spaceSpace and Physics

Astronomers Have Seen The Farthest Blazars Yet


Dr. Alfredo Carpineti

Senior Staff Writer & Space Correspondent

clockFeb 1 2017, 17:00 UTC

Artist's impression of a quasar. NASA/M. Weiss/CfA

Fermi, NASA’s gamma-ray observatory, has discovered some of the farthest blazars yet. Blazars are some of the brightest and most extreme objects in the universe, and Fermi has been able to peer right into their hearts.

As reported in the Astrophysical Journal, the light from the five new gamma-ray blazars started from when the universe was between 1.9 and 1.4 billion years old, just over 10 percent of its current age. But don’t let the age of the blazars fool you. These objects host some of the biggest supermassive black holes known.


"That they developed so early in cosmic history challenges current ideas of how supermassive black holes form and grow, and we want to find more of these objects to help us better understand the process," co-author Roopesh Ojha, an astronomer at NASA's Goddard Space Flight Center, said in a statement.

The international team studied the sources using several telescopes to gain as much insight into these galaxies as possible. All of the blazars emit the energy equivalent of more than 2 trillion Suns, and two of them had black holes larger than 1 billion solar masses. By comparison, the Milky Way’s own supermassive black hole is lightweight at about 4 million times the mass of the Sun.

"The main question now is how these huge black holes could have formed in such a young universe," added co-author Dario Gasparrini of the Italian Space Agency. "We don't know what mechanisms triggered their rapid development."

The previous record holder was active when the universe was 2.1 billion years old. To find these incredible objects, the researchers went through a catalog of over 1.4 million quasars, a related class of astrophysical objects. Blazars are very compact quasars and much brighter than your average one, so the team selected only the brightest objects to follow-up with Fermi.


"We think Fermi has detected just the tip of the iceberg, the first examples of a galaxy population that previously has not been detected in gamma rays," said Marco Ajello, who works at Clemson University in South Carolina and was one of the team leaders.

The team will continue with their deep search of blazers to hopefully find many more.


spaceSpace and Physics
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