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The earliest example of merging galaxies ever found

Galaxies are not very rare, but they are important events. Not just for the galaxies involved, but for scientists trying to merge how the galaxies evolve. Now, astronomers using ALMA have found the earliest example than merging galaxies.

The pair of merged galaxies in question is called B14-65666, an unmanageable name but scientifically useful. (For now, we refer to it as "the object".) The object is 13 billion light years away in the constellation of Sextans. This means that the light we see now left the object 13 billion years ago, just after the beginning of the universe.

This is not the first time this item has been detected. Previously, Hubble discovered this object, but it appeared to Hubble as two separate objects, probably star clusters. But the team using the Atacama Large Millimeter / submillimeter array (ALMA), perhaps the world's most sensitive radio telescope, has shown that the object is actually two merged galaxies 1

3 billion years ago.

The results of these new observations are published in the publications of Japan's astronomical community on June 18, 2019. The name of the paper is "Big Three Dragons": az = 7.15 Lyman Break Galaxy Detected in [OIII] 88 um, [CII] 158 um and Dust Continuum with ALMA. "Lead author of the study is Takuya Hashimoto from Waseda University, Japan.

When Hubble looked at the object, it was limited to ultraviolet spectrum. With that limitation, the object appeared to be two-star clusters, one in the northeast and one in the southwest. But when Hashimoto and his team used Alma's power to study the object, they saw something else: the digital fingerprints of chemical elements.

ALMA could see the radio wave emissions of coal, oxygen and dust in the object. The discovery of the three signals was the key to unlocking the object's nature.

Analysis showed that the object actually has two parts, just like the Hubble saw, but the signals from coal, oxygen and dust added another layer of information on the object thanks to ALMA, showing that while the two blobs are distinct, they form a single system Each blob moves at a different speed, showing that they are two galaxies being merged.

The artist's impression of the The merged galaxies B14-65666 are 13 billion light-years away. Credit: NAOJ.

"With rich data from ALMA and HST, coupled with advanced data analysis, we were able to combine the pieces to show that B14-65666 is a pair of merged galaxies in the earliest times of the universe," Hashimoto explains in a press release. "Radio wave detection from three components in such a distant object demonstrates ALMA's high ability to investigate the distant universe."

According to the study, the object is now the earliest known example of a galaxy fusion. The researchers also estimated the total star mass B14-65666 as less than 10% of the winter street mass. This means that the object is in the earliest stages of its development. It makes sense, because it is ancient.

Although the object is young, it is much more active in star production than our own galaxy is. ALMA observations discovered high temperatures and brightness in dust. The authors say it is probably the result of very powerful ultraviolet radiation produced by active star formation. The active star formation is another indication of the merging of galaxies, as colliding galaxies undergo much gas compression, triggering disturbances of the star formation. As the authors say in their paper, "… we claim that B14-65666 is a starburst galaxy induced by a larger merger."

This is a composite image of the object B14-65666. Red is dust, oxygen is green and carbon is blue. White is the stars seen by the Hubble Space Telescope. Image Credit: ALMA (ESO / NAOJ / NRAO), NASA / ESA Hubble Space Telescope, Hashimoto et al.

"Our next step is to search for nitrogen, another major chemical element and even the carbon monoxide molecule" Akio Inoue, a professor at Waseda University and a part of the research group. "Ultimately, we hope to understand the circulation and accumulation of elements and materials associated with galaxy formation and evolution."

Galaxies are an important part of the development of galaxies. Often, a larger galaxy swells one less. Small galaxies can merge to form larger, but it is considered rare. Our own Milky Way has experienced mergers that helped to grow to its present huge size.

In a 2018 paper, astronomers presented evidence based on a century of observations showing that the Milky Way contains a population of stars from another galaxy. About ten billion years ago, another galaxy collided with our own, leaving a distinct population of stars in the galactic inner halo. The authors of this document argued that these stars are from a small galaxy that was about the size of the small magellanic cloud.

In about 4.5 billion years, the Milky Way will collide with the Andromeda Galaxy and merge. The resulting galaxy will be called, possibly, Milkdromeda. And right now, the Milky Way is associated with or eating, the much smaller ghost galaxy called Antlia 2 (Ant 2).

The authors of the investigators believe that, as our wake-up call, there may be more mergers in the future of the objects (formerly?) Which so far are undiscovered. In the paper, they say "Although our current data does not show company objects around B14-65666, future deeper ALMA data could reveal companion galaxies around B14-65666." They conclude that the object is an important candidate for follow-up observations. "Given the rich data available and spatially expanded, B14-65666 is one of the best targets for follow-up observations with ALMA and James Webb Space Telescope …"


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