‘Ghost particle’ image is the 1st view of our galaxy in ‘anything other than light’

Published

2 years ago

June 30, 2023

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IceCube Neutrino Observatory sits beneath a green aurora in the icy Antarctic (Image credit: IceCube/ NSF)

Scientists have traced the galactic origins of thousands of “ghost particles” known as neutrinos to create the first-ever portrait of the Milky Way made from matter and not light — and it’s given them a brand-new way to study the universe.

The groundbreaking image was snapped by capturing the neutrinos as they fell through the IceCube Neutrino Observatory, a gigantic detector buried deep inside the South Pole’s ice.

Neutrinos earn their spooky nickname because their nonexistent electrical charge and almost-zero mass mean they barely interact with other types of matter. As such, neutrinos fly straight through regular matter at close to the speed of light.

Related: Ghostly neutrino particles are blasting out of a nearby galaxy, and scientists aren’t sure why

Yet by slowing these neutrinos, physicists have finally traced the particles’ origins billions of light-years away to ancient, cataclysmic stellar explosions and cosmic-ray collisions. The researchers published their findings June 29 in the journal Science.

“The capabilities provided by the highly sensitive IceCube detector, coupled with new data analysis tools, have given us an entirely new view of our galaxy — one that had only been hinted at before,” Denise Caldwell, director of the National Science Foundation’s physics division, which funded the research, said in a statement. “As these capabilities continue to be refined, we can look forward to watching this picture emerge with ever-increasing resolution, potentially revealing hidden features of our galaxy never before seen by humanity.”

Two images of the Milky Way galaxy. The top was made with visible light and the bottom with neutrinos. (Image credit: IceCube Collaboration/U.S. National Science Foundation (Lily Le & Shawn Johnson)/ESO (S. Brunier)) How to catch a ghost particle

Every second, about 100 billion neutrinos pass through each square centimeter of your body. The tiny particles are everywhere — produced in the nuclear fire of stars, in enormous supernova explosions, by cosmic rays and radioactive decay, and in particle accelerators and nuclear reactors on Earth. In fact, neutrinos, which were first discovered zipping out of a nuclear reactor in 1956, are second only to photons as the most abundant subatomic particles in the universe.

Despite their ubiquity, the chargeless and near-massless particles’ minimal interactions with other matter make neutrinos incredibly difficult to detect. Many famous neutrino-detection experiments have spotted the steady bombardment of neutrinos sent to us from the sun, but this cascade also masks neutrinos from more unusual sources, such as gigantic star explosions called supernovas and particle showers produced by cosmic rays.

To capture the neutrinos, particle physicists turned to IceCube, located at the Amundsen-Scott South Pole Station in Antarctica. The gigantic detector consists of more than 5,000 optical sensors beaded across 86 strings that dangle into holes drilled up to 1.56 miles (2.5 kilometers) into the Antarctic ice.

The view down one of IceCube’s 86 detector strings, which dangle in holes drilled up to 1.56 miles into the ice. (Image credit: NSF/B. Gudbjartsson.)

While many neutrinos pass completely unimpeded through the Earth, they do occasionally interact with water molecules, creating particle byproducts called muons that can be witnessed as flashes of light inside the detector’s sensors. From the patterns these flashes make, scientists can reconstruct the energy, and sometimes the sources, of the neutrinos.

Finding a neutrino’s starting point depends on how clear its direction is recorded in the detector; some have very obvious initial directions, whereas others produce cascading “fuzz balls of light” that obscure their origins, lead author Naoko Kurahashi Neilson, a physicist at Drexel University in Philadelphia, said in the statement.RELATED STORIES—Astronomers propose making a neutrino detector out of the Pacific Ocean

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By feeding more than 60,000 detected neutrino cascades collected over 10 years into a machine-learning algorithm, the physicists built up a stunning picture: an ethereal, blue-tinged image showing the neutrinos’ sources all across our galaxy.

The map showed that the neutrinos were being overwhelmingly produced in regions with previously detected high gamma-ray counts, confirming past suspicions that many ghost particles are summoned as byproducts of cosmic rays smashing into interstellar gas. It also left the physicists awestruck.

“I remember saying, ‘At this point in human history, we’re the first ones to see our galaxy in anything other than light,'” Neilson said.

Just like previous revolutionary advances such as radio astronomy, infrared astronomy and gravitational wave detection, neutrino mapping has given us a completely new way to peer out into the universe. Now, it’s time to see what we find.

