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New Delhi:
Scientists from prestigious Yale University of the US have
discovered the earliest black holes ever detected, a statement
from the university said Thursday.
The scientists published in their paper that the earliest giant
black holes ever detected were found hidden from view by their
host galaxies.
"This finding tells us there is a symbiotic relationship between
black holes and their galaxies that has existed since the dawn of
time," said Kevin Schawinski, a Yale astronomer, who contributed
to the discovery.
According to Schawinski, only the most high-energy X-rays were
detected, meaning the black holes must be hidden behind large
quantities of dust and gas from their host galaxies.
"This explains why they were so difficult to find," he said.
The team used a technique called "stacking" in order to detect the
incredibly weak signals emitted by the galaxies' central black
holes, the farthest of which are 13 billion light years from
Earth. Because of their great distance, astronomers see these
black holes as they existed less than one billion years after the
Big Bang.
The universe is currently estimated to be about 13.7 billion years
old.
"The astronomers focused on more than 250 galaxies, which had
previously been detected by the Hubble Space Telescope and which
they thought were good candidates for harbouring black holes at
their centers," the official university statement said.
"They then piled multiple images taken by the orbiting Chandra
X-Ray Observatory on top of each other, essentially multiplying
the weak X-ray signals created by the black holes as they devoured
nearby gas and dust," it read.
Theorists, including Yale cosmologist Priyamvada Natarajan, used
the observations to determine that even these earliest black holes
appear to grow and evolve along with their host galaxies, which is
similar to what astronomers have observed in the nearby universe.
"These observations indicate that extremely massive black holes
already existed as early as 700-800 million years after the Big
Bang, which suggests that either they were born massive to start
with, or they experienced rapid growth burst," Natarajan said.
"Either scenario tells us much more than we previously knew, which
is very exciting," she said.
Other authors of the paper include Ezequiel Treister (University
of Hawaii and Universidad de Concepcion from Chile), Marta
Volonteri (University of Michigan) and Eric Gawiser (Rutgers
University).
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