Monday, August 29, 2022

X-shaped radio galaxies might form more simply than expected

Simple simulation accidentally leads to X-shaped galaxy for first time

NORTHWESTERN UNIVERSITY

X-shaped radio galaxy — IMAGE: A STILL IMAGE TAKEN FROM THE 3D SIMULATION OF THE NATURAL DEVELOPMENT OF AN X-SHAPED JET. THE GAS (BRIGHT RED) FALLS INTO THE BLACK HOLE, WHICH LAUNCHES A PAIR OF RELATIVISTIC JETS (LIGHT BLUE). THE JETS PROPAGATE VERTICALLY AND SHOCK THE AMBIENT GAS (DARK RED) THE OLDER CAVITIES (DARK BLUE) BUOYANTLY RISE AT AN ANGLE TO THE VERTICALLY PROPAGATING JETS TO FORM THE X-SHAPE. view more
CREDIT: ARETAIOS LALAKOS/NORTHWESTERN UNIVERSITY

When astronomers use radio telescopes to gaze into the night sky, they typically see elliptical-shaped galaxies, with twin jets blasting from either side of their central supermassive black hole. But every once in a while — less than 10% of the time — astronomers might spot something special and rare: An X-shaped radio galaxy, with four jets extending far into space.

Although these mysterious X-shaped radio galaxies have confounded astrophysicists for two decades, a new Northwestern University study sheds new insight into how they form — and its surprisingly simple. The study also found that X-shaped radio galaxies might be more common than previously thought.

The study will be published on Aug. 29 in the Astrophysical Journal Letters. It marks the first large-scale galaxy accretion simulation that tracks the galactic gas far from the supermassive black hole all the way toward it.

Simple conditions lead to messy result

Using new simulations, the Northwestern astrophysicists implemented simple conditions to model the feeding of a supermassive black hole and the organic formation of its jets and accretion disk. When the researchers ran the simulation, the simple conditions organically and unexpectedly led to the formation of an X-shaped radio galaxy.

Surprisingly, the researchers found that the galaxy’s characteristic X-shape resulted from the interaction between the jets and the gas falling into the black hole. Early in the simulation, the infalling gas deflected the newly formed jets, which turned on and off, erratically wobbled and inflated pairs of cavities in different directions to resemble an X-shape. Eventually, however, the jets became strong enough to push through the gas. At this point, the jets stabilized, stopped wobbling and propagated along one axis.

“We found that even with simple symmetric initial conditions, you can have quite a messy result,” said Northwestern’s Aretaios Lalakos, who led the study. “A popular explanation of X-shaped radio galaxies is that two galaxies collide, causing their supermassive black holes to merge, which changes the spin of the remnant black hole and the direction of the jet. Another idea is that the jet’s shape is altered as it interacts with large-scale gas enveloping an isolated supermassive black hole. Now, we have revealed, for the first time, that X-shaped radio galaxies can, in fact, be formed in a much simpler way.”

Lalakos is a graduate student in Northwestern’s Weinberg College of Arts and Sciences and a member of the Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA). He is co-advised by paper coauthor Sasha Tchekhovskoy, an assistant professor of physics and astronomy at Northwestern and key member of CIERA, and Ore Gottlieb, a CIERA postdoctoral fellow.

An accidental X-shape

Although radio galaxies emit visible light, they also encompass large regions of radio emission. Perhaps the most famous radio galaxy is M87, one of the most massive galaxies in the universe, which was further popularized in 2019 when the Event Horizon Telescope imaged its central supermassive blackhole. First coined in 1992, X-shaped radio galaxies make up less than 10% of all radio galaxies.

When Lalakos set out to model a black hole, he did not expect to simulate an X-shaped galaxy. Instead, he aimed to measure the amount of mass eaten by a black hole. He inputted simple astronomical conditions into the simulation and let it run. Lalakos did not initially recognize the importance of the emerging X-shape, but Tchekhovskoy reacted with enthusiastic fervor.

“He said, ‘Dude, this is very important! This is an X-shape!’” Lalakos said. “He told me that astronomers have observed this in real life and didn’t know how they formed. We created it in a way that no one had even speculated before.”

In previous simulations, other astrophysicists have attempted to create X-shaped structures artificially in order study how they arise. But Lalakos’ simulation organically led to the X-shape.

