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Astronomers Observe High Energy Particles From Black Hole Jet
New Haven CT (SPX) Jun 21, 2006 An international team of astronomers has captured infrared observations that reveal the nature of high-energy quasar particle jets that originate just outside super-massive black holes at the center of galaxies and radiate across the electromagnetic spectrum, from radio to X-ray wavelengths. The team's research - a companion study reached the same conclusions - involves the jet of the quasar 3C273, famous since its identification in 1963 as the first quasar. Based on the studies, it now appears the most powerful radiation from the jet arises from extremely energetic particles, which was not expected by most astronomers based on previously available data. "Quasar jets, although extremely luminous, are so distant as to be relatively faint and difficult to observe," said lead researcher C. Megan Urry of Yale University. "Thanks to the sensitivity of NASA's Great Observatories, we have been able to map the 3C273 jet in infrared, visible light and X-rays." "These combined data strongly suggest that ultra-energetic particles in the 3C273 jet are producing their light via synchrotron radiation," Urry added. Until now, two competing hypotheses have attempted to describe how emissions arise from the particles: - The Inverse-Compton hypothesis proposes that the emissions occur when jet particles scatter cosmic microwave background photons. - The Synchrotron Radiation hypothesis postulates a separate population of extremely energetic electrons or protons that cause the high-energy emission. "The Yale team used the Spitzer Space Telescope to observe 3C273 because it is located in space and is more sensitive to faint infrared jet emission than any previous telescope," said Yale team member Yasunobu Uchiyama. Spitzer observations enabled the team, with collaborators at Stanford University in California; the University of Southampton, England; NASA's Goddard Space Flight Center in Greenbelt, Md., and the Brera Observatory in Milan, Italy, to determine the infrared spectrum for the first time and connect it to the X-ray emission. Sebastian Jester, now at the University of Southampton, led the complementary study that used the Chandra X-ray Observatory. Jester's team, with collaborators at MIT Kavli Institute for Astrophysics and Space Research, and the Smithsonian Astrophysical Observatory in Cambridge, Mass., and at the Max Planck Institute for Astronomy in Heidelberg, Germany, obtained the first detailed study of energy distribution of X-rays from the jet, which also supported the synchrotron theory. According to the researchers, though the lifetime of the X-ray producing particles is only about 100 years, the data indicate the visibly brightest part of the jet has a length of about 100,000 light-years. Because there would be insufficient time for the particles to shoot out from the black hole at close to the speed of light and then release their energy as radiation as far out as they are seen, the particles have to be accelerated locally, where they produce their emission. Both teams also used data from the Hubble Space Telescope and the radio telescopes of the Very Large Array. The three space telescopes and the VLA can detect emissions of different wavelengths from celestial objects, and the combined data were essential to reveal the new comprehensive perspective on the jets. "The new observations show that the flow structure of this jet is more complicated than had been assumed previously," Jester said. "That the present evidence favors the synchrotron model deepens the mystery of how jets produce the ultra-energetic particles that radiate at X-ray wavelengths." "Our results call for a radical rethink of the physics of relativistic jets that black holes drive," Uchiyama said, "but we now have a crucial new clue to solving one of the major mysteries in high-energy astrophysics." The two studies are available online in the Astrophysical Journal and will appear in print in the Sept. 10 issue. Community Email This Article Comment On This Article Related Links Black hole jet paper Spitzer Chandra Hubble VLA Understanding Time and Space
Backs To The Future
San Diego CA (SPX) Jun 15, 2006Tell an old Aymara speaker to "face the past!" and you just might get a blank stare in return - because he or she already does. New analysis of the language and gesture of South America's indigenous Aymara people indicates a reverse concept of time. |
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