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We’ve Revealed A Galaxy Far, Far Away….
The galaxy was uncovered in radio emission travelling to Earth using CSIRO’s Australian SKA Pathfinder telescope (ASKAP), located at the Murchison Radio-astronomy Observatory (MRO).
The team used a special technique to detect a change in radio waves coming from within the bright centre of the galaxy PKS B1740-517, located near the Ara constellation.
The five-billion-year-old radio emission was stamped with the ‘imprint’ of hydrogen gas it had travelled through on its way to Earth.
The gas absorbs some of the emission, creating a tiny dip in the signal. “At many observatories, this dip would have been hidden by background radio noise, but our site is so radio quiet it stood out clearly,” Dr Allison said.
‘Perfect Storm’ Quenching Star Formation Around A Supermassive Black Hole
A combined Hubble Space Telescope / ALMA image of NGC 1266. Credit: NASA/ESA Hubble; ALMA (NRAO/ESO/NAOJ)
High-energy jets powered by supermassive black holes can blast away a galaxy’s star-forming fuel, resulting in so-called “red and dead” galaxies: those brimming with ancient red stars yet containing little or no hydrogen gas to create new ones.
Now astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have discovered that black holes don’t have to be nearly so powerful to shut down star formation. By observing the dust and gas at the center of NGC 1266, a nearby lenticular galaxy with a relatively modest central black hole, the astronomers have detected a “perfect storm” of turbulence that is squelching star formation in a region that would otherwise be an ideal star factory.
This turbulence is stirred up by jets from the galaxy’s central black hole slamming into an incredibly dense envelope of gas. This dense region, which may be the result of a recent merger with another smaller galaxy, blocks nearly 98 percent of material propelled by the jets from escaping the galactic center.
Trio Of Supermassive Black Holes Shake Space-Time
Astronomers have discovered three closely orbiting supermassive black holes in a galaxy more than 4 billion light years away. This is the tightest trio of black holes known to date and is remarkable since most galaxies have just one at their centre (usually with a mass between 1 million to 10 billion times that of the Sun). The discovery suggests that these closely packed supermassive black holes are far more common than previously thought. The team, led by South African Dr Roger Deane from the University of Cape Town, used a technique called Very Long Baseline Interferometry (VLBI) to discover the inner two black holes of the triple system. This technique combines the signals from large radio antennas separated by up to 10 000 kilometres to see detail 50 times finer than that possible with the Hubble Space Telescope. The observations were done with the European VLBI Network (EVN) and the data were correlated at the Joint Institute for VLBI in Europe (JIVE) in Dwingeloo, the Netherlands.
“What remains extraordinary to me is that these black holes, which are at the very extreme of Einstein’s Theory of General Relativity, are orbiting one another at 300 times the speed of sound on Earth”, says Deane. “Not only that, but using the combined signals from radio telescopes on four continents we are able to observe this exotic system one third of the way across the Universe. It gives me great excitement as this is just scratching the surface of a long list of discoveries that will be made possible with the Square Kilometre Array (SKA).”
Watching For A Black Hole To Gobble Up A Gas Cloud
Simulation. Image by ESO/MPE/Marc Schartmann
Right now a doomed gas cloud is edging ever closer to the supermassive black hole at the center of our Milky Way galaxy. These black holes feed on gas and dust all the time, but astronomers rarely get to see mealtime in action.
Northwestern University’s Daryl Haggard has been closely watching the little cloud, called G2, and the black hole, called Sgr A*, as part of a study that should eventually help solve one of the outstanding questions surrounding black holes: How exactly do they achieve such supermassive proportions?
The closest approach between the black hole and gas cloud is predicted to occur any day now. Haggard has been using two world-class observatories, the Chandra X-ray Observatory and the Very Large Array, to gather data on this potentially spectacular encounter.
Nearby Star’s Icy Debris Suggests ‘Shepherd’ Planet
An international team of astronomers exploring the disk of gas and dust around a nearby star have uncovered a compact cloud of poisonous gas formed by ongoing rapid-fire collisions among a swarm of icy, comet-like bodies. The researchers suggest the comet swarm is either the remnant of a crash between two icy worlds the size of Mars or frozen debris trapped and concentrated by the gravity of an as-yet-unseen planet.
Using the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, the researchers mapped millimeter-wavelength light from dust and carbon monoxide (CO) molecules in a disk surrounding the bright star Beta Pictoris. Located about 63 light-years away and only 20 million years old, the star hosts one of the closest, brightest and youngest debris disks known, making it an ideal laboratory for studying the early development of planetary systems.
“Although toxic to us, carbon monoxide is one of many gases found in comets and other icy bodies,” said team member Aki Roberge, an astrophysicist at NASA’s Goddard Space Flight Center in Greenbelt, Md. “In the rough-and-tumble environment around a young star, these objects frequently collide and generate fragments that release dust, icy grains and stored gases.”