“In my simulation, I tried to assume nothing,” Lalakos said. “Usually, researchers put a black hole in the middle of a simulation grid and place a large, already-formed gaseous disk around it, and then they may add ambient gas outside the disk. In this study, the simulation starts without a disk, but soon one forms as the rotating gas gets closer to the black hole. This disk then feeds the black hole and creates jets. I made the simplest assumptions possible, so the whole outcome was a surprise. This is the first time anyone has seen X-shaped morphology in simulations from very simple initial conditions.”

‘Not lucky enough to see them’

Because the X-shape only emerged early in the simulation — until the jets strengthened and stabilized — Lalakos believes X-shaped radio galaxies might appear more frequently, but last a very short time, in the universe than previously thought.

“They might arise every time the black hole gets new gas and starts eating again,” he said. “So they might be happening frequently, but we might not be lucky enough to see them because they only happen for as long as the power of the jet is too weak to push the gas away.”

Next, Lalakos plans to continue running simulations to better understand how these X-shapes arise. He looks forward to experimenting with the size of the accretion disks and spins of central black holes. In other simulations, Lalakos included accretion disks that were almost non-existent all the way up to extremely large — none led to the elusive X-shape.

“For most of the universe, it’s impossible to zoom in right at the center and see what’s happening very near a black hole,” Lalakos said. “And even the things we can observe, we are constrained by time. If the supermassive black hole is already formed, we cannot observe its evolution because human lifetime is too short. In most cases, we rely on simulations to understand what happens near a black hole.”

The study, “Bridging the Bondi and Event Horizon Scales: 3D GRMHD simulations reveal X-shaped radio galaxy morphology,” was supported by the National Science Foundation (grant numbers AST-2107839, AST-1815304, AST-1911080 and OAC-2031997).

Simulation of X-shaped radio galaxy (VIDEO)

JOURNAL

The Astrophysical Journal Letters

METHOD OF RESEARCH

Computational simulation/modeling

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Bridging the Bondi and Event Horizon Scales: 3D GRMHD simulations reveal X-shaped radio galaxy morphology

ARTICLE PUBLICATION DATE

29-Aug-2022

V'GER
An alien hunting radio telescope has picked up humanity’s most distant creation
Jon Kelvey -

PIA21740~medium.jpg© Nasa

An alien-hunting telescope has picked up a faint and interesting signal — but it’s not from aliens.

Instead, the recently refurbished Allen Telescope Array in California on 9 July picked up the signal of Voyager 1, the most distant object created by humans.

Launched on 5 September 1977, Nasa’s Voyager 1 mission provided stunning images of the outer Solar System before passing beyond the orbit of Neptune. Voyager has continued flying away from us at more than 38,000 miles per hour and has crossed into interstellar space: the spacecraft is currently about 14.5bn miles from Earth.

That’s more than 150 times the distance of the Earth to the Sun. Nevertheless, the distant probe still makes regular contact with the Deep Space Network, a series of antennas around the globe Nasa uses for keeping in touch with spacecraft in deep space.

The 42 antenna dishes of the Allen Telescope Array were also able to detect Voyager 1’s signal and record about a quarter-hour of data from the space probe, which continues to beam back information about the properties of the “interstellar medium,” the space outside the immediate electromagnetic influence of the Sun.

“The detection of Voyager 1, the farthest human-made object, with the refurbished Allen Telescope Array is an excellent display of the telescope’s capabilities and strengths, and a representation of the outstanding hard work put by the ATA team since the start of the refurbishment program in 201,” Wael Farah, a postdoctoral researcher at the Seti institute wrote in a statement.

EXPLAINER: Pakistan fatal flooding has hallmarks of warming

The familiar ingredients of a warming world were in place: searing temperatures, hotter air holding more moisture, extreme weather getting wilder, melting glaciers, people living in harm’s way, and poverty. They combined in vulnerable Pakistan to create unrelenting rain and deadly flooding.

EXPLAINER: Pakistan fatal flooding has hallmarks of warming© Provided by The Canadian Press

The flooding has all the hallmarks of a catastrophe juiced by climate change, but it is too early to formally assign blame to global warming, several scientists tell The Associated Press. It occurred in a country that did little to cause the warming, but keeps getting hit, just like the relentless rain.

