A galactic Goliath stalks the ancient universe

When we look up into the sky on a clear midnight, we see an expanse of darkness punctuated by the remote fires of myriads of stars. The stars of the Cosmos inhabit the billions of galaxies that exist in the visible Universe, which is that relatively small region of the entire incomprehensibly vast Cosmos that we can observe. This is due to the finite speed of light and the accelerated expansion of space-time. The light that travels towards us from regions beyond our cosmological horizon it hasn’t had enough time to reach us since the birth of the Big Bang Universe nearly 14 billion years ago. One of the biggest mysteries astronomers face today is understanding how galaxies form. According to the prevailing theory of galactic formation, small galaxies were born first, and eventually merged in the ancient Universe to form the large and majestic galaxies seen in the Universe today. However, large galaxies have been observed to haunt the very ancient cosmos, and they should not be there according to this bottom up galaxy formation theory.

In October 2019, a team of astronomers reported that by chance they had discovered faint traces of a huge never-before-seen “monster” galaxy, dating to the very early Universe. Making a funny comparison of his galactic discovery with the photograph of the mythical monster’s footprints. Yeti– the “abominable snowman” of the Himalayan people – astronomers commented that the scientific community once believed that these galactic giants were just folklore. This is because there was no evidence of its true existence in nature, until now.

The team of astronomers, led by postdoctoral fellow Dr. Christina Williams of the University of Arizona (Tucson), says their discovery provides new insights into the first small steps of some of the largest galaxies in the Universe. The research work appears in the The Astrophysical Journal.

Dr. Kate Whitaker, an assistant professor at the University of Massachusetts Amherst and a member of the team, is an expert on the early evolution of galaxies. She noted on an October 22, 2019 Amherst press release that “These otherwise hidden galaxies are really intriguing; it makes one wonder if this is just the tip of the iceberg, with a whole new kind of galaxy population waiting to be discovered.”

The birth of the galaxies

Currently there are two main theories that seek to explain how the first galaxies were born in the ancient Cosmos. However, some astronomers propose that the truth may actually involve both ideas.

One of the prevailing theories proposes that the first galaxies formed when huge clouds composed of gas and dust collapsed under their own gravitational pull, allowing stars to be born. This is sometimes called From top to bottom theory.

The second theory, the bottom up theory, it has gained considerable credibility in recent years. According to this idea, the young Universe contained numerous relatively small droplets of matter. These little amorphous spots (protogalaxies) they met and merged, eventually growing into the large galaxies we observe in the Universe today. Tea Hubble Space Telescope (HST) you have photographed many of these clumps of material, which may be the “seeds” that eventually became modern galaxies. According to this theory, most of the great ancient galaxies were spirals. However, as time passed, many of the spirals collided and merged to create elliptical galaxies. Elliptical they are very large egg-shaped galaxies that are home to mostly old red stars. The stars that dwell within elliptical galaxies travel in chaotic orbits, which are different from the stellar populations of the neater and more elegant spirals that host stars of all ages, like our own Milky Way.

But the galactic birth process is not over. The Universe continues to evolve over time. Small galaxies are frequently eaten up by larger ones. Our own Milky Way may contain the tragic remnants of previous festivals, having eaten up many of its smaller galactic relatives, in the same way that big fish devour their little neighbors. Our galaxy is currently digesting at least one duo of unfortunate little galaxies, and it is quite possible that it will rise in others for the next billions of years. Such mergers are common because the Cosmos is crowded on the galactic distance scale.

In fact, there is a massive merger in the distant future of our Galaxy. The closest major galaxy, the great spiral Andromeda, which is slightly larger than our Milky Way, is currently at a safe distance of 2.5 million light-years. This means that the distance between this duo of large galaxies is only about 25 times greater than the size of the galaxies themselves. Like our own galaxy, Andromeda is home to stars of various ages and contains a rich supply of gas. Gravity is pulling Andromeda towards us at about 100 kilometers per second. In about 4.5 billion years, the Andromeda galaxy and our Milky Way will collide and form a single and immense elliptical galaxy that astronomers have already called the great Milkomeda Galaxy. The future Milkomeda The galaxy will be twice as large as the duo of unfortunate spirals that collided with each other to create it. Supermassive black holes, which haunt the dark hearts of both ancient spirals, will also merge, becoming twice as massive as the two black holes that collided to form a single entity. Technically, however, the Andromeda galaxy will eat our Milky Way. This is because Andromeda is a slightly larger galactic “fish”.

