Cal Poly study analyzes nearshore California marine heatwaves and cold spells amid changing climate conditions

Peer-Reviewed Publication

CALIFORNIA POLYTECHNIC STATE UNIVERSITY

The first-ever study to look at drivers of both marine heatwaves and cold spells in the shallow nearshore along the California Current —coordinated by California Polytechnic State University, San Luis Obispo (Cal Poly) and the Virginia Institute of Marine Science, William & Mary — found that certain environmental conditions and the state of the ocean can lead to an enhanced risk for ocean temperature extremes.  

The findings were recently published in Nature Scientific Reports in an article titled “Effects of basin-scale climate modes and upwelling on nearshore marine heatwaves and cold spells in the California Current.”  

Extreme marine heatwaves, which can cause detrimental effects to marine ecosystems and ocean-related ecology, are exacerbated by rising global temperatures like those of 2023, which is shaping up to be one of the hottest years on record worldwide. Using temperature data that spanned four decades, the researchers identified environmental conditions that led to extreme warm and cold periods. Scientists and environmental managers can use these findings to inform the preservation and protection of vital ecosystems critical to the California ocean economy, known as the Blue Economy.  

When ocean temperatures along the California coast warm during El Niño years, such as the one forecasted to take place this winter, marine ecosystems can be severely impacted if temperatures get too hot. In the past, these marine heatwaves have led to giant kelp forest loss, mass die-offs of seabirds and economically important fisheries, and harmful algal blooms.   

There is high confidence in the scientific community that, because of climate change, El Niño events will increase in frequency and intensity with potential for harmful effects on marine ecosystems and ocean-related ecology, said Ryan Walter, a Cal Poly physical oceanography associate professor and article co-author. 

“And so, if we have stronger El Niño events in the future, we expect to see more frequent and more extreme marine heatwaves and all the consequences that come with it,” Walter said. During the last major El Niño in 2015-2016, a long duration marine heatwave contributed to the collapse of the iconic and species-rich kelp forests in parts of California.   

Along with variable ocean and weather conditions caused by events such as El Niño and La Niña years, the study found that upwelling patterns on a short-term basis also can initiate some of these marine heatwaves and cold spells, depending on if the upwelling and related cooling effects are stronger or weaker.  

It has long been known that coastal upwelling -- the wind-driven transport of deep, cold water into shallow areas along the coast -- has a strong cooling effect on coastal waters, creating foggy marine layers and stimulating marine productivity. Upwelling helps to maintain healthy fisheries and robust marine life. The cold waters also help buffer against rising water temperatures frequently found farther from shore.  

“If we didn't have upwelling along our coast, we’d see far more heatwaves," Walter said. “So, the upwelling is cooling down nearshore regions along the coast and causes the climate change-induced warming signal to be more muted. This also provides a thermal refuge for marine organisms.”   

Thermal stress, both hot and cold, can significantly affect aquaculture and fisheries, both important components of California’s Blue Economy. In the future, it will be important to understand how changes in wind patterns and surface warming from climate change will affect upwelling along California’s coast.   

“Upwelling systems in general are among the world's most productive ecosystems, including many of the world's fisheries and beautiful kelp forests,” Walter said. “Because the deep upwelled waters are cold, they help mitigate some of the warm water extremes. Additionally, these deep, cold waters are full of nutrients and when they upwell, they effectively fertilize the surface of the ocean and lead to strong biological productivity.”  

Cal Poly undergraduate physics major Michael Dalsin served as the lead author of the journal article along with co-authors Walter and Piero Mazzini, a physical oceanography professor at the Virginia Institute of Marine Science at William & Mary. 

The team analyzed ocean temperature data, spanning from 1978-2020, taken in a fixed location in shallow water near the coastline of Diablo Canyon Nuclear Power Plant on California’s Central Coast. The unique reference point is insightful because coastal ocean temperature data lasting more than three decades is less common and needed to statistically quantify the extreme events. Also, temperature data close to shore collected from satellites has interference caused by fog and lower in resolution, the researchers said.   

