Month: March 2019

Earth’s Deep Mantle Flows Dynamically

As ancient ocean floors plunge over 1,000 km into the Earth’s deep interior, they cause hot rock in the lower mantle to flow much more dynamically than previously thought, finds a new UCL-led study.

The discovery answers long-standing questions on the nature and mechanisms of mantle flow in the inaccessible part of deep Earth. This is key to understanding how quickly Earth is cooling, and the dynamic evolution of our planet and others in the solar system.

“We often picture the Earth’s mantle as a liquid that flows but it isn’t — it’s a solid that moves very slowly over time. Traditionally, it’s been thought that the flow of rock in Earth’s lower mantle is sluggish until you hit the planet’s core, with most dynamic action happening in the upper mantle which only goes to a depth of 660 km. We’ve shown this isn’t the case after all in large regions deep beneath the South Pacific Rim and South America,” explained lead author, Dr Ana Ferreira (UCL Earth Sciences and Universidade de Lisboa).

“Here, the same mechanism we see causing movement and deformation in the hot, pressurised rock in the upper mantle is also occurring in the lower mantle. If this increased activity is happening uniformly over the globe, Earth could be cooling more rapidly than we previously thought,” added Dr Manuele Faccenda, Universita di Padova.

The study, published today in Nature Geoscience by researchers from UCL, Universidade de Lisboa, Universita di Padova, Kangwon National University and Tel Aviv University, provides evidence of dynamic movement in the Earth’s lower mantle where ancient ocean floors are plunging towards the planet’s core, crossing from the upper mantle (up to ~660 km below the crust) to the lower mantle (~660 — 1,200 km deep).

The team found that the deformation and increased flow in the lower mantle is likely due to the movement of defects in the crystal lattice of rocks in the deep Earth, a deformation mechanism called “dislocation creep,” whose presence in the deep mantle has been the subject of debate.

The researchers used big data sets collected from seismic waves formed during earthquakes to probe what’s happening deep in Earth’s interior. The technique is well established and comparable to how radiation is used in CAT scans to see what’s happening in the body.

“In a CAT scan, narrow beams of X-rays pass through the body to detectors opposite the source, building an image. Seismic waves pass through the Earth in much the same way and are detected by seismic stations on the opposite side of the planet to the earthquake epicentre, allowing us to build a picture of the structure of Earth’s interior,” explained Dr Sung-Joon Chang, Kangwon National University.

By combining 43 million seismic data measurements with dynamic computer simulations using the UK’s supercomputing facilities HECToR, Archer and the Italian Galileo Computing Cluster, CINECA the researchers generated images to map how the Earth’s mantle flows at depths of ~1,200 km beneath our feet.

They revealed increased mantle flow beneath the Western Pacific and South America where ancient ocean floors are plunging towards Earth’s core over millions of years.

This approach of combining seismic data with geodynamic computer modelling can now be used to build detailed maps of how the whole mantle flows globally to see if dislocation creep is uniform at extreme depths.

The researchers also want to model how material moves up from the Earth’s core to the surface, which together with this latest study, will help scientists better understand how our planet evolved into its present state.

“How mantle flows on Earth might control why there is life on our planet but not on other planets, such as Venus, which has a similar size and location in the solar system to Earth, but likely has a very different style of mantle flow. We can understand a lot about other planets from revealing the secrets of our own,” concluded Dr Ferreira.

Matter-Antimatter Asymmetry In Charmed Quarks

Physicists in the College of Arts and Sciences at Syracuse University have confirmed that matter and antimatter decay differently for elementary particles containing charmed quarks.

Distinguished Professor Sheldon Stone says the findings are a first, although matter-antimatter asymmetry has been observed before in particles with strange quarks or beauty quarks.

He and members of the College’s High-Energy Physics (HEP) research group have measured, for the first time and with 99.999-percent certainty, a difference in the way D0 mesons and anti-D0 mesons transform into more stable byproducts.

Mesons are subatomic particles composed of one quark and one antiquark, bound together by strong interactions.

“There have been many attempts to measure matter-antimatter asymmetry, but, until now, no one has succeeded,” says Stone, who collaborates on the Large Hadron Collider beauty (LHCb) experiment at the CERN laboratory in Geneva, Switzerland. “It’s a milestone in antimatter research.”

