The IceCube Neutrino Observatory is possibly the strangest telescope on Earth. From its home at the South Pole, it sits and waits for fundamental particles called neutrinos to pass through its 5,160 optical detectors buried in the ice. When a neutrino interacts with a hydrogen or oxygen atom in the ice, it produces a signal that IceCube can detect.
But IceCube isn’t the only neutrino experiment in Antarctica. There is also the ANITA (the ANtarctic Impulsive Transient Antenna) experiment, which flies a balloon over the continent and points radio antennae toward the ground. ANITA searches for radio waves because extremely high-energy neutrinos—those hundreds of times more energetic than the ones that IceCube commonly detects—can produce intense radio signals when they smash into an atom in the ice.
From its balloon flights, ANITA claimed to have detected a few events that appear to be signals of these extremely high-energy neutrinos, so the IceCube Collaboration decided to investigate. In a paper submitted today to The Astrophysical Journal, they outline their search for an intense neutrino source in the direction of the events detected by ANITA. The collaboration found that these neutrinos could not have come from an intense point source. Other explanations for the anomalous signals—possibly involving exotic physics—need to be considered.
When ANITA reported signals that looked like extremely high-energy neutrinos, physicists were puzzled. These neutrinos had arrived at an angle that suggested they had just traveled through most of the planet, which is not expected for neutrinos at these energies.
“It’s commonly said that neutrinos are ‘elusive’ or ‘ghostly’ particles because of their remarkable ability to pass through material without smashing into something,” says Alex Pizzuto of the University of Wisconsin–Madison, one of the leads on this paper. “But at these incredible energies, neutrinos are like bulls in a china shop—they become much more likely to interact with particles in Earth.”
Many scientists have since come up with potential explanations for these weird signals, and one possibility is that a really intense neutrino source produced them. After all, if a source produced huge numbers of neutrinos, it is more plausible that one or two made it to ANITA.
So Pizzuto and his collaborators decided to see whether there was an intense neutrino source shooting a beam of neutrinos toward Earth—a point source. To do this, the researchers took eight years of IceCube data and looked for correlations between the locations of the ANITA events and the locations of the IceCube events.
Since the researchers could not know how long a potential point source might have been emitting neutrinos, their analyses used three different and complementary approaches equipped to find coincidences on different timescales. Their analyses also had to account for uncertainty in the ANITA events’ directions because the events do not have definite positions on the sky.
Once they had addressed those challenges, the researchers simulated neutrinos passing through Earth to see how many incident neutrinos would be necessary for ANITA to see one event, and they then did the same for IceCube.
In all three searches, they found no evidence for a neutrino source in the direction of the strange ANITA events. This is particularly intriguing because, due to a process called tau neutrino regeneration, the extremely high-energy events that don’t make it all the way to ANITA should still be detectable by IceCube.
“This process makes IceCube a remarkable tool to follow up the ANITA observations, because for each anomalous event that ANITA detects, IceCube should have detected many, many more—which, in these cases, we didn’t,” says Anastasia Barbano of the University of Geneva in Switzerland, another lead on this paper. “That means that we can rule out the idea that these events came from some intense point source, because the odds of ANITA seeing an event and IceCube not seeing anything are so slim.”
When the ANITA events were detected, the main hypotheses were an astrophysical explanation (like an intense neutrino source), a systematics error (like not accounting for something in the detector), or physics beyond the Standard Model. “Our analysis ruled out the only remaining Standard Model astrophysical explanation of the anomalous ANITA events,” says Pizzuto. “So now, if these events are real and not just due to oddities in the detector, then they could be pointing to physics beyond the Standard Model.”
Ibrahim Safa of UW–Madison, another lead on this paper, says that while it has been an exciting time for physicists trying to explain these events, “it looks like we’ll have to wait for the next generation of experiments, which will increase exposure and sensitivity, to get a clear understanding of this anomaly.”
Researchers are remarking at the newly discovered remains of an Ice Age bird that has been identified as a horned lark and is estimated to be 46,000-years-old.
A recently published study says that the bird was buried and frozen within the permafrost in near the village of Belaya Gora that is located in northeastern Siberia. The bird still had many of its feathers and the researchers state that it is “exceptionally well-preserved.”
Experts from the Swedish Museum of Natural History tested the bird’s feathers and say that there is a chance it could be an ancestor to two subspecies of lark that are alive today.
“This finding implies that the climatic changes that took place at the end of the last Ice Age led to the formation of new subspecies,” said Dr. Love Dalén during an interview with CNN.
The bird carcass that was found in Siberian permafrost. Credit: Love Dalén
The study says that it is a significant finding for this body of research because it is a rare opportunity to learn more about past ecosystems and what the climatic conditions at that period of time were like. The researchers state that learning about this species habitat and their response to the changing climate will enable a better understanding of how species, populations, and communities could respond to present-day climate change.
Interestingly, the bird was found at the same site as an 18,000-year-old frozen puppy called “Dogor,” which researchers are still trying to determine if the specimen is a wolf or dog. The dog was found in nearly perfect condition within the permafrost and some scientists think that this could be the oldest dog ever found.
Antarctica is supposed to be an extremely cold place. The annual mean temperature of the snow-laden continent’s central area is -57 degrees Celsius (−70.6°F); even the coast averages around -10°C (14°F).
It beat out the former record of 17.5°C, from 24 March 2015.
This latest heatwave lasted for about a week, and images of Eagle Island, taken by the Operational Land Imager on Landsat 8, have now captured a pretty depressing picture of its impact.
The tiny Eagle Island is located just off the coast of Graham Land in the Antarctic Peninsula. The record-high temperatures have resulted in a large amount of Eagle Island’s ice cap melting into the sea, while areas towards the middle of the island saw melt ponds form astonishingly quickly.
“You see these kinds of melt events in Alaska and Greenland, but not usually in Antarctica.”
Pelto also notes that the source of this melt event – persistent high temperatures significantly above freezing – is not typical of Antarctic weather patterns. Nevertheless, these have become more common recently.
In total, snow pack on Eagle Island had over 10 centimetres (4 inches) of melt in the span of just a few days – between February 6 and February 11.
Air temperatures on February 9. (GEOS-5/NASA)
This isn’t even the first heatwave this season, but represents the third major melt event of the 2019-2020 Southern Hemisphere summer, with both November and January also suffering from exceptionally warm weather.
“If you think about this one event in February, it isn’t that significant,” said Pelto.
“It’s more significant that these events are coming more frequently.”
Well over a year after NASA’s InSight lander parachuted down to the Martian surface, the space agency still hasn’t been able to drill too far into the red soil.
NASA has tried a few different techniques to get the drill, known as the “mole,” deeper into the ground to measure the desert planet’s inner temperature — with the greater goal of understanding geologic activity on Mars.
On Friday, NASA announced a new idea. From tens of millions of miles away, the space agency will direct the InSight lander to take its robotic arm (which has a black shovel on the end), to “push” on top of the drill.
“The InSight team hopes that pushing on this location will help the mole it bury itself and enable the heat probe to take Mars’ temperature,” NASA said.
Eventually, NASA hopes the mole will drill down 16 feet. So far, however, the agency hasn’t gone much more than a foot.
The new extraterrestrial operation is expected to take a few weeks, if it works at all.
“We’re cautiously optimistic that one day we’ll get the mole working again,” Ashitey Trebi-Ollennu, the lead InSight arm engineer at NASA’s Jet Propulsion Laboratory, said five months ago, when attempting another drilling scheme.
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