Galaxy mergers were more common in the early Cosmos than today because during that ancient time the Universe was smaller and considerably more populated than it is now. Therefore, the small galactic “blobs” had a better chance of colliding with each other and merging. Ancient galaxies are generally thought to be different from what we see today. The earliest galaxies showed much greater diversity, and there was a much larger population of irregular galaxies, which are usually small galaxies that have low masses and do not have a specific shape.

Which brings us to the strange existence of the “monster” galaxy that shouldn’t exist in the early Universe, where it was once thought that only the smallest protogalaxies they could exist and perform their fiery dance in the newborn light of the Cosmos.

The good news is that galactic collisions rarely result in head-on collisions between the individual constituent stars that inhabit the colliding duo. Even when two galaxies collide with each other, the distance between their stars is so great that they rarely suffer from the catastrophe. However, there are stars that can suffer as a result of the shipwreck. Some stars can be thrown into new orbits, or even shot howling from their mother galaxies, doomed to wander lost and alone in the dark nature of intergalactic space.

Although galactic collisions do not generally destroy stars, they often result in the birth of stars. As the huge clouds composed of gas and dust within the merged galaxies collide with each other, they can give birth to millions of bright new fiery baby stars.

A galactic Goliath that shouldn’t be There

Dr. Williams and her team used Atacama Large Millimeter Array (ALMA) collection of 66 radio telescopes, located high in the mountains of Chile, to make their discovery. In new observations made with extremely sensitive detection limits, Dr. Williams detected a very dim spot of light. “It was very mysterious, but the light seemed not to be linked to any known galaxy at all. When I saw that this galaxy was invisible at any other wavelength, I was very excited, because it meant that it was probably very far away and hidden by clouds of dust. “commented Dr. Williams on October 22, 2019 Amherst press release.

Astronomers estimate that the faint signal originated from so far away that it took 12.5 billion years to reach Earth. At that time, the Universe was still in its infancy. Scientists believe that the observed emission is the result of the warm glow of dust particles (effectively obscuring all light) that have been heated by fiery stars being born deep within a young galaxy.

Study co-author Dr. Ivo Labbe noted in the Amherst press release that “We discovered that the galaxy is actually a massive monster galaxy with as many stars as our Milky Way but brimming with activity, forming new stars at 100 times the speed of our own Galaxy.” Dr. Labbe is from Swinburne University of Technology in Melbourne, Australia.

The new discovery is important because it can potentially solve a long-standing puzzle in astronomy. Some of the larger galaxies that inhabit the early Universe appear to have grown and matured very rapidly, which conflicts with the theoretical predictions of the bottom up galaxy formation theory. Even more mysterious, these large, mature galaxies appear to have appeared out of nowhere when the Universe was comparatively young – barely 10% its current age, astronomers note.

Also, astronomers never seem to catch them at the point where they are first forming, Dr. Williams continued to explain to the press. Smaller galaxies have been observed in the early Universe with the hubble space telescope, but they are not growing fast enough. Other monstrous galaxies have also been previously reported. However, those sightings are too rare to provide a satisfactory explanation of what was happening in that ancient time. “Our hidden monster galaxy has precisely the right ingredients to be that missing link, because they are probably much more common,” continued Dr. Williams in the Amherst press release.

The unsolved mystery today, astronomers point out, is exactly how many of these gigantic galaxies there are. The current study was conducted in a small region of the sky, less than 1/100 the size of the full Moon. It could mean that finding “Yeti tracks” in a small strip of desert means that it was a lucky find or that they are engulfed in clouds of dust, but hidden everywhere.

Dr. Williams added that “at this time we are looking forward to the James Webb Space Telescope (JWST) to take a look at these things. JWST We will be able to look through the veil of dust so that we can learn how big these agalaxias really are and how fast they are growing, to better understand why models fail to explain them. “

Tea JWST It is a revolutionary new telescope that will be launched in March 2021.

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