The findings may also indicate new physics beyond the Standard Model, which describes how fundamental particles interact with one another. “Till then, we need to await theoretical attempts to explain the observation in less esoteric means,” he adds.

Every particle of matter has a corresponding antiparticle, identical in every way, but with an opposite charge. Precision studies of hydrogen and antihydrogen atoms, for example, reveal similarities to beyond the billionth decimal place.

When matter and antimatter particles come into contact, they annihilate each other in a burst of energy — similar to what happened in the Big Bang, some 14 billion years ago.

“That’s why there is so little naturally occurring antimatter in the Universe around us,” says Stone, a Fellow of the American Physical Society, which has awarded him this year’s W.K.H. Panofsky Prize in Experimental Particle Physics.

The question on Stone’s mind involves the equal-but-opposite nature of matter and antimatter. “If the same amount of matter and antimatter exploded into existence at the birth of the Universe, there should have been nothing left behind but pure energy. Obviously, that didn’t happen,” he says in a whiff of understatement.

Thus, Stone and his LHCb colleagues have been searching for subtle differences in matter and antimatter to understand why matter is so prevalent.

The answer may lie at CERN, where scientists create antimatter by smashing protons together in the Large Hadron Collider (LHC), the world’s biggest, most powerful particular accelerator. The more energy the LHC produces, the more massive are the particles — and antiparticles — formed during collision.

It is in the debris of these collisions that scientists such as Ivan Polyakov, a postdoc in Syracuse’s HEP group, hunt for particle ingredients.

“We don’t see antimatter in our world, so we have to artificially produce it,” he says. “The data from these collisions enables us to map the decay and transformation of unstable particles into more stable byproducts.”

HEP is renowned for its pioneering research into quarks — elementary particles that are the building blocks of matter. There are six types, or flavors, of quarks, but scientists usually talk about them in pairs: up/down, charm/strange and top/bottom. Each pair has a corresponding mass and fractional electronic charge.

In addition to the beauty quark (the “b” in “LHCb”), HEP is interested in the charmed quark. Despite its relatively high mass, a charmed quark lives a fleeting existence before decaying into something more stable.

Recently, HEP studied two versions of the same particle. One version contained a charmed quark and an antimatter version of an up quark, called the anti-up quark. The other version had an anti-charm quark and an up quark.

Using LHC data, they identified both versions of the particle, well into the tens of millions, and counted the number of times each particle decayed into new byproducts.

“The ratio of the two possible outcomes should have been identical for both sets of particles, but we found that the ratios differed by about a tenth of a percent,” Stone says. “This proves that charmed matter and antimatter particles are not totally interchangeable.”

Adds Polyakov, “Particles might look the same on the outside, but they behave differently on the inside. That is the puzzle of antimatter.”

The idea that matter and antimatter behaves differently is not new. Previous studies of particles with strange quarks and bottom quarks have confirmed as such.

What makes this study unique, Stone concludes, is that it is the first time anyone has witnessed particles with charmed quarks being asymmetrical: “It’s one for the history books.”

HEP’s work is supported by the National Science Foundation.

UPDATE: Cyclone Idai May Be ‘One of the Worst’ Disasters in the Southern Hemisphere

Officials with global aid groups and in Mozambique, where the storm hit hardest, are only beginning to reckon with its destruction. Potentially 1.7 million people were in the direct path of the cyclone, the United Nations estimated on Tuesday, and rain is forecast to continue in parts of the region for several days.

Cyclone Idai, the storm that has killed hundreds of people, submerged homes and battered cities in southeastern Africa, may prove to be one of the worst weather-related disasters ever in the Southern Hemisphere, a United Nations official said on Tuesday.

Herve Verhoosel, a spokesman for the United Nations World Food Program, said in an interview that the agency’s workers had described seeing “water and water for miles and miles” – flooding so severe it resembled an inland ocean where homes and towns had stood.

The situation remained dire, he said, for potentially hundreds of thousands of people in need of food, clean water and evacuation.

What happened

Cyclone Idai made landfall last Thursday into Friday on the coast of Southeast Africa, striking Mozambique, Malawi and Zimbabwe. (Like hurricanes and typhoons, a cyclone is a low-pressure circular storm system with winds greater than 74 miles per hour, each termed according to where it forms.)

