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A network of neurons in the brain seems to be larger in people with depression, which could change how we think about the condition's causes

Patchy garbage collection services result in more than 50 million tonnes of unmanaged plastic waste each year, and the majority of this is incinerated

After an mRNA vaccine for mpox achieved promising results in monkeys, researchers say it could have several advantages over existing vaccines – but cold storage requirements mean it will be hard to roll out in some hard-hit countries

With its particles in two places at once, quantum theory strains our common sense notions of how the universe should work. But one group of physicists says we can get reality back if we just redefine its foundations

Black holes are by their very nature, challenging to observe and difficult to spot. It’s usually observations of the accretion disk that reveal properties of the hidden black hole. There is often enough material within the accretion disk to make them shine so brightly that they can often be among the brightest objects in space. A wonderful image has been released which shows the highest resolution simulation of a black hole accretion disk ever created. 

The concept of black holes was first theorised by physicist John Mitchell in 1784 but it was Einstein’s theory of General Relativity that provided the necessary physics to understand them. The first indirect observation of a black hole came in 1971 of Cygnus X-1, the black hole at the centre of our Milky Way galaxy. Since then, more candidates have been identified with the first image of a black hole being captured in 2019.

This X-ray image of Cygnus X-1 was taken by a balloon-borne telescope, the High Energy Replicated Optics (HERO) project. NASA image.

The anatomy of black holes is fascinating and one of the most useful to astronomers is the accretion disk. It’s a swirling disk of dust and gas that orbits the black hole slowly spiralling inward before being lost beyond the event horizon. As the material accelerates, it heats up due to gravitational forces and emits the energy which we can often detect from Earth in the form of X-rays and ultraviolet radiation. 

A team of researchers from the Tohoku University and the University of Utsunomiya have announced their breakthrough in understanding the accretion disks. Using the power of  supercomputers like RIKEN’s (Japan’s largest comprehensive research institution) “Fugaku” and the National Astronomical Observatory of Japan’s “ATERUI II”, the team created the highest resolution simulations of an accretion disk to model the complex, almost chaotic nature of turbulence in the disks. 

Attempts have been made before but none of them have observed the inertial range largely due to the lack of computer power..until now. This recent study by the Japanese team has successfully reproduced the observed connections between large and small eddies in the accretion disk turbulence, the so called ‘inertial range.’ The results provide a significant step forward in understanding the physics of the environments and processes around black holes and how turbulence allows material to be transported toward the central black hole.

An artist’s illustration of a supermassive black hole (SMBH.) The SMBH in a distant galaxy expelled all the material in its accretion disk, clearing out a vast area. Image Credit: ESA

The team also discovered just why ions are selectively heated in accretion disks. Slow magnetosonic waves propagate and dominate the region causing the heating. These waves are low frequency compression waves that are driven by the interaction between a magnetic field and an electrically conductive material. The team showed that it was these waves that are thought to drive the heating process.

The study, which was published in Science Advances on 28 August, will help with the interpretation of data from telescopes like the Event Horizon telescope which is one of a number engaged in black hole studies. 

Source : Supercomputer Simulations Reveal the Nature of Turbulence in Black Hole Accretion Disks

The post Simulating the Accretion Disk Around a Black Hole appeared first on Universe Today.

Today’s Jesus and Mo strip, called “relaying“, came with the sentence, “it all makes perfect sense.” And it does, if you accept Mo’s tortured logic.  More than anyone else, Mo’s behavior defines the original meaning of “begging the question” (“assuming that which is to be proved”) rather than the current and debased meaning (‘raising the question”):

Two more installments, and we’re out of the bush. We’d spent the previous night at the Satara Rest Camp, with superb rooms in small thatched huts (photos tomorrow).  And we took off especially early because there were rumors of lions nearby: the cats who apparently killed the African buffalo whose remains I showed yesterday.