“This study lays the foundation for understanding how temperature extremes in our ocean will respond to climate change,” said Dalsin, an undergraduate who has won multiple awards for his work on the study, including an American Meteorological Society (AMS) Student Award for his oral presentation at the 2023 annual meeting. He was also one of 10 students selected to represent Cal Poly at the 2023 Cal State Student Research Competition.  

“One fascinating aspect of our research is that we can predict the likelihood of one of these extreme marine events given the state of our ocean,” Dalsin added. “The state of the ocean, as determined by large-scale climate modes and local-scale upwelling winds, could be used to forecast heatwaves and cold spells in the future.”  

This research provides a better understanding of the when, where, and why these marine extreme events occur. “One thing, however, is clear,” said Walter, “These extreme temperature events are not going away so it is critical that we continue to explore their drivers and consequences.”  

The research was supported by the William and Linda Frost Fund in the Cal Poly Bailey College of Science and Mathematics.  

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JOURNAL

Scientific Reports

DOI

10.1038/s41598-023-39193-4 

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Effects of basin-scale climate modes and upwelling on nearshore marine heatwaves and cold spells in the California Current

ARTICLE PUBLICATION DATE

31-Jul-2023

 

Researchers map cadmium in cacao: “The problem isn’t as bad as we thought”

Samples of Peru’s varied soils make it possible to predict which parts of the country can produce cacao low in the toxic heavy metal.

Peer-Reviewed Publication

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

 

IMAGE: UP TO 89% OF THE SMALLHOLDER FARMERS IN PIURA, PERU ARE ALREADY EXPERIENCING A FINANCIAL LOSS BECAUSE OF HIGH CADMIUM LEVELS IN CACAO. view more 

CREDIT: ALLIANCE OF BIOVERSITY AND CIAT

In 2019, a wind of uncertainty was rustling through the thick green leaves of cacao trees from Venezuela to Peru. After 4 years, the European Union had implemented limits on cadmium—a toxic heavy-metal— in chocolate and cacao. Although the limits are set in the final product, preliminary data suggested that chocolate produced from Latin American beans was higher in cadmium than in other parts of the world. For many countries in the region, cacao is an export crop, produced by hundreds of thousands of smallholder farmers living in difficult economic situations. With the biggest market being the EU, these limits put an additional worry on the cacao value chain with possible implications not only for sellers, but also on the livelihoods of farmers. 

However, although it was becoming obvious that the problem did not affect the whole of the cacao growing region in Latin America, it was not clear which regions were the worst affected or what the cause was.

Samples from across Peru show that soil is key

The Government of Peru awarded Bioversity International* funding to better understand this and together with two key organizations in the Ministry of Agriculture (MIDAGRI); SENASA and INIA, the team spent the next few years sampling cacao and soil across the length and breadth of the country. This culminated in a study published in Science of the Total Environment, which synthesized data from over 2,000 samples across Peru, making it the largest study to date of cadmium and cacao.

The study demonstrated that the most important predictor of cadmium in cacao beans is cadmium in the soil. In other words, it depends on the location of the farm. Cadmium is taken up by the roots of cacao trees, and the study confirmed that the amount of uptake is directly linked to the concentration of cadmium in the soil. This helps to explain why cadmium is a greater concern in Latin America, which has younger, less eroded soils when compared to other  cacao producing regions. The study also showed how variable soil cadmium levels are across the country, due to the complicated geological history of Peru, not only of the geology under a farm, but also soil moved by rivers over millennia from mineral rich deposits in the Andes. In addition, soil pH, soil type and even rainfall all influence the extent to which cadmium accumulates in cacao beans.

Good and bad news for farmers

The good news is that the study shows the majority of cacao grown in Peru can be used to make chocolate that will comply with the EU cadmium limits, with over 80% of farmers expected to experience little to no impact on their livelihoods.

The bad news is that there are areas in the country that, due to their soils, cannot easily comply. These areas include several valleys in the department of Piura, famous for a native fine flavor cultivar called Blanco de Piura. It is sold to high-end, European niche markets for its distinctive taste, which in turn allows farmers to receive a better price for their beans. With high levels of cadmium in many valleys in Piura, farmers are forced to sell into less lucrative internal markets. The study estimated that up to 89% of the smallholder farmers in this region are already experiencing a financial loss because of high cadmium levels. Cooperatives and buyers are working hard to carefully select and mix cacao from farms in Piura to allow consumers to continue enjoying the unique flavors, ensuring low cadmium in the chocolate while also maintaining prices for the farmers.

