Most distant galaxy ever spotted with nature’s zoom lenses
NASA’s Hubble Space Telescope and Spitzer Space Telescope have discovered the most distant galaxy yet seen, according to a space agency report.
Astronomers say that the farthest galaxy ever seen in the universe makes the scene as a small blob that is much tinier than our Milky Way galaxy. The distant galaxy gives astronomers a glimpse of the past when the universe was three percent of its present age of 13.7 billion years. The farthest galaxy, called MACS0647-JD, was observed 420 million years after the big bang. Astronomers note that its light has traveled 13.3 billion years to reach Earth.
This discovery is the latest find from a program that uses gravitational lensing to identify distant galaxies in the early universe. The Cluster Lensing And Supernova Survey with Hubble (CLASH) uses massive galaxy clusters to magnify distant galaxies behind them.
Astronomers say that without nature’s “zoom lenses,” the farthest galaxy would have never been spotted. Gravitational lensing helped the CLASH team grab three images of MACS0647-JD with the Hubble telescope. The cluster’s gravity make the images look approximately eight, seven, and two times brighter than they would have normally looked.
“This cluster does what no manmade telescope can do,” saidÂ Marc Postman of the Space Telescope Science Institute. “Without the magnification, it would require a Herculean effort to observe this galaxy.”
Astronomers believe that the farthest galaxy is small enough that it could be in the process of forming a larger galaxy. Astronomers believe that a galaxy of similar age should be approximately 2,000 light-years wide (this galaxy is less than 600 light-years wide).
“This object may be one of many building blocks of a galaxy,” said lead author Dan Coe of the Space Telescope Science Institute. “Over the next 13 billion years, it may have dozens, hundreds, or even thousands of merging events with other galaxies and galaxy fragments.”
The farthest galaxy was spotted with 17 filters. Mr. Coe spotted the galaxy in February while examining a catalogue of thousands of gravitationally lensed objects seen in Hubble pictures of 17 clusters in the CLASH survey. Only the two reddest filters showed the galaxy, notes NASA.
“So either MACS0647-JD is a very red object, only shining at red wavelengths, or it is extremely distant and its light has been ‘redshifted’ to these wavelengths, or some combination of the two,” Mr. Coe said. “We considered this full range of possibilities.”
The CLASH team spotted multiple images of eight galaxies gravitationally lensed by the galaxy cluster. The team was able to create a map of the cluster’s mass.
“It’s like a big puzzle,” Mr. Coe said. “We have to arrange the mass in the cluster so that it deflects the light of each galaxy to the positions observed.
The team’s analysis showed that the cluster’s mass distribution generated three lensed images of the farthest galaxy at the positions and relative brightness seen in the Hubble image.
Astronomers spent countless hours making sure that the object wasn’t a red star, brown dwarf or a red galaxy.
Astronomers say that images taken by the Spitzer Space Telescope confirmed the distant nature of the galaxy. The farthest galaxy, for example, was barely detected at longer wavelengths.
Astronomers believe that the farthest galaxy stole the record for the most distant object ever seen even though its great distance from Earth may never be determined because it is too far away.
“All three of the lensed galaxy images match fairly well and are in positions you would expect for a galaxy at that remote distance when you look at the predictions from our best lens models for this cluster,” Mr. Coe said.
Astronomers hope to use Hubble and Spitzer to discover more objects from the earliest years of the universe.
The study’s findings will be detailed in the December 20 issue of The Astrophysical Journal.