Science & Technology

“Double” galaxy mysteries Hubble astronomers – “We were really confused”

This Hubble Space Telescope snapshot shows three magnified images of distant galaxies embedded in a cluster of galaxies. These images are produced by a natural trick called a gravitational lens. The huge gravity of the cluster of galaxies magnifies and distorts the light from the distant galaxies behind it, creating multiple images. The cluster of galaxies, cataloged as SDSS J223010.47-081017.8, is 7 billion light-years away from Earth. Hubble has observed many gravitational lens galaxies. However, the images found in this Hubble snapshot are unique. The two magnified images shown in the lower right drawer are exactly copied to each other. The two bright ovals are the galactic centers. This rare phenomenon occurs because the background galaxies straddle the ripples in the structure of space. This “ripple” is the region of maximum magnification caused by the gravity of large amounts of dark matter, the invisible adhesive that makes up most of the mass of the universe. When light from a distant galaxy passes through the cluster along this ripple, two mirror images are generated, and the third image can be seen from the side. A close-up of the third image is shown in the upper right drawer. This image most closely resembles a remote galaxy located more than 11 billion light-years away. Based on this image reconstruction, researchers have determined that distant galaxies appear to be straight barred spiral galaxies with ongoing massive star formation. The mirror images are named “Hamilton’s Objects” after the astronomers who discovered them. Credit: Joseph DePasquale (STScI)

Looking at the universe is like looking in the mirror of a fan house. This is because gravity distorts the structure of space and creates an optical illusion.

Many of these optical illusions appear when the light of a distant galaxy expands, stretches, and brightens as it passes through the giant galaxy or cluster of galaxies in front of it. This phenomenon, called a gravitational lens, produces multiple stretched, bright images of the galaxy in the background.

This phenomenon allows astronomers to study galaxies that are so far away that they can only be seen by the gravitational lensing effect. The challenge is to try to reconstruct a galaxy far away from the strange shape created by the lens.

But astronomers Hubble Space Telescope While analyzing the burning core of active galaxies, quasars, I came across one of those strange forms. They found two bright, linear objects that looked like mirror images of each other. There was another strange object nearby.

Its features were so confusing to astronomers that they took years to unravel the mystery. With the help of two gravitational lens experts, the researchers determined that the three objects were distorted images of distant, undiscovered galaxies. But the biggest surprise was that the linear objects were exact copies of each other. This is a rare event caused by the precise alignment of the background galaxy and the lens cluster in the foreground.

Hubble Space Telescope on Earth

A 3D animation showing the Hubble Space Telescope on Earth. Credit: ESA / Hubble (M. Kornmesser & LL Christensen)

Astronomers have seen some pretty weird things scattered in our vast universe, from exploding stars to colliding galaxies. So when they see a strange object, you will think they can identify it.

However NASAThe Hubble Space Telescope has discovered what looks like a pair of identical objects that look so strange that astronomers took years to determine what they were.

“We were really confused,” said Timothy Hamilton, an astronomer at Shawnee State University in Portsmouth, Ohio.

The oddball object consists of a pair of galactic bulges (hubs filled with stars in the center of the galaxy) and at least three nearly parallel split stripes. While using Hubble to investigate the collection of quasars, the burning core of active galactic nuclei, Hamilton accidentally discovered them.

After chasing dead-end theory, asking colleagues for help, and headaches, a growth team led by Hamilton and Richard Griffiths at the University of Hawaii in Hilo has finally put together all the clues to solve the mystery.

The linear object was a stretched image of a distant galaxy with a gravitational lens at a distance of more than 11 billion light-years. And they looked like mirror images of each other.

The team found that the enormous gravity of the intervening, uncatalogized cluster of galaxies distorts space and magnifies, brightens, and stretches images of the distant galaxies behind it. This is a phenomenon called gravitational lens. Hubble’s research reveals much of the distortion of these fanhouse mirrors caused by gravitational lenses, but this object was uniquely embarrassing.

In this case, accurate alignment between the background galaxy and the cluster of galaxies in the foreground produces two magnified copies of the same image of distant galaxies. This rare phenomenon occurs because the background galaxies straddle the ripples in the structure of space. This “ripple” is the region of maximum magnification caused by the gravity of large amounts of dark matter, the invisible adhesive that makes up most of the mass of the universe. When light from a distant galaxy passes through the cluster along this ripple, two mirror images are generated, and the third image can be seen from the side.

Griffith compares this effect to the bright wavy pattern found at the bottom of the pool. “Think of the wavy surface of the pool on a sunny day. You can see a bright light pattern at the bottom of the pool,” he explained. “These bright patterns on the bottom are caused by the same kind of effect as gravitational lenses. The ripples on the surface act as partial lenses, concentrating sunlight on the bright wavy patterns on the bottom.”