A map to predict cadmium levels

To help understand the variation in cadmium across the country, the scientists have consolidated all the data in an interactive map. Available at cacaodiversity.org, the map provides predictions about the levels of cadmium likely to be present in soils and cacao beans in Peru’s cacao-growing areas. Besides informing the sector about the problem, this user-friendly resource aims to reach policy- and other decision-makers. This knowledge is also being put to use to further scientific studies on solutions to minimize cadmium uptake by cacao trees in a regional project funded by the EU Desira program in Ecuador, Colombia, and Peru.

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*Bioversity International is now operating as the Alliance of Bioversity and CIAT, a CGIAR research center. Learn more about our work on sustainable cacao in Peru here and here.

 

Cacao from areas such as Piura have been found to contain high levels of cadmium 

Good news: the majority of cacao grown in Peru can be used to make chocolate that will comply with EU cadmium limits.

CREDIT

Alliance of Bioversity and CIAT

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JOURNAL

Science of The Total Environment

DOI

10.1016/j.scitotenv.2023.163372 

METHOD OF RESEARCH

Data/statistical analysis

ARTICLE TITLE

The distribution of cadmium in soil and cacao beans in Peru

 

Anu awarded $200,000 grant to mass manufacture its aeroponic seed pods that grow produce in controlled environments

Purdue alumni founders’ goal is for users to collectively become the largest farm in the world without owning any land

Grant and Award Announcement

PURDUE UNIVERSITY

 

IMAGE: SCOTT MASSEY, FOUNDER AND CEO AT ANU, HOLDS A SUNFLOWER CULTIVATED IN ONE OF THE COMPANY’S SEED PODS. THE COMPANY HAS RECEIVED A $200,000 INDIANA MANUFACTURING READINESS GRANTS AWARD TO MASS MANUFACTURE ITS AEROPONIC SEED POD CONSUMABLES. THE GRANTS ARE PROVIDED BY THE INDIANA ECONOMIC DEVELOPMENT CORP. AND ADMINISTERED BY CONEXUS INDIANA AND THE NEXT LEVEL MANUFACTURING INSTITUTE. view more 

CREDIT: PHOTO/INDIANA ECONOMIC DEVELOPMENT CORP.

EVANSVILLE, Ind. – A startup company founded by Purdue University alumni has received funding from the state of Indiana to advance the manufacture of its products. 

Heliponix LLC, doing business as anu™ (previously gropod®), has received a $200,000 Indiana Manufacturing Readiness Grants (MRG) award to mass manufacture its aeroponic seed pod consumables.

Manufacturing Readiness Grants are provided by the Indiana Economic Development Corp. and administered by Conexus Indiana and the Next Level Manufacturing Institute. They are available to Indiana manufacturers willing to make capital investments to integrate smart technologies and processes that improve capacity, productivity and competitiveness. Launched in 2020, the MRG program has supported tech-enabled investment in smart manufacturing all around the state.

Anu, founded by Purdue Polytechnic Institute alumni Scott Massey and Ivan Ball, sells a smart garden appliance. The small, fully automated, in-home greenhouse grows daily servings of produce from subscription seed pods.

Aeroponics is a form of hydroponics, or growing plants without soil. Massey said the pods empower consumers to grow fresh, high-quality produce including most leafy green vegetables, culinary herbs, ornamental/flowering plants and an increasing number of fruiting plant varieties such as peppers, tomatoes and more in a controlled environment.

“Our cultivation chambers use deep-learning, computer-vision algorithms to produce higher yields than other controlled-environment agriculture technology,” Massey said. “The chambers consume less energy and more than 95 percent less water than conventional field farming. With zero use of pesticides or preservatives, they represent an environmentally friendly solution for year-round accelerated growing.”

Massey said the funding will allow anu to scale a sustainable platform for consumers by supplying growers with recurring seed pod subscriptions.

