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Astronomers Detect First-Ever Mystery Object in The 'Mass Gap' of Cosmic Collisions – ScienceAlert

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In August of last year, the LIGO and Virgo collaborations made a first-of-its-kind gravitational wave detection – what seemed to be a black hole swallowing up a neutron star. Now LIGO has confirmed the event, giving it the name GW190814. And it looks like the neutron star was not actually… a neutron star.

That would mean the detection is the first of a different kind – the smallest black hole we’ve ever detected, narrowing the mysterious ‘mass gap’ between neutron stars and black holes. But, like most answers the Universe gives us, it opens up a dozen more.

“This is going to change how scientists talk about neutron stars and black holes,” said physicist Patrick Brady of University of Wisconsin-Milwaukee, and the LIGO Scientific Collaboration spokesperson.

“The mass gap may in fact not exist at all but may have been due to limitations in observational capabilities. Time and more observations will tell.”

Into the mass gap

The mass gap is a curious exception in our detections of black holes and neutron stars. Both types of objects are the collapsed, dead cores of massive stars. For neutron stars, the progenitor stars are around 8 to 30 times the mass of the Sun; they blow off most of their mass before they die, and the cores collapse down to objects of around 1.4 solar masses.

Meanwhile, progenitor stars larger than around 30 solar masses collapse down into black holes, with a wide range of masses.

Which leads us to the gap. We’ve never seen a pre-merger object between particular upper and lower limits – a neutron star larger than around 2.3 solar masses, or a black hole smaller than 5 solar masses.

GW190814 has now delivered that object. Analysis of the gravitational wave signal has revealed that the larger of the two merging objects – interpreted as a black hole – was 23 solar masses. The smaller of the two was just 2.6 solar masses, nine times smaller than the other.

This mass means it could be the biggest neutron star we’ve ever detected; or, much more likely, the tiniest black hole.

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“It’s a challenge for current theoretical models to form merging pairs of compact objects with such a large mass ratio in which the low-mass partner resides in the mass gap. This discovery implies these events occur much more often than we predicted, making this a really intriguing low-mass object,” explained astrophysicist Vicky Kalogera of Northwestern University in Illinois.

“The mystery object may be a neutron star merging with a black hole, an exciting possibility expected theoretically but not yet confirmed observationally. However, at 2.6 times the mass of our Sun, it exceeds modern predictions for the maximum mass of neutron stars, and may instead be the lightest black hole ever detected.”

The limit on neutron stars

The reason astronomers aren’t sure what resides in the mass gap is that it’s really difficult to calculate something called the Tolman-Oppenheimer-Volkoff limit (TOV limit). This is the limit above which the mass of a neutron star is so great, the outward pressure of neutrons can no longer repel each other against the inward pressure of gravity, and the object collapses into a black hole.

As our observations grow more robust, constraints on the TOV limit for neutron stars are closing in. Calculations generally put it somewhere between 2.2 and 2.4 solar masses; and data from GW170817 – a 2017 neutron star merger that produced a post-merger mass-gap black hole of 2.7 solar masses – have narrowed it down to around 2.3 solar masses.

The uncertainty over the smaller object in GW190814 arises from the wiggle room in the TOV limit – but, according to the team’s analysis, if the 2.3 solar mass calculation is taken, there’s only a chance of around three percent that the object is a neutron star.

“GW190814 is probably not the product of a neutron star-black hole coalescence, despite its preliminary classification as such,” the researchers wrote in their paper. “Nonetheless, the possibility that the secondary component is a neutron star cannot be completely discounted due to the current uncertainty in [the TOV limit].”

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Now what?

While a neutron star-black hole merger would have been super exciting, the fact that GW190814 has likely turned out to feature a tiny black hole is really awesome, too.

For one, the finding can now help astronomers to constrain the mass gap. And, importantly, it throws our formation models of both neutron stars and binary systems into quite a disarray.

You see, astronomers think that stellar-mass black holes are produced by really massive stars that go supernova and collapse into a black hole. And we believe neutron stars form the same way. But theorists were producing formation models that fit around the mass gap; now that a pre-merger mass gap object has been found, those models will need to be reevaluated.

The other problem is the huge mass discrepancy. Most of the gravitational wave mergers detected to date involve two objects of more or less equal size. Earlier this year, scientists announced a black hole merger with a mass ratio of roughly 3:1, but GW190814 is way more extreme.

There are two main ways for binary systems to form. Either they are born together out of the same chunk of interstellar cloud, living together for their entire lifespans, and then dying together; or they come together later in life. But it’s really hard for these binary formation models to produce systems with such extreme mass ratios.

And the fact that GW190814 was detected just a few years after the first gravitational wave detection in 2015 implies that such extreme systems aren’t even that uncommon.

“All of the common formation channels have some deficiency,” astronomer Ryan Foley of the University of California, Santa Cruz told ScienceAlert. Foley was a member of the team who found the initial GW190814 detection, and was not involved in this new paper.

