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Détection d’une nouvelle succession de sursauts radio rapides

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Les sursauts radio rapides sont de courtes impulsions d’ondes radio, très énergétiques, mais aussi très brèves (elles ne durent que quelques millisecondes). En fait, elles émettent autant d’énergie en une milliseconde que le Soleil en 10 000 ans.

De rares sursauts en série

La particularité de la présente détection est son caractère répétitif, c’est-à-dire qu’il s’agit d’une suite de sursauts radio rapides, qui sont surtout connus, à ce jour, pour ne se produire qu’une seule fois.

Un premier cas de succession de SRR avait été observé en 2007, et sa source, une lointaine galaxie naine, avait été déterminée en 2017.

L’observation de cette nouvelle série confirme qu’il ne s’agit pas d’anomalies dans l’analyse des données, et pourrait aider à expliquer les causes des SRR.

Les astrophysiciens pensent que ce phénomène mystérieux émanerait d’événements astronomiques puissants qui se produisent à des milliards d’années-lumière de la Terre.

Un SRR pourrait provenir d’un amas dense, comme un reste de supernova (l’explosion d’une étoile en fin de vie), ou encore d’un point situé près du trou noir central d’une galaxie. Une chose est sûre : la dispersion observée nous indique qu’il s’agit d’un endroit spécial.

Cherry Ng, Université de Toronto

Le CHIME, un effort canadien

Le présent SRR est l’un des 13 sursauts détectés au cours d’une période d’à peine trois semaines pendant l’été 2018 à l’aide du radiotélescope CHIME.

Le radiotélescope CHIME occupe un espace qui équivaut à celui de cinq patinoires de la LNH.Le radiotélescope CHIME occupe un espace qui équivaut à celui de cinq patinoires de la LNH. Photo : CHIME

En fait, la découverte de ce signal extragalactique est l’un des premiers résultats obtenus par CHIME (Expérience canadienne de cartographie de l’intensité de l’hydrogène).

Cette collaboration pluridisciplinaire regroupe des chercheurs de l’Université McGill, de l’Université de Toronto, de l’Université de la Colombie-Britannique et de l’Observatoire fédéral de radioastrophysique exploité par le Conseil national de recherches du Canada (CNRC).

Selon ces scientifiques, cette deuxième détection montre clairement les capacités du nouveau télescope, qui n’en était alors qu’à l’étape de prédémarrage et ne fonctionnait qu’à une fraction de sa capacité au moment de la détection.

Deux mystères en série

Une trentaine de SRR avaient été détectés avant l’annonce d’aujourd’hui, mais seulement un d’entre eux se répétait.

La découverte de ce deuxième cas nous permet de croire qu’il pourrait y en avoir d’autres. Si nous pouvions étudier plus de SRR répétitifs et plus de sources, nous pourrions peut-être découvrir la provenance de ces phénomènes et leurs causes.

Ingrid Stairs, Université de la Colombie-Britannique

La précision avec laquelle CHIME trouve des SRR accélérera certainement les progrès accomplis en vue de résoudre le mystère de leur origine.

Ils semblent prendre leur origine à environ 1,5 milliard d’années-lumière de la Terre, provenant peut-être « d’un amas dense, comme un reste de supernova, ou encore d’un point situé près du trou noir central d’une galaxie ».

Le détail de ces travaux est l’objet de deux articles publiés dans le magazine Nature (Nouvelle fenêtre) (en anglais).

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Federal Budget 2021: Ottawa adds $1B to broadband fund for rural, remote communities

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The federal government will add $1 billion to a fund for improving high-speed communications in rural and remote areas of Canada, bringing the total to $2.75 billion by 2026, the Liberals said Monday in their first full budget since the pandemic began last year.

The money is going to the Universal Broadband Fund, which is designed to support the installation of “backbone” infrastructure that connects underserved communities to high-speed internet.

It’s one of many government and private-sector initiatives that have gained urgency since the pandemic began, as Canadians became more dependent on internet service for applications ranging from e-learning to daily business operations.

Ottawa says the additional money will keep it on track to have high-speed broadband in 98 per cent of the country by 2026, and 100 per cent by 2030.

Money spent on high-speed communications will be good for a recovering economy, said Pedro Antunes, chief economist at the Conference Board of Canada, a non-partisan think-tank.

The latest data from Statistics Canada says there were about five million people working from home during the pandemic, up from about two million prior to that, Antunes said in an interview.

“That’s a quarter or so of the workforce,” he added. “And I think a fair number of those people are going to continue to work from home, at least in some part-time way.”

Improved connections to high-speed broadband and mobile communications will add to the productive capacity of the economy overall, especially as it reaches beyond Canada’s cities, Antunes said.

He said there’s been a “real issue” with economic growth outside major urban centres and the improved connectivity “is something that can help stimulate that.”

The Universal Broadband Fund was initially mentioned in the 2019 budget, though specifics were not available until last November’s fiscal update.

The $1-billion top-up to the broadband fund announced today is in addition to $1.75 billion promised to the fund by the federal government’s November fiscal update.

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COVID-19: What you need to know for April 19

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Provincewide

  • Per today’s government report, there are 4,447 new cases in Ontario, for a total of 421,442 since the pandemic began; 2,202 people are in hospital, 755 of them in intensive care, and 516 on ventilators. To date, 7,735 people have died.
  • According to data from the Ministry of Health and Long-Term Care, there are 40 outbreaks in long-term-care facilities, 36 confirmed active cases of positive residents, and 127 confirmed active cases of positive staff. To date, there have been 3,755 confirmed resident deaths and 11 confirmed staff deaths.
  • Per the government’s report on Ontario’s vaccination program, as of 7 p.m. yesterday, Ontario has administered 66,897 new doses of COVID-19 vaccines, for a total of 3,904,778 since December 2020. 3,212,768 people have received only one dose, and 346,005 people have received both doses.

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Federal budget 2021 highlights: Child care, recovery benefits, OAS increases – everything you need to know

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The federal government’s first budget in more than two years certainly looks the part: At 739 pages, it is a hefty document chock full of billions in new spending.

Those funds will be spread among a number of key groups – students, seniors, parents and small-business owners, to name a few – as Ottawa looks to bolster Canada’s recovery from COVID-19 but also plan for life beyond the pandemic.

To that end, the deficit is projected to hit $354.2-billion in the 2020-21 fiscal year, which just ended – better than expected about five months ago, given the economy’s resilience over the winter months. It is estimated to fall to $154.7-billion this fiscal year, before dropping further in the years to come as pandemic spending recedes from view.

Here are some of the highlights from Monday’s budget.

The budget outlines tens of billions of dollars in federal subsidies for a national child-care program, a promise the Liberal Party has made in some form since the early 1990s. Child-care supports became a point of national debate during pandemic lockdowns as parents with young children struggled to juggle work and family responsibilities.

In total, the government proposes spending as much as $30-billion over the next five years, and $8.3-billion each year after that, to bring child-care fees down to a $10-a-day average by 2026. The proposal, which requires negotiation with the provinces and territories, would split subsidies evenly with those governments and targets a 50-per-cent reduction in average child-care fees by the end of 2022.

The federal program is largely modelled on Quebec’s subsidized child-care system, implemented in the 1990s in an effort to increase women’s access to the labour market. Since then, labour participation rates for women aged 25 to 54 in the province have grown to exceed the national average by four percentage points.

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