Circles, bursts, and transients

I hate it when popular media reports on science stories with headlines like, "New Discovery Has Researchers Stumped!" and "This Will Rewrite Every Textbook On The Subject!" and "Recent Find Sends Scientists Back To The Drawing Board!"

The truth is that it's very seldom that real, honest-to-goodness paradigm shifts happen in science.  We've been at this long enough that most of the basic theory, in just about every branch of science, is on rock-solid footing.  It's highly doubtful that much of anything will "rewrite all the textbooks," and as far as the last one, I tend to agree with eminent astrophysicist Neil deGrasse Tyson.  "As scientists, we're always at the drawing board.  If you're not at the drawing board, you're not doing science."

As we've seen over the last few days' posts, however, that doesn't mean the experts have everything figured out.  Even if the overall edifice of science is on a firm enough foundation that it's doubtful it'll ever be significantly overturned, there's still plenty of area to explore around what NdGT calls "the perimeter of our ignorance."

So appropriately enough, given our recent theme of "Stuff We Haven't Figured Out Yet," today we're going to look at three recently discovered astronomical phenomena that thus far, have eluded astrophysicists' best attempts at an explanation.

First, we have the aptly-named odd radio circles that were discovered through work at the Australian Square Kilometre Array Pathfinder Telescope (ASKAP).  These structures, which "do not seem to correspond to any... known object or artefact," resemble gossamer soap bubbles in space, glowing faintly in the radio region of the electromagnetic spectrum (thus the name).  As far as astronomers have found, none of them seem to have anything at the center, which seems to rule out something like a planetary nebula, which is the (usually) spherical shell of ionized gas blown off the surface of a red giant star as it nears the end of its life.

Odd radio circle ORC J-2103-6200, in an image from the MeerKAT Radio Telescope in South Africa [Image licensed under the Creative Commons Jayanne English MeerKAT, ORC J2103-6200 2022, CC BY-SA 4.0]

Thus far, five odd radio circles have been identified, but astrophysicists have no good explanation of how they form.

Second, we have high energy neutrino bursts.  You probably know that neutrinos are tiny, electrically-neutral particles with such a vanishingly small rest mass that they almost never interact with matter at all.  As you read that last sentence, literally billions of neutrinos went right through you, and very likely not a single one affected any of your atoms in the slightest.  

So as you might imagine, studying such an aloof particle isn't easy.  But that's exactly what the IceCube Neutrino Observatory at Amundsen-Scott South Pole Station in Antarctica does -- uses highly sensitive detectors, dropped into deep holes bored into the Antarctic ice sheet, to catch the elusive motes of energy when they do interact with the matter they're flying through.

And at IceCube, they found twenty-eight separate events that defy explanation -- neutrinos that carried an astonishing energy of 50 trillion electron volts.  "The events cannot be explained by other neutrino fluxes, such as those from atmospheric neutrinos, nor by other high-energy events, such as muons produced by the interaction of cosmic rays in the atmosphere," the researchers said.  "The neutrinos are known to be extra-galactic in origin, and reach such extreme energies that, according to current physics, they must be generated in the equivalent of a huge-scale natural particle accelerator of some kind -- possibly black-hole driven."

But what process could give neutrinos such ridiculously high energies is thus far unknown.

If that's not extreme enough for you, consider a newly-discovered class of astronomical objects called fast blue optical transients.  FBOTs, as they're called, create sudden bursts of energy peaking in the blue region of the visible light spectrum, but (true to their name) fade almost as soon as they peak.  This makes spotting them tricky; you have to have your telescope pointing exactly the right direction at exactly the right time to see them.  The result is that only three have been observed thus far, but what we've seen is nothing short of astonishing.

FBOTs are high on the list of the most energetic phenomena ever studied.  In a fraction of a second, they eject material with a mass of around one-tenth that of the Sun -- at a velocity of 55%  of the speed of light.  The study, which appeared in Astrophysical Journal Letters, reflects how hard it is to talk about these things without lapsing into superlatives.

"This was unexpected," said Northwestern University's Deanne Coppejans, first author of the study, which is such an understatement it's kind of funny.  "We know of energetic explosions that can eject material at almost the speed of light, specifically gamma ray bursts, but they only launch a small amount of mass -- about one millionth the mass of the sun.  CSS161010 [one of the FBOTs Coppejans and her team studied] launched between one and ten percent the mass of the Sun at more than half the speed of light -- evidence that this is a new class of transient."

"We thought we knew what produced the fastest outflows in nature," said Raffaella Margutti, also of Northwestern, and a senior author of the study.  "We thought there were only two ways to produce them -- by collapsing a massive star with a gamma ray burst or two neutron stars merging.  We thought that was it.  With this study, we are introducing a third way to launch these outflows.  There is a new beast out there, and it's able to produce the same energetic phenomenon."

However, the mechanism by which these objects propel that kind of mass at such phenomenal speeds is completely unknown.

So there we are.  Three astrophysical puzzles that are on the other side of the "perimeter of our ignorance."  Thus illustrating what I've said many times before, which is that if you're interested in science, you'll never be bored.  Also shows that Shakespeare had it spot-on four-hundred-odd years ago, doesn't it?  "There are more things in heaven and earth, Horatio/ Than are dreamt of in your philosophy."

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Ghost rings and interstellar mysteries

I love a good mystery.  There's something about the phrase "there's something going on here, but we don't know what it is" that immediately makes my ears perk up.  And for someone of that bent, there's no field like astrophysics.