The first sign of lions were spotted hyenas in the road (their minds were squirming like a toad). I hadn’t seen a hyena crossing before, but it was a harbinger of felids to come:

Clearly they were after the carcass of the buffalo that had been killed by lions, and now was topped with a hungry vulture. But why were the hyenas staying away from the carcass? They should be all over it, nomming the rotting buffalo meat.

The reason was that the predators who killed it (and there may have been more) were very close nearby, resting and waiting to finish picking at the carcass. Yes, ladies and gentlemen, brothers and sisters, and comrades, meet the first African lions (Panthera leo) that we saw in Kruger: two males. (Note that there is a small endangered population of the same species inhabiting the Gir Forest in India.)

As we watched, one male rolled over, exposing a distended tummy. He and the other lion had clearly eaten their fill of buffalo. Look at that fat boy!

The hyenas were there because they wanted a chance at the carcass, too, having clearly smelled or seen it, but they dared not approach it because of the lions. And so they stood around hungry, their gaze riveted on the carcass:

Fixated:

“I want some!”

But this one deigned to look at us (remember, we were in a car). I think hyenas should be in Isaac’s “ugly five” of animals, but they’re not. (I believe the Marabou stork is.)

As we drove along further, we spotted an ostrich. Is this a male or a female? (There is no third sex.). A male, of course, for male ostriches are black while females are brown:

A waterbuck  (Kobus ellipsiprymnus), recognizable from its shaggy coat, the horns (found only in males) and the white ring around its butt. Some Fun Waterbuck Facts from Wikipedia:

The waterbuck has a robust build. The shaggy coat is reddish brown to grey, and becomes progressively darker with age. Males are darker than females.  Though apparently thick, the hair is sparse on the coat. The hair on the neck is, however, long and shaggy. When sexually excited, the skin of the waterbuck secretes a greasy substance with the odour of musk, giving it the name “greasy kob”. The odor of this is so unpleasant that it repels predators. This secretion also assists in water-proofing the body when the animal dives into water. The facial features include a white muzzle and light eyebrows and lighter insides of the ears. A cream-coloured patch (called “bib”) is on the throat. Waterbuck are characterised by a long neck and short, strong, black legs. Females have two nipples. Preorbital glands, foot glands, and inguinal glands are absent.

The odiferous secretion apparently is detectable in the meat if it isn’t properly prepared, and so waterbuck aren’t eaten by humans as often as are other antelope.

Why don’t we do it in the road? Martim identified this bird as a Tawny Eagle (Aquila rapax), consuming its kill, which I couldn’t identify, in the road. Its feathery legs place it in the group of “booted eagles” (subfamily Aquilinae), but it’s not the named “booted eagle” found rarely in Kruger:

A rare spot in Kruger, a secretarybird (Sagittarius serpentarius).  It’s a ground-dwelling predator that doesn’t fly often—mostly at night when it finds a tree to roost in.

From Wikipedia:

The secretarybird is instantly recognizable as a very large bird with an eagle-like body on crane-like legs that give the bird a height of as much as 1.3 m (4 ft 3 in). The sexes are similar in appearance. Adults have a featherless red-orange face and predominantly grey plumage, with a flattened dark crest and black flight feathers and thighs.

.  . The neck is not especially long, and can only be lowered down to the intertarsal joint, so birds must stoop to reach down to the ground.

. . . Prey may consist of insects such as locusts, other grasshoppers, wasps, and beetles, but small vertebrates often form main biomass. Secretarybirds are known to hunt rodents, frogs, lizards, small tortoises, and birds such as warblers, larks, doves, small hornbills, and domestic chickens. They occasionally prey on larger mammals such as hedgehogs, mongooses, small felids such as cheetah cubs, striped polecats, young gazelles, and both young and full-grown hares.

