Tag Archives: underestimated

Previously underestimated activity of ultra-large black holes discovered in the Milky Way

Posted on by
Reply

According to an analysis of new data from NASA/ESA/CSA James Webb Space Telescope, the ejaculation ability that orbits Sagittarius a* emits a constant flow of flares with no period of rest. Some flares are faint flickering for a few seconds, while others are blindly bright eruptions that spit out every day. There is also slight flicker than the surges for several months at a time.

The artist's concept depicts an ultra-high Massive black hole in the heart of the Milky Way galaxy known as Sagittarius a*. Image credits: NASA/ESA/CSA/RALF CRAWFORD, STSCI.

“We expect flares to occur in essentially every super-large black hole, but our black holes are unique,” says Dr. Farhad Yousef Zadeh, an astronomer at Northwestern University. Ta.

“It's always bubbled up with activity and doesn't seem to reach a stable state.”

“We observed Sagittarius A* multiple times throughout 2023 and 2024, and noticed changes in all observations.”

“We saw something different each time, and that's really surprising. It didn't stay the same.”

Dr. Yousefzadeh and his colleagues used it Webb's nircam instrument Observe Sagittarius A* in total of 48 hours, increments of 8-10 hours over a year.

They expected to see the flare, but Sagittarius A* was more active than he had expected.

The accretion disk surrounding the black hole produced 5-6 large flares per day, during which several small subflares were generated.

“Our data showed constantly changing and bubbly brightness,” Dr. Yusef-Zadeh said.

“And boom! A huge explosion of brightness suddenly appeared. Then it settled down again. No patterns were found in this activity. It seems random. The activity profile of the black hole is what we see every time we see it. It was new and exciting.”

“It appears to be caused by two separate processes: short bursts and long flares. If the accretion disk is a river, the short, faint flicker is like a small ripple that fluctuates randomly on the surface of the river. .”

“But longer, brighter flares are like tidal waves caused by more important events.”

“Mild faults in the accretion disk can produce faint flickers. Specifically, turbulent fluctuations within the disk cause plasma (high-temperature charge gas) to be compressed and temporary. It can cause a burst of radiation.”

“This is similar to the way the solar magnetic fields gather together to compress and eject solar flares.”

“Of course, the environment around the black hole is much more energetic and extreme, so the process is more dramatic. But the surface of the sun also bubbles up with activity.”

Astronomers attribute large, bright flares to magnetic reconnection events. This is the process in which two magnetic fields collide and release energy in the form of accelerated particles. These particles, moving at a speed close to the speed of light, emit a burst of bright radiation.

“The magnetic reconnection event is like a static electricity spark, and in some ways it is also an electrical reconnection,” Dr. Yusef-Zadeh said.

The team wants to use Webb to observe Sagittarius A* for a long period of time.

“When you're watching such a weak flare event, you have to compete with the noise,” said Dr. Yousef Zadeh.

“If you can observe 24 hours a day, you can reduce the noise and see features that you didn't see before. That would be great. Also, these flares show periodicity (or repeat yourself) or really You can also check if it is random.”

Survey results It will be published in Astrophysics Journal Letter.

____

F. Yusef-Zadeh et al. 2025. Nonstop Variation of SgrA** Uses JWST at wavelengths of 2.1 and 4.8 microns: evidence of clear populations of faint and bright variable emissions. apjlin press; Arxiv: 2501.04096

Source: www.sci.news

Britain’s security chief warns of underestimated cyberattack threats from hostile states and gangs

Posted on by
Reply

Britain is being warned by its cybersecurity chief about the seriousness of online threats from hostile states and criminal organizations. Richard Horne, director of the GCHQ National Cyber Security Center, highlighted a threefold increase in “serious” incidents due to Russia’s “aggression and recklessness” and China’s “highly sophisticated” digital operations.

In his recent speech, Mr. Horne emphasized the growing hostile activity in UK cyberspace, driven by adversaries aiming to cause disruption and destruction. He mentioned Russia’s aggressiveness and recklessness and China’s continued sophistication as cyber attackers.

Despite the increasing risks, Horne expressed concern that the severity of the threats facing the UK has been underestimated. This serves as a wake-up call for businesses and public sector organizations.

The NCSC reported a significant increase in serious cyber incidents over the past year, with 430 incidents requiring assistance compared to 371 in the previous year. Horne stressed the need to enhance protection and resilience against cyber threats across critical infrastructure, supply chains, and the economy.

The NCSC’s investigation does not differentiate between nation-state attacks and criminal incidents, but ransomware attacks remain a significant concern in the UK. Recent incidents targeting high-profile organizations like the British Library and Synnovis highlight the reliance on technology and the potential human cost of cyberattacks.

With various cyber threats emanating from Russia, China, Iran, and North Korea, the NCSC is urging organizations to ramp up their cybersecurity measures and stay vigilant. The warning signals the need for a collective effort to safeguard against cyber dangers.

Alan Woodward, a cybersecurity expert, reiterated the importance of staying alert to cyber threats. The government’s warning serves as a reminder for both public and private sectors to prioritize cybersecurity measures.

Source: www.theguardian.com

The complexity of Viking expansion into the North Atlantic was underestimated.

Posted on by
Reply

Vikings played a prominent role among the peoples of the North Atlantic, and the populations founded by them might be expected to be genetically similar and homogeneous. New research suggests that the Icelandic and Faroese people had distinctly different founding fathers. This result is consistent with a scenario in which the male population of the Faroe Islands was formed by a more diverse population from the more diverse Scandinavian population than from neighboring Icelanders. Furthermore, this study conclusively shows that there is no evidence of post-founder admixture between the Faroese and Icelandic gene pools.

