New fossil reveals origin of arthropod breathing system

University of Manchester research fellow David Legg, in collaboration with a team of international scientists from China, Switzerland, and Sweden, has today announced a new fossil that reveals the origin of gills in arthropods.

Arthropods, the group of animals that includes creepy crawlies like spiders and woodlice, are the largest phylum in the animal kingdom and are found everywhere from the deepest ocean trench to the top of Mount Everest.

Research published today shows the newest addition to the group is a 520-million-year-old (about 10 times as old as the dinosaurs) organism called Erratus sperare. Erratus sperare was discovered in the Chengjiang Fossil Site, a UNESCO World Heritage Site located in Yunnan, China. The Chengjiang Fossil Site preserves an ancient underwater ecosystem which included the relatives of some well-known arthropod fossils like trilobites and anomalocarids.

Modern water dwelling arthropods have biramous limbs, legs that have two parts -- one for breathing and one for walking -- but how such specialised limbs evolved was a mystery. Some of the earliest fossil arthropods, like Anomalocaris, had swimming flaps that may have doubled as gills, but until now researchers didn't know how arthropods made the jump from these specialised flaps to the biramous limbs of modern arthropods.

Erratus sperare provides the missing link between arthropods that used such specialised flaps and arthropods with biramous limbs. It has both legs and flaps.

Dr David Legg, one of the authors of this study, said: "Fish aren't the only organisms that have gills! Arthropods have gills too… they just have them on their legs. When it came to arthropods, however, we just weren't sure where these gills came from.

"Thanks to this new fossil, Erratus sperare, we now have a much clearer idea. These gills also probably went on to evolve into the wings of insects and the lungs of terrestrial arthropods like spiders so were a very important innovation."

From Science Daily

Large new titanosaurian dinosaur from the Pyrenees

Researchers from the Institut Català de Paleontologia Miquel Crusafont (ICP), the Conca Dellà Museum (MCD), the Universitat Autònoma de Barcelona (UAB), the University of Zaragoza (UNIZAR) and the NOVA University of Lisbon (UNL) have described the new species of titanosaur dinosaur Abditosaurus kuehnei from the remains excavated at the Orcau-1 site, in the southern Pyrenees (Catalonia, Spain). The semiarticulated 70.5-million-year-old skeleton is the most complete specimen of this herbivorous group of dinosaurs discovered so far in Europe. Moreover, Abditosaurus is the largest titanosaur species found in the Ibero-Armorican island -- an ancient region nowadays comprising Iberia and the south of France -- representing a senescent individual estimated to be 17,5 meters in length with body mass of 14,000 kg.

The size of this giant is one of the most surprising facts to researchers. "Titanosaurs from the Upper Cretaceous of Europe tend to be small or medium-sized due to their evolution in insular conditions," explained Bernat Vila, paleontologist at the ICP leading the research. During the Upper Cretaceous (between 83 and 66 million years ago), Europe was a large archipelago made up of dozens of islands. The species that evolved there tend to be relatively small, or even dwarves compared to their relatives living in large landmasses, due primarily to the limitation of food resources in islands. "It is a recurring phenomenon in the history of life on Earth, we have several examples worldwide in the fossil record of this evolutionary trend. That's why we were astonished by the large dimensions of this specimen," said Vila.

The fieldwork conducted over several decades unearthed 53 skeletal elements of the specimen. These include several teeth, vertebrae, ribs, and limb, scapular and pelvic bones, as well as a semiarticulated fragment of the neck formed by 12 cervical vertebrae. "We were really lucky, it is unusual to find such complete specimens in the Pyrenees due to its troubled geologic history," explains Àngel Galobart, ICP researcher and director of the Conca Dellà Museum (Isona, Catalonia).

The excavation of the neck in 2014 was a technical challenge. Once prepared for extraction, the neck was encased in a large block of polyurethane foam, becoming one of the largest jackets ever excavated in Europe.

