Across the vast desert plains of Western Australia, on the lands of the Wajarri Yamatji people, lies one of the most capable radio telescope arrays in the world. Containing 36 dish antennas, the Australian Square Kilometre Array Pathfinder, ASKAP, is an eye to the universe. The three dozen antennas watch for radio waves that crash over the Earth.
Over the last two years the antennas have, on occasion, been pointed toward the heart of the Milky Way, our home galaxy. And, on occasion, they’ve detected a highly unusual radio signal — one that does not seem to fit with any object we currently know is lurking in the cosmos.
The name of the strange signal is a mouthful: ASKAP J173608.2-321635. We’re going to call it the Ghost. Between April 2019 and August 2020, the Ghost was spotted 13 times but without any consistent timing.
It exhibits a range of characteristics that make it highly unusual and unlike other radio sources from the depths of the Milky Way.
“This object was unique in that it started out invisible, became bright, faded away and then reappeared,” said Tara Murphy, an astrophysicist at the University of Sydney and co-author on the paper, in a press release. “This behaviour was extraordinary.”
Originally, the team thought the radio signal might be emanating from a pulsar, a kind of neutron star that is incredibly dense and throws off electromagnetic radiation while spinning rapidly in space. The team went searching for the pulsar using the Murriyang telescope at the Parkes observatory in Australia. They came up empty.
Further searches through data obtained by NASA’s Neil Gehrels Swift Observatory found no X-rays associated with the signal and data from the VISTA telescope, in Chile, also showed no near-infrared signal.
The Ghost left little trace.
Paraneutron activity
In an attempt to hunt down the Ghost, the team turned to the Meerkat array in South Africa, which is very similar to ASKAP — with double the antennas.
Listening in with Meerkat, the signal reappeared. But the Ghost had morphed into something new. No longer was the radio signal lasting for weeks, it now disappeared within a day.
This irregular buzzing is one confusing aspect of the discovery, but perhaps the most unusual feature is the Ghost’s circular polarization. Polarization relates to how the radio wave moves through space and time — we’re not going to get into it here, but this entry on Wikipedia is actually quite good at explaining it. What you need to know is circular polarization is a rare phenomenon in the cosmos, making this radio signal rather interesting.
“Much less than 1% of sources are circularly polarized,” says Ziteng Wang, a doctoral student at the University of Sydney, Australia and first author on the study, adding “usually polarized sources are associated with magnetic fields.”
Potentially, the magnetic field of an object is messing with the radio signal on its way to Earth. That might be something as common as a dusty debris field or it could be something else entirely.
Magnetic fields are likely associated with another kind of weird radio signal from the depths of the cosmos, known as a fast radio burst. Tracing these signals leads back to a type of dead star known as a magnetar. You can see the similarities, perhaps, but Wang points out that these signals are different from the Ghost and that FRBs last for much shorter time periods or repeat on much clearer timeframes. Nevertheless, magnetic fields appear to be a powerful way to mess with a radio signal.
There is another group of objects, known as galactic center radio transients, that might explain the Ghost, too, but Wang has reservations about this hypothesis. “The timescale of this signal and GCRTs are different,” he says, noting that these transients are still a mystery to astronomers, too, and if the Ghost is another GCRT, we’re not much closer to working out what that really means.
We do know that, lurking within the heart of our Milky Way is a gigantic black hole known as Sagittarius A*, but there’s no indication it has anything to do with the Ghost, either.
One of the limitations of the study is the “sparse sampling” of the Ghost, Wang says. He also notes that it’s hard to say exactly how often the Ghost might repeat, because the amount of observations is still quite small. He doesn’t rule out that it’s a pulsar or star, but says the observations don’t fit with either of these objects.
So what is it? I know what you’re thinking, but we never jump to the “A” word around here. It’s almost certainly not aliens.
It definitely is a mystery — for now. Further observations should be able to refine the characteristics of the Ghost a little more, bringing its murky origins into clearer view.
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.
