Quasars emit a light as bright as that of one trillion stars. Scientists think they get their energy from supermassive black holes.
But where do the supermassive black holes get their fuel?
Hubble Space Telescope may have the answer: the merger of two galaxies.
“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,” says C. Megan Urry, a professor of astronomy and astrophysics at Yale University.
“These mergers are also the sites of future black hole mergers, which we hope will one day be visible with gravitational wave telescopes,” Urry adds.
The researchers used Hubble’s sensitivity at near-infrared wavelengths of light to see past the intense glow of the quasar, to the host galaxies themselves.
“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,” says Eilat Glikman of Middlebury College in Vermont, lead author of the study published in the Astrophysical Journal.
“We are seeing the quasars in their teenage years, when they are growing quickly and all messed up.”
Glikman decided to look for “dust reddened quasars” in several ground-based infrared and radio sky surveys. These quasars are enveloped in dust, dimming their visible light.
Using Hubble’s Wide Field Camera 3, Glikman looked at 11 such quasars from the peak of the universe’s star-formation era, 12 billion years ago.
“The new images capture the dust-clearing transitional phase of the merger-driven black hole scenario,” Glikman says. “The Hubble images are both beautiful and descriptive.”
Other authors of the study are Brooke Simmons of Oxford University; Madeline Mailly of Middlebury College; Kevin Schawinski of ETH Zurich; and M. Lacy of the National Radio Astronomy Observatory in Charlottesville, Virginia.
Source: Yale University