And they kill almost entirely by stomping on their prey!:

The birds often flush prey from tall grass by stomping on the surrounding vegetation. Their crest feathers may raise during a hunt, which may serve to help scare the target and provide shade for the face. A bird will chase after prey with the wings spread and kill by striking with swift blows of the feet. Only with small prey items such as wasps will the bird use its bill to pick them directly. There are some reports that, when capturing snakes, a secretarybird will take flight with their prey and then drop them to their death, although this has not been verified. Even with larger prey, food is generally swallowed whole through the birds’ considerable gape. Occasionally, like other raptors, they will hold down a food item with their feet while tearing it apart with their bill.

You can’t see how long its legs are below because they’re hidden in the tall grass:

Here’s a photo of a secretarybird skeleton taken from Wikipedia, showing how weird its body is. No other raptor looks like this:

Ryan Somma, CC BY-SA 2.0, via Wikimedia Commons

A grey heron (Ardea cinerea), widely distributed in Africa, Asia, and Europe:

A yellow-billed stork, found only in sub-Saharan Africa and Madagascar. I believe I’ve shown this bird earlier:

A beautiful Cape Starling (Lamprotornis nitens), endemic to southern Africa. It also hangs around places like rest stops and people’s houses where it might get a tidbit. Because its blue iridescence is seen only in certain lights, it often looks black, and thus its beauty isn’t noticed. (This is also true of our common starling.)

A panoramic view of the bush from an overlook. Click to enlarge the photo:

And a non-panoramic view of the bush. Remember, its barren absence of green-ness is because now in Africa it’s the dry season (winter). In summer, I’m told, the entire landscape is lush and looks completely different.

Photo below: an elephant has used its tusks to carve off pieces of this tree’s bark. Why do the pachyderms do this? For several reasons:

Where nature reserves house elephants, Africa’s largest land mammal is often singled out as the leading cause of destruction of the large trees that they share the landscape with. Elephants break trees to get easier access to the leaves, roots and nutrients. They also remove the bark to get access to the nutritious cambium layer underneath. As bark often strips off in a circular manner around the trunk, this may lead to ring barking, causing the tree to die off as the cambium layer is responsible for transporting nutrients upwards from the soil.

Here’s a video of an elephant removing bark:

The underappreciated impala:

I love their faces. Along with male nyalas, they may be the most beautiful of all antelopes I’ve seen, but I haven’t seen the tiny ones like klipspringers and dik-diks, whose photos are ineffably cute:

An older male impala whose horns have started to curve:

Two Egyptian geese (Alopochen aegyptiaca) and a Nile Crocodile. The birds are endemic to sub-Saharan Africa but have been introduced widely. I first saw them in a bay beside the Amsterdam railway station!

A male elephant leaning its butt against a tree. Yes, they can kill trees this way, too.

Another waterbuck with the “toilet-seat” ring around its butt:

I always try the local food when I can. The rest camp had a restaurant featuring this kind of food, including “chicken, pap, and ‘sas’ [sauce]”, and I much wanted to try pap.  Below is my dinner, with a roasted leg and thigh. Pap, formally called “ugali“, is a type of cornmeal similar but not identical to grits, and can be served in many different ways.

In this meal pap serves the same purpose as grits: a largely flavorless but nutritious starch that serves as a substrate for sauce or other toppings.  I loved the stuff when the ‘sas’, a type of tomato sauce made with various ingredients I’ve forgotten, was poured over the pap.

I love grits, too, though many people can’t abide their tastelessness. But they’re the perfect accompaniment to a breakfast of fried eggs, country ham, and red-eyed gravy. And I scarfed this meal down, too. It turns out that Isaac had independently ordered the same thing. See below for uncooked pap:

Pap comes in these large bags, which I saw when food was being given to hungry African villagers. It looks like white flour, with a very fine texture. Nutrients and vitamins are often added to the pap to supplement the diet:

And some signs at the Satara Rest camp extolling those who protect rhinos:

A rhino ranger with his equipment, including two horns that have presumably been removed to render the rhino immune from poaching:

And praise for the “honorary rangers” who protect the rhinos (click to enlarge the photo):

Sadly, this was our last full night at Kruger. But we had most of the next day in the park, too, and got to see the white lions at last! Stay tuned for the last segment: Day 5.

