NASA's Fermi Gamma-ray space telescope has identified the farthest gamma-ray blazars, a type of galaxy whose intense emissions are powered by super-sized black holes.

"Despite their youth, these far-flung blazars host some of the most massive black holes known," said Roopesh Ojha, an astronomer at NASA's Goddard Space Flight Center in Greenbelt, Maryland.

Light from the most distant object began its journey to us when the universe was 1.4 billion years old, or nearly 10 per cent of its present age.

Previously, the most distant blazars detected by Fermi emitted their light when the universe was about 2.1 billion years old.

"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," Ojha said while presenting the findings at the American Physical Society meeting in Washington on Monday.

Blazars constitute roughly half of the gamma-ray sources detected by Fermi's Large Area Telescope (LAT).

Astronomers think their high-energy emissions are powered by matter heated and torn apart as it falls from a storage, or accretion, disk toward a supermassive black hole with a million or more times the sun's mass.

"The main question now is how these huge black holes could have formed in such a young universe," one of the researchers Dario Gasparrini from Italian Space Agency's Science Data Centre in Rome said.

"We don't know what mechanisms triggered their rapid development," Gasparrini noted.

Two of the blazars that the team detected boast black holes of a billion solar masses or more. In the meantime, the team plans to continue a deep search for additional examples.

"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 from Clemson University in South Carolina, US.