It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Monday, March 11, 2024
A new sensor detects harmful “forever chemicals” in drinking water
The technology could offer a cheap, fast way to test for PFAS, which have been linked to cancer and other health problems.
MASSACHUSETTS INSTITUTE OF TECHNOLOGY
CAMBRIDGE, MA -- MIT chemists have designed a sensor that detects tiny quantities of perfluoroalkyl and polyfluoroalkyl substances (PFAS) — chemicals found in food packaging, nonstick cookware, and many other consumer products.
These compounds, also known as “forever chemicals” because they do not break down naturally, have been linked to a variety of harmful health effects, including cancer, reproductive problems, and disruption of the immune and endocrine systems.
Using the new sensor technology, the researchers showed that they could detect PFAS levels as low as 200 parts per trillion in a water sample. The device they designed could offer a way for consumers to test their drinking water, and it could also be useful in industries that rely heavily on PFAS chemicals, including the manufacture of semiconductors and firefighting equipment.
“There’s a real need for these sensing technologies. We’re stuck with these chemicals for a long time, so we need to be able to detect them and get rid of them,” says Timothy Swager, the John D. MacArthur Professor of Chemistry at MIT and the senior author of the study, which appears this week in the Proceedings of the National Academy of Sciences.
Other authors of the paper are former MIT postdoc and lead author Sohyun Park and MIT graduate student Collette Gordon.
Detecting PFAS
Coatings containing PFAS chemicals are used in thousands of consumer products. In addition to nonstick coatings for cookware, they are also commonly used in water-repellent clothing, stain-resistant fabrics, grease-resistant pizza boxes, cosmetics, and firefighting foams.
These fluorinated chemicals, which have been in widespread use since the 1950s, can be released into water, air, and soil, from factories, sewage treatment plants, and landfills. They have been found in drinking water sources in all 50 states.
In 2023, the Environmental Protection Agency created an “advisory health limit” for two of the most hazardous PFAS chemicals, known as perfluorooctanoic acid (PFOA) and perfluorooctyl sulfonate (PFOS). These advisories call for a limit of 0.004 parts per trillion for PFOA and 0.02 parts per trillion for PFOS in drinking water.
Currently, the only way that a consumer could determine if their drinking water contains PFAS is to send a water sample to a laboratory that performs mass spectrometry testing. However, this process takes several weeks and costs hundreds of dollars.
To create a cheaper and faster way to test for PFAS, the MIT team designed a sensor based on lateral flow technology — the same approach used for rapid Covid-19 tests and pregnancy tests. Instead of a test strip coated with antibodies, the new sensor is embedded with a special polymer known as polyaniline, which can switch between semiconducting and conducting states when protons are added to the material.
The researchers deposited these polymers onto a strip of nitrocellulose paper and coated them with a surfactant that can pull fluorocarbons such as PFAS out of a drop of water placed on the strip. When this happens, protons from the PFAS are drawn into the polyaniline and turn it into a conductor, reducing the electrical resistance of the material. This change in resistance, which can be measured precisely using electrodes and sent to an external device such as a smartphone, gives a quantitative measurement of how much PFAS is present.
This approach works only with PFAS that are acidic, which includes two of the most harmful PFAS — PFOA and perfluorobutanoic acid (PFBA).
A user-friendly system
The current version of the sensor can detect concentrations as low as 200 parts per trillion for PFBA, and 400 parts per trillion for PFOA. This is not quite low enough to meet the current EPA guidelines, but the sensor uses only a fraction of a milliliter of water. The researchers are now working on a larger-scale device that would be able to filter about a liter of water through a membrane made of polyaniline, and they believe this approach should increase the sensitivity by more than a hundredfold, with the goal of meeting the very low EPA advisory levels.
“We do envision a user-friendly, household system,” Swager says. “You can imagine putting in a liter of water, letting it go through the membrane, and you have a device that measures the change in resistance of the membrane.”
Such a device could offer a less expensive, rapid alternative to current PFAS detection methods. If PFAS are detected in drinking water, there are commercially available filters that can be used on household drinking water to reduce those levels. The new testing approach could also be useful for factories that manufacture products with PFAS chemicals, so they could test whether the water used in their manufacturing process is safe to release into the environment.
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The research was funded by an MIT School of Science Fellowship to Gordon, a Bose Research Grant, and a Fulbright Fellowship to Park.
