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Faint Starlight in New Hubble Images Lets Astronomers ‘See’ Dark Matter

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Intracluster light (blue) in the galaxy cluster Abell S1063. One new technique uses intralight, imaged by Hubble, to map and study dark matter. (Credit: NASA, ESA, and M. Montes (University of New South Wales, Sydney, Australia)

Intracluster light (blue) in the galaxy cluster Abell S1063. One new technique uses intracluster light, imaged by Hubble, to map and study dark matter. (Credit: NASA, ESA, and M. Montes (University of New South Wales, Sydney, Australia)

Two astronomers have devised a method that lets them “see” dark matter with the light from rogue stars. The pair has shown how images of faint starlight taken with the Hubble Space Telescope can be used to map dark matter’s distribution in galaxy clusters. The novel technique could ultimately help explore the nature of dark matter.

Dark matter remains one of the great mysteries of modern science. A theoretical form of matter, dark matter is thought to make up about 85 percent of all matter in the universe. Because dark matter doesn’t absorb, reflect or emit light, it is very hard to spot. In fact, it has never been directly observed and some even question whether or not it actually exists.

This new method, however, lets astronomers detect dark matter in galaxy clusters using what’s called intracluster light. Intracluster light is faint starlight that’s created by interactions between galaxies. When galaxies interact, their respective stars can be ripped apart from them, left to float freely throughout the galaxy cluster.

“These stars have an identical distribution to the dark matter, as far as our current technology allows us to study,” lead study author Mireia Montes of the University of New South Wales, said in a statement.

Because the intracluster light aligns with the dark matter in these clusters, it allows astronomers to see how the dark matter is distributed. In this study, the pair of astronomers used data from the Frontier Fields Hubble Space Telescope program. The research is published in Monthly Notices of the Royal Astronomical Society.

“Seeing” Dark Matter

“We have found a way to ‘see’ dark matter. We have found that very faint light in galaxy clusters, the intracluster light, maps how dark matter is distributed,” Montes said about this new method.

Other efforts to map the distribution of dark matter use gravitational lensing — a technique that uses the light bent by matter in between a light source and the observer. But, while gravitational lensing requires accurate lensing and time-intensive spectroscopy, this new technique only requires deep-space imaging. Because of this, the astronomers who devised the new technique say it will be a more effective tool for mapping and studying galaxy clusters.

Aside from providing an effective method with which astronomers can map dark matter, this new research also offers opportunities to better explore the nature of dark matter itself. For example, dark matter appears to interact with regular matter only gravitationally. But, if researchers using this method find that dark matter actually distributes differently than the floating starlight, it could mean that dark matter is self-interacting. This would significantly change our current understanding of dark matter, what it might be, and how it behaves.

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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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