“This funding has dramatically increased our ability to manufacture these seed pods, but in a volume that will quickly outpace the collective yields of the largest farms in the world,” Massey said. “It further accelerates our pursuit to collectively become the largest farm in the world without owning any land.” 

Mitch Landess, vice president of innovation and digital transformation at Conexus Indiana, said manufacturing entrepreneurship, especially when it involves technology, is vital for Indiana.

“Small firms founded and led by entrepreneurs that leverage the resources around them and form credible partnerships are interesting to the Manufacturing Readiness Grants program,” Landess said. “The mix of intellectual property, local venture capital, Small Business Innovation Research funding and participation of larger manufacturing partners made it easy to support anu’s investment in production technology.”

Conexus Indiana recently named Massey to the Conexus Indiana Rising 30 Class of 2023, which recognizes distinguished advanced manufacturing and logistics professionals under the age of 30.

Massey said he and his colleagues at anu appreciate support from Conexus for the Rising 30 recognition and from the IEDC for the $200,000 Manufacturing Readiness Grants award.

“It was only a few years ago that I was a Purdue University student with an idea and the drive to bring it to the market — to empower everyone to grow their own produce. Conexus has done a phenomenal job extending these resources and recognition to make this idea a reality as we continue growing our highly experienced team, creating jobs and attracting more talent to the great state of Indiana,” Massey said. 

“Indiana’s support for small businesses is not just unparalleled, but Indiana’s long-standing history of advanced manufacturing has resulted in it being the best possible headquarter base for us.”

Anu received a $100,000 investment from the Ag-Celerator Fund, co-founded by the Purdue Research Foundation and Purdue’s College of Agriculture. It also has received Phase I and Phase II SBIR grants from the National Science Foundation and matching funds from Elevate Ventures. 

About Purdue University

Purdue University is a public research institution with excellence at scale. Ranked among top 10 public universities (Times Higher Education/Wall Street Journal and QS), with two colleges in the top 4 in the United States (U.S. News & World Report), Purdue discovers and disseminates knowledge with a quality and at a scale second to none. More than 105,000 students study at Purdue across modalities and locations, with 50,000 in person on the West Lafayette campus. Committed to affordability and accessibility, Purdue’s main campus has frozen tuition 12 years in a row. See how Purdue never stops in the persistent pursuit of the next giant leap, including its first comprehensive urban campus in Indianapolis, the new Mitchell E. Daniels, Jr. School of Business, and Purdue Innovates, at https://stories.purdue.edu.

Writer/Media contact: Steve Martin, sgmartin@prf.org

Source: Scott Massey, scott@growanu.com

 

Substitution of tolerant for sensitive species balances ecosystems in agricultural areas, study says

Research conducted in manipulated sugarcane plots showed that small water bodies such as ponds and puddles can contribute to sustainable farming even with environmentally hostile practices.

Peer-Reviewed Publication

FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO

 

IMAGE: RESEARCH CONDUCTED IN MANIPULATED SUGARCANE PLOTS SHOWED THAT SMALL WATER BODIES SUCH AS PONDS AND PUDDLES CAN CONTRIBUTE TO SUSTAINABLE FARMING EVEN WITH ENVIRONMENTALLY HOSTILE PRACTICES view more 

CREDIT: EDMAR MAZZI/CENA-USP

Contributing to the pursuit of sustainable farming, especially sugarcane growing, Brazilian researchers have shown that water bodies such as ponds and even puddles can maintain ecosystem services, provided there are tolerant animals in the vicinity to replace those most sensitive to agricultural practices.

In an innovative study involving manipulation of large areas of cropland, the group tested the effects of intensifying land use by converting extensive pasture to intensive pasture and sugarcane plantations in Southeastern Brazil. The experimental plots contained 4,000-liter mesocosms simulating ponds and puddles commonly found in productive landscapes. Mesocosms are enclosed environments that allow a small part of a natural environment to be observed under controlled conditions.

Despite application of insecticides and vinasse to the sugarcane, the biomass in the habitat remained stable in all three settings. This was only possible because, after application of the products, colonization by tolerant mid-ranking predators such as beetles and bugs offset local extinction of a sensitive top predator (a dragonfly). As a result, community stability tended to increase with biomass asynchrony and species richness, evidencing a “portfolio” effect of biodiversity, with the advent of new species offsetting the disappearance of others.