RESEARCHERS HAVE DEVELOPED A NEW THREE-DIMENSIONAL 2-FOLD INTERPENETRATING POLYOXOVANADATE-BASED METAL-ORGANIC FRAMEWORK THAT SHOWS SATISFYING CATALYTIC PERFORMANCES FOR THE SELECTIVE OXIDATION OF 2-CHLOROETHYL ETHYL SULFIDE (CEES) TO CORRESPONDING SULFOXIDE (CEESO) AND PHOTODEGRADATION TOWARD PHENOL, 2-CHLOROPHENOL AND M-CRESOL UNDER VISIBLE LIGHT.
CREDIT: POLYOXOMETALATES, TSINGHUA UNIVERSITY PRESS
A team of researchers from Bohai University in China have designed and synthesized a bifunctional catalyst that can solve the environmental pollution caused by mustard gas and phenolic compounds. They synthesized this bifunctional catalyst, a new three-dimensional polyoxovanadate-based metal-organic framework, under hydrothermal conditions.
Their work is published in the journal Polyoxometalates on March 4, 2024.
The team’s bifunctional catalyst shows satisfying catalytic performances for the selective oxidation of 2-chloroethyl ethyl sulfide (CEES) to corresponding sulfoxide (CEESO) and photodegradation toward phenol, CEES, and m-cresol under visible light. A bifunctional catalyst is one that provides both acidic and basic catalytic functions.
In recent years, the problem of organic hazardous substances that cause pollution has raised considerable concern. Scientists have focused their work on developing reasonable methods for degrading these organic hazardous substances. CEES, or mustard gas, is a chemical warfare agent that causes severe skin diseases, strong irritation of the respiratory tract, and even death. Since mustard gas was first used in World War I, researchers have sought ways to detoxify this chemical warfare agent. M-cresol is an organic compound that is extracted from coal tar and is used in the production of other chemicals, including pesticides. It is corrosive to the eyes, skin, and respiratory tract.
Phenolic pollutants often persist in polluted waste water that flows from industrial, agricultural, and domestic work. Once they make their way into the water systems, phenolic pollutants can be very harmful to humans and the environment. These pollutants can be acutely toxic to the point of causing the death of animals, birds, or fish. They can also stunt the growth of or kill plants. Scientists have been working to design by synthesis new bifunctional catalysts that can convert these types of dangerous pollutants into low toxicity degradants. However, up to this point in time, scientists had not successfully achieved the preparation of high dimensional interpenetrating metal-organic frameworks that can act as bifunctional catalysts capable of oxidizing CEES to CEESO and degrading phenolic compounds under visible light.
Polyoxometalates (POMs) are a kind of inorganic metal oxide clusters with diverse architectural structures and attractive properties. Because of their wide array of structures and functionalities, they are one of the most useful classes of inorganic molecular materials. Within the POMs family, polyoxovanadates (POVs) have attracted increasing attention from scientists because of their diverse structures and remarkable properties.
The researchers used a bis-pyridyl-bis-amide ligand to construct the new POV-based metal-organic framework. They then studied the 3D POV-based metal-organic framework using single crystal X-ray diffraction analysis, IR spectroscopy, and powder X-ray diffraction. “The long feature of the amide-based ligand induces the formation of the unusual 2-fold interpenetrating structure,” said Guo-Cheng Liu, an associate professor at Bohai University.
The team’s bifunctional catalyst successfully catalyzed the selective oxidation of toxic CEES to the corresponding safer sulfoxide in the presence of H2O2, or hydrogen peroxide, as an eco-friendly oxidant. It worked under visible light with an effective recyclability and stability. The successful conversion was greater than 99 percent and the selectivity was 97 percent.
In addition, the bifunctional catalyst showed excellent photocatalytic degradation activity toward phenol, CEES, and m-cresol under visible light. The team successfully achieved degradation efficiencies above 92.6 percent for 140 minutes. They also investigated in detail the photocatalytic reaction kinetics, the mechanisms of photodegradation, and recycling capability of phenol. “This work provides important guidance for the development of new POVs-based bifunctional catalysts for the decontamination in water,” said Liu.
The research team includes Shuang Li, Yuan Zheng, Guo-Cheng Liu, Xiao-Hui Li, Zhong Zhang, and Xiu-Li Wang from the Liaoning Professional Technology Innovation Center of Liaoning Province for Conversion Materials of Solar Cell, College of Chemistry and Materials Engineering, Bohai University, China.
