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Astronomers watch black holes as galaxies collide

Astronomers have detected enormous black holes as multiple pairs of galaxies collide and merge into larger galaxies.

Using powerful telescopes to see through the galaxies' thick walls of gas and dust surrounding their cores, the academics have managed – for the first time – to observe supermassive black holes fall into each other and coalesce into an even more giant black hole.

Black holes are areas of space-time which are so dense that nothing – whether matter or energy – can escape them.

Astrophysicists currently believe there are about 10,000 black holes at the centre of our own galaxy, the Milky Way, all of which surround a supermassive black hole at its core.

A team led by research scientist Michael Koss surveyed hundreds of nearby galaxies using existing imagery and published their findings in the journal Nature.

"Seeing the pairs of merging galaxy nuclei associated with these huge black holes so close together was pretty amazing," said Mr Koss said.

"In our study, we see two galaxy nuclei right when the images were taken. You can't argue with it; it's a very 'clean' result, which doesn't rely on interpretation."

:: Supercomputer provides black hole breakthrough

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Video: Using supercomputer simulations, astronomers have discovered more about how black holes interact with space-time

The high-resolution images have provided the scientists with a close-up of galactic collisions, something which is believed to have been more frequent in the early universe.

When the black holes at the centre of galaxies collide they will unleash incredibly powerful energy in the form of gravitational waves – ripples in the very fabric of space-time which have only recently been detected.

The team said it was inspired to conduct the survey by an image captured by the Hubble telescope of two interacting galaxies which are collectively called NGC 6240.

They initially scanned for active black holes that were hidden from normal visual wavelengths of light by analysing a decade's worth of X-ray data from the Burst Alert Telescope (BAT) aboard NASA's Neil Gehrels Swift Observatory.

"The advantage to using Swift's BAT is that it observes high-energy, 'hard' X-rays," said the study's co-author, Richard Mushotzky, a professor of astronomy.

"These X-rays penetrate through the thick clouds of dust and gas that surround active galaxies, allowing the BAT to see things that are literally invisible in other wavelengths."

Mr Koss explained: "People had conducted studies to look for these close interacting black holes before, but what really enabled this particular study were the X-rays that can break through the cocoon of dust.

"We also looked a bit farther in the universe so that we could survey a larger volume of space, giving us a greater chance of finding more luminous, rapidly-growing black holes.

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"Computer simulations of galaxy smashups show us that black holes grow fastest during the final stages of mergers, near the time when the black holes interact, and that's what we have found in our survey," added Laura Blecha.

Ms Blecha, who is an assistant professor of physics at the University of Florida and a co-author of the study, added: "The fact that black holes grow faster and faster as mergers progress tells us galaxy encounters are really important for our understanding of how these objects got to be so monstrously big."

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Scientists redefine kilogram as original measure loses mass

By Thomas Moore, science and medical correspondent

A quiet revolution could this week change the standard for weighing everything from drug doses to jumbo jet fuel.

Scientists from more than 60 countries will vote on Friday on whether a lump of metal held in a Parisian vault should continue to be the definition of a kilogram.

Le Grand K, a small cylinder of titanium alloy, has set the standard since 1889. All the scales in the world are ultimately calibrated against it, even those weighing in pounds and ounces.

It's so important to the global economy that three key-holders are needed to unlock the vault. When the Nazis occupied Paris they left untouched the building that houses "Le Grand K".

The problem, though, is that while the mother of all kilograms has only been taken out of its protective case four times in the last century, it has lost atoms and therefore mass.

It amounts to just 20 billionths of a gram, about the weight of an eyelash, but in a world that needs to weigh objects with ever greater accuracy, that's a big deal.

Work on a definition of a kilogram is taking place at the National Physical Laboratory
Image: Work on the definition of a kilogram is taking place at the National Physical Laboratory

Britain has a copy of Le Grand K called Kilo 18, which it won in a lottery in 1889, and is stored at the National Physical Laboratory (NPL) in West London.

Stuart Davidson, a metrologist or weight scientist at NPL, is one of the trusted guardians.

"Once you get up to a few tens of tonnes – things like filling an aircraft with fuel – everything needs to be traceable back to a standard," he told Sky News.

"The same is true when you get down to very small masses like a milligram – for example the active ingredients of pharmaceuticals.

"You like to know you are getting the right dose of drugs when you are given a prescription."

Shoppers will not notice any difference as they buy groceries
Image: Shoppers will not notice any difference as they buy groceries

Scientists at the lab are now part of the global effort to devise a more accurate, immutable definition of a kilogram that is no longer dependent on a physical object.

They are using what is known as a Kibble Balance, named after the British physicist who first conceptualised, to express the mass of a kilogram in terms of the amount of upward electromagnetic force is needed to balance the downward drag of gravity.

Then with some heavy-duty maths, they relate that to a fundamental physical law of nature.

By taking the answer – a number called Planck's Constant – they can reverse the process and calibrate scales with unprecedented accuracy.

Ian Robinson, a fellow at NPL, has been leading the work.

He says labs around the world will be able to have a kibble balance, liberating the definition of a kilogram from its physical and geographical ties.

"You are not reliant on any one object anymore," he said.

"Effectively our mass scale is spread out and everyone can contribute. I see it as egalitarian – a form of democracy for mass."

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Other important standard units have already been updated.

The metre is no longer defined by a rod of metal, but by the distance light travels in a set, and very small, fraction of a second.

And a second is no longer defined by a fraction of the time it takes for the Earth to complete one rotation, which scientists now know varies, but by vibrations in a caesium atom.