“We demonstrated experimentally that the functioning of aquatic ecosystems in agricultural environments can be maintained despite harmful practices, as long as there are tolerant species coming from outside the plantation to replace more sensitive species. The indicator we used for ecosystem functioning was animal biomass production in terms of the number of grams observed over time. We found that it remained constant even in cane fields. This is very interesting from the standpoint of the discussion about the importance of biodiversity in maintaining local ecosystem services, among other functions,” said biologist Luis César Schiesari, a professor of environmental management at the University of São Paulo (USP) in Brazil, and first author of an article on the study published in the Journal of Applied Ecology, one of the most prestigious in the field. 

The study was supported by FAPESP via the Thematic Project “Environmental effects of pasture-sugarcane conversion and pasture intensification”, part of FAPESP’s Research Program on Global Climate Change (RPGCC). The principal investigator is Luiz Antonio Martinelli, last author of the article and an agronomist at the Center for Nuclear Energy in Agriculture (CENA-USP). 

The study was also supported via a research grant awarded to Victor Satoru Saito, second author of the article and a biologist at the Federal University of São Carlos (UFSCar) in São Paulo state.

Sustainability

Previous research showed that this supply of species is not available in real croplands, where aquatic ecosystem biodiversity is comparatively impoverished (read more at: onlinelibrary.wiley.com/doi/10.1111/gcbb.12279). The authors therefore recommend that crop management practices include protection for swamps, marches and ponds on the edge of croplands to serve as water bodies for species colonization and providers of biodiversity. 

“These organisms are beneficial for crops. They feed back into the ecosystem and also prey on crop pests. Insects and amphibians lay eggs in temporary puddles. The larvae that hatch from the eggs feed on the aquatic environment and later metamorphose into terrestrial adults. The adults may die in the terrestrial environment, ‘exporting’ the matter that accumulates in the puddle, including nitrogen, phosphorus and potassium, back into the plantation. These ecosystem functions satisfy the premises of sustainable precision agriculture,” Schiesari told Agência FAPESP.

Mitigating environmental impacts on supply chains and managing the effects of climate change to promote sustainable development are high on the global agenda. In this context, agricultural production and the energy transition to clean fuels and renewables are a focus for worldwide attention. 

As the world’s leading producer of sugarcane and one of the leaders in ethanol, for some years Brazil has discussed the sustainability of this supply chain and the socio-economic cost of land use in the sector. Sugarcane production is set to rise 4.4% in the crop year 2023-24 compared with the previous year, reaching 637.1 million metric tons, according to CONAB, the federal government’s food supply agency.

“In my line of research, I try to understand how changes in the environment due to human activity affect biodiversity,” Schiesari said. “Specifically in the past 15 years, I’ve focused on understanding the consequences of the conversion of native habitats such as forests and savannas to pasture, and the intensification of pasture in areas of soybeans, sugarcane and other kinds of monoculture farming. This process of conversion and environmental intensification entails structural, physical and chemical changes.”

Pasture is the main land use throughout Brazil, accounting for 152 million hectares and present in six biomes, according to a report by MapBiomas, a collaborative network formed by NGOs, universities, and technology startups dedicated to mapping land cover and land use in Brazil. That is practically equivalent to the area of Amazonas state, which is 156 million hectares. 

Stages

The study area was part of an experimental farm belonging to the São Paulo’s Agency for Agribusiness Technology (APTA) in Brotas. It was divided into 15 plots measuring 50m by 50m. Five were extensive pasture without prior soil preparation or tillage, and with grass growing naturally in accordance with fertility in the area. Another five were converted to intensive pasture with soil grading using tractors, liming to raise soil pH, fertilizing, and planting of Brachiaria forage grass, widely used for both intensive and extensive pasture in Brazil.

Sugarcane was grown on the other five plots, using technology, inputs and management practices similar to those used by growers in Brazil. Cuttings were suitable to the soil and climate. Fertilizer and insecticide were applied, as well as vinasse, the final residue from fermentation of sugarcane juice to obtain ethanol. Vinasse promotes growth of bacteria and consumption of oxygen when discharged into aquatic ecosystems.

