Quasar study surprises scientists
By Kevin Dayton
Advertiser Big Island Bureau
HILO, Hawai'i — New research done at the Gemini Observatory on Mauna Kea has rattled some of astronomers' ideas about quasars, the most brilliant celestial objects in the universe.
The widely accepted theory about quasars is that they are fueled by material spiraling into supermassive black holes, which have a mass on the order of a billion suns.
As the black holes' enormous gravitational pull yanks objects in, scientists believe the process releases huge amounts of energy, creating a quasar. The objects generate light at all wavelengths, from brilliant visible light to radio waves and X-rays.
Until now scientists associated the most powerful quasars with large galaxies, with the bigger galaxies presumably providing ample material to fuel the quasars' huge releases of energy.
But new observations at the Frederick C. Gillett Gemini North Telescope at Mauna Kea found some of the most powerful quasars reside in relatively small galaxies, casting some doubt on scientists' thinking about how quasars work.
Dr. David Schade of the National Research Council Canada presents the observations at the first Gemini Science Conference in Vancouver, British Columbia today.
In the nearer regions of the universe, quasars seem to vary in strength according to the galaxies in which they are found. Big galaxies have brighter quasars, which led scientists to draw a theoretical connection between the size of a galaxy and the energy of the quasar within it.
Many astronomers expected that more distant quasars' host galaxy would also be massive, and might show signs of having collided with another galaxy to trigger a quasar.
Not so, the Gemini research found. The new Gemini study focused on nine quasars each about 10 billion light years away, and found that the host galaxies of all but one of the quasars were so small and faint they could not be detected even with Gemini's sensitive equipment.
The one galaxy that could be detected was "remarkably unremarkable" because it was similar in brightness and size to the Milky Way galaxy, according to a Gemini statement announcing the research.
"Basically we are in some sort of conundrum where we don't understand what's going on," said Jean-Rene Roy, associate director of Gemini North. "That's what it's telling us, that we don't understand what's going on to create the luminosity" of the powerful, more distant quasars.
The study was led by Dr. Scott Croom of the Anglo-Australian Observatory in Australia, with Schade; Dr. Tom Shanks of the University of Durham (in Britain), Brian Boyle of Australia Telescope National Facility; Lance Miller of Oxford University; and Robert Smith of Liverpool John Moores University.
Reach Kevin Dayton at kdayton@honoluluadvertiser.com or (808) 935-3916.