I overestimated people’s ability to spot the white lion in yesterday’s post, probably because I knew where it is. It’s hunkered down in the grass with only its back showing, and the circle below shows you where it is:

A photo with the camera zoomed in to the max:

We’ll have more and better photos tomorrow. I took this intending it to be a “spot the” photo.  Soon we’ll have a double entendre photo: “spot the leopard.”

The Moon has been a source of interest of late largely due to the focus on getting humans back to the Moon. Future human explorers though will likely be there to stay in permanent lunar bases. Making this a reality means it is of vital importance to harvest materials from the Moon and water is just one of them. Recently, ESA Announced they have secured a ride to the Moon for their Prospect package in 2027. It consists of a drill and tiny laboratory that will hunt for water and other volatiles, paving the way for human exploration.

The existence of water on the Moon was confirmed in 2009 by NASA’s Lunar Crater Observation and Sensing Satellite. It primarily exists in the form of ice in the permanently shadowed craters in the polar regions. It was a significant discovery because it meant that future human explorers might be able to harvest the water and use for drinking, oxygen and even rocket fuel. Accessing it remains however, challenging because the polar areas are a particularly harsh and challenging environment. 

Map displaying water content across the lunar surface, which was the focus of this study as researchers examined how the Earth’s magnetic field contributes to water on the Moon. As the data indicates, lunar water is primarily concentrated near the lunar poles. (Credit: Li, et al., 2023)

The search for, and analysis of the distribution of water on and under the lunar surface continues apace and one of the upcoming missions, the European Space Agency’s Prospect mission has just booked its ride to the Moon. In 2027, NASA’s Commercial Lunar Payload Services initiative will journey to the Moon and carry with it the Prospect probe that will include a drill and miniature laboratory. 

Prospect’s drill is called ‘ProSEED’ will drill into the lunar regolith (the lunar surface material) to a depth of one metre. At that depths it is expected to find temperatures less than -100 °C and so any water at that depth will be ice. It will collect samples at that depth to be transferred into the laboratory (named ProSPA) for analysis. ProSEED is capable of its own analysis work as it carries a multispectral imager (always makes me think of the Ghostbusters movie!) and a permittivity sensor. This allows the drill to measure capacitance of the material and detect volatile substances and the mineral make up of the landing site.

Once the material is transferred into ProSPA, samples will be placed into a multitude of sections like a carousel with multiple ovens, they will be sealed and heated to extract the cold trapped volatiles. It will measure the nature and concentration of volatiles from the gasses released as the samples are heated. It will also test processes for the extraction of the volatiles for future missions.

Simply understanding that water exists on the Moon is not sufficient for its future use to be planned. It is imperative that we understand just how much water is present and more importantly how accessible it is. If relatively accessible then it would be much more economical to extract the water from the Moon than to transport it there. Once it has been harvested, oxygen can be extracted to for human habitats or for rocket fuel and of course, can be used as water to drink. 

Image of the Multi-Purpose Habitat (MPH) being developed through a recent partnership between the Italian Space Agency and Thales Alenia Space. (Credit: Thales Alenia Space)

ProdSEED has already been going through extensive testing and trials in an environment similar to the surface of the Moon with low temperatures and low pressures and has proved capable of drilling into hard material to extract samples. A successful mission will not only lay the foundations for future human exploration but will also help us to get a more fuller understanding of the lunar environment.

Source : European drill and mini lab secure ride to the Moon

The post Europe is Sending a Drill to the Moon to Search for Water appeared first on Universe Today.