The history of the research that has led to the description of the new species dates back to 1954, when German paleontologist Walter Kühne collected the first remains and sent them to Madrid. The site fell into oblivion until 1986, when some more remains began to be extracted until a great storm forced the cancellation of the excavation. Subsequently, fieldwork on the site fell again into oblivion until a paleontologist from the ICP resumed systematic excavations in Orcau-1. The story of this finding was featured in the 2017 documentary "Europe's last giant." The generic name Abditosaurus means 'forgotten reptile' and the specific epithet kuehnei is a tribute to its discoverer.

A migrating dinosaur

In their article published in Nature Ecology & Evolution, researchers conclude that Abditosaurus belongs to a group of saltasaurine titanosaurs from South America and Africa, different from the rest of European titanosaurs that are characterized by a smaller size. These authors hypothesize that the Abditosaurus lineage reached the Ibero-Armorican island taking advantage of a global drop in sea level that reactivated ancient migration routes between Africa and Europe.

"Other evidence support the migration hypothesis," explains Albert Sellés, paleontologist at the ICP and co-author of the article. "In the same site we have found eggshells of dinosaur species known to have inhabited Gondwana, the southernmost continent."

The new finding is a major advance in the understanding of the evolution of sauropod dinosaurs at the end of the Cretaceous and brings a new perspective to the phylogenetic and paleobiogeographic puzzle of sauropods in the last 15 million years before their extinction.

In addition to Vila, Sellés and Galobart, Novella Razzolini (Institut Català de Paleontologia Miquel Crusafont and Conca Dellà Museum), Miguel Moreno (Museu de Lurinhã and NOVA University of Lisbon), Iñaki Canudo (Aragosaurus-IUCA Group, University of Zaragoza) and Alejandro Gil (Universitat Autònoma de Barcelona) participated in this study.

"During the Jurassic and Cretaceous, Iberia was the point of connection between Eurasia, Africa and North America. Studying how Abditosaurus relates to the fauna of these continents helps us to understand when there were connections between them, and when they became isolated," says Miguel Moreno, researcher at the Museu de Lurinhã and NOVA University of Lisbon that has performed the paleobiogeographic study.

The large Cretaceous herbivores

Titanosaurs are a group of sauropod dinosaurs that become very diverse and abundant in the terrestrial ecosystems of the Cretaceous. All of them were quadrupeds and phytophagous. Titanosaurs had a small and pointed skull, with small nail-shaped teeth used to uproot vegetation. Their body was robust, with forelimbs shorter than the hindlimbs and a long necks and tails. Some species sported a skin covered with bony plates named osteoderms that may have served as a protective shield or as a reserve of calcium.

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Vaccine protection against SARS-CoV-2 infection wanes quickly but is better maintained against severe disease, study finds

The vaccine-induced protection against SARS-CoV-2 infection wanes within a couple of months, but at different speed according to vaccine type. However, protection against severe COVID-19 appears to be better maintained. This is shown in a nationwide, registry-based study performed by researchers at Umeå University, Sweden, that now is published in The Lancet.

"The bad news is that the protection against infection seems to be diminished by seven months after the second dose of vaccine," says Peter Nordström, professor of geriatric medicine at Umeå University. "The good news, however, is that the protection against a severe infection that leads to hospitalization or death seems to be better maintained. Vaccination is therefore very wise and important."

The study, which received much attention once first posted as a 'preprint' in October, has now been peer-reviewed and the results as such confirmed. Following extensive revision and additional analyses, leading to results that more clearly show that the protection against severe COVID-19 seems better maintained than that against infection, the study has now been published in The Lancet.

The study is a nationwide, observational study based on registry-data from the Public Health Agency of Sweden, the National Board of Health and Welfare, and Statistics Sweden. The main analysis included almost 1.7 million individuals, and the results were confirmed in an even larger population of almost 4 million individuals. The results showed that protection against infection of any severity waned progressively following the peak which occurred a month after the second dose.

Six months after vaccination, the remaining protection against infection was 29 per cent from two doses of Pfizer, and 59 per cent from two doses of Moderna. There was no remaining protection from months and onwards for AstraZeneca. With respect to infections that were severe enough to warrant a hospital stay, or where the individual died within 30 days of confirmed infection, the protection was better maintained.

