The galaxy cluster called MOO J1142+1527 can be seen here as it existed
when light left it 8.5 billion years ago. The red galaxies at the center
of the image make up the heart of the galaxy cluster. Image credit:
NASA/JPL-Caltech/Gemini/CARMA. › Full image and caption
Astronomers have discovered a giant gathering of galaxies in a very
remote part of the universe, thanks to NASA's Spitzer Space Telescope
and Wide-field Infrared Survey Explorer (WISE). The galaxy cluster,
located 8.5 billion light-years away, is the most massive structure yet
found at such great distances.
Galaxy clusters are gravitationally bound groups of thousands of
galaxies, which themselves each contain hundreds of billions of stars.
The clusters grow bigger and bigger over time as they acquire new
members.
How did these clusters evolve over time? What did they look like
billions of years ago? To answer these questions, astronomers look back
in time to our youthful universe. Because light takes time to reach us,
we can see very distant objects as they were in the past. For example,
we are seeing the newfound galaxy cluster -- called Massive Overdense
Object (MOO) J1142+1527 -- as it existed 8.5 billion years ago, long
before Earth formed.
As light from remote galaxies makes its way to us, it becomes
stretched to longer, infrared wavelengths by the expansion of space.
That's where WISE and
Spitzer help out.
For infrared space telescopes, picking out distant galaxies is like
plucking ripe cherries from a cherry tree. In the infrared images
produced by Spitzer, these distant galaxies stand out as red dots, while
closer galaxies look white. Astronomers first combed through the WISE
catalog to find candidates for clusters of distant galaxies. WISE
catalogued hundreds of millions of objects in images taken over the
entire sky from 2010 to 2011.
They then used Spitzer to narrow in on 200 of the most interesting
objects, in a project named the "Massive and Distant Clusters of WISE
Survey," or MaDCoWS. Spitzer doesn't observe the whole sky like WISE,
but can see more detail.
"It's the combination of Spitzer and WISE that lets us go from a
quarter billion objects down to the most massive galaxy clusters in the
sky," said Anthony Gonzalez of the University of Florida in Gainesville,
lead author of a new study published in the Oct. 20 issue of the
Astrophysical Journal Letters.
From these observations, MOO J1142+1527 jumped out as one of the most extreme.
The W.M. Keck Observatories and Gemini Observatory on Mauna Kea in
Hawaii were used to measure the distance to the cluster at 8.5 billion
light-years. Using data from the Combined Array for Research in
Millimeter-wave Astronomy (CARMA) telescopes near Owens Valley in
California, the scientists were then able to determine that the
cluster's mass is a quadrillion times that of our sun -- making it the
most massive known cluster that far back in space and time.
MOO J1142+1527 may be one of only a handful of clusters of this heft
in the early universe, according to the scientists' estimates.
"Based on our understanding of how galaxy clusters grow from the very
beginning of our universe, this cluster should be one of the five most
massive in existence at that time," said co-author Peter Eisenhardt, the
project scientist for WISE at NASA's Jet Propulsion Laboratory in
Pasadena, California.
In the coming year, the team plans to sift through more than 1,700
additional galaxy cluster candidates with Spitzer, looking for biggest
of the bunch.
"Once we find the most massive clusters, we can start to investigate
how galaxies evolved in these extreme environments," said Gonzalez.
JPL managed and operated WISE for NASA's Science Mission Directorate
in Washington. In September 2013, WISE was reactivated, renamed NEOWISE
and assigned a new mission to assist NASA's efforts to identify
potentially hazardous near-Earth objects. JPL manages the Spitzer Space
Telescope mission for NASA's Science Mission Directorate, Washington.
Science operations and data processing for Spitzer and NEOWISE take
place at the Infrared Processing and Analysis Center at the California
Institute of Technology in Pasadena. Caltech manages JPL for NASA.
More information about WISE is online at: http://www.nasa.gov/wise
More information about Spitzer is online at: http://www.nasa.gov/spitzer - http://spitzer.caltech.edu
Media Contact
Whitney Clavin
Jet Propulsion Laboratory, Pasadena, California
818-354-4673
whitney.clavin@jpl.nasa.gov
Source: JPl-Caltech
