The gargantuan supermassive black holes at the center of seemingly every galaxy are among the most fascinating and extreme objects known to modern astronomy and cosmology. With masses well in excess of millions, and sometimes billions that of our Sun, it is nearly impossible to comprehend the extraordinary size of these celestial leviathans. One of the great mysteries of modern astrophysics is answering how such enormous objects got started. In a press release published on March 10th, researchers propose that the origins of supermassive black holes may lie with long since extinct, first-generation stars with masses far above the most massive stars in the modern Universe. Not only do they propose such giants existed, but also they suggest that they’ve found a way to detect a particular subset of these stars. This breakthrough is thanks to our old friend, Einstein’s General Theory of Relativity.
The most massive stars in the Universe today weigh in near 150 solar masses. The primordial supermassive stars thought to be the origin or seed of supermassive black holes are believed to be orders of magnitude more massive. We’re talking in the 10,000-100,000 solar mass range! When stars enter this mass regime, their behavior is markedly different than that of more modern and modestly massive stars.
A model showing the predicted supernova behavior of a supermassive star. Credit Dr. Ke-Jung Chen, ASIAA
When these vast stars burn out at the end of their lives, the gravity is so strong that they can collapse directly into a black hole without the spectacular supernova explosions that we associate with massive star death today. This poses a real problem when it comes to detecting these events. Obviously, black holes are dark, and without a bright, signature supernova, these extreme stars would be rendered essentially undetectable. Keep in mind that since these stars only existed for a short time during the earliest stages of galaxy formation in the young Universe. We can only see their neighborhoods by looking billions of light-years away, and thus billions of years into the past.
I spoke with one of the lead researchers about the ingenious, relativistic solution to this seemingly unsolvable mystery. Dr. Ke-Jung Chen of Academia Sinica Institute of Astronomy and Astrophysics in Taipei, Taiwan, commented on a ‘sweet spot’ in the mass of these stars revealed by extensive modeling.
Another supernova model that Dr. Chen dubbed the ‘brainstar’. Credit Credit Dr. Ke-Jung Chen, ASIAA
“The model showed that at about 55,000 solar masses, there was a very interesting behavior due to general relativity.” Chen explained, “…because Einstein says the energy of everything, photons, gas, etc., contribute to the gravity field. The pressure starts to contribute to the gravitational field… it starts a violent nuclear reaction and then releases a large amount of energy and a supernova explosion.”
Dr. Chen went on to explain that this occurs only at the sweet spot of 55,000 solar masses. Less than that and the relativistic contribution is too little to cause these particular violent nuclear reactions. More and the gravity is so extreme that everything ends up within the black hole and all we see is darkness. With the billions of galaxies out on the edge of the observable universe, it is incredibly likely that at least some of these goldilocks 55,000 solar mass supernovae should be detectable.
Another question that immediately comes to mind when considering these primordial stellar giants: Why don’t we see stars this size in the modern Universe?
Supermassive black holes like the one at the center of galaxy M87 (pictured above from the famous event horizon telescope observations of 2019) are millions or billions of times the mass of the sun. Their mysterious origins may be explained by primordial supermassive stars in the early Universe. Credit: Event Horizon Telescope Collaboration
“We believe a supermassive star can only form in the early Universe. This is because of metals, that is, elements other than hydrogen and helium. In the Big Bang, we only have hydrogen and helium and a tiny amount of lithium. We don’t have carbon, oxygen, elements required to make life, etc. Because those (metals) elements have large atomic numbers and many electrons in their orbits, they can form molecules and compounds. This will cool the (surrounding) gas efficiently, leading to collapse and the formation of a star cluster.” Essentially, without heavy elements leading to local cooling and condensation of gas clouds, a large volume of gas in the predominantly hydrogen and helium environment of the early Universe is more likely to collapse into a supermassive star rather than a multitude of stars as we see in the open clusters of the modern Universe. This conversation also highlights a fun habit of astronomers that drives some chemists mad, which is referring to all elements heavier than hydrogen and helium as metals!
Chen described his hopes for detecting the signature supernovae of those supermassive stars whose mass happens to land right on the 55,000 solar mass sweet spot. “These observations are possible, especially for the upcoming James Webb Space Telescope.” If so, the observations will shed light on the very nature of galaxy formation and evolution itself.
Artist’s concept of James Webb Space Telescope Credit: Adriana Manrique Gutierrez, NASA Animator
The fundamental nature of supermassive black holes may be linked to these supermassive stars. Sweet spot supernovae may light the way to a new era of cosmology. Dr. Chen beams with a sense of curiosity and a passion for discovery and exploration when describing his research. It’s hard not to feel the same sense of excitement, both for the fantastic observational and theoretical achievements that have led us here and the massive (pun intended) discoveries just around the corner.
Lead Image: Colors reveal complex interactions of oxygen abundance driving a supernova in a 55,000 solar mass star.Credit Dr. Ke-Jung Chen, ASIAA
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.
