The young galaxy SDSS090122.37+181432.3,
also known as S0901, is seen here as the bright arc to the left of the
central bright galaxy. Credit: NASA/STScI; S. Allam and team; and the
Master Lens Database, L. A. Moustakas, K. Stewart, et al (2014). Full image and caption
Scientists have discovered a young galaxy acting in unexpectedly
mature ways. The galaxy, called S0901, is rotating in a calm manner
typical of more developed galaxies like our own spiral Milky Way.
"Usually, when astronomers examine galaxies in an early era, they
find that turbulence plays a much greater role than it does in modern
galaxies. But S0901 is a clear exception to that pattern," said James
Rhoads of Arizona State University, Tempe.
It has taken the light from the galaxy 10 billion years to reach us across
space, so we are seeing it when it was comparatively young.
"This galaxy is the equivalent of a 10-year-old. I can tell you from
watching my kids' classes that 10-year-olds like to fidget! S0901 is
unusual because it's not fidgeting, and instead is very well behaved."
Rhoads is lead author of the research, appearing in the May 20 issue of
the Astrophysical Journal.
The discovery was made using the Herschel space observatory, a European Space Agency mission with important NASA contributions.
"This is a truly surprising result that reminds us that we still
don't understand many details of the evolution of the universe.
Facilities like Herschel help us understand this complex story," said
Paul Goldsmith, U.S. Herschel Project Scientist at NASA's Jet Propulsion
Laboratory, Pasadena, Calif.
When galaxies form, they accumulate mass because their gravity
attracts vast, external gas clouds. As the gas clouds enter a particular
galaxy, they fall into haphazard orbits. These disordered paths cause
turbulence in the host galaxy, which can drive star formation.
To investigate the internal conditions of forming galaxies, Rhoads
and Sangeeta Malhotra, also from Arizona State University, and
colleagues targeted two young galaxies, one of them being S0901.
Using a cosmic magnifier known as a gravitational lens, the
researchers got a better view of the galaxies than they would have
otherwise. An instrument on Herschel, the Heterodyne Instrument for the
Far-Infrared (HIFI), was then able to pick up the signature of ionized
carbon, revealing the motion of the gas molecules in the galaxies. This
motion was much smoother than anticipated in the S0901 galaxy. Results
for the second galaxy hinted at a calm rotation too, but were less
clear.
"Galaxies 10 billion years ago were making stars more actively than
they do now," says Malhotra. "They usually also show more turbulence,
likely because they are accumulating gas faster than a modern galaxy
does. But here we have cases where an early galaxy combines the calm
rotation of a modern one with the active star formation of their early
peers."
More observations with other telescopes should help reveal if other
galaxies behave in similarly grown-up ways, or if S0901 is oddly ahead
of its time.
Read the news release from ESA online at: http://sci.esa.int/herschel/53992-herschel-discovers-mature-galaxies-in-the-young-universe
Herschel is a European Space Agency mission, with science instruments
provided by consortia of European institutes and with important
participation by NASA. While the observatory stopped making science
observations in April 2013, after running out of liquid coolant as
expected, scientists continue to analyze its data. NASA's Herschel
Project Office is based at JPL. JPL contributed mission-enabling
technology for two of Herschel's three science instruments, including
HIFI. The NASA Herschel Science Center, part of the Infrared Processing
and Analysis Center at the California Institute of Technology in
Pasadena, supports the U.S. astronomical community. Caltech manages JPL
for NASA.
More information is online at these websites:
Whitney Clavin 818-354-4673
Jet Propulsion Laboratory, Pasadena, Calif.
whitney.clavin@jpl.nasa.gov