Protection against severe disease was 89 per cent after one month and 64 per cent from four months an onwards during the rest of the maximum follow-up of nine months. There was some evidence to suggest a lower protection in the oldest individuals and in individuals with homemaker service.

"The results underscore and support the decision to offer a third dose," says Marcel Ballin, doctoral student in geriatric medicine at Umeå University and co-author of the study. In particular, the results show that it was correct to prioritize the oldest and frailest individuals."

Prior to this study, a few observational studies and follow-up studies of the clinical trials have investigated waning vaccine protection in other countries. However, these have mostly covered the initial four to six months, and for the Pfizer vaccine.

"What this study contributes with is the longer follow-up time and the fact that we were able to explore how well the protection is maintained according to different types of vaccines," says Anna Nordström, adjunct professor in public health at Umeå University and co-author of the study.

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Impact of COVID-19 social isolation measures on early development

An international consortium with researchers from 13 countries has investigated the impact of Covid-19 related social isolation measures on 2,200 young infants and toddlers between 8 and 36 months of age. Their findings provide insights into the effects of lockdown on language acquisition and screen time in the generation of youngsters growing up during this extraordinary period. A study on the impact of lockdown-related activities on language development, led by the University of Oslo, was published in the journal Language Development Research. A second study on the increase in screen-time during lockdown and its impact on language development, led by the University of Göttingen with the Max Planck Institute for Psycholinguistics in Nijmegen and the University of Applied Sciences and Arts Western Switzerland, was published in the journal Scientific Reports.

Shortly after lockdown began in early March 2020 across 13 countries, parents were asked to complete an online questionnaire containing questions on the child's age, exposure to different languages, number of siblings and vocabulary development. Parents were then contacted again at the end of the lockdown (for that family or in that area, in general). They were asked about the activities that they undertook with their child during lockdown, the amount of time their child had access to screens both during lockdown and before, as well as questions on how much screen time they typically had themselves and their attitudes towards children's screen time. Parents were also asked to complete a standardized vocabulary checklist indicating the number of words their child understood and/or said at the beginning, and again, at the end of lockdown so that an increase in the number of words gained over lockdown could be calculated.

The studies find that, during lockdown, children who were read to more frequently were reported by their caregivers to have learned more words, relative to their peers who were read to less frequently. However, children with increased exposure to screens learned to say fewer words, relative to their peers with less screen time. In addition, while children were exposed to more screen time during lockdown than before, overall, children were reported to have gained more words than expected during lockdown, relative to pre-pandemic levels. The increase in screen time during lockdown was greater if lockdown was longer, and in families with fewer years of education, and where parents reported using screens for longer themselves.

"Identifying the effects of parent-child activities on the child's vocabulary growth is a significant finding, given that we assessed changes in children's vocabularies over an average period of just over one month in our study," says Professor Julien Mayor, University of Oslo.

"While this suggests that the relatively short isolation did not detrimentally impact language in young children, we should be cautious in assuming this would apply during normal times or to longer lockdowns, given the extraordinary circumstances that children and their parents faced during this time," adds Associate Professor Natalia Kartushina, University of Oslo.

Indeed, the authors attribute increased screen time precisely to the unprecedented circumstances that families found themselves in during lockdown, including but not limited to the closure of day care centres, sport facilities and play groups for children. "Many caregivers were in the novel situation of caring for and entertaining their young infants at home all day without recourse to other activities and in addition to their other responsibilities. Allowing your child increased screen time is an understandable solution to this unprecedented situation, in which caregivers were juggling multiple responsibilities -- meetings at work or chores that require concentration, together with a small child who needs entertaining. We've all done it during lockdown," says Professor Nivedita Mani, University of Göttingen.

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Harnessing strongest magnetic fields in universe could reveal elusive particle

Finding an elusive elementary particle is more viable than ever after an international team of scientists conducted the first experiment to explore magnetic monopoles using the Large Hadron Collider.

