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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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Here’s how Helene and other storms dumped a whopping 40 trillion gallons of rain on the South

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More than 40 trillion gallons of rain drenched the Southeast United States in the last week from Hurricane Helene and a run-of-the-mill rainstorm that sloshed in ahead of it — an unheard of amount of water that has stunned experts.

That’s enough to fill the Dallas Cowboys’ stadium 51,000 times, or Lake Tahoe just once. If it was concentrated just on the state of North Carolina that much water would be 3.5 feet deep (more than 1 meter). It’s enough to fill more than 60 million Olympic-size swimming pools.

“That’s an astronomical amount of precipitation,” said Ed Clark, head of the National Oceanic and Atmospheric Administration’s National Water Center in Tuscaloosa, Alabama. “I have not seen something in my 25 years of working at the weather service that is this geographically large of an extent and the sheer volume of water that fell from the sky.”

The flood damage from the rain is apocalyptic, meteorologists said. More than 100 people are dead, according to officials.

Private meteorologist Ryan Maue, a former NOAA chief scientist, calculated the amount of rain, using precipitation measurements made in 2.5-mile-by-2.5 mile grids as measured by satellites and ground observations. He came up with 40 trillion gallons through Sunday for the eastern United States, with 20 trillion gallons of that hitting just Georgia, Tennessee, the Carolinas and Florida from Hurricane Helene.

Clark did the calculations independently and said the 40 trillion gallon figure (151 trillion liters) is about right and, if anything, conservative. Maue said maybe 1 to 2 trillion more gallons of rain had fallen, much if it in Virginia, since his calculations.

Clark, who spends much of his work on issues of shrinking western water supplies, said to put the amount of rain in perspective, it’s more than twice the combined amount of water stored by two key Colorado River basin reservoirs: Lake Powell and Lake Mead.

Several meteorologists said this was a combination of two, maybe three storm systems. Before Helene struck, rain had fallen heavily for days because a low pressure system had “cut off” from the jet stream — which moves weather systems along west to east — and stalled over the Southeast. That funneled plenty of warm water from the Gulf of Mexico. And a storm that fell just short of named status parked along North Carolina’s Atlantic coast, dumping as much as 20 inches of rain, said North Carolina state climatologist Kathie Dello.

Then add Helene, one of the largest storms in the last couple decades and one that held plenty of rain because it was young and moved fast before it hit the Appalachians, said University of Albany hurricane expert Kristen Corbosiero.

“It was not just a perfect storm, but it was a combination of multiple storms that that led to the enormous amount of rain,” Maue said. “That collected at high elevation, we’re talking 3,000 to 6000 feet. And when you drop trillions of gallons on a mountain, that has to go down.”

The fact that these storms hit the mountains made everything worse, and not just because of runoff. The interaction between the mountains and the storm systems wrings more moisture out of the air, Clark, Maue and Corbosiero said.

North Carolina weather officials said their top measurement total was 31.33 inches in the tiny town of Busick. Mount Mitchell also got more than 2 feet of rainfall.

Before 2017’s Hurricane Harvey, “I said to our colleagues, you know, I never thought in my career that we would measure rainfall in feet,” Clark said. “And after Harvey, Florence, the more isolated events in eastern Kentucky, portions of South Dakota. We’re seeing events year in and year out where we are measuring rainfall in feet.”

Storms are getting wetter as the climate change s, said Corbosiero and Dello. A basic law of physics says the air holds nearly 4% more moisture for every degree Fahrenheit warmer (7% for every degree Celsius) and the world has warmed more than 2 degrees (1.2 degrees Celsius) since pre-industrial times.

Corbosiero said meteorologists are vigorously debating how much of Helene is due to worsening climate change and how much is random.

For Dello, the “fingerprints of climate change” were clear.

“We’ve seen tropical storm impacts in western North Carolina. But these storms are wetter and these storms are warmer. And there would have been a time when a tropical storm would have been heading toward North Carolina and would have caused some rain and some damage, but not apocalyptic destruction. ”

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Follow AP’s climate coverage at https://apnews.com/hub/climate

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Follow Seth Borenstein on Twitter at @borenbears

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Associated Press climate and environmental coverage receives support from several private foundations. See more about AP’s climate initiative here. The AP is solely responsible for all content.

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‘Big Sam’: Paleontologists unearth giant skull of Pachyrhinosaurus in Alberta

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It’s a dinosaur that roamed Alberta’s badlands more than 70 million years ago, sporting a big, bumpy, bony head the size of a baby elephant.

On Wednesday, paleontologists near Grande Prairie pulled its 272-kilogram skull from the ground.

