NASA’s Spitzer and Hubble Space Telescopes have spotted what might be
one of the most distant galaxies known, harkening back to a time when
our universe was only about 650 million years old (our universe is 13.8
billion years old). The galaxy, known as Abell2744 Y1, is about 30 times
smaller than our Milky Way galaxy and is producing about 10 times more
stars, as is typical for galaxies in our young universe.
The discovery comes from the Frontier Fields program, which is
pushing the limits of how far back we can see into the distant universe
using NASA’s multi-wavelength suite of Great Observatories. Spitzer sees
infrared light, Hubble sees visible and shorter-wavelength infrared
light, and NASA’s Chandra X-ray Observatory sees X-rays. The telescopes
are getting a boost from natural lenses: they peer through clusters of
galaxies, where gravity magnifies the light of more distant galaxies.
The Frontier Fields program will image six galaxy clusters in total.
Hubble images of the region are used to spot candidate distant galaxies,
and then Spitzer is needed to determine if the galaxies are, in fact,
as far as they seem. Spitzer data also help determine how many stars are
in the galaxy.
These early results from the program come from images of the Abell
2744 galaxy cluster. The distance to this galaxy, if confirmed, would
make it one of the farthest known. Astronomers say it has a redshift of
8, which is a measure of the degree to which its light has been shifted
to redder wavelengths due to the expansion of our universe. The farther a
galaxy, the higher the redshift. The farthest confirmed galaxy has a
redshift of more than 7. Other candidates have been identified with
redshifts as high as 11.
“Just a handful of galaxies at these great distances are known,” said
Jason Surace, of NASA’s Spitzer Science Center at the California
Institute of Technology, Pasadena. “The Frontier Fields program is
already working to find more of these distant, faint galaxies. This is a
preview of what’s to come.”
The findings, led by astronomers from the Instituto de Astrofísica de
Canarias and La Laguna University, are accepted for publication in the
scientific journal Astronomy and Astrophysics Letters.