NASA's Spitzer Space Telescope images show galaxies at the forefront
cosmic consolidations. Although galaxies seem separate now, gravity is
gathering them, and soon they will combine to form new merged galaxies.
Some merged galaxies will experience billions of years of growth. For the others,
However, the merger will launch processes that will eventually stop the star
training, condemning galaxies to fade prematurely.
a few percent of the galaxies of the nearby universe are merging, but galaxy
Mergers were more common between 6 and 10 billion years ago and these processes
deeply shaped our modern galactic landscape. For more than 10 years, scientists
work on the big
LIRG Observatory on all heavens, or
GOALS, used nearby galaxies to study the details of galaxy fusions
and use them as local labs for this earlier period in the universe
l & # 39; history. The investigation is focused on 200 nearby objects, including many galaxies
at different stages of the merger. The images above show three of these targets,
pictured by Spitzer.
In these images, different
the colors correspond to different wavelengths of infrared light, which are not
visible to the human eye. Blue is 3.6 microns, and
the green is 4.5 microns – both strongly emitted by the stars. red
corresponds to 8.0 microns, a wavelength mainly emitted by dust.
Primary processes considered to be responsible for a sudden cessation of star formation
inside a fused galaxy is a supercharged black hole. In the center of most galaxies
is a supermassive black hole – a powerful beast millions to billions of times
more massive than the sun. During a galactic fusion, gas and dust are driven out
in the center of the galaxy, where they help to make young stars and also feed
the central black hole.
a sudden activity can create an unstable environment. Shockwaves or
the strong winds produced by the growing black hole can sweep the galaxy,
eject large amounts of gas and stop the formation of stars. Enough
powerful or repetitive exits can hinder the galaxy's ability to create new stars.
relationship between mergers, starburst chips and black hole activity
is complex and scientists are still trying to fully understand it. A die
newly fused galaxies is the subject of a detailed study with the W.M. Keck Observatory
in Hawaii, where GOALS scientists searched for galactic shockwaves driven by
the central active galactic core, an extremely bright object powered by a
supermassive black hole feeding on the material around it. The lack of shock
the signatures suggest that the role of galactic nuclei active in the formation of the galaxy
growth during a merger may not be simple.
galaxies from the near universe appear particularly bright in the infrared
observatories like Spitzer. GOALS studies have also relied on observations from
target galaxies by other space observatories, including NASA's Hubble
space telescopes Chandra and, the Herschel satellite of the European Space Agency,
as well as field facilities including the Keck Observatory, the
The very large network of the National Science Foundation and the great millimeter of Atacama
manages the Spitzer Space Telescope mission for NASA's scientific mission
Direction to Washington. Scientific operations are conducted at Spitzer
Caltech Science Center in Pasadena, California. The operations of spaceships are
based at the Lockheed Martin space in Littleton, Colorado. The data is archived at
Infrared Science Archive hosted at IPAC in Caltech.
More information on the GOALS survey is available at:
Jet Propulsion Laboratory, Pasadena, California