Astronomers announced today that they had discovered something new out in the dark: a stellar corpse too heavy to be a neutron star — the remnant of a supernova explosion — but not heavy enough to be a black hole.
Whatever it once was, it is long gone. About 780 million years ago — and 780 light-years away — it was eaten by a black hole 23 times more massive than the sun. That feast left behind an even heavier black hole — a vast, hungry nothing with the mass of 25 suns.
News of that event only recently reached Earth, in the form of space-time ripples known as gravitational waves. These evanescent vibrations were felt on Aug. 14, 2019, by an array of antennas in Italy and the United States called the International LIGO-Virgo Collaboration, and the results were published on Tuesday in Astrophysical Journal Letters.
According to a theory that has been the backbone of decades of astrophysical excitement, a star can wind up in one of three final states, depending on its mass: a perpetually cooling cinder known as a white dwarf; a dense star, with the mass of a couple of suns compressed into a ball only 12 or so miles wide, known as a neutron star; or a black hole, a beast reluctantly predicted by Albert Einstein to be so dense that nothing, not even light, can escape its gravity.
The victim in this collision weighed in at 2.6 solar masses, according to the LIGO-Virgo calculations. That is heavier than the accepted limit of 2.5 suns for a neutron star. But the lightest black hole ever measured was about five solar masses.
So the mystery object lies squarely in what astrophysicists call the “mass gap.” Astronomers have long wondered what, if anything, could occupy this astronomical no-man’s land.
“We’ve been waiting decades to solve this mystery” Vicky Kalogera of Northwestern University, one of the main authors of the paper, said in an interview. “We don’t know if this object is the heaviest known neutron star or the lightest known black hole, but either way it breaks a record.”
She added: “If it’s a neutron star, it’s an exciting neutron star. If it’s a black hole, it’s an exciting black hole.”
In a statement issued by the Science and Technology Facilities Council in Britain, Charlie Hoy, a graduate student at Cardiff University and Dr. Kalogera’s co-author, said, “I did not believe the alert when I first saw it come through.”
The LIGO observatory made history in 2016 when it detected gravitational waves from a pair of colliding black holes, proving the existence both of gravitational waves, a century after Einstein predicted them, and of black holes. The instrument consists of twin L-shaped antennas in Hanford, Wash., and Livingston, La.
Since then, LIGO has been joined in its exploration of the darkness by another antenna known as Virgo, in Cascina, Italy. The combined LIGO-Virgo Collaboration consists of about 2,000 scientists around the world. The alphabetical listing of their names and institutions takes up the first five and a half pages of the new paper.
The puzzling collision recorded last August was one of 56 possible gravitational wave events — most of which appear to be black hole collisions — detected during the observatory’s third run, which went from April 2019 until March 2020, when the coronavirus pandemic shut down most scientific activities around the world. The collaboration is still reviewing the data in an effort to analyze and confirm them.
Dr. Kalogera said that the event was exciting for several reasons. The ratio of the two colliding masses was the most extreme — nine to one — of the gravitational wave collisions that have been observed so far. Astronomers have difficulty imagining how such unmatched stars could get together in a binary double-star system to begin with.
“This is very hard for formation theories to explain,” she said.
The signal — a characteristic “chirp” caused by the colliding objects circling faster and faster as they approach their moment of ultimate doom — lasted about 10 seconds. “Due to the favorable circumstance of having observed such a loud signal with quite different component masses and for about 10 seconds, we achieved the most precise gravitational-wave measurement of a black hole spin to date,” Alessandra Buonanno, of the Albert Einstein Institute in Potsdam, Germany, said in a statement issued by the institute’s arm in Hannover, Germany.
A black hole’s spin carries important information about the birth and evolution of the black hole, Dr. Buonanno noted. In this case, it revealed that the black hole was spinning “rather slowly,” less than one-tenth the rate allowed by the strictures of Einstein’s theory.
Nobody had any immediate explanation or candidate for what kind of entity could fill this mass gap — a “dearth,” Dr. Kalogera called it — except to affirm that the calculations were robust.