The research is funded by the National Natural Science Foundation of China and the Natural Science Foundation and Education Department of Liaoning Province.
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New two fold interpenetrating 3D polyoxovanadate-based metal–organic framework as bifunctional catalyst for the removal of 2-chloroethyl ethyl sulfide and phenolic compounds
Mathematicians use AI to identify emerging COVID-19 variants
Scientists at The Universities of Manchester and Oxford have developed an AI framework that can identify and track new and concerning COVID-19 variants and could help with other infections in the future.
The framework combines dimension reduction techniques and a new explainable clustering algorithm called CLASSIX, developed by mathematicians at The University of Manchester. This enables the quick identification of groups of viral genomes that might present a risk in the future from huge volumes of data.
The study, presented this week in the journal PNAS, could support traditional methods of tracking viral evolution, such as phylogenetic analysis, which currently require extensive manual curation.
Roberto Cahuantzi, a researcher at The University of Manchester and first and corresponding author of the paper, said: “Since the emergence of COVID-19, we have seen multiple waves of new variants, heightened transmissibility, evasion of immune responses, and increased severity of illness.
“Scientists are now intensifying efforts to pinpoint these worrying new variants, such as alpha, delta and omicron, at the earliest stages of their emergence. If we can find a way to do this quickly and efficiently, it will enable us to be more proactive in our response, such as tailored vaccine development and may even enable us to eliminate the variants before they become established.”
Like many other RNA viruses, COVID-19 has a high mutation rate and short time between generations meaning it evolves extremely rapidly. This means identifying new strains that are likely to be problematic in the future requires considerable effort.
Currently, there are almost 16 million sequences available on the GISAID database (the Global Initiative on Sharing All Influenza Data), which provides access to genomic data of influenza viruses.
Mapping the evolution and history of all COVID-19 genomes from this data is currently done using extremely large amounts of computer and human time.
The described method allows automation of such tasks. The researchers processed 5.7 million high-coverage sequences in only one to two days on a standard modern laptop; this would not be possible for existing methods, putting identification of concerning pathogen strains in the hands of more researchers due to reduced resource needs.
Thomas House, Professor of Mathematical Sciences at The University of Manchester, said: “The unprecedented amount of genetic data generated during the pandemic demands improvements to our methods to analyse it thoroughly. The data is continuing to grow rapidly but without showing a benefit to curating this data, there is a risk that it will be removed or deleted.
“We know that human expert time is limited, so our approach should not replace the work of humans all together but work alongside them to enable the job to be done much quicker and free our experts for other vital developments.”
The proposed method works by breaking down genetic sequences of the COVID-19 virus into smaller “words” (called 3-mers) represented as numbers by counting them. Then, it groups similar sequences together based on their word patterns using machine learning techniques.
Stefan Güttel, Professor of Applied Mathematics at the University of Manchester, said: “The clustering algorithm CLASSIX we developed is much less computationally demanding than traditional methods and is fully explainable, meaning that it provides textual and visual explanations of the computed clusters.”
Roberto Cahuantzi added: “Our analysis serves as a proof of concept, demonstrating the potential use of machine learning methods as an alert tool for the early discovery of emerging major variants without relying on the need to generate phylogenies.
“Whilst phylogenetics remains the ‘gold standard’ for understanding the viral ancestry, these machine learning methods can accommodate several orders of magnitude more sequences than the current phylogenetic methods and at a low computational cost.”
Unsupervised identification of significant lineages of SARS-CoV-2 through scalable machine learning methods
Tuberculosis bacteria also present in 90% of those with symptoms, who are not diagnosed with TB
Amsterdam UMC and University of Cape Town study shows that Mycobacterium tuberculosis is present in the respiratory aerosol of 90% of suspected TB patients, including those who returned negative sputum tests
Mycobacterium tuberculosis (Mtb), the bacteria that causes a tuberculosis infection, is present in exhaled breath of 90% of those presenting with suspected tuberculosis. This includes those who were negative on conventional sputum testing and not diagnosed with TB. This raises the possibility that those who have tested negative may be unknowingly transmitting the infection. Researchers from the University of Cape Town and Amsterdam UMC analysed results from over 100 patients who presented themselves to clinics in South Africa. These findings are published today in PNAS.