The Faroe Islands consist of an archipelago of 18 small islands located in the North Atlantic Ocean between southern Norway, Iceland, and Scotland. As a result of their demographic history and relative geographical isolation, the Faroe Islands, like other North Atlantic island populations, are genetically homogeneous compared to mainland populations. Historical and archaeological sources report that the Faroe Islands were settled around 800 AD by Vikings, primarily from western Norway. However, increasing evidence suggests that these islands were settled earlier, perhaps by Celtic monks or other people from the British Isles. Carbon dating of peat moss and barley grain supports two pre-Viking periods of settlement, approximately 300-500 AD and 500-700 AD. More recently, scientists detected sheep DNA in archaeological deposits from 500 AD, and based on modern whole-genome data, the original founding of the Faroe Islands occurred between 50 and 300 AD. estimated that it may have been two to three centuries earlier than previously thought. Based solely on archaeological findings. Image credit: Oscar CR

From the 8th century to about 1050 AD, Vikings roamed the Atlantic in longships all the way to Newfoundland, Labrador, and Greenland, as well as exploring the Mediterranean and Eurasia.

Among the places they are known to have settled are the Faroe Islands, an archipelago of 18 islands in the North Atlantic Ocean.

They probably weren’t the first. Archaeologists have found evidence that these islands have been inhabited since about 300 AD, perhaps by Celtic monks or other people from the British Isles.

However, according to Fairinga Sagawritten around 1200, a Viking chieftain called Grimur Kamban settled in the Faroe Islands between about 872 and 930 AD. But where in Scandinavia did Grimur and his followers come from?

“We have strong evidence here that the Faroe Islands were colonized by a diverse group of male settlers from multiple Scandinavian populations,” said University of Louisville researcher Dr. Christopher Tillquist. .

In this study, Dr. Tillquist and his colleagues genotyped 12 “short tandem repeat” (STR) loci on the Y chromosome of 139 men from the Faroese islands of Bordoloi, Streymoy, and Suzloj.

They assigned each man to the most likely haplogroup. Each haplogroup has a different known distribution across Europe today.

They compared the genotype distribution to that found in 412 men from Norway, Sweden, Denmark, Iceland, and Ireland.

This allowed the team to reconstruct the source population of the founders of the Viking population.

Advanced analysis showed that the Faroe Islands sample range was similar to the broader Scandinavian genotype range, whereas the Icelandic genotypes were different.

The authors also developed a powerful and innovative genetic method called “variational distance from modal haplotype” to analyze SNP (single nucleotide polymorphism) variation within STRs.

This has led to the “founder effect” (vestiges of random loss of diversity during historical colonization by a small number of people) that remains in the genetic composition of male populations in the Faroe Islands and Iceland today. was able to clarify.

“Scientists have long thought that the Faroe Islands and Iceland were settled by similar Nordic peoples,” Dr Tillquist says.

“However, our new analysis showed that these islands were founded by people belonging to different gene pools within Scandinavia.”

“One group of diverse Scandinavian origins settled in the Faroe Islands, while a more genetically distinct group of Vikings colonized Iceland. They had separate genetic characteristics that continue to this day. Masu.”

“Despite their geographic proximity, there appears to have been no subsequent interbreeding between these two populations.”

“Our findings show that Viking expansion into the North Atlantic was more complex than previously thought.”

“Each longship that sailed to these distant islands carried a different genetic heritage, and not just Vikings.”

“We can now trace the separate journeys of conquest and settlement, revealing a more nuanced story of Viking exploration than is told in history books.”

of findings appear in the diary frontiers of genetics.

_____

Alison E. Mann others. 2024. Genetic evidence points to distinct patrilineal colonization of the Faroe Islands and Iceland. front. Genet 15;doi: 10.3389/fgene.2024.1462736

Source: www.sci.news

The Harmful Effects of Extreme Drought on Plants may be Underestimated

Posted on by
Reply

One of the shelters used to simulate extreme drought. It is located at the Central Plains Experiment Station in Colorado.

melinda smith

An experiment conducted at 100 sites around the world shows that during extreme droughts, grassland productivity declines much more than we thought. This finding suggests that plants may be struggling to cope with more frequent and severe droughts that are expected to result from climate change.

melinda smith Researchers at Colorado State University have designed a shelter that can be placed on top of land and topped with a piece of plastic to deflect some of the rain away from the vegetation below.

Working with other researchers around the world, Smith and her team were able to install such shelters in 100 grassland or shrubland locations across six continents.

For each site, Smith said, the team aimed to recreate conditions that would be considered extreme drought in the area, the type of conditions that occur once every 100 years. For example, in areas of Europe with high rainfall, more plastic strips are placed on roofs compared to drier areas to better simulate drought.

A year later, the researchers discovered that while some experiments were successful in reproducing drought conditions, others were unsuccessful because certain areas had higher than average rainfall.

In the 44 sites that experienced extreme drought, plant growth decreased by 38% in grasslands and 21% in shrublands. “That was huge,” Smith said, adding that the reduction in plant growth was much more severe than the researchers had observed in previous studies.

They also found that arid regions with low biodiversity are particularly vulnerable to drought. “Dry places are already at their limit,” Smith said. “Their systems don't have a lot of buffers to deal with it.”

Smith hopes these insights can improve global climate models that have previously underestimated the role of drought in the carbon cycle.

topic:

Source: www.newscientist.com