A mysterious astronomical object merged with a black hole 780 million light-years away and created gravitational waves that could be detected on Earth. The object exists inside what scientists call the “mass gap,” a range between the heaviest known neutron star and the lightest known black hole. And it could change how astronomers understand black holes.
In August 2019, astronomers using gravitational wave detectors in the US and Italy detected ripples in space and time, a gravitational wave event they dubbed GW190814. Given the fact that this occurred so far from Earth, the event occurred 780 million years ago, but the gravitational waves are just now reaching us.
The merger occurred between an object that was 2.6 times the mass of our sun with a black hole that was 23 times the mass of our sun. This large difference in the sizes of both objects, differing by a factor of nine, makes it the most extreme mass ratio for a gravitational wave event known to date.
The merger led to a black hole about 25 times the mass of the sun. Some of the mass was blasted out as gravitational waves.
The Laser Interferometer Gravitational-Wave Observatory, or LIGO, and Virgo were used to detect the event. The National Science Foundation’s LIGO includes two detectors — one in Livingston, Louisiana, and another in Hanford, Washington. The Virgo detector is located in Cascina, Italy.
Black holes are created when massive stars die and collapse. Stars that are less massive explode in a supernova. The remnant of this outburst is a neutron star, which is small but very dense.
Currently, the heaviest known neutron star is 2.5 times the mass of our sun and the lightest black hole is five times the mass of our sun. In between is the “mass gap” into which this object fits.
An international team of astronomers were involved in the study, which published Tuesday in The Astrophysical Journal Letters.
“We’ve been waiting decades to solve this mystery,” said Vicky Kalogera, study coauthor and Daniel I. Linzer distinguished university professor of physics and astronomy at Northwestern University, in a statement.
“Mergers of a mixed nature — black holes and neutron stars — have been predicted for decades, but this compact object in the mass gap is a complete surprise. We are really pushing our knowledge of low-mass compact objects,” Kalogera said.
“Even though we can’t classify the object with conviction, we have seen either the heaviest known neutron star or the lightest known black hole. Either way, it breaks a record,” said Kalogera, who is also director of Northwestern’s Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA).
A DIFFERENT KIND OF DETECTION
When LIGO and Virgo scientists detected this event, they sent out an immediate alert across the astronomy community to allow for follow-up by Earth and space-based telescopes. The hope is to find light waves also caused by the event.
This has only been seen once during a gravitational wave event, known as GW170817, which occurred in August 2017. It was the result of two neutron stars colliding and releasing light, gravitational waves and even creating elements like gold. Neutron star collisions are fiery, energetic and messy, releasing matter in all directions, and light is a by-product.
Mergers between two black holes, however, aren’t believed to create light.
When telescopes followed up on the August 2019 event, they didn’t pick up any signals of light waves. Scientists believed this is due to the distance of the event, which was six times farther away than the 2017 merger. If it was in fact a merger between two black holes, no light would be produced. And if it was a neutron star, the black hole was so much larger that it may have simply swallowed it.
“I think of Pac-Man eating a little dot,” Kalogera said. “When the masses are highly asymmetric, the smaller compact object can be eaten by the black hole in one bite.”
The detection challenges current theoretical models of how stars die as well as how they pair up in binary systems. Binary systems, like two stars orbiting each other, occur when the two objects are close enough for gravity to create a central orbit.
“The mass gap has been an interesting puzzle for decades, and now we’ve detected an object that fits just inside it,” said Pedro Marronetti, program director for gravitational physics at the National Science Foundation, in a statement.
“That cannot be explained without defying our understanding of extremely dense matter or what we know about the evolution of stars,” Marronetti said. “This observation is yet another example of the transformative potential of the field of gravitational-wave astronomy, which brings novel insights to light with every new detection.”
AN ASYMMETRIC BINARY SYSTEM
The researchers said they didn’t expect to find a binary system including two objects with such different masses, but now they know these are actually being created somewhere in the universe. Next, they have the challenge of trying to figure out what exactly they are and how they work, according to Alberto Vecchio, study co-author and director of the Institute for Gravitational Wave Astronomy.