Gordon Baym, an expert on neutron stars at the University of Illinois, pointed out that the collision of a pair of neutron stars in 2017, which produced a cosmic fireworks spectacle, left behind a neutron star with about 2.7 solar masses, thus briefly occupying the mass gap. But that object is thought to have collapsed into a black hole almost immediately.
Most well-measured neutron stars have masses of around 1.4 suns, Dr. Baym said, and only a handful have masses more than two. In theoretical calculations, he said, “it is very hard to make matter stiff enough, using reasonable physics,” to conjure a neutron star in the range of 2.6 solar masses.
Daniel Holz, an astronomy professor at the University of Chicago who is a member of the LIGO collaboration, but not one of the principal authors of this paper, mused that neutron stars and black holes are in some sense “polar opposites.”
“A neutron star is composed of the densest matter in the universe, and is in some sense the ultimate star,” he said in an email. “A black hole is just warped space and time. It doesn’t even have a physical surface! And the interior of a black hole is in some sense not even part of our universe, since nothing can come out of it.”
He added: “What is astounding is that, despite their profound differences, in this particular case we can’t tell which is which!” All the clues disappeared into the resultant black hole.
“So we’re not sure if this object is a neutron star or a black hole, and either way it’s exciting and we learn something new,” Dr. Holz said. “It’s a win-win! Lots of theorists are now sharpening their pencils to try to explain what we’ve seen.”
Newfoundland and Labrador premier tries to allay border fears – The Telegram
ST. JOHN’S, N.L. —
Local Journalism Iniative Reporter
As controversy continues to swirl around the prospect of opening Canada’s domestic borders, Newfoundland and Labrador’s premier and health minister are striving to allay fears.
On Wednesday, the premier fielded questions about a date that was tossed out last month around the same time the province announced it was joining an Atlantic bubble.
The opening of Atlantic regional borders, which allows permanent residents of all four provinces to travel freely without self-isolating, took effect July 3.
But Dwight Ball said a proposed opening of all provincial borders on July 17 has not been part of recent discussions.
“We know that around the province right now there’s considerable fear in opening up those borders,” he said this week. “We recognize from a Newfoundland and Labrador perspective that the areas that will line up and have more travellers come into our province would be from provinces like Alberta, provinces like Ontario.”
However, he said there has been talk lately about when, or even if, that may happen.
“First and foremost, I can assure people in Newfoundland and Labrador, it will be the safety of Newfoundlanders and Labradorians that will be the priority and will be what will influence the decision made by all of us before we ease any more travel restrictions.”
Ban not total
Ball also touched on a common misconception about travel into and out of the province since a travel ban was implemented on May 15. At least 8,000 exemptions have been granted to non-residents, for a variety of reasons. That doesn’t include the fact that residents are free to travel outside the province and return again.
“Keep in mind we have a lot of Newfoundlanders and Labradorians that leave the province and go visit families in Alberta and Ontario and other places,” he said. “They can leave. There’s no restriction on leaving. The restriction is when they come back.”
Any person arriving from outside the Atlantic bubble, including those who’ve passed through the region from elsewhere, are still required to self-isolate for 14 days.
The premier also clarified that five new cases in P.E.I. last weekend stemmed from a U.S. citizen who had arrived legally in Halifax and was picked up by family members from P.E.I. The island province turned him back at its border, so he returned to self-isolate in Halifax. Another P.E.I. resident was confirmed positive on Thursday, stemming from the same cluster.
“I think the officials within all of the Maritime provinces — New Brunswick, Nova Scotia and P.E.I. — will clearly say and articulate that what happened with this traveller was not at all connected to the Atlantic bubble,” Ball said.
New Brunswick also reported one new case on Thursday, stemming from travel.
Meanwhile, a nursing professor at Memorial University had some thoughts this week on the safety of flying with strangers as airlines start filling planes again.
The issue made headlines last weekend when a Halifax man decided to walk off a plane rather than fly in close quarters with passengers from outside the Atlantic bubble.
“I have mixed feelings about airplanes, and I travel a lot,” Donna Moralejo, who specializes in infection control, said in an interview.