Scientists from the European Organisation for Nuclear Research (CERN) and physicists from the University of Nottingham and Monopole and Exotics Detector (MoEDAL) used the Large Hadron Collider to explore a production mechanism theorized by Julian Swinger, a Nobel Prize winning American Physicist. Their findings are published today in Nature.

The team is searching for magnetic monopoles, hypothetical fundamental particles with only one magnetic pole predicted by several theories, but not yet detected. Confirming their existence would be transformative for physics, proving that there are laws of nature not captured by the currently ruling theory of physics, the Standard Model, and allowing to probe new laws in unique ways.

"This specific monopole search was pioneering and opened a new, promising avenue for further searches," said Igor Ostrovskiy, a MoEDAL physicist at The University of Alabama and corresponding author of the paper. "Ours was the first search where magnetic monopoles with finite size -- the type predicted by recent theories -- were realistically detectable, and while we did not find any, we were able to set the first reliable limits on the monopole's mass."

The team searched for magnetic monopole production in the collisions of heavy ions on the world's largest and most powerful particle accelerator. The collisions generated strong magnetic fields, more powerful than those of fast-spinning neutron stars, and such strong fields could give rise to spontaneous creation of magnetic monopoles via the Schwinger mechanism.

"A big advantage of the Schwinger mechanism is that we can calculate its rate more reliably than for any other production processes explored at the LHC so far," said Oliver Gould, a research fellow at the University of Nottingham, who performed theoretical calculations for this search. "This gives us a good idea about how many monopoles should be seen by the experiment as a function of their mass and magnetic charge. And since none have been seen, we can reliably say that magnetic monopoles must be heavier than a certain value."

To detect magnetic monopoles, the MoEDAL researchers used a superconductive magnetometer to scan the detector modules exposed to the LHC lead-lead collisions for signatures of trapped magnetic charge. With no signs of the signal, the researchers were able to exclude the existence of monopoles lighter than 75 GeV/c2, where c is the speed of light, for magnetic charges ranging from 1 to 3 base units of magnetic charge.

Oliver concludes: "The search for magnetic monopoles has a rich history, bound up with many theoretical proposals in particle physics. Yet this is the first experiment that has enabled us to deduce explicit constraints on the properties of any possible magnetic monopoles. Doing so relied on the close collaborations between theorists and experimentalists."

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Scientists unveil promising new approach to diabetes prevention

A team of scientists from Scripps Research has conducted promising early tests of a new strategy that might one day be used to prevent or treat type 2 diabetes.

The scientists, whose results are reported in Nature Communications, tested an experimental compound called IXA4 in obese mice. They showed that the compound activates a natural signaling pathway that protects the animals from harmful, obesity-driven metabolic changes that would normally lead to diabetes.

"We were able to activate this pathway in both the liver and the pancreas with this one compound, and that added up to a significant overall improvement in metabolic health of obese animals," says Scripps Research's Luke Wiseman, PhD.

"This is the first time anyone has shown that a small molecule activating this pathway in this manner works to treat disease in a live animal," adds Enrique Saez, PhD.

The study was a collaboration between the laboratories of Saez and Wiseman, who are both professors in the Department of Molecular Medicine at Scripps Research and co-senior authors on the new paper.

Type 2 diabetes remains a major public health problem: about 30 million people are estimated to have it in the U.S. alone. Driven largely by overweight and obesity, it features the loss of normal blood sugar regulation, and brings a multitude of health issues including higher risks of heart disease, stroke, kidney disease, nerve damage, retinal degeneration, and some cancers. There are many drugs for treating type 2 diabetes, but none that works well for every patient.

For several years, Wiseman's lab has been studying a signaling pathway involving two proteins called IRE1 and XBP1s. When activated by a certain type of cellular stress, IRE1 activates XBP1s, which in turn alters the activity of a host of genes, including many metabolic genes, in an effort to reduce the cellular stress. Prior studies suggest that the activity of this pathway, at least in the short-term, can protect liver and fat cells from stresses caused by obesity -- stresses that can harm these cells in ways that promote diabetes.