A newly spotted asteroid named 2024 RW1 burned up in the atmosphere over the South Pacific, creating a spectacular bright flash in the sky over the Philippines just hours after first being detected

A newly spotted asteroid dubbed CAQTDL2 will impact just east of the Philippines. There is no danger from the space rock, which will burn up in the atmosphere and could appear as bright as the moon in the night sky

In our increasingly technological we are constantly exposed to radio frequency electromagnetic waves (RF-EMF). It would certainly be inconvenient, to say the least, if this ubiquitous and essential technology had negative health effects. But of course we would need to know if this were the case so that steps could be taken to fix it. Fortunately, a recent systematic review conducted by […]

The post WHO Systematic Review of RF and Cancer first appeared on Science-Based Medicine.

Meanwhile, in Dobrzyn, Hili is remembering things past:

Hili: I’m a bit sad.
A: Why?
Hili: Because I no longer feel like climbing trees.

Hili: Trochę mi smutno.
Ja: Dlaczego?
Hili: Że nie chce mi się już wdrapywać na drzewa.

A pen which can transform Braille into English text has been developed.

A pen which can transform Braille into English text has been developed.

Where on Earth did life originate, and where else could it occur? A comprehensive answer is most likely a long way off. But it might depend on how many suitable sites for abiogenesis there are on different worlds.

We only have one data point for life: dear old Earth. Examining abiogenesis, the natural process where life originates from non-living matter, can’t be done by observing other places where it occurred. Instead, scientists use models to dig into the big question.

Manasvi Lingam is an astrobiologist at Florida Tech University. In new research, Lingam and his co-researchers examine the probability of life originating in different sites on Earth. The research is titled “A Bayesian Analysis of the Probability of the Origin of Life Per Site Conducive to Abiogenesis.” It’s published in the journal Astrobiology, and the other authors are Ruth Nichols and Amedeo Balbi.

“We can’t peer back in time. Sometimes you can arrive at answers just through very clever use of limited data… but there is a part that you’ll never know.”

Manasvi Lingam, Astrobiologist, Florida Tech University

A Bayesian Analysis uses existing knowledge—in this case, the appearance of life on Earth—to estimate how probable it is that the same thing will occur elsewhere. Disregarding panspermia, we know that life originated on Earth at least once. Scientists can use it to try to determine how probable it is that life arose elsewhere.

There are many roadblocks on our path to understanding the spontaneous appearance of life. “One of the foremost among these current limitations is our lack of conclusive knowledge regarding the minimal set of conditions necessary for engendering abiogenesis, as well as the absence of definitive data pinpointing the likely location(s) where this process took place,” the authors write.

But the fact that it did arise on Earth, at least once but possibly in multiple locations, is an information-rich fact. But the information doesn’t announce its presence. Scientists have to tease it out. “Nevertheless, the occurrence of abiogenesis on Earth still holds significant informative value,” the authors explain.

An image of Earth taken by the Galileo spacecraft in 1990. Even though we don’t know how life started, scientists can use the fact that life exists to examine the probability. Image Credit: NASA/JPL

In new research, Lingam and his co-researchers developed a model based on urable sites. Urable sites are those that are viable places where life could start. The results were surprising and counter-intuitive.

Urable sites are environments where we think life can arise. They include hydrothermal vents, impact sites, lakes and ponds, and natural atomic reactors like the one that existed in Gabon two billion years ago.

In this work, the researchers compiled a list of urable sites, and each type has a corresponding level of conduciveness for life to get going. They shaped their models according to two questions: on how many sites could life have originated on Earth, and what is the probability of life emerging for each one.

It’s critical to understand that this work can’t tell us how and where life originated. Instead, the goal was to understand how to interpret the models’ results.

In their simulations, the researchers considered three different scenarios, each with a different number of urable sites. One had only 10 urable sites, one had 1016 urable sites, and one had 1031 urable sites. They also worked with optimistic, pessimistic, and uninformative scenarios. The optimistic had a higher probability of life appearing per urable sites, the pessimistic had a lower probability, and uninformative means the results were just that.