Michael de Podesta, a principle research scientist at NPL, said the public will not notice any difference when grocery shopping.

"But it means people like me won't worry about the kilogram losing weight," he said.

"It will make it future-proof.

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"Scientists will be able to measure things in ever more detail and engineers fabricate things with ever more precision.

"Improvements in measurement will lead to advances in science."

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Apple share plunge knocks US tech stocks

A plunge in Apple's share price has been reflected in wider US technology stocks.

Apple's market value fell by almost 5% at one stage on Monday to a level not seen since July after two of its suppliers cut their full-year forecasts.

That sparked a sell-off in other iPhone component makers while the ugly mood later spread across US stock markets with the Nasdaq Composite – mainly made up of technology firms – down 2.5%.

The Apple Watch Series 4 being introduced at Apple's special event
Image: Apple's latest growth forecasts disappointed investors last month

Market experts pointed to the Veterans Day closure of US bond markets exacerbating the negative sentiment for stocks.

There was a costly correction in values worldwide last month,which some commentators said signalled the end of the bull run of recent years in the US.

It helped take Apple's market capitalisation above $1tn earlier in 2018, though it has since slipped back to $970bn.

The value drain in October was blamed on several factors including rising US interest rates and the effects of Donald Trump's trade war with China.

Lumentum Holdings, which supplies Apple's Face ID technology, said before the market opened that it had trimmed its revenue and profit expectations because a major customer, which it did not name, had reduced its orders.

Screen maker Japan Display was the other firm to lower investors' expectations.

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It raised fears in Apple shareholders, traders said, that its own revenue forecasts issued last month could come up short.

Lumentum shares were 31% lower.

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A rebound in oil prices had offered some relief to energy stocks earlier but they later succumbed to the broader selling pressure.

Financials were also hit, with Goldman Sachs more than 6% down.

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Russia denies claim it meddled in NATO war games

Russia has denied suggestions that it was responsible for Finland having its GPS signal disrupted during NATO war games.

Finnish Prime Minister Juha Sipila revealed on Sunday that air navigation services across the country had to issue traffic warnings due to the interruption last week, which is believed to have been deliberate.

Norway posted a similar warning about the loss of GPS signals for pilots in its own airspace at the end of October, when the NATO exercise off its Trondheim coast got under way.

Thirty-one countries took part in the war games
Image: Thirty-one countries took part in the war games

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Mr Silipa appeared to point the finger at the Russians during an interview with Finnish public broadcaster Yle, noting that the Kremlin "is known to possess such capabilities".

The Kremlin has developed a strong CEMA (cyber and electromagnetic activity) military capability which NATO has been focusing on counteracting in recent years.

Two German Eurofighter jets simulate the interception of a plane over the Baltic sea during the drill
Image: Two German Eurofighter jets simulate the interception of a plane over the Baltic sea during the drill

Russia has said it has "no information" about the allegation, which has not been made by any of the other 31 countries that had forces taking part in the war games – military exercises used to test tactics and equipment.

The so-called Trident Juncture was the largest NATO exercise in decades and came to a close last Wednesday, with some non-member nations – including Finland – joining in as allies.

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It took place close to Russia in an area stretching from the Baltic Sea to Iceland.

Finland has a testing history with Russia, with which it shares an 833-mile (1,340 km) border, and part of the reason why it has not signed up to NATO is to avoid any potential confrontation with its eastern neighbour.

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Large shark nursery found off Irish coast

A rare shark nursery has been found off the Irish coast by marine scientists exploring the country's coral reefs.

Scientists working on the Irish government's INFOMAR programme used a remotely operated vehicle to dive to depths of 750m, where the nursery was discovered.

According to the chief scientist, it is the largest ever found in Irish waters.

Image: A 'near-threatened' Sailfin roughshark was also spotted

David O’Sullivan, of INFOMAR and chief scientist on the SeaRover survey, said: "We are delighted to report the discovery of a rare shark nursery on a scale not previously documented in Irish waters.

"This discovery shows the significance of documenting sensitive marine habitats, and will give us a better understanding of the biology of these beautiful animals and their ecosystem function in Ireland’s Biologically Sensitive Area."

The sharks and eggs were discovered at depths of 750m
Image: The sharks and eggs were discovered at depths of 750m

The rover filmed very large numbers of egg cases, often called mermaids purses, indicating females may be gathering in that area to lay their eggs. Such high concentrations are rare, say experts.

A large school of Blackmouth catshark, which are abundant in the northeast Atlantic, were spotted in the Irish waters, and it is thought the eggs are of this species.

Species observed included starfish and sponges
Image: Starfish and sponges were also seen

There was also a second and more solitary species, the Sailfin roughshark, which is listed as "near threatened" by the International Union for the Conservation of Nature.

Mr O'Sullivan said: "No pups were obvious at the site and it is believed that the adult sharks might be utilising degraded coral reef and exposed carbonate rock on which to lay their eggs.

The coral reef is home to a diverse range of species
Image: The coral reef is home to a diverse range of species

"A healthy coral reef in the vicinity, may act as a refuge for the juvenile shark pups once they hatch. It is anticipated that further study of the site will answer some important scientific questions on the biology and ecology of deep water sharks in Irish waters."

The nursery was found 200 miles off the coast in one of six offshore Special Areas of Conservation (SAC) designated under the EU Habitats Directive.

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They host a diverse range of marine animals, like starfish, crustaceans, sponges and sea fans.



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This SeaRover survey is the second of three commissioned and jointly funded by the Irish government and the EU's European Maritime and Fisheries Fund.

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