“It’s that the rate [of this kind of event] is relatively high. [And] it’s not just that you have masses that are different by a factor of nine. It’s also that one of them is in this mass gap. And one of them is really, really massive. So all those things combined, I don’t think that there’s a good model that really solves those three separate issues.”

There’s plenty in this one detection to keep theorists busy for a while, re-imagining those formation scenarios to determine how a system like GW190814, and its separate components, can come into being – whether the smaller object is a neutron star or a black hole.

As for figuring out the latter, that will be a matter of more detections. LIGO is currently offline while it undergoes upgrades. It’s expected to come back online sometime next year, more sensitive than ever – hopefully to detect more events like GW190814, which will help resolve some of the outstanding questions.

“This is the first glimpse of what could be a whole new population of compact binary objects,” said astrophysicist Charlie Hoy of the LIGO Scientific Collaboration and Cardiff University in the UK.

“What is really exciting is that this is just the start. As the detectors get more and more sensitive, we will observe even more of these signals, and we will be able to pinpoint the populations of neutron stars and black holes in the Universe.”

The research has been published in The Astrophysical Journal Letters.

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Grizzly bears in the dark as they try to share living space with humans: study – BayToday

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EDMONTON — Grizzly bears are doing their best to get along with people, but it still isn’t enough.

Newly published research concludes that without large wilderness areas to replenish their numbers, grizzlies would disappear from landscapes they share with humans.

“The persistence of bears near people, when we see them along highways or near towns, they’re really propped up by the fact they exist near some sort of secure wilderness,” said Clayton Lamb, a University of Alberta biologist and lead author of a paper published in the Proceedings of the National Academy of Sciences.

Researchers found bears in populated areas in Alberta and British Columbia have even changed how they hunt in an attempt to share living space with humans.

“The bears are doing what they can,” Lamb said. “The difference might have to be made up by us.”

The study set out to examine an emerging phenomenon in wildlife conservation — large carnivores re-establishing themselves on mixed landscapes including cities, highways, rural communities and patchworks of natural habitat.

It digested 41 years worth of mortality, movement and demography among 2,669 grizzlies over nearly 400,000 square kilometres of British Columbia.

It found mortality has increased steeply with the amount of human impact measured through an index that includes human population, land use, infrastructure, coastlines, roads, railroads and navigable rivers.

Deaths have outnumbered births and the difference is being made up through emigration of young grizzlies from nearby wilderness. For every point the index increases, a local bear population must increase the number of individuals it draws by about two per cent.

“Grizzly bear range is quite tied to the distance from some secure piece of wilderness,” said Lamb.

That’s despite the grizzlies’ efforts to adapt to humans. The study found young, newly arrived bears gradually learned ways to avoid contact, such as hunting and gathering at night.

Adolescent bears in areas dominated by humans have increased their nocturnal time by up to three per cent annually, which has led to corresponding increases in survival. The cost, however, is steep. 

The scientists found it takes 14 years for a grizzly to learn how to co-exist with humans. For every bear that makes it, 29 don’t. 

“A lot of those bears would have been born on a mountaintop 10 kilometres away and lived with mom in an avalanche chute and lived a normal bear life,” Lamb said.

“Then they find a home near town and get lured in by an apple tree. The gauntlet they have to run is very difficult.”

The study shows that high mortality has impacts far from where the deaths take place. Bears dying in mixed-used areas draws more grizzlies from the wilderness to take their place. 

“Conflicts with people have rippling effects on (bear) populations far removed,” Lamb said. 

Highway overpasses are one good way to reduce deaths, he suggests. But humans living with bears have to get better at removing attractants such as roadkill or fruit trees to end the bears’ constant, often fatal, migration from the wilderness.  

“We’re not quite there,” said Lamb. “The system relies quite heavily on adjacent wilderness.”

This report by The Canadian Press was first published July 7, 2020

— Follow @row1960 on Twitter

Bob Weber, The Canadian Press

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Bear population attempting to live alongside people, but it’s not enough: study – Globalnews.ca

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Grizzly bears are doing their best to get along with people, but it still isn’t enough.

Newly published research concludes that without large wilderness areas to replenish their numbers, grizzlies would disappear from landscapes they share with humans.

“The persistence of bears near people, when we see them along highways or near towns, they’re really propped up by the fact they exist near some sort of secure wilderness,” said Clayton Lamb, a University of Alberta biologist and lead author of a paper published in the Proceedings of the National Academy of Sciences.

Read more:
Northern Alberta bear encounter captured on video

Researchers found bears in populated areas in Alberta and British Columbia have even changed how they hunt in an attempt to share living space with humans.

Story continues below advertisement

“The bears are doing what they can,” Lamb said. “The difference might have to be made up by us.”

The study set out to examine an emerging phenomenon in wildlife conservation — large carnivores re-establishing themselves on mixed landscapes including cities, highways, rural communities and patchworks of natural habitat.