“This year Pakistan has received the highest rainfall in at least three decades. So far this year the rain is running at more than 780% above average levels,” said Abid Qaiyum Suleri, executive director of the Sustainable Development Policy Institute and a member of Pakistan’s Climate Change Council. “Extreme weather patterns are turning more frequent in the region and Pakistan is not a exception.”

Climate Minister Sherry Rehman said “it’s been a catastrophe of unprecedented proportions.”

Pakistan “is considered the eighth most vulnerable country to climate change,” said Moshin Hafeez, a Lahore-based climate scientist at the International Water Management Institute. Its rain, heat and melting glaciers are all climate change factors scientists warned repeatedly about.

While scientists point out these classic climate change fingerprints, they have not yet finished intricate calculations that compare what happened in Pakistan to what would happen in a world without warming. That study, expected in a few weeks, will formally determine how much climate change is a factor, if at all.

The “recent flood in Pakistan is actually an outcome of the climate catastrophe ... that was looming very large,” said Anjal Prakash, a research director at India’s Bharti Institute of Public Policy. “The kind of incessant rainfall that has happened ... has been unprecedented."

Pakistan is used to monsoons and downpours, but “we do expect them spread out, usually over three months or two months,” said the country's climate minister Rehman.

There are usually breaks, she said, and not as much rain -- 37.5 centimeters (14.8 inches) falls in one day, nearly three times higher than the national average for the past three decades. “Neither is it so prolonged. ... It’s been eight weeks and we are told we might see another downpour in September.”

“Clearly, it’s being juiced by climate change,” said Jennifer Francis, a climate scientist at the Woodwell Climate Research Center in Massachusetts.

There’s been a 400% increase in average rainfall in areas like Baluchistan and Sindh, which led to the extreme flooding, Hafeez said. At least 20 dams have been breached.

The heat has been as relentless as the rain. In May, Pakistan consistently saw temperatures above 45 degrees Celsius (113 Fahrenheit). Scorching temperatures higher than 50 degrees Celsius (122 Fahrenheit) were recorded in places like Jacobabad and Dadu.

WION Climate Tracker: Floods wreak havoc in Pakistan, over a million people affected by rains View on Watch Duration 2:29

Warmer air holds more moisture -- about 7% more per degree Celsius (4% per degree Fahrenheit) — and that eventually comes down, in this case in torrents.

Across the world “intense rain storms are getting more intense,” said Princeton University climate scientist Michael Oppenheimer. And he said mountains, like those in Pakistan, help wring extra moisture out as the clouds pass.

Instead of just swollen rivers flooding from extra rain, Pakistan is hit with another source of flash flooding: The extreme heat accelerates the long-term glacier melting then water speeds down from the Himalayas to Pakistan in a dangerous phenomena called glacial lake outburst floods.

“We have the largest number of glaciers outside the polar region, and this affects us,” climate minister Rehman said. “Instead of keeping their majesty and preserving them for posterity and nature. We are seeing them melt.”

Not all of the problem is climate change.

Pakistan saw similar flooding and devastation in 2010 that killed nearly 2,000 people. But the government didn’t implement plans to prevent future flooding by preventing construction and homes in flood prone areas and river beds, said Suleri of the country's Climate Change Council.

The disaster is hitting a poor country that has contributed relatively little to the world's climate problem, scientists and officials said. Since 1959, Pakistan has emitted about 0.4% of heat-trapping carbon dioxide, compared to 21.5% by the United States and 16.4% by China.

“Those countries that have developed or gotten rich on the back of fossil fuels, which are the problem really,” Rehman said. “They’re going to have to make a critical decision that the world is coming to a tipping point. We certainly have already reached that point because of our geographical location.”

—-

Borenstein reported from Kensington, Maryland, and Arasu from New Delhi. AP journalists Munir Ahmed in Islamabad, Pakistan, and Aniruddha Ghosal in New Delhi contributed to this report.

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Follow AP’s climate and environment coverage at https://apnews.com/hub/climate-and-environment

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Follow Seth Borenstein on Twitter at @borenbears and Sibi Arasu at @sibi123.

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Associated Press climate and environmental coverage receives support from several private foundations. See more about AP’s climate initiative here. The AP is solely responsible for all content.