The IRE1/XBP1s pathway is not a straightforward diabetes drug target, however. Past research has shown that keeping IRE1/XBP1 switched on chronically ends up harming cells, triggering inflammation and worsening overall metabolic dysfunction.

"IRE1/XBP1s signaling is a response to cellular stress, and keeping it on all the time essentially tells the cell that the stress can't be resolved -- so the cell in effect kills itself," Wiseman says.

In the new study, the researchers showed that a compound they identified a few years ago, IXA4, activates IRE1/XBP1s for just a few hours at a time. Because it otherwise allows IRE1 to turn off, it can in principle be given daily without triggering the deleterious signaling seen with constant IRE1 activation, making it a promising candidate to explore for human treatments.

The team used IXA4 to treat mice that were obese from a high-fat, high-calorie diet. After just eight weeks, the treated mice had improved glucose metabolism and insulin activity, less fat buildup and inflammation in the liver, and no loss of insulin-producing cells in the pancreas, compared to untreated obese mice.

IXA4 can reach only a limited set of tissues including the liver and pancreas, and so the team is now developing other compounds that can get into a broader set of cells including fat cells.

"We're also continuing to work with IXA4 as a potential treatment for other metabolic disorders such as fatty liver disease," Saez says.

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Puffy planets lose atmospheres, become super-Earths

Astronomers have identified two different cases of "mini-Neptune" planets that are losing their puffy atmospheres and likely transforming into super-Earths. Radiation from the planets' stars is stripping away their atmospheres, driving hot gas to escape like steam from a pot of boiling water.

"Most astronomers suspected that young, small mini-Neptunes must have evaporating atmospheres," says Michael Zhang, lead author of both studies and a graduate student at Caltech. "But nobody had ever caught one in the process of doing so until now."

The findings are published in two separate papers in The Astronomical Journal: one is based on data from W. M. Keck Observatory on Maunakea, Hawai'i and the other paper involves observations from NASA's Hubble Space Telescope. Together, the studies help paint a picture of how exotic worlds like these form and evolve.

Mini-Neptunes are a class of exoplanets, which are planets that orbit stars outside our solar system. These worlds, which are smaller, denser versions of the planet Neptune, consist of large rocky cores surrounded by thick blankets of gas.

In the new studies, a team of astronomers led by Caltech used Keck Observatory's Near-Infrared Spectrograph (NIRSPEC) to study one of two mini-Neptune planets in the star system called TOI 560, located 103 light-years away; and they used Hubble to look at two mini-Neptunes orbiting HD 63433, located 73 light-years away.

Their results show that atmospheric gas is escaping from the innermost mini-Neptune in TOI 560, called TOI 560.01, and from the outermost mini-Neptune in HD 63433, called HD 63433 c.

Furthermore, Keck Observatory data surprisingly showed the gas around TOI 560.01 was escaping predominantly toward the star.

"This was unexpected, as most models predict that the gas should flow away from the star," says Professor of Planetary Science Heather Knutson, Zhang's advisor and a co-author of the study. "We still have a lot to learn about how these outflows work in practice."

Planetary Gap Explained?

Since the first exoplanets orbiting Sun-like stars were discovered in the mid-1990s, thousands of others have been found. Many of these orbit close to their stars, and the smaller, rocky ones generally fall into two groups: mini-Neptunes and super-Earths. The super-Earths are as large as 1.6 times the size of Earth (and occasionally as large as 1.75 times the size of Earth), while the mini-Neptunes are between two and four times the size of Earth. Few planets with sizes between these two planet types have been detected.

One possible explanation for this gap is that mini-Neptunes are transforming into super-Earths. The mini-Neptunes are theorized to be cocooned by primordial atmospheres made of hydrogen and helium. The hydrogen and helium are left over from the formation of the central star, which is born out of clouds of gas. If a mini-Neptune is small enough and close enough to its star, stellar X-rays and ultraviolet radiation can strip away its primordial atmosphere over a period of hundreds of millions of years, scientists theorize. This would then leave behind a rocky super-Earth with a substantially smaller radius, which could, in theory, still retain a relatively thin atmosphere similar to that surrounding our own planet.