World

Mexico and Canada agree to bolster US border security in return for tariff pause

Published

60 mins ago

February 4, 2025

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Mexico and Canada agree to bolster US border security in return for tariff pause

Both Canada and Mexico have agreed to strengthen border security with the United States in return for a 30-day pause in tariffs.

President Trump announced on Sunday he was imposing 25% taxes on goods from his country’s northern and southern neighbours.

Mexico was first to reach a deal with the White House. Its president, Claudia Sheinbaum, said she was sending 10,000 National Guard troops to the US border immediately in return for a tariff delay.

Mr Trump said the Mexican soldiers would be “specifically designated” to stop the flow of the synthetic opioid fentanyl into the US, as well as illegal migrants. Further negotiations will now be carried out, he added.

Ms Sheinbaum said she had a “good conversation” with him lasting at least 30 minutes just hours before the tariffs were due to begin.

She also extracted a concession from Mr Trump – after explaining the “seriousness” of high-powered weapons coming over the border from the US and getting into the hands of criminal groups.

“It gives them firepower,” she said. “We asked that the US also help our country by helping stop this arms trafficking… he agreed.”

Canada made similar moves. Prime Minister Justin Trudeau said almost 10,000 frontline personnel “are and will be working on protecting the border”.

He added on X that his country was appointing a “fentanyl czar”, drugs cartels would be listed as terrorists, and there would be “24/7 eyes on the border”.

There will also be a Canada-US joint strike force to “combat organised crime, fentanyl and money laundering”, Mr Trudeau announced.

Both Trudeau and Trump will view the deal as a win – Trump for seemingly forcing the US’s northern neighbour to act, and Trudeau for heading off sanctions with measures that for the most part (with the exception of the fentanyl czar) had already been announced in December.

Donald Trump said he was “very pleased with this initial outcome” and work will begin see how a “Final Economic Deal” with Canada can be structured.

Analysis: Has it all just been theatre?

First Mexico, now Canada. In another whirlwind day, both of America’s closest neighbours appear to have capitulated to President Trump.
The 25% tariffs on all goods from both countries were due to come into effect at midnight US Eastern time. But after calls between all three leaders, suddenly the tariffs were paused.

So what’s going on? Is this a clear signal of the power Trump wields? His blunt tool of using the threat of tariffs as a negotiating tool has paid off? Bullying tactics work? Well, maybe. At least that’s how Mr Trump wants everyone to think. Dance to my tune, or else.

And it’s absolutely the case that Mexico and Canada were in panic mode this weekend. But surely Donald Trump was panicking a little too when he saw the stock markets on Monday. He claimed this afternoon not to be taking any notice of their sharp falls. But we know he cares deeply about market reactions.

Here’s what’s interesting: the statement from Canadian Prime Minister Justin Trudeau sounded at first glance like it was announcing something new.
“Canada is implementing our $1.3bn border plan… nearly 10,000 frontline personnel are and will be working on protecting the border…”

But it’s not a new announcement. Look at the language – “are and will be”. In other words, “we’re doing this already Mr President, but if you want me to reiterate it to placate you, then I will…” All that Justin Trudeau has done today is reiterate a border plan he announced last December.

Mexico too has been doing an increasing amount in the fight against fentanyl though it could and probably now will do more.

So has it all been theatre this past 24 hours?

A show of brinkmanship from Donald Trump, which could have had a cliff-edge ending, but instead ended with him looking strong (and freaking out much of the developed world in the process) and his closest neighbours forced to reiterate their existing plans.

Regarding China, a 10% tariff – in addition to those already in place – is still set to go ahead, though the White House said Mr Trump is due to talk to President Xi Jinping.

The US president has, however, said 10% could be just the start.

“China hopefully is going to stop sending us fentanyl, and if they’re not, the tariffs are going to go substantially higher,” he said.

China has described fentanyl as America’s problem, and said it would challenge the tariffs at the World Trade Organisation, as well as taking other countermeasures.

But it also left the door open for talks.

What is the UK situation on tariffs?

President Trump hates trade deficits, and does not want to import more goods from another country than are sent there in return, says Sky’s economics and data editor, Ed Conway.

But Britain has bigger trade deficits than the US, Conway adds, and is one of the few countries in the world to import more goods from America than America imports from it.

In addition, because the UK is no longer part of the European Union, any tariffs imposed on Brussels will not affect London.

When asked about the UK, Mr Trump said: “I think that one can be worked out.”

Sir Keir Starmer said it was “early days”.

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