In the distant galaxies of gravitational lenses, the ripples greatly magnify and distort the light from the background galaxies passing through the cluster. Ripples act like an incomplete curved mirror that produces dual copies.

Solve the mystery

However, when Hamilton discovered a strange linear feature in 2013, this rare phenomenon was not well known.

When he looked at the quasar image, a snapshot of the stripes parallel to the mirrored image stood out. Hamilton had never seen anything like that and had no other team members.

“My first thought was probably that they were interacting with the arms that stretched the galaxy properly,” Hamilton said. “It didn’t fit really well, but I didn’t know what else to think about.”

There Hamilton and his team began their quest to solve the mystery of these appetizing straight lines, later called Hamilton’s Objects for their discoverers. They gave a strange image to their colleagues at an astronomical conference that elicited a variety of reactions, from cosmic strings to planetary nebulae.

But then Griffith, who wasn’t a member of the original team, provided the most compelling explanation when Hamilton showed him the image at the 2015 NASA meeting. Images of other giant galaxy clusters amplifying images of very distant galaxies. Griffith confirmed this idea when he learned of a similar linear object in one of Hubble’s deep cluster studies.

However, the researchers still had problems. They could not identify the lens cluster. Astronomers who study clusters usually first look at the cluster in the foreground causing the lens effect, and then find a magnified image of a distant galaxy within the cluster. A search of the Sloan Digital Sky Survey image revealed that there was a cluster of galaxies in the same area as the magnified image, but it did not appear in the cataloged survey. Nevertheless, the fact that the strange image is in the center of the cluster made it clear to Griffith that the cluster was producing the lens image.

The researcher’s next step was to determine if the three lens images were at the same distance, and thus all were distorted portraits of the same distant galaxy. Spectroscopic measurements at the Gemini and WM Keck Observatory in Hawaii helped researchers confirm that, and showed that the lens images were from a galaxy more than 11 billion light-years away.

The remote galaxy based on the reconstruction of the third lens image looks like a straight barred spiral galaxy with ongoing massive star formation.

Almost at the same time as the spectroscopic observations by Griffith and Hiro’s undergraduates, another group of researchers in Chicago identified the cluster and used Sloan data to measure its distance. The clusters are more than 7 billion light-years away.

However, with little information about the clusters, Griffith’s team was still struggling with how to interpret these anomalous lens shapes. “This gravitational lens is very different from most lenses previously studied by Hubble, especially in the Hubble Frontier Field Survey of Clusters,” Griffith explained. “You don’t have to stare at these clusters for a long time to find many lenses. For this object, this is the only lens we have. And at first we didn’t even know about the clusters.”

Invisible mapping

At that time, Griffith called on gravitational lens theory expert Jenny Wagner of the University of Heidelberg in Germany. Wagner studied similar objects and worked with his colleague Nicholas Tessole, now at the University of Manchester, England, to develop computer software to interpret such unique lenses. Their software helped the team understand what all three lens images looked like. They conclude that the dark matter around the stretched image needs to be “smoothly” distributed in space on a small scale.

“It’s great that we only need two mirror images to get a scale of how much dark matter agglomerates in these positions,” Wagner said. “We are not using a lens model here. We just get the observables of multiple images and the fact that they can be converted to each other. They can be folded together by our method. Already shows how smooth the dark matter needs to be in these two positions. “

According to Griffith, this result is important. Because astronomers still don’t know what dark matter is, almost a century after it was discovered. “We know it’s some form of problem, but we don’t know what the constituent particles are, so we have no idea how it works. It has mass and We know that it is affected by gravity. The importance of limiting the size of agglomerates or smoothness is that it gives us some clues as to what the particles are. The smaller the mass of matter, the larger the particles must be. “

The team’s treatise appears in the September issue of. Monthly Notification of the Royal Astronomical Society..

See also: “Hamilton Objects-Galaxy Cluster Gravity-Collectic Alkali Massive Galaxy: Constrains of Dark Matter Aggregation” Richard E Griffith, Mitchell Rudisel, Jenny Wagner, Timothy Hamilton, Pochifan, Carolyn Vilfort, May 17, 2021 Monthly Notification of the Royal Astronomical Society..
DOI: 10.1093 / mnras / stab1375

The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland operates Hubble Science. STScI is operated for NASA by the Association of Astronomy Research Universities in Washington, DC.

“Double” galaxy mysteries Hubble astronomers – “We were really confused” “Double” galaxy mysteries Hubble astronomers – “We were really confused”

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