The researchers set up 18 aquatic mesocosms, each with 4,000 liters of water in ponds and puddles. They tracked the mesocosms’ physicochemical parameters, nutrients, pesticides, phytoplankton and spontaneously colonizing biodiversity. 

“Our research was conducted in a single season with temporary puddles, an intrinsically transitory model ecosystem. Future studies should test the long-term consequences of land use, exploring the effects of the landscape context, and hence of spatial isolation and limited dispersal, on the capacity of the pond communities to keep biomass production stable despite dangerous management practices,” Schiesari said.

About São Paulo Research Foundation (FAPESP)

The São Paulo Research Foundation (FAPESP) is a public institution with the mission of supporting scientific research in all fields of knowledge by awarding scholarships, fellowships and grants to investigators linked with higher education and research institutions in the State of São Paulo, Brazil. FAPESP is aware that the very best research can only be done by working with the best researchers internationally. Therefore, it has established partnerships with funding agencies, higher education, private companies, and research organizations in other countries known for the quality of their research and has been encouraging scientists funded by its grants to further develop their international collaboration. You can learn more about FAPESP at www.fapesp.br/en and visit FAPESP news agency at www.agencia.fapesp.br/en to keep updated with the latest scientific breakthroughs FAPESP helps achieve through its many programs, awards and research centers. You may also subscribe to FAPESP news agency at http://agencia.fapesp.br/subscribe.

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JOURNAL

Journal of Applied Ecology

DOI

10.1111/1365-2664.14423 

ARTICLE TITLE

Community reorganization stabilizes freshwater ecosystems in intensively managed agricultural fields

Fact-checking can influence recommender algorithms

Peer-Reviewed Publication

CORNELL UNIVERSITY

ITHACA, N.Y. – In January 2017, Reddit users read about an alleged case of terrorism in a Spanish supermarket. What they didn’t know was that nearly every detail of the stories, taken from several tabloid publications and amplified by Reddit’s popularity algorithms, was false. Now, Cornell University research has shown that urging individuals to actively participate in the news they consume can reduce the spread of these kinds of falsehoods.

J. Nathan Matias, assistant professor of communication, conducted an experiment with a community of 14 million on Reddit and found that encouraging people to participate in knowledge-gathering could, in fact, move an algorithm’s needle.

Suggesting that community members fact-check suspect stories, he found, led to those stories being dropped in Reddit’s rankings.

“One of the lessons here is that we don’t have to think of ourselves as captive to tech platforms and algorithms,” said Matias, author of the study which published in Scientific Reports.

Working with the volunteer community leaders of the world news group on Reddit and focusing on news websites with a reputation for publishing inaccurate claims, researchers developed a software program that observed when a community member submitted a link for discussion. The software would then assign the discussion one of three conditions:

• Readers were shown a persistent message encouraging them to fact-check the article, and comment with links to further evidence refuting the article’s claims.
• Readers were shown the message and encouraged to consider down-voting the article. Reddit articles are voted up or down by community members, known as “redditors,” and ranked; accordingly.
• And in the control group, no action was taken.

Matias said he expected that fact-checking could backfire. If fact-checking focused more attention on an unreliable story, the algorithm might view it as positive reinforcement of the article and cause it to be ranked higher on average.

“There’s the concern that if you repeat a falsehood often enough, is that going to anchor it in someone’s mind?” he said. “And is there something similar with these recommendation algorithms that can’t necessarily distinguish right from wrong? Even if you’re fact-checking, the algorithm might see more engagement and show it to more people.’”

That turned out not to be the case. In a total of 1,104 news discussions, compiled from December 2016 to February 2017, Matias found that merely encouraging fact-checking – even without the down-voting prompt – caused a drop in story rank by an average of minus-25 spots. On Reddit, that would cause a story to drop off the front page, and likely be missed by a significant number of readers.

Though conducted on a narrow scale, Matias sees his experiment as proof that people can collectively take control of the information they are fed, and not just accept a steady diet of falsehoods.

