The first image from Webb was shown on Monday in an event at the White House by President Biden on Monday. And it was not just any pretty picture.
The image goes by the name of SMACS 0723. It is a patch of sky visible from the Southern Hemisphere on Earth and often visited by Hubble and other telescopes in search of the deep past. It includes a massive cluster of galaxies about 4 billion light-years from here that astronomers use as a kind of cosmic telescope. The cluster’s enormous gravitation field acts as a lens, warping and magnifying the light from galaxies behind it that would otherwise be too faint and faraway to see.
An earlier Hubble image of the region was taken by a team called RELICS, for Reionization Lensing Cluster Survey. They work at the Space Telescope Science Institute in Baltimore, which manages both Hubble and the Webb. Previous analyses of this visible light image have identified galaxies poking out of the fog of creation some 700 million years after the Big Bang. The universe is 13.8 billion years old.
The current record for the earliest and farthest galaxy yet seen is 420 million years after the Big Bang, It is held by a galaxy called GN-z11 that strutted its fury some 13.3 billion years ago.
Webb is expected to smash that record, again and again starting with this image of SMACS 0723. Thomas Zurbuchen, NASA’s associate administrator for space science, described this image as the deepest view yet into the past of our cosmos. Later images will surely look back even further, he added.
Adam Riess, a Nobel-Prize winning cosmologist at the Space Telescope Science Institute and Johns Hopkins University, said the new Webb image had detected objects a trillionth the brightness of the star Vega, a astronomical standard for the magnitude of a star. That corresponds to a magnitude of 30.5 in astronomical lingo. . Astronomers also used to the telescope’s instruments to detailed spectral measurements from which the distance and other properties of these baby galaxies can be determined. He added in an email that in his opinion, “this can’t really be over hyped.”
Marcia Rieke of the University of Arizona agreed with him. She who led the building of one of the cameras used to take the picture, known as NIRcam.
“This image will not hold the ‘deepest’ record for long but clearly shows the power of this telescope.” (Her husband, George Rieke, also an astronomer at Arizona, led the building of the other camera, known as MIRI)
She also expressed amazement that the Webb instruments had taken only two hours to achieve what had taken Hubble days and days of observation.
Indeed, she said there is already a deeper image in the can, which she expects to be released later this week.
“This will be an incredibly exciting week,” said Garth Illingworth, a veteran galaxy hunter at the University of California, Santa Cruz, who was present at the creation of the Webb project 33 years ago.
