Chuck Bednar for redOrbit.com – @BednarChuck
Thanks to the infrared vision of the Hubble Space Telescope, researchers from Yale University and Middlebury College in Vermont have shed new light on the formation of quasars, some of the brightest objects in the known universe.
Quasars, also known as quasi-stellar radio sources, are the most distant objects yet detected in the universe and can be up to a trillion times brighter than the Sun. They also emit a tremendous amount of energy, which scientists believe is produced by massive black holes in the centers of the galaxies where they are located. However, their origins have long remained a mystery.
Now, Eilat Glikman of Middlebury College and her colleagues report in the latest edition of The Astrophysical Journal that quasars are actually born when galaxies crash into each other, fueling supermassive black holes and causing the host galaxies to undergo a radical transformation.
“The Hubble images confirm that the most luminous quasars in the universe result from violent mergers between galaxies, which fuels black hole growth and transforms the host galaxies,” said C. Megan Urry, the Israel Munson Professor of Astronomy and Astrophysics at Yale University, and co-author of the study. “These mergers are also the sites of future black hole mergers, which we hope will one day be visible with gravitational wave telescopes.”
Quasars during awkward teenage years
Over the past 20 years, experts have determined that supermassive black holes inside the cores of distant galaxies are the source of the energy for quasars, but that does not explain how or where the black holes actually get their fuel. The new research uses Hubble’s sensitivity at near-infrared wavelengths to confirm a previous theory that the energy comes from a galactic merger.
“The Hubble observations are telling us that the peak of quasar activity in the early universe is driven by galaxies colliding and then merging together,” explained Glikman, lead author of the study. “We are seeing the quasars in their teenage years, when they are growing quickly and all messed up.”
Using Hubble’s Wide Field Camera 3, Glikman and her colleagues looked for “dust reddened quasars” in several ground-based infrared and radio sky surveys. They found 11 of these quasars that are enveloped in dust and as a result give off lower levels of visible light.
Glikman said that the new images were “both beautiful and descriptive” and “capture the dust-clearing transitional phase of the merger-driven black hole scenario.”
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