The
question of "nature vs. nurture" applies to more than just child development.
Astronomers have long tried to answer this same question about galactic
evolution. And according to a recent study, environment may be an important
factor in shaping a galaxy's
properties over time.
At the
beginning of the 20th century, Edwin Hubble realized that galaxies today are
not randomly distributed. Old, red elliptical galaxies, which have no or few
new stars, tend to be found in clusters,
whereas young, blue spiral galaxies, where stars are still forming, tend to
have fewer neighbors.
Astronomers
theorized that either this had always been the case in the universe, or some influence of the
surrounding environment must have changed the distribution and shape of
galaxies over time.
A team of
astronomers investigated this conundrum using the European Southern
Observatory's Very
Large Telescope to build a three-dimensional atlas of the universe going
back more than 9 billion years. They studied more than 6,500 galaxies to see
how their properties varied over different timescales.
"We
discovered that, when the universe was younger, this segregation between
galaxies' form and environment did not exist," astronomer Christian Marinoni of
the Laboratoire d'Astrophysique de Marseille, France told LiveScience.
Their research
showed that both elliptical and spiral galaxies were found in different
environments, which suggests that the shape of galaxies is affected by some
physical mechanism that has acted over nearly the whole life of the universe.
"This is
the smoking gun we were looking for," Marinoni said.
The team's
findings suggest if a galaxy is located in a cluster, its ability to form new
stars is quenched more quickly than galaxies located in sparser areas.
Simulations agree with these findings--according to Marinoni the gas
in clusters become too hot to cool down and collapse to form new
stars.
More luminous
galaxies also exhaust their star-forming material more quickly.
"Our
results indicate that environment is a key player in galaxy evolution, but
there's no simple answer to the 'nature versus nurture' problem in galaxy
evolution," said astronomer Olivier Le Fèvre. "They suggest that galaxies as we
see them today are the product of their inherent genetic information, evolved
over time, as well as complex interactions with their environments."
This
article is part of SPACE.com's weekly Mystery Monday series.
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