This Hubble Space Telescope image shows the farthest galaxy yet seen in
an image that has been stretched and amplified by a phenomenon called
gravitational lensing. Credits: NASA , ESA, and B. Salmon (STScI). › Full image and caption
An intensive survey deep into
the universe by NASA's Hubble and Spitzer space telescopes has yielded the
proverbial needle-in-a-haystack: the farthest galaxy yet seen in an image that
has been stretched and amplified by a phenomenon called gravitational lensing.
The embryonic galaxy named
SPT0615-JD existed when the universe was just 500 million years old.
Though a
few other primitive galaxies have been seen at this early epoch, they have
essentially all looked like red dots, given their small size and tremendous
distances. However, in this case, the gravitational field of a massive
foreground galaxy cluster not only amplified the light from the background
galaxy but also smeared the image of it into an arc (about 2 arcseconds long).
"No other candidate galaxy
has been found at such a great distance that also gives you the spatial
information that this arc image does. By analyzing the effects of gravitational
lensing on the image of this galaxy, we can determine its actual size and
shape," said the study's lead author, Brett Salmon of the Space Telescope
Science Institute in Baltimore. He is presenting his research at the 231st
meeting of the American Astronomical Society in Washington.
First predicted by Albert
Einstein a century ago, the warping of space by the gravity of a massive
foreground object can brighten and distort the images of far more distant
background objects. Astronomers use this "zoom lens" effect to go
hunting for amplified images of distant galaxies that otherwise would not be
visible with today's telescopes.
SPT0615-JD was identified in Hubble's
Reionization Lensing Cluster Survey (RELICS) and companion S-RELICS Spitzer program. "RELICS was
designed to discover distant galaxies like these that are magnified brightly
enough for detailed study," said Dan Coe, principal investigator of
RELICS. RELICS observed 41 massive galaxy clusters for the first time in
infrared with Hubble to search for such distant lensed galaxies. One of these
clusters was SPT-CL J0615-5746, which Salmon analyzed to make this discovery.
Upon finding the lens-arc, Salmon thought, "Oh, wow! I think we're on to
something!"
By combining the Hubble and
Spitzer data, Salmon calculated the lookback time to the galaxy of 13.3 billion
years. Preliminary analysis suggests the diminutive galaxy weighs in at no more
than 3 billion solar masses (roughly 1/100th the mass of our fully grown Milky
Way galaxy). It is less than 2,500 light-years across, half the size of the
Small Magellanic Cloud, a satellite galaxy of our Milky Way. The object is
considered prototypical of young galaxies that emerged during the epoch shortly
after the big bang.
The galaxy is right at the
limits of Hubble's detection capabilities, but just the beginning for the
upcoming NASA James Webb Space Telescope's powerful capabilities, said Salmon.
"This galaxy is an exciting target for science with the Webb telescope as
it offers the unique opportunity for resolving stellar populations in the very
early universe." Spectroscopy with Webb will allow for astronomers to
study in detail the firestorm of starbirth activity taking place at this early
epoch, and resolve its substructure.
NASA's Jet Propulsion
Laboratory, Pasadena, California, manages the Spitzer Space Telescope mission
for NASA's Science Mission Directorate, Washington, D.C. Science operations are
conducted at the Spitzer Science Center at Caltech in Pasadena. Spacecraft
operations are based at Lockheed Martin Space, Littleton, Colorado. Data are
archived at the Infrared Science Archive housed at IPAC at Caltech. Caltech
manages JPL for NASA.
The
Hubble Space Telescope is a project of international cooperation between NASA
and ESA (European Space Agency). NASA's Goddard Space Flight Center in
Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute
(STScI) in Baltimore conducts Hubble science operations. STScI is operated for
NASA by the Association of Universities for Research in Astronomy, Inc., in
Washington.
News Media Contact
Guy Webster
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-6278
guy.webster@jpl.nasa.gov
Ray Villard
Space Telescope Science Institute, Baltimore, Maryland
410-338-4514
villard@stsci.edu
Laurie Cantillo / Dwayne Brown
NASA Headquarters, Washington
202-358-1077 / 202-358-1726
laura.l.cantillo@nasa.gov / dwayne.c.brown@nasa.gov
Source: JPL-Caltech/News