Moralejo said the air in a plane is actually safer than most households because of built-in filtration systems. But surface contacts must be avoided, and close proximity means masks are essential.
“It’s probably not as unsafe as it sounds, given the airflow, but it’s less than ideal, especially on longer flights,” she said.
Peter Jackson is a Local Journalism Initiative reporter covering health for The Telegram.
4 thriller objects spotted in deep room, compared with nearly anything at any time seen – haveeruonline
LiveScience.com documented on Thursday that the highly circular objects that appear vibrant alongside the edges had been found when astronomers reviewed archival info from radio telescopes in Australia and India.
Kristine Spekkens, an astronomer from the Royal Military services College or university of Canada and Queen’s College, told the science internet site that the objects look to be a little something not nevertheless probed.
“It could also be that these are an extension of earlier known course of objects that we have not been in a position to discover,” she claimed. Researchers have referred to the objects as ORCs, or “odd radio circles.”
The Australian astronomers in the study noted that the objects ended up uncovered though functioning on the Evolutionary Map of the Universe Pilot, an all-sky continuum study, working with a square kilometer array pathfinder telescope.
The objects ended up described as circular, “edge-brightened discs.” They do not “correspond to any recognized style of object.” Two of them are reasonably close together, which could point out some relation. Two also attribute “an optical galaxy in the vicinity of the center of the radio emission.”
“We speculate that they could represent a spherical shock wave from an more-galactic transient occasion, or the outflow, or a remnant, from a radio galaxy considered finish-on,” the experts wrote.
The scholarly papers ended up posted on Arxiv.org.
The paper lists a several possible explanations but dismisses them. They theorized that it could be a supernova remnant, galactic planetary nebula or a deal with-on star-forming galaxy or ring galaxy.
The face-on star-forming galaxy principle, for case in point, was dashed, in part, owing to the “lack of measurable optical emission” in comparison to the radio emission.
Astronomers just spotted something in space that they can't explain – BGR – BGR
- Astronomers have spotted a new class of radio objects in space that has never been documented before.
- The researchers ruled out most possible explanations but a few remain, including that the signals are the leftover remnants of some cosmic event.
- In a new research paper, the scientists offer their best guesses, but can’t say for certain what they saw.
When astronomers used high-powered telescopes to peer deep into space they never know what they might find, but generally speaking, they know what they’re looking at once they see it. Finding a totally new class of unidentified object is rare, but that’s just what researchers using the Australian Square Kilometer Array Pathfinder telescope found while scanning the skies for radio signatures.
The team of scientists found four strange objects that they describe as “circular edge-brightened discs” which don’t correspond to any known object in the records. The team has named them ORCs, short for “odd radio circles,” and they’re eager to learn more about them.
As LiveScience reports, the researchers were quickly able to dismiss some possible explanations, such as newborn galaxies, nebulas, or supernovas. They even considered whether the strange objects might just be imaging artifacts, but were able to also rule that out. They’re a real mystery, but the researchers have other theories they can neither prove nor disprove at this point. One such explanation is that the rings are what remains of some massive explosive event far away in space.
What makes ORCs so hard to pin an explanation on is the fact that while they are visible in radio wavelengths they can’t be seen using visible light or even infrared. They appear to be purely radio signals, but their uniform shape suggests that the signal may be radiating out from a central point, supporting the idea that the circles are cosmic shockwaves spreading into space.
Still, even if that theory holds water, researchers still don’t know what caused them, how old they are, or what might happen to them in the future. They’re believed to be extragalactic, meaning that they’re not located within the Milky Way, but the team can’t say for certain how far away these strange signals are.
“We have discovered, to the best of our knowledge, a new class of radio-astronomical object, consisting of a circular disc, which in some cases is limb-brightened, and sometimes contains a galaxy at its center. None of the known types of radio object seems able to explain it,” the researchers write. “We, therefore, consider it likely that the ORCs represent a new type of object found in radioastronomy images. The edge-brightening in some ORCs suggests that this circular image may represent a spherical object, which in turn suggests a spherical wave from some transient event.”
It’s all pretty exciting, but we may have to wait a while before astronomers figure out exactly what they’re looking at.
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