Astronomers discover earliest ever black holes

June 16th, 2011 - 5:09 pm ICT by IANS  

Hubble Space Telescope New Delhi, June 16 (IANS) 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).

Indo-Asian News Service
ao/sak/vt

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