"A planet in the gap would have enough atmosphere to puff up its radius, making it intercept more stellar radiation and thereby enabling fast mass loss," says Zhang. "But the atmosphere is thin enough that it gets lost quickly. This is why a planet wouldn't stay in the gap for long."

Other scenarios could explain the gap, according to the astronomers. For instance, the smaller rocky planets might have never gathered gas envelopes in the first place, and mini-Neptunes could be water worlds and not enveloped in hydrogen gas. This latest discovery of two mini-Neptunes with escaping atmospheres represents the first direct evidence to support the theory that mini-Neptunes are indeed turning into super-Earths.

Signatures in the Sunlight

The astronomers were able to detect the escaping atmospheres by watching the mini-Neptunes cross in front of, or transit, their host stars. The planets cannot be seen directly but when they pass in front of their stars as seen from our point of view on Earth, telescopes can look for absorption of starlight by atoms in the planets' atmospheres. In the case of the mini-Neptune TOI 560.01, the researchers found signatures of helium. For the star system HD 63433, the team found signatures of hydrogen in the outermost planet they studied, called HD 63433 c, but not the inner planet, HD 63433 b.

"The inner planet may have already lost its atmosphere," Zhang explains.

The speed of the gases provides the evidence that the atmospheres are escaping. The observed helium around TOI 560.01 is moving as fast as 20 kilometers per second, while the hydrogen around HD 63433 c is moving as fast as 50 kilometers per second. The gravity of these mini-Neptunes is not strong enough to hold on to such fast-moving gas. The extent of the outflows around the planets also indicates escaping atmospheres: the cocoon of gas around TOI 560.01 is at least 3.5 times as large as the radius of the planet, and the cocoon around HD 63433 c is at least 12 times the radius of the planet.

As for the strange discovery that the gas lost from TOI 560.01 was flowing toward -- instead of away from -- its host star, future observations of other mini-Neptunes should reveal if TOI 560.01 is an anomaly or whether an inward-moving atmospheric outflow is more common.

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CRISPR-Cas9 can generate unexpected, heritable mutations

CRISPR-Cas9, the "genetic scissors," creates new potential for curing diseases; but treatments must be reliable. In a new study, researchers have discovered that the method can give rise to unforeseen changes in DNA that can be inherited by the next generation. These scientists therefore urge caution and meticulous validation before using CRISPR-Cas9 for medical purposes.

CRISPR-Cas9 is an effective tool for genome modification in microorganisms, as well as animals and plants. In health care, the method creates scope for curing numerous genetic diseases, provided the DNA is modified correctly and undergoes no unexpected changes. To date, such unwanted mutations have been studied in cells, but knowledge of the consequences in living organisms remains limited.

"In this project, we studied the effects of CRISPR-Cas9 in zebrafish, a small aquarium fish. Since DNA molecules and their mechanisms are similar in all animals, we think the results should be similar in humans, for example," says Adam Ameur, associate professor at Uppsala University and the Science for Life Laboratory (SciLifeLab).

When they studied the genome of more than 1,000 zebrafish from two generations, the researchers found unexpected mutations of various types. In some cases, DNA fragments that were larger than anticipated underwent changes, while in other cases mutations occurred in the wrong location in the genome. Unforeseen mutations were found in first-generation zebrafish, but also in their offspring.

"Knowing these unexpected mutations are heritable is important, since they can have long-term consequences for future generations. But that can happen only if you change the genome of embryos or germ cells," says Ida Höijer, PhD of Uppsala University and SciLifeLab.

In healthcare, methods tailored to correct genes in a particular tissue or cell type are now being developed. Although such treatments pose no risk to future generations, caution is advisable.

"CRISPR-Cas9 can be an amazingly valuable tool in health care. But we need to minimise the risk of unwanted effects, and we can do this by carefully validating the modified cells with the latest DNA sequencing technologies," Ameur says.

