Using data from the Atacama Large Millimeter Array (ALMA) and Very Large Telescope (VLT) of the European Southern Observatory (ESO), a European team of astronomers measures the gas pressure and studies how the powerful jets of a supermassive black hole alter the conditions for star formation in interstellar clouds.
The pressure maps of IC 5063. The left panel shows the internal pressure of molecular clouds as measured from CO and HCO+ emission lines. The right panel shows the pressure of the ionized medium as measured from ionized sulfur and nitrogen emission lines. This pressure is considered external to molecular clouds. Crosses mark the position of the radio core and white contour lines the jet trail as traced by the Hubble Space Telescope Wide Field Planetary Camera 2 narrow-band image. Image Credit: University of Cologne.
A European group of astronomers headed by Professor Kalliopi Dasyra of the National and Kapodistrian University of Athens, Greece, under the participation of Dr. Thomas Bisbas from the University of Cologne, modeled numerous emission lines in the Atacama Large Millimeter Array (ALMA) and Very Large Telescope (VLT) observations to quantify the gas pressure in both ambient clouds and jet-impacted clouds.
With these unparalleled predictions, reported recently in the journal Nature Astronomy, the researchers found out that the jets considerably alter the internal and external pressure of molecular clouds in their path.
In the same galaxy, it is possible for clouds to compress and start star formation as well as for clouds to dissipate and delay star formation, depending on which of the two pressures changes the most.
Our results show that supermassive black holes, even though they are located at the centers of galaxies, could affect star formation in a galaxy-wide mannerstudying the impact of pressure changes in the stability of clouds was key to the success of this project. Once few stars actually form in a wind, it is usually very hard to detect their signal on top of the signal of all other stars in the galaxy hosting the wind.
Kalliopi Dasyra, Professor, Department of Astrophysics, Astronomy, & Mechanics, Faculty of Physics, National and Kapodistrian University of Athens
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It is thought that supermassive black holes are situated at the center of the majority of the galaxies in the Universe.
When particles that were incursive onto such black holes have been trapped by magnetic fields, they could be ejected outwards and travel further inside galaxies in the form of huge and strong jets of plasma.
Such jets tend to be frequently perpendicular to galactic disks. But in a galaxy 156 million light years away called IC 5063, the jets are actually generating inside the disk, thereby interacting with dense and cold molecular gas clouds.
From this interaction, compression of jet-impacted clouds has been theorized to be possible. This results in gravitational instabilities and, finally, star formation as a result of the gas condensation.
For the experiment, the research group utilized the emission of formyl cation (HCO+) and carbon monoxide (CO) provided by ALMA and the emission of ionized nitrogen and ionized sulfur offered by VLT. They then made use of sophisticated and innovative astrochemical algorithms to spot the environmental conditions in the outflow and the encircling medium.
Such environmental conditions comprise data regarding the strength of the far-ultraviolet radiation of stars. This is the rate at which relativistic charged particles ionize the gas, and then the mechanical energy is deposited on the gas by the jets.
Narrowing down such conditions disclosed the densities and gas temperatures illustrative of various parts of this galaxy, which were further utilized to offer pressures.
“We have performed many thousands of astrochemical simulations to cover a wide range of possibilities that may exist in IC 5063,” stated co-author Dr. Thomas Bisbas, DFG Fellow of the University of Cologne and former postdoctoral researcher at the National Observatory of Athens.
A challenging aspect of the work was to carefully determine as many physical constraints as possible to the analyzed range that every parameter could have.
This way, we could get the optimal combination of physical parameters of clouds at different locations of the galaxy.
Georgios Filippos Paraschos, Study Co-Author and PhD Student, Max Planck Institute for Radio Astronomy
Georgios Filippos Paraschos was a Master’s student at the National and Kapodistrian University of Athens.
As a matter of fact, pressures were not just quantified for a few locations in IC 5063. Rather, maps of this and other quantities in the center of this galaxy were made. Such maps enabled the authors to envision how the gas properties shift from one location to another due to the jet passage.
At present, the team is looking forward to using the James Webb Space Telescope for additional investigations of the pressure in the outer cloud layers, as probed by the warm H2.
We are truly excited about getting the JWST dataas they will enable us to study the jet-cloud interaction at an exquisite resolution.
Kalliopi Dasyra, Professor, Department of Astrophysics, Astronomy, & Mechanics Faculty of Physics, National and Kapodistrian University of Athens
Journal Reference:
Dasyra, K. M., et al. (2022) Insights into the collapse and expansion of molecular clouds in outflows from observable pressure gradients. Nature Astronomy. doi.org/10.1038/s41550-022-01725-9
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.
