The makeup and the growth of the Universe have never been clearer — or as confusing — as they’ve been revealed to be in a massive new survey of the markers astronomers use to measure the cosmos.
A new analysis called Pantheon+ has narrowed down the uncertainty in the expansion and makeup of the Universe. To do this, Pantheon+ builds on two long-standing astronomical projects — one called Pantheon, combining observations of 1,550 supernovae reaching back 10 billion years; and another called SH0ES, which measures relatively close pulsing stars known as Cepheids within 10 million light years.
The Pantheon+ analysis of the makeup and expansion of the Universe published recently in The Astrophysical Journal finds that 66.2 percent of the Universe is made up of dark energy, the mysterious accelerator driving the Universe’s speeding expansion, slightly less than past estimates of about 68 percent.
Only 33.8 percent of the Universe is matter — and the vast majority of that is impossible-to-observe dark matter, whose existence astronomers can only infer from galactic-scale gravitational effects. At the accepted rate of 85 percent dark matter to 15 percent normal (baryonic) matter, that means just slightly less than 5 percent of the mass of the Universe is the stuff we can see around us.
Pantheon+ was also able to measure the Universe’s expansion to within 1.3 percent uncertainty, close enough that it is now undeniable that the early Universe and the current Universe don’t expand at the same pace.
Speaking with Inverse, lead author Dillon Brout, a NASA Einstein fellow at the Center for Astrophysics | Harvard-Smithsonian, says that this degree of precision means that instead of being limited by the data for measuring the growth of the Universe, “we’re approaching the limit where we’re limited by the uncertainties of our method.”
WHAT’S NEW — Pantheon+ offers as precise a measurement of dark energy, dark matter, and baryonic matter as can currently be assembled.
And “assembled” is the right word — this work combines analysis from the original Pantheon, which measured dark matter, and the Supernova H0 for the Equation of State (SH0ES), which measures the Hubble constant at which the Universe expands.
Pantheon+ synthesizes two decades of data from different telescopes and astronomers into a single analysis; it represents “an all-star sample,” Brout explains. And this is the biggest set of exploding stars that have been put together — over 1500, half again as many as an earlier version that focused just on the supernovae.
But Brout notes that’s about all that can be gained with current equipment. The limiting factor is time. “We get about one supernova per year that helps us measure the Hubble constant, and we’ve got 42 of them now. So we’re going to have to wait a while just to double our data set,” he says.
The cosmic microwave background is one of the best ways to understand the early universe. Print Collector/Hulton Archive/Getty Images
WHY IT MATTERS — Surveys like Pantheon+ allow astronomers to cross-check their results across different methods and different targets. Some components measure Cepheids, relatively nearby stars whose brightness waxes and wanes regularly; others measure supernovae who outshone galaxies up to 10 billion years ago.
For the time being, this is about as accurate as these kinds of measurements can get. “A lot of people will think ‘of course, you have to use James Webb,’” says Brout, “and the answer to that is ‘yes’ — but it’s not immediately clear how much it’s going to help us.” The James Webb Space Telescope will let astronomers look at the ways stellar dust and observations in different wavelengths impact observations of the anchors that hold their measurements in place.
The increasing accuracy of this analysis has also increased one of the biggest problems in cosmology. Pantheon+ has narrowed down the speed at which the Universe is expanding to 73.4 kilometers per second per megaparsec — give or take 1.3 percent. This means that, locally, space is getting bigger at about 164,000 miles per hour.
But that’s just here and, more importantly, now. Measurements of the cosmic microwave background show that in its earliest days, the Universe was definitely expanding slower, about 67 kilometers per second per megaparsec. As surveys like Pantheon+ get more accurate, it gets clearer and clearer that this discrepancy — the Hubble tension — can’t just be explained away by the difficulty of getting clear observations.
The Universe’s expansion has undeniably sped up, but it’s not quite clear why.
WHAT’S NEXT — As an overview of the field, Brout notes Pantheon+ is a way of capturing the state of the art right before an enormous transformation. Over the next two years, the Vera Rubin Observatory in Chile will come on line, and “the game is going to kind of change in the future.”
While work measuring dark matter, dark energy, and the expansion of the cosmos have been built on many different observations with many different tools, “going forward we have these big, billion-dollar telescopes that are collecting really enormous samples on their own.”
How enormous? The Rubin Observatory expects to find over a million of the right kind of ancient supernovae in the next dozen years – a thousand times more than what Pantheon+ collates.
The scale of the teams working on this data will change, too: “these are going to be huge collaborations with hundreds of people and they’re going to nail a lot of these things down.” But for now, “before these really big giant telescopes turn on,” Brout hopes Pantheon+ can be the apex of an era.
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.