Warm little ponds are one type of urable site. This artist’s impression shows the early Earth, where the continental crust was below sea level, and the only exposed land was volcanic islands. On these islands, bombarded by lightning, gas from volcanoes could’ve formed increasingly complex molecules in little ponds. Eventually, a molecule capable of storing information, replicating it, and mutating randomly may have formed. As these islands were eroded away, these molecules could’ve been spread into the ocean. Image Credit: NASA

The researchers anticipated that a larger number of urable sites would mean a higher probability of life emerging. But to their surprise, the opposite was true. More sites meant a lower probability of life emerging, and fewer sites meant a higher probability.

“That’s the two situations that are here. One where there are lots of sites, but there’s very low probability [of life] per site. And the second where there are very few sites, but there’s a very high probability per site,” Lingam said in a press release.

“Normally ‘the more, the better’ is the attitude for many things in life,” Lingam says. “But more is not always better. If it’s fewer, but it’s the right kind of fewer, then that can actually be better.”

This means that in their model, where Earth had the fewest urable sites, the probability of life emerging on any single site is higher. When there are plentiful sites, the probability of life emerging on any one of them is lower.

This black smoker hydrothermal vent was discovered in the Atlantic Ocean in 1979. It’s fueled from deep beneath the surface by magma that superheats the water. The plume carries minerals and other materials out to the sea. Vents like these are one type of urable site. Image Credit: USGS.

Though counterintuitive, Lingam says these results are valuable. There’s no consensus on what urable site life arose on, so different researchers can use them in their experiments to understand their own preferred environments in experiments. “Then they can do laboratory experiments, try to get a feel for how many trials might be needed to actually move to something like life,” Lingam says.

Even with all we don’t know about the origin of life, and even though these models can’t tell us how life arose, Lingam’s work can still help other researchers make progress.

“We can’t peer back in time,” Lingam says. “Sometimes you can arrive at answers just through very clever use of limited data… but there is a part that you’ll never know.”

The post Asking the Big Question: Where Did Life Originate? appeared first on Universe Today.

An intricate atlas of the inner lining of the uterus could help researchers better understand conditions like endometriosis, infertility and abnormal menstruation

A faint glow from all of the galaxies that have ever existed fills the cosmos, and NASA's New Horizons spacecraft has made the best measurement ever of just how faint it is

As part of the Commercial Crew Program (CCP), NASA contracted with commercial space partners to develop crew-capable spacecraft to restore domestic launch capability to U.S. soil. In addition to SpaceX’s Crew Dragon vehicle, which was validated in 2020 and has been transporting crews to the International Space Station (ISS) ever since. Concurrently, Boeing developed the CT-100 Starliner, which has suffered a seemingly endless string of technical issues and delays. After undergoing a long checklist of fixes, the Starliner completed its first orbital flight test (OFT-1) in May 2022.

The Starliner then made its first crewed flight to the ISS on June 5th, 2024, carrying two astronauts – Butch Wilmore and Sunita Williams. Unfortunately, malfunctions with the spacecraft’s RCS thrusters have forced it to remain in orbit until the necessary fixes were made. In addition to its thrusters, astronaut Butch Wilmore identified a strange pulsing sound coming from the Starliner crew capsule. That sound has since been identified as feedback from one of the capsule’s speakers, apparently due to an audio configuration between the ISS and Starliner.

Radio noise and feedback are common aboard the ISS and are the result of the station’s complex audio system, which allows multiple spacecraft and modules to be interconnected. Per standard practice, crews are asked to contact mission control whenever they hear sounds coming from the comm system to determine if there is a larger technical issue at work. According to NASA, the feedback Wilmore reported has no technical impact on the crew, the Starliner, or station operations and will not prevent the ship from returning.

Still, due to ongoing safety concerns, NASA has decided that the Starliner will return to Earth uncrewed no earlier than Friday, Sept. 6th. After undocking from the station and reentry, it will land at NASA’s White Sands Space Harbor in New Mexico at 12:03 AM local time (02:03 PM EDT; 11:03 AM PDT) on Sept. 7th. In the meantime, Wilmore and Williams will become part of the Expedition 71/72 crew on the station alongside cosmonauts Aleksey Ovchinin, Ivan Vagner, and NASA astronaut Donald Pettit.

