Astronomers may be getting closer to discovering as-yet hidden cosmic secrets, such as the nature of dark matter and the presence of widespread distortions in space-time, researchers reported at the 237th American Astronomical Society meeting, held virtually this week.
The existence of dark matter, an the invisible substance thought to make up more than four-fifths of all matter in the universe, may help explain a variety of cosmic puzzles, such as how galaxies can spin as fast as they do without getting ripped apart. However, much about the nature of dark matter — and even whether it exists at all — remains unknown.
To help pinpoint dark matter’s properties, researchers sought to directly measure the gravitational effects that dark matter should have on the speed at which stars are moving in the Milky Way. They focused on galactic lighthouses known as pulsars, or spinning neutron stars that emit twin beams of radio waves from their magnetic poles as they rotate. (Neutron stars are the remains of large stars that perished in catastrophic explosions known as supernovas.)
“It is a very, very small number we are trying to measure,” study lead author Sukanya Chakrabarti, an astrophysicist at the Rochester Institute of Technology in New York, said during a news conference held on Monday (Jan. 11). “In terms of change in velocity, it’s just a few centimeters per second, or roughly the speed of a crawling baby, and not a very fast baby at that.”
Pulsars spin at very steady rates, so they can serve as precise clocks. By monitoring tiny variations in the spin of 14 pulsars, the researchers could estimate the speeds at which these pulsars are moving and thus deduce the gravitational force that dark matter is exerting on them.
The scientists found that across the galaxy, the average amount of dark matter may be slightly lower than previous estimates. The researchers also calculated the amount of dark matter contained within the volume of the Earth is just 1.63 lbs. (740 grams), Chakrabarti said. These findings in turn can help current experiments seeking to directly detect dark matter “try and understand the nature of dark matter particles,” she added. For instance, this might affect how often one might expect such particles to interact with detectors.
In addition, scientists are now analyzing an unusually high number of gamma rays from the center of the Milky Way to see if they might come from annihilating dark matter particles. Previous research suggested dark matter could be made of new kinds of particle, ones that annihilate when they come in contact with each other, generating high-energy gamma rays.
Based on 11 years of data from NASA’s Fermi Gamma-Ray Space Telescope, “we can say what are good candidates for dark matter,” study lead author Mattia di Mauro, an astrophysicist at the National Institute for Nuclear Physics in Torino, Italy, said during the same news conference. These include weakly interacting massive particles, or WIMPS, hypothetical elementary particles that only barely interact with ordinary matter except through their gravitational pull.
“In the future, the Large Hadron Collider or other particle physics detectors could test these specific candidates,” he added.
The gravitational background
Researchers at the premiere astronomy conference also reported finding the first possible hints of a mysterious new kind of gravitational wave, cosmic ripples that warp the fabric of space and time itself.
Scientists reported the first-ever direct detection of gravitational waves in 2016 using the Laser Interferometer Gravitational-Wave Observatory (LIGO), a discovery that earned the 2017 Nobel Prize in Physics. The space-time distortions those researchers saw were created when two black holes collided with each other about 130 million light-years from Earth. Since then, LIGO has observed dozens more such signals.
But the gravitational waves that LIGO are best at detecting are the most powerful ones, loud outbursts released when extraordinarily massive objects collide with one another. Researchers now also want to detect gravitational waves that are more like the background noise of small talk at a crowded party.
In theory, merging galaxies and other cosmic events should generate such a “gravitational wave background.” Detecting this steady hum could shed light on mysteries such as how galaxies have grown over time.
However, these waves are huge, posing a major challenge for detecting this gravitational wave background. Whereas existing gravitational-wave observatories on Earth are designed to search for gravitational waves on the order of seconds long, ripples from the gravitational wave background are years or even decades long.
Now researchers say they may have detected a strong signal of the gravitational wave background using a U.S. and Canadian project called the North American Nanohertz Observatory for Gravitational Waves (NANOGrav).
“We’re seeing incredibly significant evidence for this signal,” study lead author Joseph Simon, an astrophysicist at the University of Colorado Boulder, said during the AAS press conference. “Unfortunately, we can’t quite say what it is yet.”
NANOGrav uses telescopes on the ground to monitor dozens of pulsars. Gravitational waves can alter the steady blinking pattern of light from pulsars, squeezing and expanding the distances these rays travel through space.
“As these waves pass us, the Earth gets pushed around very slightly,” Simon said. “As Earth is pushed closer to pulsars in one part of the sky, those pulsars’ pulses will appear a little bit sooner than expected, and pulses from pulsars in the other part of the sky appear to come a bit later.”
Analyzing this pulsar light could therefore help scientists detect signs of the gravitational wave background.
“By monitoring signals from a large number of these pulsars, we created a galaxy-size gravitational-wave detector within our own Milky Way,” Simon said.
To find these subtle hints, NANOGrav scientists have attempted to observe as many pulsars as they can for as long as possible. So far, they have observed 45 pulsars for at least three years, and in some cases, for more than a dozen years.
“These pulsars are spinning about as fast as your kitchen blender,” Simon said in a statement. “And we’re looking at deviations in their timing of just a few hundred nanoseconds.”
Now the researchers said they have detected potential evidence of a common process distorting the light from many of the pulsars. As of yet, they cannot verify whether this signal is evidence for the gravitational wave background, “but we also don’t have evidence against it,” Simon said.
The scientists caution they still need to look at more pulsars and monitor them for longer time periods to confirm whether the gravitational background is the cause.
If the researchers can verify they have detected the gravitational wave background, they next want to pinpoint what causes these waves and what such signals can tell scientists about the universe.
The scientists detailed their findings Jan. 11 at an online meeting of the American Astronomical Society. Chakrabarti and her colleagues detailed their findings in a study accepted in the journal Astrophysical Journal Letters. Simon and his colleagues detailed their NANOGrav findings online Dec. 24 in the journal The Astrophysical Journal Letters.
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.