In addition to the 1.7 million people potentially affected in Mozambique, the World Food Program estimated that 920,000 people were affected in Malawi and 15,000 in Zimbabwe.

Because of the flooding, most roads and bridges are closed, and many regions have no power – shutting down communications and airports that could be used to bring in supplies and evacuate people. Mr. Verhoosel said that people were stranded on rooftops and climbing into trees to escape the water, and were without food, safe water or medicine.

President Filipe Nyusi of Mozambique said in a televised statement on Tuesday that the cyclone had killed more than 200 people, Reuters reported. In Zimbabwe, state news media reported that more than 100 people had died.

Earlier Mr. Nyusi had reportedly said he feared as many as 1,000 people could be found dead. Mr. Verhoosel said the death toll was expected to climb into the hundreds.

“If these reports, these fears, are realized, then we can say that this is one of the worst weather-related disasters – tropical cyclone-related disasters…Pin the Southern Hemisphere,” said Clare Nullis, a spokeswoman for the World Meteorological Organization, citing the president’s figure.

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Shiveluch Volcano (Kamchatka, Russia): Continuing Activity, Frequent Small Glowing Avalanches

The activity at the volcano has been a bit lower during the past days, although overall similar to the past weeks. The lava dome continues to grow steadily.

During the past nights, we observed frequent, but mostly small glowing avalanches from the active dome as well as small ash emissions and intense steaming. The upper third of the dome, now over 800 m high, seems to be active with many incandescent spots visible.

No larger events (pyroclastic flows traveling beyond the base of the cone or explosions with significant ash emissions) have been observed since our arrival on 16 Mar. According to the volcano observatory, internal activity remains elevated, and the risk of a major dome collapse continues to increase.

Never Seen So Much Rain’: Zimbabweans Struggle With Storm floods

Chipinge, Zimbabwe – The death toll from Cyclone Idai continues to rise as southern African countries struggle to deal with the devastating aftermath of the torrential downpours.

The powerful storm has killed at least 64 people in Zimbabwe in recent days, government officials say, while in neighbouring Mozambique the death toll has jumped to 48.

Idai made landfall in Mozambique on Thursday evening before proceeding to Zimbabwe and Malawi, causing flash floods, wrecking infrastructure and leaving communities without electricity.

More than a million people have been affected, including tens of thousands who have been displaced, according to the International Federation of Red Cross and Red Crescent Societies.

In Zimbabwe’s Eastern Highlands, the heavy rains had died out by Sunday – but only after causing widespread destruction.

In Chipinge, an eastern town some 450km southeast of the capital, Harare, transport links were cut off after a road was damaged due to water pressure.

A bus carrying passengers bound for Harare was stuck in a mush of soft tar and mud. A few small cars managed to bypass the sludge when volunteers and soldiers laid down a makeshift path made of wooden planks.

Transport engineers told Al Jazeera that the works to repair the damaged road could take up to a day, leaving locals trying to leave the flooded town stranded.

Gladys Nyandoro, a 58-year-old Chipinge resident whose home had been flooded, said she would seek alternative transport to continue her journey with her son to a temporary shelter in Harare.

“I could only leave with a few clothes, but my house is full of water. I have never seen so much rain since we moved back here,” she said of her husband’s communal home.

“I just want to go back to Harare; this area is too much for me.”

Anesu Chitepo, a 22-year-old shopkeeper, said his grocery store had been affected by erratic power outages caused by the heavy rains.

“We can’t be happy to think this rain is a blessing when everything it touches is destroyed,” he said. “This will only bring us more trouble, than the real water we wanted.”

Zimbabwe’s government has declared the torrential storm a disaster and dispatched members of the military and national youth service to help evacuate stranded villagers.

Meanwhile, the country’s Civil Protection Unit has been using helicopters to gain access to the remote town of Chimanimani, on the northeastern border with Mozambique.

Local aid groups have yet to access the area where dozens are thought to be missing and hundreds more are in urgent need of humanitarian aid.

According to Joshua Sacco, a local member of parliament, all four bridges leading to the mountainous town have been damaged.

“We have people stranded in this area, but the access roads to this area have landslides,” he said.

