1,000 mysterious lines have been found at the center of the Milky Way
An unprecedented new photograph of the Milky Way shows nearly 1,000 mysterious silk threads at its turbulent center, oscillating incomprehensibly through space. Astronomers describe some of these threads as "harp strings". Perhaps the reason for this description is that they appear in groups and have a balanced space between the edges. Here is a photo of a mysterious linear harp-like structure taken up close. Image credit: Northwestern/Southern African Radiation Observatory (SARAO)/Oxford(Oxford).
Nearly 1,000 mysterious filaments
Maybe you saw this latest stitched image of the galactic center last week. After more than three years of surveying, the stitched image was finally released on 26 January 2022 by the South African Radio Astronomy Observatory (SARAO), revealing what an unprecedented center of the Milky Way looks like. The most fascinating part of this image is the imaging of a group of mysterious filaments located at the center of the Milky Way.
According to information provided by Northwestern University about these bizarre filaments, an astronomer at the university had already discovered some filaments in the 1980s. However, SARAO's newly released images show that these filaments are more than ten times as large as previously predicted; some of them are as long as 150 light-years away; and in addition, they are neatly arranged in the image: they are sometimes paired in groups, sometimes crisscrossed, sometimes curved into arcs, sometimes distributed like the strings of a harp — what are they?
We certainly don't know what they are. Astronomers never expected to find these filaments, and we have never observed them in such large and detailed manner before. Astronomers ruled out that supernovae are the source of strange filaments that are inherently magnetic. They hypothesized that the magnetic filaments might be related to the 4 million solar-mass black hole at the center of the Milky Way, as well as to the huge bubble that emitted radio waves discovered by Northwestern University in September 2019. Specifically, they believe that these filaments may consist of the following substances:
...... Cosmic ray electrons rotate the magnetic field at a speed close to the speed of light.
But this is just a well-founded guess. The origin of these filaments remains an unsolved mystery.
A recent study of filaments is now available online and published in the Astrophysical Journal Letters.
This image shows the magnetic field strength distribution of nearly 1,000 filaments found in the center of our Milky Way. Image courtesy of Northwestern University/SARAO/Oxford.
First discovered in 1984!
Farhad Youssef-Zad, an astrophysicist at Northwestern University, discovered the first filaments in 1984. He noted in a statement:
We have been studying individual filaments with the "myopic" field of view for a long time. Studying these filaments alone makes it difficult for us to really understand what they are and how they are formed.
Now, we have finally seen the whole picture of them – a sufficient amount of filaments with a panoramic field of view. This is a watershed moment in which we can further recognize these structures.
This is also the first time we have been able to study the statistical characteristics of these filaments. After counting them, we can learn more about the nature of these unusual sources.
It's like if you're from another planet and you meet a particularly tall person on Earth, you might assume that all Earthlings are tall. But if you count all the populations, you can get a real average height.
That's what we're doing. We can get the strength, length, direction, and spectrum of radiation of their magnetic fields.
More pictures of the mysterious filaments
This new radio image from SARAO's galactic heart — which took 3 years to make — is 10 times more than previously discovered. It's a close-up of the structure, which astronomer Yusef-Zadeh and his team say is "like a waterfall." Through sarao's images, we see such a large number of filaments that astronomers will be statistically studying them for the first time. Image courtesy of Northwestern University/SARAO/University of Oxford.
A close-up of a cluster of magnetic fibers, like a harp with broken strings. Image courtesy of Northwestern University/SARAO/University of Oxford.
At the center of our galaxy, a close-up image of a criss-crossing cluster of magnetic fibers. What are they? Image courtesy of Northwestern University/SARAO/University of Oxford.
It's a close-up photo with lines of curved filaments that astronomers call "a ring similar to Saturn." Image courtesy of Northwestern University/SARAO/University of Oxford.
Pictures of the new Milky Way
Through South Africa's MeerKAT radio telescope, SARAO took a new image of the Milky Way's core in 200 hours. The researchers stitched together 20 different observations that pointed to the center of the Milky Way 25,000 light-years from Earth. A team led by Astrophysicist Ian Heywood at the University of Oxford created new radio images. It captures more than just these lines. This image shows many phenomena, including erupting stars, star-bred regions, and new supernova remnants. Heywood said:
During the production process, I spent a lot of time looking at this picture and never got tired of it. When I show this picture to people who are unfamiliar with radio astronomy, I always try to emphasize to them that radio imaging is not always like this, and given its actual capabilities, MeerKAT is indeed a leap forward. It's been my privilege to be able to work with sarao's colleagues over the years and build this amazing telescope with them.
To more precisely observe these filaments, Yusef-Zadeh's team used a technique capable of removing the background from the main image. This is done to isolate the filaments from the surrounding structures. The resulting photos surprised him, adding:
It's like a modern work of art, the images are so beautiful and rich, and this mysterious thing makes it even more interesting.
South Africa's MeerKAT radio telescope has released this new mosaic image. This image was made over 3 years and is the heart of the Milky Way. Overall, the image covers 6 square degrees, or 30 times the area of a full moon. The plane of the Milky Way (which contains the flat part of almost all stars) passes horizontally through this image. In more detail, some of the darker regions are supernova remnants, some are star-forming regions, and some belong to a large number of mysterious radio wires. The vertical broadband (gray) across the galaxy's center marks the inner part of a giant radio bubble (previously discovered) spanning 1400 light-years. Image from I. Heywood/ SARAO。
This is the annotation diagram of the image above. This labeled image shows 1,000 mysterious silk threads that astronomers are currently exploring. They are a particularly large vertical slash that runs through the entire image. Image courtesy of Northwestern University/SARAO/University of Oxford.
We learned
In their latest paper, Yusef-Zadeh and his partners specifically explored the magnetic field of filaments and the role of cosmic rays in illuminating the magnetic field. They explain:
The changes in radiation emitted from the filaments are very different from the newly discovered supernova remnants. This phenomenon illustrates that they have different origins. The researchers found that these filaments are more likely to be related to the past activity of the supermassive black hole in the central Milky Way than to supernova explosions. These filaments may also be associated with huge bubbles that emit radios, which [we] discovered in 2019.
[We] already know that these filaments are magnetized, and [we] can also say that the magnetic field is amplified along the filaments, which is a major feature common to all filaments.
What we don't know
Among the remaining unsolved mysteries, Yusef-Zadeh is particularly puzzled by the structure of the filaments. The filaments in the cluster are exactly equal to each other — roughly equivalent to the distance from Earth to the Sun. He said thoughtfully:
They are very similar to the regular intervals of the sun ring. "We still don't know why they come together, how they separate, and even less how these regular intervals happen." Every time we answer a question, more other questions arise. “
Yusef-Zadeh and his team still don't know if the filaments move or change over time, or what causes electrons to accelerate at such an alarming rate. One of his questions:
How do you make electrons accelerate at a speed close to the speed of light? One idea is that there are some input sources at the ends of these fibers that are accelerating the particles.
Yusef-Zadeh and his team are currently identifying and classifying each filament. The angle, curve, magnetic field, spectrum and intensity of each filament will be published in future studies. Understanding these properties will provide more clues for astrophysics in understanding the elusive nature of filaments.
Summary: Scientists are exploring something new at the center of the Milky Way, under the sun ... Under billions of stars! The essence of 1000 mysterious filaments.
BY：Deborah Byrd
FY：Astronomical volunteer team
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