By learning that galaxies merging is what ignites quasars, the brightest,
most potent objects in the universe, scientists have solved one of their
greatest riddles.
Quasars, which were first identified 60 years ago, have the brightness of a
trillion stars concentrated into an area the size of our solar system. Since
they were originally noticed, it has been a mystery as to what may have
caused such intense activity. It has just been discovered that it is a
result of galaxies colliding together, according to new research undertaken
by experts from the Universities of Sheffield and Hertfordshire.
Monthly Notices of the Royal Astronomical Society is where the work is
published.
Researchers used deep imaging data from the Isaac Newton Telescope in La
Palma to find the collisions after noticing deformed patterns in the
quasar-hosting galaxies' outer regions.
Supermassive black holes are found in the cores of most galaxies. They also
contain a significant quantity of gas, but for the most part, this gas is
circling far from the galaxy centers and is therefore beyond of the black
holes' range. The black hole at the heart of the galaxy is drawn into the
gas by collisions between galaxies; just before the gas is sucked into the
black hole, it releases enormous quantities of energy in the form of
radiation, giving the quasar its distinctive brightness.
The emergence of a quasar can have drastic effects on whole galaxies; it
can expel the galaxy's remaining gas, preventing it from producing new stars
for billions of years.
This is the first time a sample of this size of quasars has been observed
at this sensitivity level. Researchers came to the conclusion that galaxies
harboring quasars are around three times as likely to be interacting or
colliding with other galaxies by comparing views of 48 quasars and their
host galaxies with pictures of over 100 non-quasar galaxies.
We now have a much better knowledge of how these strong things are started
and fed thanks to the study.
"Quasars are one of the most extreme phenomena in the universe, and what we
see is likely to represent the future of our own Milky Way galaxy when it
collides with the Andromeda galaxy in about five billion years," said
Professor Clive Tadhunter from the Department of Physics and Astronomy at
the University of Sheffield.
Fortunately, Earth won't be in the path of one of these cataclysmic
incidents for quite some time. "It's exciting to observe these events and
finally understand why they occur."
Quasars are significant to astronomers because, because of their
brilliance, they shine out at great distances and serve as beacons to the
universe's early eras.
"It's an area that scientists around the world are keen to learn more
about," says Dr. Jonny Pierce, Post-Doctoral Research Fellow at the
University of Hertfordshire. "NASA's James Webb Space Telescope was designed
with the primary goal of studying the earliest galaxies in the universe, and
Webb is capable of detecting light from even the most distant quasars,
emitted nearly 13 billion years ago. Our understanding of the universe's
past and perhaps even the Milky Way's future depends heavily on
quasars.
Provided by
University of Sheffield