“There is nothing, we don’t have any road accessible,” added Sacco.

“The best form of help we need is an excavator or a grader to clear the roads.”

The cyclone has brought torrential rains and winds thought to be worst in decades since Cyclone Eline struck the region in 2000.

Astronomers Discover 83 Supermassive Black Holes In The Early Universe

Astronomers from Japan, Taiwan and Princeton University have discovered 83 quasars powered by supermassive black holes in the distant universe, from a time when the universe was less than 10 percent of its present age.

“It is remarkable that such massive dense objects were able to form so soon after the Big Bang,” said Michael Strauss, a professor of astrophysical sciences at Princeton University who is one of the co-authors of the study. “Understanding how black holes can form in the early universe, and just how common they are, is a challenge for our cosmological models.”

This finding increases the number of black holes known at that epoch considerably, and reveals, for the first time, how common they are early in the universe’s history. In addition, it provides new insight into the effect of black holes on the physical state of gas in the early universe in its first billion years. The research appears in a series of five papers published in The Astrophysical Journal and the Publications of the Astronomical Observatory of Japan.

Supermassive black holes, found at the centers of galaxies, can be millions or even billions of times more massive than the sun. While they are prevalent today, it is unclear when they first formed, and how many existed in the distant early universe. A supermassive black hole becomes visible when gas accretes onto it, causing it to shine as a “quasar.” Previous studies have been sensitive only to the very rare, most luminous quasars, and thus the most massive black holes. The new discoveries probe the population of fainter quasars, powered by black holes with masses comparable to most black holes seen in the present-day universe.

The research team used data taken with a cutting-edge instrument, “Hyper Suprime-Cam” (HSC), mounted on the Subaru Telescope of the National Astronomical Observatory of Japan, which is located on the summit of Maunakea in Hawaii. HSC has a gigantic field-of-view — 1.77 degrees across, or seven times the area of the full moon — mounted on one of the largest telescopes in the world. The HSC team is surveying the sky over the course of 300 nights of telescope time, spread over five years.

The team selected distant quasar candidates from the sensitive HSC survey data. They then carried out an intensive observational campaign to obtain spectra of those candidates, using three telescopes: the Subaru Telescope; the Gran Telescopio Canarias on the island of La Palma in the Canaries, Spain; and the Gemini South Telescope in Chile. The survey has revealed 83 previously unknown very distant quasars. Together with 17 quasars already known in the survey region, the researchers found that there is roughly one supermassive black hole per cubic giga-light-year — in other words, if you chunked the universe into imaginary cubes that are a billion light-years on a side, each would hold one supermassive black hole.

The sample of quasars in this study are about 13 billion light-years away from the Earth; in other words, we are seeing them as they existed 13 billion years ago. As the Big Bang took place 13.8 billion years ago, we are effectively looking back in time, seeing these quasars and supermassive black holes as they appeared only about 800 million years after the creation of the (known) universe.

It is widely accepted that the hydrogen in the universe was once neutral, but was “reionized” — split into its component protons and electrons — around the time when the first generation of stars, galaxies and supermassive black holes were born, in the first few hundred million years after the Big Bang. This is a milestone of cosmic history, but astronomers still don’t know what provided the incredible amount of energy required to cause the reionization. A compelling hypothesis suggests that there were many more quasars in the early universe than detected previously, and it is their integrated radiation that reionized the universe.

“However, the number of quasars we observed shows that this is not the case,” explained Robert Lupton, a 1985 Princeton Ph.D. alumnus who is a senior research scientist in astrophysical sciences. “The number of quasars seen is significantly less than needed to explain the reionization.” Reionization was therefore caused by another energy source, most likely numerous galaxies that started to form in the young universe.

The present study was made possible by the world-leading survey ability of Subaru and HSC. “The quasars we discovered will be an interesting subject for further follow-up observations with current and future facilities,” said Yoshiki Matsuoka, a former Princeton postdoctoral researcher now at Ehime University in Japan, who led the study. “We will also learn about the formation and early evolution of supermassive black holes, by comparing the measured number density and luminosity distribution with predictions from theoretical models.”

Based on the results achieved so far, the team is looking forward to finding yet more distant black holes and discovering when the first supermassive black hole appeared in the universe.