“There’s a lot of talk about this idea of determinism – that the decisions of an engineer somewhere in Silicon Valley influence our minds, and lock us into certain patterns of behavior,” he said. “And while they do have influence, these systems are designed to react to humans. So, when people work together to improve our information environments, the algorithms can respond accordingly.

“This is a really powerful example of something that was very practical for this community,” he said, “and is making fundamental contributions to scientific knowledge.”

Support for this research came from the Templeton World Charity Foundation, the Siegel Family Endowment and the Annenberg Foundation.

For additional information, see this Cornell Chronicle story.

Cornell University has dedicated television and audio studios available for media interviews. 

-30-

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JOURNAL

Scientific Reports

DOI

10.1038/s41598-023-38277-5 

SPACE

Webb spotlights gravitational arcs in ‘El Gordo’ galaxy cluster

Peer-Reviewed Publication

NASA/GODDARD SPACE FLIGHT CENTER

 

IMAGE: WEBB’S INFRARED IMAGE OF THE GALAXY CLUSTER EL GORDO (“THE FAT ONE”) REVEALS HUNDREDS OF GALAXIES, SOME NEVER BEFORE SEEN AT THIS LEVEL OF DETAIL. EL GORDO ACTS AS A GRAVITATIONAL LENS, DISTORTING AND MAGNIFYING THE LIGHT FROM DISTANT BACKGROUND GALAXIES. **DOWNLOAD THE FULL-RESOLUTION VERSION FROM THE SPACE TELESCOPE SCIENCE INSTITUTE. view more 

CREDIT: IMAGE: NASA, ESA, CSA. SCIENCE: JOSE DIEGO (INSTITUTO DE FÍSICA DE CANTABRIA), BRENDA FRYE (UNIVERSITY OF ARIZONA), PATRICK KAMIENESKI (ARIZONA STATE UNIVERSITY), TIM CARLETON (ARIZONA STATE UNIVERSITY), AND ROGIER WINDHORST (ARIZONA STATE UNIVERSITY). IMAGE PROCESSING: ALYSSA PAGAN (STSCI), JAKE SUMMERS (ARIZONA STATE UNIVERSITY), JORDAN D’SILVA (UNIVERSITY OF WESTERN AUSTRALIA), ANTON KOEKEMOER (STSCI), AARON ROBOTHAM (UNIVERSITY OF WESTERN AUSTRALIA), AND ROGIER WINDHORST (ARIZONA STATE UNIVERSITY).

A new image of the galaxy cluster known as “El Gordo” is revealing distant and dusty objects never seen before, and providing a bounty of fresh science. The infrared image, taken by NASA’s James Webb Space Telescope, displays a variety of unusual, distorted background galaxies that were only hinted at in previous Hubble Space Telescope images.

El Gordo is a cluster of hundreds of galaxies that existed when the universe was 6.2 billion years old, making it a “cosmic teenager.” It’s the most massive cluster known to exist at that time. (“El Gordo” is Spanish for the “Fat One.”)

The team targeted El Gordo because it acts as a natural, cosmic magnifying glass through a phenomenon known as gravitational lensing. Its powerful gravity bends and distorts the light of objects lying behind it, much like an eyeglass lens.

“Lensing by El Gordo boosts the brightness and magnifies the sizes of distant galaxies. This lensing effect provides a unique window into the distant universe,” said Brenda Frye of the University of Arizona. Frye is co-lead of the PEARLS-Clusters branch of the Prime Extragalactic Areas for Reionization and Lensing Science (PEARLS) team and lead author of one of four papers analyzing the El Gordo observations.

The Fishhook

Within the image of El Gordo, one of the most striking features is a bright arc represented in red at upper right. Nicknamed “El Anzuelo” (The Fishhook) by one of Frye’s students, the light from this galaxy took 10.6 billion years to reach Earth. Its distinctive red color is due to a combination of reddening from dust within the galaxy itself and cosmological redshift due to its extreme distance.

By correcting for the distortions created by lensing, the team was able to determine that the background galaxy is disk-shaped but only 26,000 light-years in diameter – about one-fourth the size of the Milky Way. They also were able to study the galaxy’s star formation history, finding that star formation was already rapidly declining in the galaxy’s center, a process known as quenching.