They call it “Big Sam.”

The adult Pachyrhinosaurus is the second plant-eating dinosaur to be unearthed from a dense bonebed belonging to a herd that died together on the edge of a valley that now sits 450 kilometres northwest of Edmonton.

It didn’t die alone.

“We have hundreds of juvenile bones in the bonebed, so we know that there are many babies and some adults among all of the big adults,” Emily Bamforth, a paleontologist with the nearby Philip J. Currie Dinosaur Museum, said in an interview on the way to the dig site.

She described the horned Pachyrhinosaurus as “the smaller, older cousin of the triceratops.”

“This species of dinosaur is endemic to the Grand Prairie area, so it’s found here and nowhere else in the world. They are … kind of about the size of an Indian elephant and a rhino,” she added.

The head alone, she said, is about the size of a baby elephant.

The discovery was a long time coming.

The bonebed was first discovered by a high school teacher out for a walk about 50 years ago. It took the teacher a decade to get anyone from southern Alberta to come to take a look.

“At the time, sort of in the ’70s and ’80s, paleontology in northern Alberta was virtually unknown,” said Bamforth.

When paleontogists eventually got to the site, Bamforth said, they learned “it’s actually one of the densest dinosaur bonebeds in North America.”

“It contains about 100 to 300 bones per square metre,” she said.

Paleontologists have been at the site sporadically ever since, combing through bones belonging to turtles, dinosaurs and lizards. Sixteen years ago, they discovered a large skull of an approximately 30-year-old Pachyrhinosaurus, which is now at the museum.

About a year ago, they found the second adult: Big Sam.

Bamforth said both dinosaurs are believed to have been the elders in the herd.

“Their distinguishing feature is that, instead of having a horn on their nose like a triceratops, they had this big, bony bump called a boss. And they have big, bony bumps over their eyes as well,” she said.

“It makes them look a little strange. It’s the one dinosaur that if you find it, it’s the only possible thing it can be.”

The genders of the two adults are unknown.

Bamforth said the extraction was difficult because Big Sam was intertwined in a cluster of about 300 other bones.

The skull was found upside down, “as if the animal was lying on its back,” but was well preserved, she said.

She said the excavation process involved putting plaster on the skull and wooden planks around if for stability. From there, it was lifted out — very carefully — with a crane, and was to be shipped on a trolley to the museum for study.

“I have extracted skulls in the past. This is probably the biggest one I’ve ever done though,” said Bamforth.

“It’s pretty exciting.”

This report by The Canadian Press was first published Sept. 25, 2024.

The Canadian Press. All rights reserved.

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The ancient jar smashed by a 4-year-old is back on display at an Israeli museum after repair

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TEL AVIV, Israel (AP) — A rare Bronze-Era jar accidentally smashed by a 4-year-old visiting a museum was back on display Wednesday after restoration experts were able to carefully piece the artifact back together.

Last month, a family from northern Israel was visiting the museum when their youngest son tipped over the jar, which smashed into pieces.

Alex Geller, the boy’s father, said his son — the youngest of three — is exceptionally curious, and that the moment he heard the crash, “please let that not be my child” was the first thought that raced through his head.

The jar has been on display at the Hecht Museum in Haifa for 35 years. It was one of the only containers of its size and from that period still complete when it was discovered.

The Bronze Age jar is one of many artifacts exhibited out in the open, part of the Hecht Museum’s vision of letting visitors explore history without glass barriers, said Inbal Rivlin, the director of the museum, which is associated with Haifa University in northern Israel.

It was likely used to hold wine or oil, and dates back to between 2200 and 1500 B.C.

Rivlin and the museum decided to turn the moment, which captured international attention, into a teaching moment, inviting the Geller family back for a special visit and hands-on activity to illustrate the restoration process.

Rivlin added that the incident provided a welcome distraction from the ongoing war in Gaza. “Well, he’s just a kid. So I think that somehow it touches the heart of the people in Israel and around the world,“ said Rivlin.

Roee Shafir, a restoration expert at the museum, said the repairs would be fairly simple, as the pieces were from a single, complete jar. Archaeologists often face the more daunting task of sifting through piles of shards from multiple objects and trying to piece them together.

Experts used 3D technology, hi-resolution videos, and special glue to painstakingly reconstruct the large jar.

Less than two weeks after it broke, the jar went back on display at the museum. The gluing process left small hairline cracks, and a few pieces are missing, but the jar’s impressive size remains.

The only noticeable difference in the exhibit was a new sign reading “please don’t touch.”

The Canadian Press. All rights reserved.

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