Sep 11, 2020 12:15 AM
(This post was last modified: Sep 11, 2020 11:09 PM by C C.)
Not aliens but ORCs: What are these mysterious giant radio rings in the sky?
https://www.syfy.com/syfywire/not-aliens...in-the-sky
EXCERPTS: The astronomers who found them call them ORCs, for Odd Radio Circles — I have to give them credit for that, it cuts to the chase — and skipping ahead a chapter or two: They don't know what they are. [...] The ORCs are very faint, and very rare, which is likely why they've been missed before. ... None of the four seems to have a counterpart in optical or infrared light, or in X-rays.
The fact that they appear to be rings is interesting. This is typical of spherical shells, like soap bubbles. [...] But it's not clear what's going on with these ORCs. Two of them are actually close together in the sky, implying they're related, but the other two are not. Weirdly, they're all about the same apparent size on the sky ... Three of them appear to be partly filled with material, and the fourth looks more like a disk.
Two of them have galaxies near their centers. One of them may be coincidence, but the other one's galaxy is emitting radio waves, so maybe it's creating this ring. If it is, at the galaxy's distance of 4 billion light years, the ring would be over a million light years across. That's… quite large. Roughly 8 times the diameter of our entire galaxy!
[...] The authors go through a laundry list of possible causes, but none is really satisfying. One guess would be gas flowing out of a galaxy — they look at a few ways this could happen — but even that seems unlikely. Nothing really ticks all the boxes with these objects. Of course, it's possible they're seeing different phenomena that all happen to make big faint circles of radio emission. Who knows. There's so little info it's hard to say... (MORE - details)
New Hubble Data Suggests There is an Ingredient Missing from Current Dark Matter Theories
https://www.spacetelescope.org/news/heic2016/
Nearby Supernova Should Be Common, So Why Aren’t They?
https://www.forbes.com/sites/briankoberl...rent-they/
INTRO: We know that supernovae are relatively common in other galaxies. Telescope observations of supernova have occurred regularly since the 1800s. Since then, we've observed more than 10,000 supernovae in other galaxies. So why don't we periodically see supernovae in the Milky Way? One idea is that while supernovae do happen, they occur in regions obscured by gas and dust. There is some evidence to support this... (MORE)
A New Cosmic Tension: The universe might be too thin
https://www.quantamagazine.org/a-new-cos...-20200908/
INTRO: The cosmos is starting to look a bit weird. For a few years now, cosmologists have been troubled by a discrepancy in how fast the universe is expanding. They know how fast it should be going, based on ancient light from the early universe, but apparently the modern universe has picked up too much speed — a clue that scientists might have overlooked one of the universe’s fundamental ingredients, or some aspect of how those ingredients stir together.
Now a second crack in the so-called standard model of cosmology may be forming. In late July, scientists announced that the modern universe also looks unexpectedly thin. Galaxies and gas and other matter haven’t clumped together quite as much as they should have. A few earlier studies offered similar hints, but this new analysis of seven years of data represents the cleanest stand-alone indication of the anomaly yet.
“If we were having conferences,” said Michael Hudson, a cosmologist at the University of Waterloo in Canada who is not involved in the research, “all the coffee chatter would be about these results.”
Like most measurements of the large-scale structure of the present-day universe, the study is fraught with technical difficulties. It’s also possible, though unlikely, that the results are due to chance. Nevertheless, some researchers wonder if the trend toward increasingly funky measurements may foreshadow the discovery of a new cosmic agent. “We’ve already got dark matter and dark energy,” Hudson said. “I hope we don’t need another dark thing.” (MORE)
https://www.syfy.com/syfywire/not-aliens...in-the-sky
EXCERPTS: The astronomers who found them call them ORCs, for Odd Radio Circles — I have to give them credit for that, it cuts to the chase — and skipping ahead a chapter or two: They don't know what they are. [...] The ORCs are very faint, and very rare, which is likely why they've been missed before. ... None of the four seems to have a counterpart in optical or infrared light, or in X-rays.
The fact that they appear to be rings is interesting. This is typical of spherical shells, like soap bubbles. [...] But it's not clear what's going on with these ORCs. Two of them are actually close together in the sky, implying they're related, but the other two are not. Weirdly, they're all about the same apparent size on the sky ... Three of them appear to be partly filled with material, and the fourth looks more like a disk.
Two of them have galaxies near their centers. One of them may be coincidence, but the other one's galaxy is emitting radio waves, so maybe it's creating this ring. If it is, at the galaxy's distance of 4 billion light years, the ring would be over a million light years across. That's… quite large. Roughly 8 times the diameter of our entire galaxy!
[...] The authors go through a laundry list of possible causes, but none is really satisfying. One guess would be gas flowing out of a galaxy — they look at a few ways this could happen — but even that seems unlikely. Nothing really ticks all the boxes with these objects. Of course, it's possible they're seeing different phenomena that all happen to make big faint circles of radio emission. Who knows. There's so little info it's hard to say... (MORE - details)
New Hubble Data Suggests There is an Ingredient Missing from Current Dark Matter Theories
https://www.spacetelescope.org/news/heic2016/
Nearby Supernova Should Be Common, So Why Aren’t They?
https://www.forbes.com/sites/briankoberl...rent-they/
INTRO: We know that supernovae are relatively common in other galaxies. Telescope observations of supernova have occurred regularly since the 1800s. Since then, we've observed more than 10,000 supernovae in other galaxies. So why don't we periodically see supernovae in the Milky Way? One idea is that while supernovae do happen, they occur in regions obscured by gas and dust. There is some evidence to support this... (MORE)
A New Cosmic Tension: The universe might be too thin
https://www.quantamagazine.org/a-new-cos...-20200908/
INTRO: The cosmos is starting to look a bit weird. For a few years now, cosmologists have been troubled by a discrepancy in how fast the universe is expanding. They know how fast it should be going, based on ancient light from the early universe, but apparently the modern universe has picked up too much speed — a clue that scientists might have overlooked one of the universe’s fundamental ingredients, or some aspect of how those ingredients stir together.
Now a second crack in the so-called standard model of cosmology may be forming. In late July, scientists announced that the modern universe also looks unexpectedly thin. Galaxies and gas and other matter haven’t clumped together quite as much as they should have. A few earlier studies offered similar hints, but this new analysis of seven years of data represents the cleanest stand-alone indication of the anomaly yet.
“If we were having conferences,” said Michael Hudson, a cosmologist at the University of Waterloo in Canada who is not involved in the research, “all the coffee chatter would be about these results.”
Like most measurements of the large-scale structure of the present-day universe, the study is fraught with technical difficulties. It’s also possible, though unlikely, that the results are due to chance. Nevertheless, some researchers wonder if the trend toward increasingly funky measurements may foreshadow the discovery of a new cosmic agent. “We’ve already got dark matter and dark energy,” Hudson said. “I hope we don’t need another dark thing.” (MORE)