“We were able to carefully dissect the shroud of dust that envelops the galaxy center where stars are actively forming," said Patrick Kamieneski of Arizona State University, lead author on a second paper. "Now, with Webb, we can peer through this thick curtain of dust with ease, allowing us to see firsthand the assembly of galaxies from the inside out."

The Thin One

Another prominent feature in the Webb image is a long, pencil-thin line at left of center. Known as “La Flaca” (the Thin One), it is another lensed background galaxy whose light also took nearly 11 billion years to reach Earth.

Not far from La Flaca is another lensed galaxy. When the researchers examined that galaxy closely, they found a single red giant star that they nicknamed Quyllur, which is the Quechua term for star.

Previously, Hubble has found other lensed stars (such as Earendel), but they were all blue supergiants. Quyllur is the first individual red giant star observed beyond 1 billion light-years from Earth. Such stars at high redshift are only detectable using the infrared filters and sensitivity of Webb.

“It's almost impossible to see lensed red giant stars unless you go into the infrared. This is the first one we’ve found with Webb, but we expect there will be many more to come,” said Jose Diego of the Instituto de Física de Cantabria in Spain, lead author of a third paper on El Gordo.

Galaxy Group and Smudges

Other objects within the Webb image, while less prominent, are equally interesting scientifically. For example, Frye and her team (which includes nine students from high school to graduate students) identified five multiply lensed galaxies which appear to be a baby galaxy cluster forming about 12.1 billion years ago. There are another dozen candidate galaxies which may also be part of this distant cluster.

“While additional data are required to confirm that there are 17 members of this cluster, we may be witnessing a new galaxy cluster forming right before our eyes, just over a billion years after the big bang,” said Frye.

A final paper examines very faint, smudge-like galaxies known as ultra-diffuse galaxies. As their name suggests, these objects, which are scattered throughout the El Gordo cluster, have their stars widely spread out across space. The team identified some of the most distant ultra-diffuse galaxies ever observed, whose light traveled 7.2 billion years to reach us.

“We examined whether the properties of these galaxies are any different than the ultra-diffuse galaxies we see in the local universe, and we do actually see some differences. In particular, they are bluer, younger, more extended, and more evenly distributed throughout the cluster. This suggests that living in the cluster environment for the past 6 billion years has had a significant effect on these galaxies,” explained Timothy Carleton of Arizona State University, lead author on the fourth paper.

“Gravitational lensing was predicted by Albert Einstein more than 100 years ago. In the El Gordo cluster, we see the power of gravitational lensing in action,” concluded Rogier Windhorst of Arizona State University, principal investigator of the PEARLS program. “The PEARLS images of El Gordo are out-of-this-world beautiful. And, they have shown us how Webb can unlock Einstein's treasure chest.”

The paper by Frye et al. has been published in the Astrophysical Journal. The paper by Kamieneski et al. has been accepted for publication in the Astrophysical Journal. The paper by Diego et al. has been published in Astronomy & Astrophysics. The paper by Carleton et al. has been accepted for publication in the Astrophysical Journal.

The James Webb Space Telescope is the world's premier space science observatory. Webb is solving mysteries in our solar system, looking beyond to distant worlds around other stars, and probing the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and the Canadian Space Agency.

Two of the most prominent features in the image include the Thin One, highlighted in box A, and the Fishhook, a red swoosh highlighted in box B. Both are lensed background galaxies. The insets at right show zoomed-in views of both objects.

CREDIT

Image: NASA, ESA, CSA. Science: Jose Diego (Instituto de Física de Cantabria), Brenda Frye (University of Arizona), Patrick Kamieneski (Arizona State University), Tim Carleton (Arizona State University), and Rogier Windhorst (Arizona State University). Image processing: Alyssa Pagan (STScI), Jake Summers (Arizona State University), Jordan D’Silva (University of Western Australia), Anton Koekemoer (STScI), Aaron Robotham (University of Western Australia), and Rogier Windhorst (Arizona State University).

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JOURNAL

The Astrophysical Journal Letters

DOI

10.3847/1538-4357/acd929