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Too many disk galaxies than theory allows

The Standard Model of Cosmology describes how the universe came into being according to the view of most physicists. Researchers at the University of Bonn have now studied the evolution of galaxies within this model, finding considerable discrepancies with actual observations. The University of St. Andrews in Scotland and Charles University in the Czech Republic were also involved in the study. The results have now been published in the Astrophysical Journal.

Most galaxies visible from Earth resemble a flat disk with a thickened center. They are therefore similar to the sports equipment of a discus thrower. According to the Standard Model of Cosmology, however, such disks should form rather rarely. This is because in the model, every galaxy is surrounded by a halo of dark matter. This halo is invisible, but exerts a strong gravitational pull on nearby galaxies due to its mass. "That's why we keep seeing galaxies merging with each other in the model universe," explains Prof. Dr. Pavel Kroupa of the Helmholtz Institute for Radiation and Nuclear Physics at the University of Bonn.

This crash has two effects, the physicist explains: "First, the galaxies penetrate in the process, destroying the disk shape. Second, it reduces the angular momentum of the new galaxy created by the merger." Put simply, this greatly decreases its rotational speed. The rotating motion normally ensures that the centrifugal forces acting during this process cause a new disk to form. However, if the angular momentum is too small, a new disk will not form at all.

Large discrepancy between prediction and reality

In the current study, Kroupa's doctoral student, Moritz Haslbauer, led an international research group to investigate the evolution of the universe using the latest supercomputer simulations. The calculations are based on the Standard Model of Cosmology; they show which galaxies should have formed by today if this theory were correct. The researchers then compared their results with what is currently probably the most accurate observational data of the real Universe visible from Earth.

"Here we encountered a significant discrepancy between prediction and reality," Haslbauer says: "There are apparently significantly more flat disk galaxies than can be explained by theory." However, the resolution of the simulations is limited even on today's supercomputers. It may therefore be that the number of disk galaxies that would form in the Standard Model of Cosmology has been underestimated. "However, even if we take this effect into account, there remains a serious difference between theory and observation that cannot be remedied," Haslbauer points out.

The situation is different for an alternative to the Standard Model, which dispenses with dark matter. According to the so-called MOND theory (the acronym stands for "MilgrOmiaN Dynamics), galaxies do not grow by merging with each other. Instead, they are formed from rotating gas clouds that become more and more condensed. In a MOND universe, galaxies also grow by absorbing gas from their surroundings. However, mergers of full-grown galaxies are rare in MOND. "Our research group in Bonn and Prague has uniquely developed the methods to do calculations in this alternative theory," says Kroupa, who is also a member of the Transdisciplinary Research Units "Modelling" and "Matter" at the University of Bonn. "MOND's predictions are consistent with what we actually see."

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Origin of supermassive black hole flares identified: Largest-ever simulations suggest flickering powered by magnetic 'reconnection'

Black holes aren't always in the dark. Astronomers have spotted intense light shows shining from just outside the event horizon of supermassive black holes, including the one at our galaxy's core. However, scientists couldn't identify the cause of these flares beyond the suspected involvement of magnetic fields.

By employing computer simulations of unparalleled power and resolution, physicists say they've solved the mystery: Energy released near a black hole's event horizon during the reconnection of magnetic field lines powers the flares, the researchers report January 14 in The Astrophysical Journal Letters.

The new simulations show that interactions between the magnetic field and material falling into the black hole's maw cause the field to compress, flatten, break and reconnect. That process ultimately uses magnetic energy to slingshot hot plasma particles at near light speed into the black hole or out into space. Those particles can then directly radiate away some of their kinetic energy as photons and give nearby photons an energy boost. Those energetic photons make up the mysterious black hole flares.

In this model, the disk of previously infalling material is ejected during flares, clearing the area around the event horizon. This tidying up could provide astronomers an unhindered view of the usually obscured processes happening just outside the event horizon.

"The fundamental process of reconnecting magnetic field lines near the event horizon can tap the magnetic energy of the black hole's magnetosphere to power rapid and bright flares," says study co-lead author Bart Ripperda, a joint postdoctoral fellow at the Flatiron Institute's Center for Computational Astrophysics (CCA) in New York City and Princeton University. "This is really where we're connecting plasma physics with astrophysics."