Seth Borenstein And Sibi Arasu, The Associated Press

A New 'Rage Index' Shows What Canadians Are Most Angry About & Some May Surprise You

Helena Hanson - NARCITY

What's made you mad this month? A new "rage index" considers the general mood of Canadians regarding the government, the economy and more, and the inaugural study has concluded that Canada is a country that is currently "grumpy."

The research — created by Pollara Strategic Insights — aims to gauge Canadians' perception of things like the trucker convoy, the cost of gas and the housing market to see what's getting people most angry each month.

The first survey found that an average of 49% of Canadians are feeling annoyed or angry recently, with 14% of those saying they've been very angry.

Frustration about the types of changes happening in Canada is especially widespread, Pollara Strategic Insights says, with 53% saying they're either very mad or moderately mad about the Canadian economy. Conversely, just 2% say they're very happy with the economic situation at the moment.

A significant 60% of the Canadians surveyed say the latest stories in the news in Canada gets them down too, with a mere 1% saying the news leaves them with a very happy feeling.

Other things getting Canadians fired up and feeling angry recently are the federal government (48%), provincial governments (46%) and the types of overall changes that are happening in the country right now (55%).

However, more specific news stories are what bring real "flashpoints of anger" for many Canadians, with things like inflation, gas prices, airport delays and the trucker convoy protests bringing some people to near boiling point.

The rate of inflation in Canada, for example, had as many as 41% feeling really mad, while an additional 42% described feeling annoyed or moderately angry.

Similarly, a majority of Canadians (79%) feel some level of anger over Canada's expensive gas prices.

Many people are also cross about delays at Canadian airports (57%), the housing market in Canada (55%) and the ongoing disruptions to passport services (45%).

Of those surveyed, 42% said the trucker convoy protests earlier this year made them feel very angry, while 21% described feeling annoyed to some degree. Conversely, 15% felt some degree of happiness, while the rest felt neutral.

The study added that people in the Prairies are the angriest in Canada overall, with 55% feeling some degree of frustration across the six topics.

Quebecers, on the other hand, are the most relaxed, with just 43% feeling mad about the subjects posed.

Overall, researchers concluded that despite Canada's overall current "grumpiness," feelings of intense rage are "limited to a vocal minority."

The country's general attitude on the rage index is described as "hot, not boiling," although only time will tell if this cools further or, in fact, heats up.

This article's cover image was used for illustrative purposes only.

How do land sparing vs. land sharing interventions influence human wellbeing?

Q&A with the researchers

Peer-Reviewed Publication

THE ALLIANCE OF BIOVERSITY INTERNATIONAL AND THE INTERNATIONAL CENTER FOR TROPICAL AGRICULTURE

Land interventions and human wellbeing (1) — IMAGE: INSIDE SUSTAINABLE USE RESERVES (BRAZIL): PEOPLE PRACTICE SMALL-SCALE AGRICULTURE AND LIVE PREDOMINANTLY IN HOMES MADE OF WOOD AND PALM THATCHING. THESE SUBSISTENCE LIVELIHOODS ARE DIRECTLY CONNECTED TO THE SURROUNDING LANDSCAPE. view more
CREDIT: RACHEL CARMENTA

A recent study published in People and Nature focuses on how land use approaches impact human wellbeing.

Q: Before we get into the details of the research, can you explain the terms “Land sparing” vs. “Land sharing”, and how these relate to your research?

RC: Land sharing and land sparing is a framework often used to assess how different land management strategies impact biodiversity and agricultural yields.

Specifically, it looks at the relationship between agricultural yield and species response curves, asking: do species do better in landscapes where agriculture is intensively concentrated and managed in certain patches, sparing land for nature elsewhere (ie, land sparing)? Or do species do better in landscapes that are composed of a mosaic distribution of low-intensity agriculture peppered through a ‘natural’ landscape that provides a biodiversity-friendly matrix (land sharing)?

One of the invisible factors in the spare debate is how those strategies impact people living in the landscapes. Some have argued that a more ethical and just approach should focus on the people – and that perhaps doing so can move the scientific community beyond the ‘false dichotomy’ of Sharing vs. Sparing. With this in mind, we put people at the center of our research and assessed the impact of contrasting interventions across the sharing vs. sparing spectrum on locals’ human wellbeing.

