![]() ![]() Oesch (Yale University) Surprisingly Bright This timeline shows how the discoveries of these two candidate early galaxies fit in with the history of the universe. “These sources are very intriguing, but I am not yet 100% convinced about their extremely high-redshift nature,” Oesch says, lamenting the inconclusive ALMA detection. But if that spectral line is not what it seems, then HD1 and HD2 might lie more than a billion years later in cosmic history. If real, then that ionized oxygen confirms that HD1 has a redshift of 13.27 - and bingo, we have the earliest galaxy yet seen. ALMA detected a hint of a strongly redshifted line from ionized oxygen. The team next looked at HD1 with the ALMA radio telescope in Chile, to see if they could measure the object’s precise redshift, thereby confirming that the dropout technique had really turned up early galaxies. As you move to longer, redder wavelengths (left to right, labels indicate the wavelength band), the distant galaxy HD1 becomes visible (central blur). Astronomers actually already knew of HD1 but had cataloged it as a much closer galaxy. The light that does make it to us from the galaxy is all redward of the break, telling us approximately how much the light has redshifted and thus how far back in cosmic time we’re looking.Īfter scouring the images with both computers and eyes, the team found two candidates, called HD1 and HD2. As the universe expands, the galaxy becomes more distant and its light stretches to redder and redder wavelengths, and this spectral marker in its light shifts redward. This creates what’s called the Lyman break in a galaxy’s spectrum. That’s because photons with short, blueward wavelengths (specifically, those shorter than 91.2 nanometers) are easily absorbed by neutral hydrogen, either within a galaxy or in clouds lying between us and it. They hunted for galaxies detected at the longest, reddest wavelengths but invisible at shorter ones. With these points in mind, Harikane’s team went looking for early galaxies in archival images from a combination of ground- and space-based telescopes, covering visible and infrared wavelengths. Finding the first galaxies (and their black holes) and figuring out what they were like when they formed will help astronomers solve this conundrum. It’s hard to explain how such gargantuas came together within a measly billion years. Scientists have spotted them as far back as 1 billion years post–Big Bang, but those early examples are far larger than expected - easily a billion times the mass of the Sun. These supermassive black holes present a mystery. ![]() Their stars created heavier elements (such as carbon and oxygen) than the simplest atoms made in the primordial inferno, and their black holes grew to be the behemoths we see today in the hearts of nearly every massive galaxy. They may be the earliest galaxies yet detected. These composite near-infrared images show HD1 and HD2 (red objects), two galaxies in the early universe. “We think that they evolved from smaller galaxies,” he says. Based on their brightness, the galaxies may contain at least 1 billion solar masses in stars - similar to the Magellanic Cloud dwarf galaxies, and too hefty to be the first generation. Other, less definitive finds suggest galaxies around this time had fairly mature stars, implying stars first lit up within the universe’s first 300 million years.Įven if the two new galaxies prove to lie as far away (and thus, as early) as they appear to, they likely are not from the population of first galaxies, Harikane says. ![]() GN-z11’s redshift is about 11, meaning we see it as it was 420 million years after the origin of the observable universe. The current recordholder with a secure measurement is GN-z11, announced by Pascal Oesch (now at University of Geneva) and others in 2016. Observers have previously found a handful of galaxies in the universe’s first few hundred million years. The studies have been submitted for publication but are not yet peer-reviewed. In astronomers’ lingo, that corresponds to a redshift of 13. In two papers posted to the arXiv preprint server, Yuichi Harikane (University of Tokyo) and an international team report the detection of two sources that appear to blaze at us from a mere 330 million years after the Big Bang. HD1, the candidate for the most distant galaxy discovered to date, appears as the red object in the center of the zoom-in image.Īstronomers may have found the most distant galaxies ever seen. We have also updated images in the news story below. The discovery paper is now accepted for publication in the Astrophysical Journal the accompanying analysis is accepted for publication in the Monthly Notices of the Royal Astronomical Society. Editorial note (April 7, 2022): This story was originally published on January 26, 2022. ![]()
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