Ripperda co-authored the new study with CCA associate research scientist Alexander Philippov, Harvard University scientists Matthew Liska and Koushik Chatterjee, University of Amsterdam scientists Gibwa Musoke and Sera Markoff, Northwestern University scientist Alexander Tchekhovskoy and University College London scientist Ziri Younsi.

A black hole, true to its name, emits no light. So flares must originate from outside the black hole's event horizon -- the boundary where the black hole's gravitational pull becomes so strong that not even light can escape. Orbiting and infalling material surrounds black holes in the form of an accretion disk, like the one around the behemoth black hole found in the M87 galaxy. This material cascades toward the event horizon near the black hole's equator. At the north and south poles of some of these black holes, jets of particles shoot out into space at nearly the speed of light.

Identifying where the flares form in a black hole's anatomy is incredibly difficult because of the physics involved. Black holes bend time and space and are surrounded by powerful magnetic fields, radiation fields and turbulent plasma -- matter so hot that electrons detach from their atoms. Even with the help of powerful computers, previous efforts could only simulate black hole systems at resolutions too low to see the mechanism that powers the flares.

Ripperda and his colleagues went all in on boosting the level of detail in their simulations. They used computing time on three supercomputers -- the Summit supercomputer at Oak Ridge National Laboratory in Tennessee, the Longhorn supercomputer at the University of Texas at Austin, and the Flatiron Institute's Popeye supercomputer located at the University of California, San Diego. In total, the project took millions of computing hours. The result of all this computational muscle was by far the highest-resolution simulation of a black hole's surroundings ever made, with over 1,000 times the resolution of previous efforts.

The increased resolution gave the researchers an unprecedented picture of the mechanisms leading to a black hole flare. The process centers on the black hole's magnetic field, which has magnetic field lines that spring out from the black hole's event horizon, forming the jet and connecting to the accretion disk. Previous simulations revealed that material flowing into the black hole's equator drags magnetic field lines toward the event horizon. The dragged field lines begin stacking up near the event horizon, eventually pushing back and blocking the material flowing in.

With its exceptional resolution, the new simulation for the first time captured how the magnetic field at the border between the flowing material and the black hole's jets intensifies, squeezing and flattening the equatorial field lines. Those field lines are now in alternating lanes pointing toward the black hole or away from it. When two lines pointing in opposite directions meet, they can break, reconnect and tangle. In between connection points, a pocket forms in the magnetic field. Those pockets are filled with hot plasma that either falls into the black hole or is accelerated out into space at tremendous speeds, thanks to energy taken from the magnetic field in the jets.

"Without the high resolution of our simulations, you couldn't capture the subdynamics and the substructures," Ripperda says. "In the low-resolution models, reconnection doesn't occur, so there's no mechanism that could accelerate particles."

Plasma particles in the catapulted material immediately radiate some energy away as photons. The plasma particles can further dip into the energy range needed to give nearby photons an energy boost. Those photons, either passersby or the photons initially created by the launched plasma, make up the most energetic flares. The material itself ends up in a hot blob orbiting in the vicinity of the black hole. Such a blob has been spotted near the Milky Way's supermassive black hole. "Magnetic reconnection powering such a hot spot is a smoking gun for explaining that observation," Ripperda says.

The researchers also observed that after the black hole flares for a while, the magnetic field energy wanes, and the system resets. Then, over time, the process begins anew. This cyclical mechanism explains why black holes emit flares on set schedules ranging from every day (for our Milky Way's supermassive black hole) to every few years (for M87 and other black holes).

Ripperda thinks that observations from the recently launched James Webb Space Telescope combined with those from the Event Horizon Telescope could confirm whether the process seen in the new simulations is happening and if it changes images of a black hole's shadow. "We'll have to see," Ripperda says. For now, he and his colleagues are working to improve their simulations with even more detail.

Read more at Science Daily