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When Black Hole Jets Create Natural Particle Accelerators

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a natural particle accelerator

Spinning supermassive black holes often shoot out jets of plasma from their poles. When the magnetic fields in these jets get twisted and tangled, they generate an electric field capable of accelerating particles and creating cosmic rays. (Credit:
Greg Stewart/SLAC National Accelerator Laboratory)

Cosmic rays are energetic particles moving at high speeds. Because it takes significant energy to create them, they often serve as cosmic messengers, revealing clues about the extreme environments that produce them — such as supermassive black holes. On Earth, scientists use accelerators to generate and study particles moving at high speeds, but nature needs no such apparatus. Now, researchers at the Department of Energy’s SLAC National Accelerator Laboratory have found a possible mechanism behind nature’s own particle accelerators: When the magnetic fields in the material around a supermassive black hole get tangled, they can generate conditions that send cosmic rays skipping off through the universe.

Supermassive black holes often spew jets of hot plasma from just outside their event horizon. (Plasma is a state of matter in which both ionized atoms that have lost their electrons and those lost electrons coexist.) In their work, published December 14 in Physical Review Letters, the research team created a miniature jet using the Mira supercomputer at the Argonne Leadership Computing Facility at Argonne National Laboratory. Their mini-jet contained only 550 billion particles, but based on its behavior, the team then scaled it up to real-world proportions and compare their simulation with astronomical observations.

Natural Particle Accelerator

Those simulations showed that as jets are launched from around the black hole, the magnetic fields — generated by the spinning black hole at the heart of it all — inside the jet become twisted and tangled. “We knew that these fields can become unstable,” said Paulo Alves, the paper’s lead author, in a press release. “But what exactly happens when the magnetic fields become distorted, and could this process explain how particles gain tremendous energy in these jets? That’s what we wanted to find out in our study.”

The team found that, indeed, the distorted magnetic fields could impart high energy to particles in the jet. The tangled magnetic field lines generate large electric fields inside the jet as they twist ever tighter. Particles inside the jet are then accelerated by the combination of the magnetic and electric fields, giving them enough energy, based on the team’s calculations, to allow protons to flee the jet as cosmic rays.

“Based on our simulations, we’re able to propose a new mechanism that can potentially explain how these cosmic particle accelerators work,” said SLAC staff scientist Frederico Fiúza, principal investigator of the study.

“This careful analysis identifies many surprising details of what happens under conditions thought to be present in distant jets, and may help explain some remarkable astrophysical observations,” added Roger Blandford, former director of the SLAC/Stanford University Kavli Institute for Particle Astrophysics and Cosmology, though he was not part of this study.

Based on these results, the team now plans to delve deeper into the workings of cosmic jets, looking even more closely at their behavior to see if their proposed mechanism holds up. The team also plans to conduct laboratory experiments to determine how the mechanism acts — at least in a lab on Earth

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Ecology

Today’s letters: ‘Visionary’ plans don’t always work in Ottawa

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The opinion piece written by Tobi Nussbaum, CEO of the NCC, declares that a “bold, visionary transit plan” would showcase the capital.

As a long-term resident of Ottawa, I’ve had it with visionary plans. In the 1950s, the streetcars serving Ottawa so well were sent to the scrapyards. In the early ’60s, Queensway construction bulldozed established neighbourhoods and ripped the city apart. Later in the decade, the downtown railway station, which could have formed the hub of a commuter network, was relocated to the suburbs. These actions, in the name of “progress,” were undertaken with the “vision” to make Ottawa a car-reliant city.

Now we have an LRT, built just in time for most people to realize that they do not have to go downtown as they can work from home.

Current thinking is pushing a new “link” between Ottawa and Gatineau, with yet more expensive and disruptive infrastructure projects being touted, including a tramway or another tunnel under the downtown core.

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Ecology

That was then: Biggest earthquake since 1653 rocked Ottawa in 1925

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A regular weekly look-back at some offbeat or interesting stories that have appeared in the Ottawa Citizen over its 175-year history. Today: The big one hits.

The Ottawa Senators were playing a Saturday night game against the Montreal Canadiens at the Auditorium, the score tied 0-0 halfway through the second period. Sens’ rookie Ed Gorman and the Habs’ Billy Boucher had just served penalties for a dustup when the building began to make “ominous creaking sounds.” A window crashed to the ground.

Nearby, at Lisgar Collegiate, all eyes were on teenager Roxie Carrier, in the role of Donna Cyrilla in the musical comedy El Bandido. She had the stage to herself and was singing “Sometime” when the building rocked, the spotlight went out, and someone in the audience yelled “Fire!”

At a home on Carey Avenue, one woman’s normally relaxed cat suddenly arched its back, rushed around the room two or three times, spitting angrily, and climbed up the front-window curtains.

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Ecology

Ottawa delays small nuclear reactor plan as critics decry push for new reactors

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TORONTO — Canadians will have to wait a little while longer to see the federal government’s plan for the development of small nuclear reactors, seen by proponents as critical to the country’s fight against global warming.

Speaking at the opening of a two-day virtual international conference on Wednesday, the parliamentary secretary to the minister of natural resources said the plan will lay out key actions regarding the reactors. Its launch, Paul Lefebvre said, would come in the next few weeks.

“We’re still putting the finishing touches on it,” Lefebvre said. “The action plan is too important to be rushed.”

Small modular reactors — SMRs — are smaller in size and energy output than traditional nuclear power units, and more flexible in their deployment. While conventional reactors produce around 800 megawatts of power, SMRs can deliver up to 300 megawatts.

Proponents consider them ideal as both part of the regular electricity grid as well as for use in remote locations, including industrial sites and isolated northern communities. They could also play a role in the production of hydrogen and local heating.

“SMRs will allow us to take a bold step of meeting our goal of net-zero (emissions) by 2050 while creating good, middle class jobs and strengthening our competitive advantage,” said Lefebvre.

Natural Resources Minister Seamus O’Regan had been scheduled to speak at the conference but did not due to a family emergency.

Industry critics were quick to pounce on the government’s expected SMR announcement. They called on Ottawa to halt its plans to fund the experimental technology.

While nuclear power generation produces no greenhouse gas emissions, a major problem facing the industry is its growing mound of radioactive waste. This week, the government embarked on a round of consultations about what do with the dangerous material.

Dozens of groups, including the NDP, Bloc Quebecois, Green Party and some Indigenous organizations, oppose the plan for developing small modular reactors. They want the government to fight climate change by investing more in renewable energy and energy efficiency.

“We have options that are cheaper and safer and will be available quicker,” Richard Cannings, the NDP natural resources critic, said in a statement.

Lefebvre, however, said the global market for SMRs is expected to be worth between $150 billion and $300 billion a year by 2040. As one of the world’s largest producers of uranium, Canada has to be part of the wave both for economic and environmental reasons, he said.

“There’s a growing demand for smaller, simpler and affordable nuclear technology energy,” Lefebvre said.

Joe McBrearty, head of Canadian Nuclear Laboratories, told the conference the company had signed a host agreement this week with Ottawa-based Global First Power for a demonstration SMR at its Chalk River campus in eastern Ontario. A demonstration reactor will allow for the assessment of the technology’s overall viability, he said.

“When talking about deploying a new technology like an SMR, building a demonstration unit is vital to the success of that process,” McBrearty said. “Most importantly, it allows the public to see the reactor, to kick the tires so to speak, and to have confidence in the safety of its operation.”

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