The whole science of astrophysics is a relatively new invention.  Astronomy, of course, has been around for millennia; there are complex star charts made by Chinese astronomers that date back to the eleventh century, and our observations of the constellations and planets goes back to the time of the Babylonians.  

We've been looking up for a long, long time.

The problem, of course, is that looking at the stars from a distance is one thing, but finding out anything about what they actually are when we can't physically go there is quite another.  Even finding out what they're made of was a baffling question with no obvious answer.  Up until (very) recently, our best telescopes weren't sufficient to see any detail at all on even the largest stars; even through the Mount Wilson Observatory Telescope they just look like points of light with no discernible features whatsoever.  

The first step toward seeing more than that came from research by German physicist Joseph von Fraunhofer in the early nineteenth century, when he invented the spectroscope -- basically a very well-made prism -- and found that in the light from the Sun there were dozens of dark lines (now called Fraunhofer lines in his honor).  Fraunhofer himself died at the young age of 39 without ever finding out what caused them -- poisoned by vapors from the heavy metals he used in his profession as a glassmaker -- but the research was taken over by Gustav Kirchhoff and Robert Bunsen, who showed that the lines were the absorption spectra of specific elements.  Basically, these lines occurred in the light emitted by a heated, glowing gas mixture, and could be used to identify what elements were in the mixture.  In fact, it was through its unique spectral fingerprint within the solar spectrum that British astronomer Norman Lockyer discovered the element he christened helium (after Helios, the Greek sun god) -- the first element that was identified out in space before it was detected here on Earth.

What this did was allow us to study the stars at a distance.  Their spectra told us for certain what stars thousands of light years away were composed of.  Through this new science of astrophysics we found out that most of the ordinary matter in the universe (96%, in fact) is hydrogen and helium; all of the other familiar heavier elements put together make up the other 4%.  It also led directly to the discovery of the expanding universe and the Big Bang when astronomer Edwin Hubble found that the familiar spectral lines of hydrogen in distant stars were red-shifted -- stretched out in the same fashion that the sound waves of a passing train get stretched, lowering the pitch as it passes you.  And it turns out that unlike trains, galaxies have a peculiar relationship between their distance and their speed.  The farther a galaxy is away from us, the more the spectral lines get red-shifted, so the faster it's moving.

The result: the universe is expanding, meaning at one point 13.8 billion years ago, it was coalesced into a single point.  All that, from the lines produced when you heat something hot enough to emit light.

Anyhow, all of this comes up because of a new discovery that has the scientists scratching their heads.  Astrophysicists Anna Kapinska and Emil Lenc were analyzing images from the Australian Square Kilometre Array Pathfinder (ASKAP) telescope, and found ghostly rings of radio emission that have no known source.  Here's one of them, dubbed ORC-1 ("odd radio circle"):

In an amusing parallel to the famous (and still unexplained) "Wow!" signal -- a narrow-band radio signal discovered in 1977 and so named because astronomer Jerry Ehman was so taken aback when he found it he wrote "Wow!" in the margin of the printout -- these ORCs have become known as "WTFs" because that's what Kapinska wrote on the photo of the first one she found.  Since then there have been dozens of WTFs found, and they still have no convincing explanation.  There doesn't seem to be anything at the center, such as the pulsars found in the middle of nebulae that are supernova remnants; they aren't star-formers like the Orion Nebula; and they don't show the spectral distortion you see with gravitational lensing, when a distant light source has its light warped around a massive object between it and us.

In short, we still have no idea.  Two Russian scientists have actually (seriously) suggested that we might be looking down the maw of a wormhole -- a thus-far theoretical astronomical object linking two different places in space-time, made famous by Star Trek: Deep Space Nine.  But that explanation is pretty out there (literally and figuratively), and to be scrupulously honest, at the moment they're still just... WTFs.

So once again, we have a demonstration that however far we've come from our ancestors looking up at the skies and seeing dogs and bears and scorpions and so on, we still have a long distance to cover before we'll have a convincing explanation of whatever we see up there.  I, for one, find that thrilling.  If in the past two centuries we've gone from stars being points of light to being able to detect and analyze radio emissions from billions of light years away, where will we be in another two hundred years?  And during that time, how many mysteries will cause scientists to say "WTF"?

Boggles the mind.

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What are you afraid of?

It's a question that resonates with a lot of us.  I suffer from chronic anxiety, so what I am afraid of gets magnified a hundredfold in my errant brain -- such as my paralyzing fear of dentists, an unfortunate remnant of a brutal dentist in my childhood, the memories of whom can still make me feel physically ill if I dwell on them.  (Luckily, I have good teeth and rarely need serious dental care.)  We all have fears, reasonable and unreasonable, and some are bad enough to impact our lives in a major way, enough that psychologists and neuroscientists have put considerable time and effort into learning how to quell (or eradicate) the worst of them.

In her wonderful book Nerve: Adventures in the Science of Fear, journalist Eva Holland looks at the psychology of this most basic of emotions -- what we're afraid of, what is happening in our brains when we feel afraid, and the most recently-developed methods to blunt the edge of incapacitating fears.  It's a fascinating look at a part of our own psyches that many of us are reluctant to confront -- but a must-read for anyone who takes the words of the Greek philosopher Pausanias seriously: γνῶθι σεαυτόν (know yourself).

[Note: if you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]