Credit: NASA/JPL-Caltech/P. Capak (Caltech)
About this image: J0717 isn't just a large cluster of galaxies; astronomers are using
it like a giant telephoto lens attachment to study the very distant,
very faint universe. This new infrared view from NASA's Spitzer Space
Telescope will be used in tandem with observations from other major NASA
observatories to glimpse the universe's very first galaxies. Called
Frontier Fields, the project is a collaboration with the Hubble Space
Telescope and the Chandra X-ray Observatory.
The faintness of the earliest, most distant galaxies makes studying them a challenge, even with long, deep exposures. Frontier Fields, however, can spot these primordial galaxies courtesy of foreground clusters of galaxies, whose gargantuan mass and gravity form cosmic "zoom lenses."
The clusters warp space around them, magnifying background galaxies. The cluster in this image, known as J0717, is the grouping of bright objects near the center of the field, while examples of the very distant background galaxies appear as distorted arcs at the center of the two circular call-outs.
The faintness of the earliest, most distant galaxies makes studying them a challenge, even with long, deep exposures. Frontier Fields, however, can spot these primordial galaxies courtesy of foreground clusters of galaxies, whose gargantuan mass and gravity form cosmic "zoom lenses."
The clusters warp space around them, magnifying background galaxies. The cluster in this image, known as J0717, is the grouping of bright objects near the center of the field, while examples of the very distant background galaxies appear as distorted arcs at the center of the two circular call-outs.
NASA's Spitzer Space Telescope, in tandem with other major NASA
observatories, has recently embarked on a major new mission to glimpse
the universe's very first galaxies. Called Frontier Fields, the project
is a collaboration with the Hubble Space Telescope and the Chandra X-ray
Observatory. All three telescopes, collectively known as NASA's Great
Observatories, are playing indispensable roles in this quest.
The
faintness of the earliest, most distant galaxies makes studying them a
challenge. Frontier Fields, however, can spot these primordial galaxies
courtesy of foreground clusters of galaxies, whose gargantuan mass and
gravity form cosmic "zoom lenses." Peering through these gravitational
lenses is giving astronomers an unprecedented view of the galactic
dawn.
"Our overall science goal with the Frontier Fields is to
understand how the first galaxies in the universe assembled," said Peter
Capak, a research scientist with the NASA/JPL Spitzer Science Center at
the California Institute of Technology and the Spitzer lead for the
Frontier Fields. "This pursuit is made possible by how massive galaxy
clusters warp space around them, kind of like when you look through the
bottom of a wine glass."
Although astronomers have relied on this
cosmic lensing for many years now to turn up distant galactic quarry,
Frontier Fields takes the practice to a new level. The project has
selected the most massive and distant clusters on record, thus offering
the highest magnification and deepest probe of the early universe
available.
Plus, Frontier Fields will further characterize the
foreground clusters to better gauge the lenses' magnifying, as well as
distorting, effects. On average, the gravitational warping of space by
foreground clusters magnifies background galaxies four to ten times. But
some galaxies studied via Frontier Fields will be magnified on the
order of a hundred times.
NASA's Great Observatories will view the
cluster galaxies and background galaxies in different wavelengths of
light, each of which carries important scientific information. Spitzer
observes in longer wavelength, infrared light; Hubble, in shorter
infrared and optical light; and Chandra in high-energy X-rays.
The
infrared light captured by Spitzer serves two key purposes. Firstly,
infrared light is an indicator of the number of stars in a galaxy, which
speaks to the galaxy's overall mass. In the case of extremely distant
galaxies, the optical light from their stars has been stretched out, or
"redshifted," into infrared wavelengths as a result of the expansion of
the universe. "Spitzer basically measures the mass of galaxies," said
Capak. "Because of the wavelengths it works in, Spitzer is the only
instrument capable of making mass measurements of galaxies this far
away."
Secondly, Spitzer can help determine if certain galaxies
also observed by Hubble are in fact the far-off, early galaxies of
interest or just nearby galaxies. "Spitzer and Hubble can tell if
galaxies discovered in the Frontier Fields are really at the edge of the
universe or not," said Capak.
Hubble and Spitzer scientists
envisioned this sort of synergy when the Frontier Fields were conceived
in 2012. "This program exemplifies the combined strength of NASA's Great
Observatories when it comes to digging deep into the distant universe,"
said Jennifer Lotz from the Space Telescope Science Institute, which
manages Hubble for NASA.
Chandra's role in Frontier Fields,
meanwhile, is to provide a detailed map of the hot, X-ray-emitting gas
in the galaxy clusters. Doing so will help to further pin down their
masses. Spitzer will be integral to this aspect of the project as well
by presenting astronomers with an overview of the stars in the clusters'
galaxies.
Observations of the first Frontier Field cluster,
Abell 2744, have been completed. Work is now underway on another cluster
and two more are slated for summer. The Abell 2744 effort has already
resulted in the discovery of one of the most distant galaxies ever seen,
dubbed Abell 2744 Y1. This tiny, infant galaxy was witnessed at a time
when the 13.8 billion-year-old universe was a mere 650 million years
old. Frontier Fields is expected to reveal many other similarly primeval
galaxies in the critical galaxy-forming epoch shortly after the Big
Bang.
NASA's Jet Propulsion Laboratory, Pasadena, Calif.,
manages the Spitzer Space Telescope mission for NASA's Science Mission
Directorate. Science operations are conducted at the Spitzer Science
Center at the California Institute of Technology in Pasadena. Spacecraft
operations are based at Lockheed Martin Space Systems Company,
Littleton, Colo. Data are archived at the Infrared Science Archive
housed at the Infrared Processing and Analysis Center at Caltech.
Caltech manages JPL for NASA.