Scientists just announced that they have discovered what may be some of the earliest forming galaxies in the universe, a fascinating discovery made possible by NASA’s new flagship spacecraft James Webb Space Telescope.
“This is the first large candidate galaxy sample beyond the reach of the Hubble Space Telescope,” astronomer Haojing Yan said yesterday at a press conference at the American Astronomical Society meeting. in Seattle. Yan, who is at the University of Missouri, takes the lead New research published. Because the more sensitive JWST can look further into deeper space than its Hubble predecessor, it can essentially look further back in time. In the new catalog of 87 galaxies that astronomers have discovered uses it, some of which may date back to about 13.6 billion years ago, just 200 million years after the Big Bang. That was when the galaxies gave off the light we see today—although those systems of stars, gas, and dust have changed dramatically since, if they still exist.
While scientists have been studying other distant galaxies dating back to when the universe was still young, the discoveries of Yan and his colleagues could break those records in a few hundred million years or so. But at this point, all of them are still considered “candidate galaxies”, meaning their birth dates still need to be confirmed.
Dating a galaxy can be challenging: It involves measuring its “redshift,” how much light it emits is stretched toward the stars. longer red wavelengths, which tells astronomers how quickly the galaxy is moving away from us in the rapidly expanding universe. In turn, that tells astronomers the galaxy’s distance from Earth—or more precisely, the distance that photons from its stars must travel at the speed of light before reaching a telescope. near-Earth space telescopes, such as JWST. The light from the stars in the most distant galaxy in this collection may have been emitted as far back as 13.6 billion years ago, likely quite soon after the young galaxy merged.
These new estimated distances will have to be confirmed spectroscopically, that is, measuring the light the galaxies emit on the electromagnetic spectrum and pinpointing its unique signatures. However, Yan expects many of them to be accurately dated to the early days of the universe: “I bet with $20 and a tall beer that the success rate will be more than 50%,” he says. .
Yan’s team imaged these galaxies with JWST’s NIRCam at six near-infrared wavelengths. To estimate their distances, astronomers used a standard “bypass” technique: The hydrogen gas surrounding galaxies absorbs light at a particular wavelength, hence, the wavelengths. to which an object may or may not be seen places a limit on the distance the object can appear. Okay. These 87 candidate galaxies mostly look like blobs that can only be detected at the longer (and therefore redder) near-infrared wavelengths that NIRCam can detect, which could be which means they are very far away and therefore very old.
However, it is possible that some of them may be much closer than expected, which means they are not too old. For example, it is possible that their light is too weak to be detectable at some wavelengths. Until Yan can gather more detailed data, he won’t know for sure.