It digested 41 years worth of mortality, movement and demography among 2,669 grizzlies over nearly 400,000 square kilometres of British Columbia.

It found mortality has increased steeply with the amount of human impact measured through an index that includes human population, land use, infrastructure, coastlines, roads, railroads and navigable rivers.






0:48
Grouse Mountain bears out of winter hibernation


Grouse Mountain bears out of winter hibernation

Deaths have outnumbered births and the difference is being made up through emigration of young grizzlies from nearby wilderness. For every point the index increases, a local bear population must increase the number of individuals it draws by about two per cent.

Story continues below advertisement

“Grizzly bear range is quite tied to the distance from some secure piece of wilderness,” said Lamb.

That’s despite the grizzlies’ efforts to adapt to humans. The study found young, newly arrived bears gradually learned ways to avoid contact, such as hunting and gathering at night.

Adolescent bears in areas dominated by humans have increased their nocturnal time by up to three per cent annually, which has led to corresponding increases in survival. The cost, however, is steep.






1:45
3 grizzlies spotted in Alberta woman’s backyard


3 grizzlies spotted in Alberta woman’s backyard

The scientists found it takes 14 years for a grizzly to learn how to co-exist with humans. For every bear that makes it, 29 don’t.

“A lot of those bears would have been born on a mountaintop 10 kilometres away and lived with mom in an avalanche chute and lived a normal bear life,” Lamb said.

Story continues below advertisement

“Then they find a home near town and get lured in by an apple tree. The gauntlet they have to run is very difficult.”

The study shows that high mortality has impacts far from where the deaths take place. Bears dying in mixed-used areas draws more grizzlies from the wilderness to take their place.

“Conflicts with people have rippling effects on (bear) populations far removed,” Lamb said.

Read more:
‘Never seen anything like it’: Bear cub spotted in Alberta with unique white head

Highway overpasses are one good way to reduce deaths, he suggests. But humans living with bears have to get better at removing attractants such as roadkill or fruit trees to end the bears’ constant, often fatal, migration from the wilderness.

“We’re not quite there,” said Lamb. “The system relies quite heavily on adjacent wilderness.”

Story continues below advertisement

© 2020 The Canadian Press

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Grizzly bears in the dark as they try to share living space with humans: study – Deloraine Times

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EDMONTON — Grizzly bears are doing their best to get along with people, but it still isn’t enough.

Newly published research concludes that without large wilderness areas to replenish their numbers, grizzlies would disappear from landscapes they share with humans.

article continues below

“The persistence of bears near people, when we see them along highways or near towns, they’re really propped up by the fact they exist near some sort of secure wilderness,” said Clayton Lamb, a University of Alberta biologist and lead author of a paper published in the Proceedings of the National Academy of Sciences.

Researchers found bears in populated areas in Alberta and British Columbia have even changed how they hunt in an attempt to share living space with humans.

“The bears are doing what they can,” Lamb said. “The difference might have to be made up by us.”

The study set out to examine an emerging phenomenon in wildlife conservation — large carnivores re-establishing themselves on mixed landscapes including cities, highways, rural communities and patchworks of natural habitat.

It digested 41 years worth of mortality, movement and demography among 2,669 grizzlies over nearly 400,000 square kilometres of British Columbia.

It found mortality has increased steeply with the amount of human impact measured through an index that includes human population, land use, infrastructure, coastlines, roads, railroads and navigable rivers.

Deaths have outnumbered births and the difference is being made up through emigration of young grizzlies from nearby wilderness. For every point the index increases, a local bear population must increase the number of individuals it draws by about two per cent.

“Grizzly bear range is quite tied to the distance from some secure piece of wilderness,” said Lamb.

That’s despite the grizzlies’ efforts to adapt to humans. The study found young, newly arrived bears gradually learned ways to avoid contact, such as hunting and gathering at night.

Adolescent bears in areas dominated by humans have increased their nocturnal time by up to three per cent annually, which has led to corresponding increases in survival. The cost, however, is steep.

The scientists found it takes 14 years for a grizzly to learn how to co-exist with humans. For every bear that makes it, 29 don’t.

“A lot of those bears would have been born on a mountaintop 10 kilometres away and lived with mom in an avalanche chute and lived a normal bear life,” Lamb said.

“Then they find a home near town and get lured in by an apple tree. The gauntlet they have to run is very difficult.”

The study shows that high mortality has impacts far from where the deaths take place. Bears dying in mixed-used areas draws more grizzlies from the wilderness to take their place.

“Conflicts with people have rippling effects on (bear) populations far removed,” Lamb said.

Highway overpasses are one good way to reduce deaths, he suggests. But humans living with bears have to get better at removing attractants such as roadkill or fruit trees to end the bears’ constant, often fatal, migration from the wilderness.

“We’re not quite there,” said Lamb. “The system relies quite heavily on adjacent wilderness.”

This report by The Canadian Press was first published July 7, 2020

— Follow @row1960 on Twitter

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