Seeing Double: New System Makes The VLA “Two Telescopes In One”
The Karl G. Jansky Very Large Array (VLA) will get a new system allowing it to continuously monitor the sky to study the Earth’s ionosphere and detect short bursts of radio emission from astronomical objects. The National Radio Astronomy Observatory (NRAO) and the Naval Research Laboratory (NRL) signed a $1 million contract under which NRL will fund a system to capture data from low-frequency radio receivers mounted on VLA antennas that will allow simultaneous and completely independent operation alongside the VLA’s standard scientific observations.
“This essentially will turn the VLA into two telescopes, working in parallel to perform different types of scientific research simultaneously,” said Dale Frail, NRAO’s Director for New Mexico Operations.
The new system, called VLITE (VLA Ionospheric and Transient Experiment), will tap data from 10 VLA antennas, and is a pathfinder for a proposed larger system called the Low Band Observatory (LOBO) that would equip all 27 antennas of the VLA. “The new system will operate independently of the VLA’s higher-frequency systems, using a separate path for data transmission and processing,” said Paul Ray, NRL’s VLITE system engineer.
Fledgling Supernova Remnant Reveals Neutron Star’s Secrets
Image: X-ray: NASA/CXC/UW-Madison/S. Heinz et al; Optical: DSS; Radio: CSIRO/ATNF/ATCA
With the help of NASA’s Chandra X-ray Observatory and the Australia Telescope Compact Array, an international team of astronomers has identified the glowing wreck of a star that exploded a mere 2,500 years ago — the blink of an eye in astronomical terms.
The observations, made by a team led by UW-Madison astronomy professor Sebastian Heinz, reveal an astrophysical novelty of the Milky Way: a glowing nebula created when the star exploded and, inside of it, the collapsed core of the exploded star, a neutron star, still clinging to its former companion star. It is the only known example of such a system in our galaxy.
The new observations are reported Dec. 3 in the Astrophysical Journal and are important because they provide a unique laboratory to test key theories of stellar evolution, especially about the stage of a star’s life just after most of it has been obliterated in a supernova explosion.
NASA’s Chandra Helps Confirm Evidence Of Jet In Milky Way’s Black Hole
Image Credit: X-ray: NASA/CXC/UCLA/Z. Li et al; Radio: NRAO/VLA
Astronomers have long sought strong evidence that Sagittarius A* (Sgr A*), the supermassive black hole at the center of the Milky Way, is producing a jet of high-energy particles. Finally they have found it, in new results from NASA’s Chandra X-ray Observatory and the National Science Foundation’s Very Large Array (VLA) radio telescope.
Previous studies, using a variety of telescopes, suggested there was a jet, but these reports — including the orientation of the suspected jets — often contradicted each other and were not considered definitive.
“For decades astronomers have looked for a jet associated with the Milky Way’s black hole. Our new observations make the strongest case yet for such a jet,” said Zhiyuan Li of Nanjing University in China, lead author of a study appearing in an upcoming edition of The Astrophysical Journal and available online now.
Final Antenna Delivered to ALMA
Credit: ESO/C. Pontoni
The final antenna for the Atacama Large Millimeter/submillimeter Array (ALMA) project has just been handed over to the ALMA Observatory. The 12-metre-diameter dish was manufactured by the European AEM Consortium and also marks the successful delivery of a total of 25 European antennas — the largest ESO contract so far.
The antenna is the 66th and final antenna to be delivered to the observatory. North America has provided 25 12-metre antennas, while East Asia has delivered 16 (four 12-metre and twelve 7-metre). By the end of 2013, all 66 ultra-precise millimetre/submillimetre-wave radio antennas are expected to be working together as one telescope, in an array that will stretch for up to 16 kilometres across the Chajnantor Plateau in the Atacama Desert of northern Chile.
This delivery of the last antenna now completes the ALMA antenna construction phase [1] and provides all 66 antennas for science use, marking the beginning of a new era of discoveries in astronomy. “This is an important milestone for the ALMA Observatory since it enables astronomers in Europe and elsewhere to use the complete ALMA telescope, with its full sensitivity and collecting area,” says Wolfgang Wild, the European ALMA Project Manager.
The World’s First Interferometric Image At 500 GHz With ALMA Band 8 Receivers
Credit: ALMA (ESO/NAOJ/NRAO)
ALMA opens another window to the universe in the 500 GHz frequency band. Astronomers successfully synthesized the distribution of atomic carbon around a planetary nebula NGC 6302 in test observations with the ALMA Band 8 receiver, developed by the National Astronomical Observatory of Japan (NAOJ). This is the first 500 GHz band astronomical image captured by a radio interferometer with unprecedentedly high resolution.
NGC 6302 is a planetary nebula, which is in the final stage of the life of a star with a mass several times that of the Sun. Visible light image shows a bipolar shape of gas ejected from the dying star. ALMA with the Band 8 receivers targeted at the center of the nebula and revealed that the distribution of carbon atom is concentrated in a small part, which is similar to a dust and gas disk around the central star that has been found by previous observations with other telescopes. Further observations of carbon atom with better resolution will give us more detailed view of the chemical environment in the nebula.
Full Story: http://www.nao.ac.jp/en/news/topics/2013/20130902-alma-band8.html
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