Q: Your new paper discusses the importance of “integrated interventions” in conservation of tropical landscapes. Can you explain what are integrated interventions, with an example?

RC: Integrated forms of conservation recognize that people and nature can co-exist in the same landscape, with more respect for cultural and agricultural traditions and an emphasis on collaborative, cross-sectoral efforts.

These approaches try to integrate different needs within a landscape (conservation, agriculture, climate change mitigation), rather than pursue single-sector, or ‘siloed’ goals. For instance, sustainable use reserves attempt to do this with clear rules about resource use for conservation purposes, land rights granted, small-scale diversified and sustainable agriculture allowed, etc.

However, we know little about how these interventions perform on multi-dimensional wellbeing, partly because the sharing-sparing focus measures different things (ie, yield and species responses), and partly because usually social impact, when included, involves only the material dimensions of peoples' wellbeing.

Q: What is an example of the opposite, a single-sector intervention?

NEC: The clearest examples of this are high-input conventional agriculture and strict protected areas. High-input conventional agriculture aims to maximize yields for commodities (often one crop only) and theoretically squeeze more units of yield out of a given area. With “less” land allocated to agriculture, more land would be spared for nature through strict protection, where people (often indigenous peoples) are banned from resource use or residing within the area, and land is ‘protected’ for nature alone.

More evidence is contesting the assumptions behind these types of interventions, and more robust performance assessments are also contesting the often-assumed outstanding performance. When other aspects are considered, such as the impact on human health and ecosystems in the short and long term, changes in yield over time, species mobility, and the production from other companion crops, conventional agriculture does not necessarily outperform integrated / diversified / low-input systems, particularly in the long-term.

Q: So the finding, if I understand correctly, is that human wellbeing does better integrated interventions?

RC: Yes, that's right. We looked at how these interventions impact locally salient human wellbeing. The key findings are threefold, and each relates to people more than the conservation status, agriculture performance or biodiversity in the landscape (which have been measured elsewhere).

First, by asking what matters to people, we demonstrate that the longstanding focus of impact appraisal on material things in peoples’ lives (e.g. income) is at odds with what people care most about. Material aspects of human wellbeing are of less or equal importance as the relational (“family”, “friends”, “connection with nature”) and quality of life (“good food”, “good land”) aspects of human wellbeing.
Second, by asking how the interventions affected what matters the most to people, we demonstrate that integrated interventions have more impact, and what’s more – more of that impact is positive. Meanwhile, single sector – or land sparing interventions - have less impact, and more of that is actually negative.
Third, we find a dominance of null impact across all interventions, meaning thatinterventions can be better co-designed with local communities to be locally relevant and bring significant benefits. This finding also suggests that interventions are one drop in a sea of influences - for example, political economy - that impact peoples' lives.

Overall, our research joins previous evidence showing the flaws of the land-sparing debate, particularly on how these rather simplistic interventions can negatively impact people. Our research also calls for decolonial conservation and development interventions by co-designing, co-implementation, and co-assessing impact. This will require asking people who are impacted: how have they been impacted, and which types of impacts are most salient, and what types of futures do they want to see in their landscapes and territories?

Q: What do these findings mean for other researchers, especially across international organizations working on conservation and agriculture for development?

RC: The findings support the growing recognition of the need for integrated, systems- and multidisciplinary- approaches that can sustainably and equitably govern natural resources and landscapes for society, climate and conservation outcomes. It also supports the ecological economists and other rogue economists who have been arguing that material metrics of wellbeing are insufficient, and finally, it finds traction with the many voices calling for a decolonial approach to conservation and development challenges.

Q: How do you think sustainable development organizations and other conservation actors can apply this research for better impact?

RC: Our research can support initiatives by generating the evidence that will help navigation towards positive impact on people and nature. Also, it can help to adopt bottom-up impact assessments that include the relational and subjective dimensions of peoples’ wellbeing, not only the material. Similarly, it can support holistic and systems-oriented research, combining agricultural and ecological assessments with wellbeing ones to understand trade-offs and synergies. Last but not least, this can motivate other researchers to improve, test, expand and apply our methods in other regions.

CAPTION

Intensive agriculture dominating the landscape. Communities that formally held small-scale agriculture plots are no longer farming the region, and community assembly houses and graveyards are now surrounded by a sea of soy.

CREDIT

Rachel Carmenta