EHT data reveals the donut appearance in images of the supermassive black hole Sgr A* at the center of our galaxy may be partly an artifact of the data fusion method. (Miyoshi et al)
What exactly is the supermassive black hole hiding at the center of our galaxy? This question seems simple, but the answer is not easy to obtain.
Our local black hole, called Sgr A* (short for Sagittarius A*), is just 26,000 light years from Earth, but is very difficult to capture because the matter around it moves almost as fast as light. However, after years of effort, scientists from the Event Horizon Telescope (EHT) project succeeded in taking an image in 2022. The silhouette of this black hole appears like a faint orange donut.
However, independent analysis of the EHT data suggests the donut-like appearance may be partly an artifact of the data fusion method. This finding comes from a team of scientists at the National Astronomical Observatory of Japan (NAOJ).
The ring structure actually shows intense radio waves radiating from a disk of gas rotating around the black hole, known as an “accretion disk.” Researchers suggest that these structures may actually be more elongated than they originally appeared.
“No telescope can capture astronomical images perfectly,” said NAOJ’s Makoto Miyoshi, who led the latest analysis of the EHT data. “We hypothesize these ring images arose due to errors in EHT image analysis, and are partly artifacts, not true astronomical structures.”
To date, the EHT consortium involving more than 400 researchers from 13 international institutions, including NAOJ, has not provided an official statement regarding these findings. Using only eight telescopes at six locations, there are many gaps in the data EHT collects. Katie Bouman, an assistant professor at the California Institute of Technology, described the limitations of this data as “like listening to a song on a piano that is missing a lot of keys.”
The EHT project made history in 2019 by revealing the first image of a black hole, a technological breakthrough that showed the silhouette of a giant cosmic object at the center of galaxy M87. Meanwhile, Sgr A* is more difficult to capture because it has a mass 1,600 times smaller than the black hole in M87, causing the surrounding material to move faster.
“Like a toddler who can’t stay still when being photographed,” Bouman said in a 2022 statement, describing the enormous challenge of immortalizing Sgr A*. Another challenge comes from the thick cloud of dust and gas floating between Earth and the Galactic Center which interferes with radio signals from Sgr A*.
To overcome this, the EHT team used a special computer algorithm that fills in data gaps and reconstructs the image before the signal is disrupted by turbulent gas.
“Each algorithm has a different way of determining which images are most likely,” Bouman said. “It’s as if we hired Sherlock Holmes, Hercule Poirot, Jane Marple and Jules Maigret together to see their conclusions.”
Most computer simulations of thousands of images show a bright ring of light the size of Mercury’s orbit, which matches the predictions of Albert Einstein’s general theory of relativity.
In the new study, Miyoshi and his team suggest that the ring-like structures are an artifact caused by the point spread function (PSF), which is how imaging systems measure the degree of blur caused by data gaps.
The researchers used “traditional” analysis methods on the EHT data that differ from the original EHT analysis methods. The results showed the accretion disk was slightly elongated from east to west, and the eastern part of the disk appeared brighter, which they interpreted as Doppler boost, indicating it was moving closer towards us.
“We think this appearance means the accretion disk around the black hole is rotating at about 60% the speed of light,” explains Miyoshi.
For now, both the ring look and the elongated look can still be correct. Astronomers hope that upcoming upgrades to the telescope’s technology will enable more detailed imaging, providing a better understanding of the region around Sgr A* and other black holes. (space/Z-3)
The Donut Dilemma: What’s Cooking at the Center of Our Galaxy?
Ah, the supermassive black hole Sgr A*, sitting quietly at the heart of our galaxy, quietly munching on cosmic donuts like a jailbroken kid in a donut shop. You see, capturing an image of this celestial heavyweight, located a cozy 26,000 light-years from us, has been as elusive as trying to photograph a hyperactive toddler – come to think of it, they may actually be related. Now, thanks to the mighty Event Horizon Telescope (EHT) project, we finally have an image from 2022, and surprise, surprise – it resembles a faint orange donut! 🍩
However, hold your horses, because scientists from the National Astronomical Observatory of Japan (NAOJ) are waving the red flag over this delightful donut. Their recent analysis points out that the charming ring we see may just be a fusion of data creating an illusion, like those wretched optical illusions that make it seem there’s a second floor in a one-story house!