Further Reading: NASA

The post There Was a Strange Sound Coming From Starliner. It Was Caused by a Speaker in the Capsule appeared first on Universe Today.

Black holes are famous for sucking in everything that crosses their event horizons, including light. So, why do astronomers see energetic radiation coming from the environment of a black hole in an X-ray binary system? It’s a good question that finally has an answer.

As a black hole and its companion star in the system orbit in a mutual gravitational dance, material from the star spirals toward the black hole. It forms an accretion disk which glows bright in X-rays. The disk is threaded through by strong magnetic fields that get twisted as the black hole and disk spins. But, where do the X-rays originate? It turns out they stream from turbulent regions in the disk. They don’t come from the black hole itself.

X-ray Binary Systems

To understand these binary systems better, it helps to take a general look at their origins. These odd couples generally contain a regular star (usually a main-sequence one) coupled gravitationally to a neutron star or a black hole. There are several types of systems. One is the low-mass type with a star that has a lower mass than the neutron star or black hole companion. There are intermediate-mass ones, which contain an intermediate-mass star, and the high-mass x-ray binary that has a very high-mass star in the system.

Artist’s impression of an X-ray binary system. This one is called MAXI J1820+070, with a black hole (small black dot at the center of the gaseous accretion disk) and a companion star. Image produced with Binsim (credit: R. Hynes).

The black hole/neutron star components form when a supermassive companion star explodes as a supernova. After that, the donor star starts losing mass to the dead star companion. The infalling material generally creates the accretion disk where high-energy activity takes place. Generally, the action in the accretion disk generates the emissions astronomers detect in these systems. The low-mass binaries emit more X-rays as part of their radiation “budget”, while the high-mass ones emit a lot of optical light in addition to the X-rays.

For a long time, scientists tried to understand the sources of the high-energy radiation by watching as the material was swept into the accretion disks. X-rays generally occur in extremely energetic environments. So, everyone assumed that these disks had localized energetic regions. One idea was that magnetic fields and local gas clouds interacted and that generated the x-rays. The activity looks similar to heating in the Sun’s environment created by magnetic activity related to solar flares. Flares do occur in the accretion disks around black holes, and they’re much more extreme than our Sun’s outbursts.

Making X-rays at Black Holes

Supercomputer simulations done at the University of Helsinki helped pinpoint the cause of the X-rays. They modeled interactions between radiation, superheated plasma, and magnetic fields in black hole accretion disks in binary pairs. The simulations showed that the turbulence around the black hole is incredibly strong. The plasma actually does produce X-rays emanating from accretion disks. Joonas Nättilä of the Computational Plasma Astrophysics group at the university led a team that investigated this kind of extreme plasma. He pointed out that to understand what’s happening we have to look at the effects of quantum electrodynamics on the system.

The team modeled a mix of electron-positron plasma and photons. Electron-positron plasma is a state where electrons and positrons interact in the confines of a strong magnetic field. In such conditions, the local X-ray radiation turns into electrons and positrons. Then, they annihilate back into radiation as they re-establish contact. Electrons and positrons are antiparticles of each other. That means they don’t usually occur in the same place. In addition, plasma and radiation don’t usually interact with each other. But, that can all change when you get into the environment around a black hole. There, electrons and positrons exist in close quarters and photons become so energetic that they become part of the activity.

“In everyday life, such quantum phenomena where matter suddenly appears in place of extremely bright light are, of course, not seen, but near black holes, they become crucial,” Nättilä said. “It took us years to investigate and add to the simulations all quantum phenomena occurring in nature, but ultimately, it was worth it,” he added.

For More Information

Explanation Found for X-ray radiation from Black Holes
Radiative Plasma Simulations of Black Hole Accretion Flow Coronae in the Hard and Soft states

Arxiv preprint

The post The Surprising Source of Radiation Coming From Black Holes appeared first on Universe Today.