Though the opportunity to study this event in detail has passed, this discovery will change the way astronomers understand and study neutron stars and black holes going forward.
Future detections of similar events could help astronomers determine if there are more objects that exist in the mass gap.
“This is the first glimpse of what could be a whole new population of compact binary objects,” said study coauthor Charlie Hoy, a member of the LIGO Scientific Collaboration and a graduate student at Cardiff University, in a statement.
“What is really exciting is that this is just the start,” Hoy said. “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.”
NAIROBI, Kenya (AP) — The body of Ugandan Olympic athlete Rebecca Cheptegei — who died after being set on fire by her partner in Kenya — was received Friday by family and anti-femicide crusaders, ahead of her burial a day later.
Cheptegei’s family met with dozens of activists Friday who had marched to the Moi Teaching and Referral Hospital’s morgue in the western city of Eldoret while chanting anti-femicide slogans.
She is the fourth female athlete to have been killed by her partner in Kenya in yet another case of gender-based violence in recent years.
Viola Cheptoo, the founder of Tirop Angels – an organization that was formed in honor of athlete Agnes Tirop, who was stabbed to death in 2021, said stakeholders need to ensure this is the last death of an athlete due to gender-based violence.
“We are here to say that enough is enough, we are tired of burying our sisters due to GBV,” she said.
It was a somber mood at the morgue as athletes and family members viewed Cheptegei’s body which sustained 80% of burns after she was doused with gasoline by her partner Dickson Ndiema. Ndiema sustained 30% burns on his body and later succumbed.
Ndiema and Cheptegei were said to have quarreled over a piece of land that the athlete bought in Kenya, according to a report filed by the local chief.
Cheptegei competed in the women’s marathon at the Paris Olympics less than a month before the attack. She finished in 44th place.
Cheptegei’s father, Joseph, said that the body will make a brief stop at their home in the Endebess area before proceeding to Bukwo in eastern Uganda for a night vigil and burial on Saturday.
“We are in the final part of giving my daughter the last respect,” a visibly distraught Joseph said.
He told reporters last week that Ndiema was stalking and threatening Cheptegei and the family had informed police.
Four in 10 women or an estimated 41% of dating or married Kenyan women have experienced physical or sexual violence perpetrated by their current or most recent partner, according to the Kenya Demographic and Health Survey 2022.
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.”
VICTORIA – The British Columbia government is partnering with a bear welfare group to reduce the number of bears being euthanized in the province.
Nicholas Scapillati, executive director of Grizzly Bear Foundation, said Monday that it comes after months-long discussions with the province on how to protect bears, with the goal to give the animals a “better and second chance at life in the wild.”
Scapillati said what’s exciting about the project is that the government is open to working with outside experts and the public.
“So, they’ll be working through Indigenous knowledge and scientific understanding, bringing in the latest techniques and training expertise from leading experts,” he said in an interview.
B.C. government data show conservation officers destroyed 603 black bears and 23 grizzly bears in 2023, while 154 black bears were killed by officers in the first six months of this year.
Scapillati said the group will publish a report with recommendations by next spring, while an independent oversight committee will be set up to review all bear encounters with conservation officers to provide advice to the government.
Environment Minister George Heyman said in a statement that they are looking for new ways to ensure conservation officers “have the trust of the communities they serve,” and the panel will make recommendations to enhance officer training and improve policies.
Lesley Fox, with the wildlife protection group The Fur-Bearers, said they’ve been calling for such a committee for decades.
“This move demonstrates the government is listening,” said Fox. “I suspect, because of the impending election, their listening skills are potentially a little sharper than they normally are.”
Fox said the partnership came from “a place of long frustration” as provincial conservation officers kill more than 500 black bears every year on average, and the public is “no longer tolerating this kind of approach.”
“I think that the conservation officer service and the B.C. government are aware they need to change, and certainly the public has been asking for it,” said Fox.
Fox said there’s a lot of optimism about the new partnership, but, as with any government, there will likely be a lot of red tape to get through.
“I think speed is going to be important, whether or not the committee has the ability to make change and make change relatively quickly without having to study an issue to death, ” said Fox.
This report by The Canadian Press was first published Sept. 9, 2024.
