New
Delhi: The enigmatic universe harbours countless secrets within it,
compelling scientists to put in every effort to delve deeper in order to
extract information about its existence and consequent evolution.
The universe is also home to numerous super-massive black holes,
which emanate incredibly bright and luminous distant points of light
called Quasars.
Using the positioning of these quasars, scientists have now managed
to create the largest, very first map of the large-scale structure of
the universe.
"Because quasars are so
bright, we can see them all the way across the universe," said Ashley
Ross of the Ohio State University in the US.
"That makes them the ideal objects to use to make the biggest map yet," said Ross.
The super-massive back holes are placed right in the centre of the quasars, which give them the brightness.
As matter and energy fall into a quasar's black hole, they heat up to
incredible temperatures and begin to glow. It is this bright glow that
is detected by a dedicated 2.5-metre telescope on Earth.
"These quasars are so far away that their light left them when the
universe was between three and seven billion years old, long before the
Earth even existed," said Gongbo Zhao from the National Astronomical
Observatories of Chinese Academy of Sciences.
In order to make their map, scientists used the Sloan Foundation Telescope to observe an unprecedented number of quasars.
During the first two years of the Sloan Digital Sky Survey's Extended
Baryon Oscillation Spectroscopic Survey (eBOSS), astronomers measured
accurate three-dimensional positions for more than 147,000 quasars.
The telescope's observations gave the team the quasars' distances,
which they used to create a three-dimensional map of where the quasars
are.
However, to use the map to understand the expansion history of the
universe, they had to go a step further, using a clever technique
involving studying "baryon acoustic oscillations" (BAOs).
BAOs are the present-day imprint of sound waves which travelled
through the early universe, when it was much hotter and denser than the
universe we see today.
However, when the universe was 380,000 years old, conditions changed suddenly and the sound waves became "frozen" in place.
These frozen waves are left imprinted in the three- dimensional structure of the universe we see today.
The results of the new study confirm the standard model of cosmology that researchers have built over the last 20 years.
In this standard model, the universe follows the predictions of
Einstein's General Theory of Relativity - but includes components whose
effects we can measure, but whose causes we do not understand.
(With PTI inputs)
