Webb spotlights gravitational arcs in ‘El Gordo’ galaxy cluster

A brand new picture of the galaxy cluster often known as “El Gordo” is revealing distant and dusty objects by no means seen earlier than, and offering a bounty of contemporary science. The infrared picture, taken by NASA’s James Webb House Telescope, shows a wide range of uncommon, distorted background galaxies that had been solely hinted at in earlier Hubble House Telescope photographs.

El Gordo is a cluster of a whole lot of galaxies that existed when the universe was 6.2 billion years previous, making it a “cosmic teenager.” It is probably the most huge cluster recognized to exist at the moment. (“El Gordo” is Spanish for the “Fats One.”)

The staff focused El Gordo as a result of it acts as a pure, cosmic magnifying glass by a phenomenon often known as gravitational lensing. Its highly effective gravity bends and distorts the sunshine of objects mendacity behind it, very like an eyeglass lens.

“Lensing by El Gordo boosts the brightness and magnifies the sizes of distant galaxies. This lensing impact supplies a singular window into the distant universe,” stated Brenda Frye of the College of Arizona. Frye is co-lead of the PEARLS-Clusters department of the Prime Extragalactic Areas for Reionization and Lensing Science (PEARLS) staff and lead writer of considered one of 4 papers analyzing the El Gordo observations.

The Fishhook

Inside the picture of El Gordo, one of the placing options is a brilliant arc represented in crimson at higher proper. Nicknamed “El Anzuelo” (The Fishhook) by considered one of Frye’s college students, the sunshine from this galaxy took 10.6 billion years to succeed in Earth. Its distinctive crimson colour is because of a mix of reddening from dust inside the galaxy itself and cosmological redshift attributable to its excessive distance.

By correcting for the distortions created by lensing, the staff was in a position to decide that the background galaxy is disk-shaped however solely 26,000 light-years in diameter—about one-fourth the dimensions of the Milky Way. In addition they had been in a position to research the galaxy’s star formation historical past, discovering that star formation was already quickly declining within the galaxy’s heart, a course of often known as quenching.

“We had been in a position to rigorously dissect the shroud of dust that envelops the galaxy heart the place stars are actively forming,” stated Patrick Kamieneski of Arizona State College, lead writer on a second paper. “Now, with Webb, we are able to peer by this thick curtain of dust with ease, permitting us to see firsthand the meeting of galaxies from the within out.”

The Skinny One

One other distinguished characteristic within the Webb picture is a protracted, pencil-thin line at left of heart. Generally known as “La Flaca” (the Skinny One), it’s one other lensed background galaxy whose gentle additionally took practically 11 billion years to succeed in Earth.

Not removed from La Flaca is one other lensed galaxy. When the researchers examined that galaxy intently, they discovered three photographs of a single red giant star that they nicknamed Quyllur, which is the Quechua time period for star.

Beforehand, Hubble has discovered different lensed stars (resembling Earendel), however they had been all blue supergiants. Quyllur is the primary particular person red giant star noticed past 1 billion light-years from Earth. Such stars at excessive redshift are solely detectable utilizing the infrared filters and sensitivity of Webb.

“It is virtually unimaginable to see lensed crimson large stars until you go into the infrared. That is the primary one we have discovered with Webb, however we anticipate there can be many extra to return,” stated Jose Diego of the Instituto de Física de Cantabria in Spain, lead writer of a 3rd paper on El Gordo.

Galaxy group and smudges

Different objects inside the Webb picture, whereas much less distinguished, are equally fascinating scientifically. For instance, Frye and her staff (which incorporates 9 college students from high school to graduate college students) recognized 5 multiply lensed galaxies that look like a child galaxy cluster forming about 12.1 billion years in the past. There are one other dozen candidate galaxies that will even be a part of this distant cluster.

“Whereas further knowledge are required to verify that there are 17 members of this cluster, we could also be witnessing a brand new galaxy cluster forming proper earlier than our eyes, simply over a billion years after the large bang,” stated Frye.

A closing paper examines very faint, smudge-like galaxies often known as ultra-diffuse galaxies. As their title suggests, these objects, that are scattered all through the El Gordo cluster, have their stars extensively unfold out throughout space. The staff recognized a number of the most distant ultra-diffuse galaxies ever noticed, whose gentle traveled 7.2 billion years to succeed in us.

“We examined whether or not the properties of those galaxies are any totally different than the ultra-diffuse galaxies we see within the native universe, and we do really see some variations. Particularly, they’re bluer, youthful, extra prolonged, and extra evenly distributed all through the cluster. This means that dwelling within the cluster surroundings for the previous 6 billion years has had a big impact on these galaxies,” defined Timothy Carleton of Arizona State College, lead writer on the fourth paper.

“Gravitational lensing was predicted by Albert Einstein greater than 100 years in the past. Within the El Gordo cluster, we see the ability of gravitational lensing in motion,” concluded Rogier Windhorst of Arizona State College, principal investigator of the PEARLS program. “The PEARLS photographs of El Gordo are out-of-this-world stunning. And, they’ve proven us how Webb can unlock Einstein’s treasure chest.”

The paper by Frye et al. has been revealed within the Astrophysical Journal. The paper by Kamieneski et al. has been accepted for publication within the Astrophysical Journal. The paper by Diego et al. has been revealed in Astronomy & Astrophysics. The paper by Carleton et al. has been accepted for publication within the Astrophysical Journal.