As Makoto Miyoshi, the brave soul leading the study, pointed out, “No telescope can capture astronomical images perfectly.” Imagine telling that to a toddler who has just smashed your new phone! Their hypothesis? It’s a real head-scratcher: the ring doesn’t represent true astronomical structures but rather an intricate kind of cosmic ‘whoopsie.’ Well, that’s got to be a blow for all those who use ‘donut’ as their universe’s favorite snack!
The image itself showcases the intense radio waves emanating from the swirling dance of gas in the accretion disk surrounding the black hole – it’s like the weekend party that just won’t end! And while we all love a good cosmic ring, the researchers suggest what we might really be looking at is an elongated structure. Fancy that!
We’ve had our fair share of breakthroughs. Who can forget the monumental achievement of 2019 when the EHT project unveiled the first image of a black hole, from a different cosmic neck of the woods in galaxy M87? But Sgr A* is like that friend who takes forever to get ready, as it roams the universe with a mass 1,600 times smaller than its M87 counterpart, making its surroundings whirl in high-speed chaos.
As Katie Bouman, a self-proclaimed “black hole whisperer” at Caltech, so aptly put it, capturing Sgr A* is akin to “listening to a song on a piano that is missing a lot of keys.” Ouch! Talk about musical challenges! A bit like a karaoke night gone wrong, we must say!
But fear not, dear astronomy enthusiasts. The intriguing aspect of this research routes back to the “point spread function” (PSF). In layman’s terms, it’s just a fancy way of saying how blurry an image can be when data decides to play hide-and-seek. Sounds romantic, doesn’t it? Unfortunately, what Miyoshi and his stellar crew are suggesting is that our cosmic pastry may not be quite what it appears. The analysis shows the accretion disk might be elongated, and some parts are moving closer to us, making them brighter – it’s like cosmic gossip that travels faster than light!
Miyoshi firmly states, “We think this appearance means the accretion disk around the black hole is rotating at about 60% the speed of light.” So, if we planned a road trip with Sgr A*, we’d better call Uber – this black hole doesn’t do speed limits!
So, what’s next? Well, both the donut look and the elongated profile could be correct – just imagine trying to convince your friends that one of you is actually an adventurer while the other is more of a couch potato. Astronomers are hopeful that upcoming upgrades to the telescope’s technology will allow us to get a more precise look. Who knows, maybe by then we might also figure out how to capture a photo of a toddler at rest. Now that would truly be groundbreaking!
Rch is that it doesn’t entirely dismiss the existence of the donut shape or the interpretations tied to it; rather, it adds a layer of complexity to our understanding of black holes and the data surrounding them. After all, science is often about peeling back layers to reveal the deeper truths beneath.
Miyoshi and his team, through their alternative yet just as rigorous analysis, uncovered a slightly more elongated structure of the accretion disk surrounding Sgr A*, particularly noting a brighter eastern section due to a phenomenon known as the Doppler effect, which suggests that part of the disk is moving towards us at an impressive velocity—about 60% the speed of light! This is mind-boggling as it underscores not only the dynamics at play in the vicinity of black holes but also the continued evolution of observational techniques.
As we gear up for technological upgrades in telescope capabilities, we anticipate more exciting revelations. Imagine standing behind a curtain, and with every advance in technology, that curtain is lifted just a little more. Each reveal promises to add depth to our cosmic understanding—who knows what other secrets Sgr A* is keeping?
Ultimately, the ongoing debate and research into Sgr A* and other cosmic phenomena underscore the iterative nature of scientific discovery. As new methods are employed and technologies improve, what we think we know may always be subject to revision. So, whether we end up with a cosmic donut or an elongated snack, the quest for knowledge continues, and that’s the most delicious part of it all! 🍩✨
