to find a tumor's 'address'
16.11.2018 | Purdue University
Microgel powder fights infection and helps wounds heal
14.11.2018 | Michigan Technological University
Researchers at the University of New Hampshire have captured a difficult-to-view singular event involving "magnetic reconnection"--the process by which sparse particles and energy around Earth collide producing a quick but mighty explosion--in the Earth's magnetotail, the magnetic environment that trails behind the planet.
Magnetic reconnection has remained a bit of a mystery to scientists. They know it exists and have documented the effects that the energy explosions can...
Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.
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Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.
In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...
On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.
When choosing materials to make something, trade-offs need to be made between a host of properties, such as thickness, stiffness and weight. Depending on the application in question, finding just the right balance is the difference between success and failure
Now, a team of Penn Engineers has demonstrated a new material they call "nanocardboard," an ultrathin equivalent of corrugated paper cardboard. A square...
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16.11.2018 | Life Sciences