“If someone carries Mtb in their respiratory tract, this may also mean they can spread it. Therefore, since these results suggest a much broader range of people transmitting TB than previously recognised, there are significant implications for public health interventions designed to interrupt transmission.” says Ben Patterson, external Ph.D. candidate at Amsterdam UMC and the Amsterdam Institute for Global Health and Development.
Participants in the study attended two community clinics in the south-west of Cape Town before being either diagnosed with TB, or not. Subsequently, aerosol samples were collected in a community-based dedicated TB aerobiology lab using a novel method optimised to find low concentrations of Mtb. These samples were then used to detect the presence of Mtb, finding it in the samples given by 90% of patients, including those that had tested negative by sputum for tuberculosis.
"This rather shatters the paradigm on the transmission of tuberculosis. Previously we understood that Mtb was only expelled by those who have the disease, but this study shows that also those with symptoms who test negative do this and probably spread the infection, " says Frank Cobelens, professor of Global Health at Amsterdam UMC and senior fellow at the AIGHD.
Aerosol samplings were repeated at three separate timepoints over six months for all participants. The presence of Mtb decreased in those on treatment as well, surprisingly, as those not on treatment over this time period. Nevertheless, 20% of all participants continued to test positively for Mtb in aerosol after six months. This suggests that transmission can continue over a period longer than previously thought. Indeed, a recent study from the University of Cape Town suggests that tuberculosis could be present in the lungs for up to four years prior to the onset of symptoms.
"Together, our results indicate how complex tuberculosis is, and perhaps also why it is so difficult to eliminate tuberculosis in endemic areas. Even when public health agencies work, according to the current guidelines, effectively against symptomatic TB cases. In this sense, a revaluation of our practices is necessary,” adds Cobelens.
JOURNAL
Proceedings of the National Academy of Sciences
METHOD OF RESEARCH
Randomized controlled/clinical trial
SUBJECT OF RESEARCH
People
ARTICLE TITLE
Aerosolization of viable Mycobacterium tuberculosis bacilli by tuberculosis clinic attendees independent of sputum-Xpert Ultra status
THIS IMAGE OF NGC 5468, A GALAXY LOCATED ABOUT 130 MILLION LIGHT-YEARS FROM EARTH, COMBINES DATA FROM THE HUBBLE AND JAMES WEBB SPACE TELESCOPES. THIS IS THE FARTHEST GALAXY IN WHICH HUBBLE HAS IDENTIFIED CEPHEID VARIABLE STARS. THESE ARE IMPORTANT MILEPOST MARKERS FOR MEASURING THE EXPANSION RATE OF THE UNIVERSE. THE DISTANCE CALCULATED FROM CEPHEIDS HAS BEEN CROSS-CORRELATED WITH A TYPE IA SUPERNOVA IN THE GALAXY. TYPE IA SUPERNOVAE ARE SO BRIGHT THEY ARE USED TO MEASURE COSMIC DISTANCES FAR BEYOND THE RANGE OF THE CEPHEIDS, EXTENDING MEASUREMENTS OF THE UNIVERSE'S EXPANSION RATE DEEPER INTO SPACE.
CREDIT: NASA, ESA, CSA, STSCI, ADAM G. RIESS (JHU, STSCI)
When you are trying to solve one of the biggest conundrums in cosmology, you should triple check your homework. The puzzle, called the "Hubble Tension," is that the current rate of the expansion of the universe is faster than what astronomers expect it to be, based on the universe's initial conditions and our present understanding of the universe’s evolution.
Scientists using NASA's Hubble Space Telescope and many other telescopes consistently find a number that does not match predictions based on observations from ESA's (European Space Agency's) Planck mission. Does resolving this discrepancy require new physics? Or is it a result of measurement errors between the two different methods used to determine the rate of expansion of space?
Hubble has been measuring the current rate of the universe’s expansion for 30 years, and astronomers want to eliminate any lingering doubt about its accuracy. Now, Hubble and NASA’s James Webb Space Telescope have tag-teamed to produce definitive measurements, furthering the case that something else – not measurement errors – is influencing the expansion rate.
“With measurement errors negated, what remains is the real and exciting possibility we have misunderstood the universe,” said Adam Riess, a physicist at Johns Hopkins University in Baltimore. Riess holds a Nobel Prize for co-discovering the fact that the universe’s expansion is accelerating, due to a mysterious phenomenon now called “dark energy.”
As a crosscheck, an initial Webb observation in 2023 confirmed that Hubble measurements of the expanding universe were accurate. However, hoping to relieve the Hubble Tension, some scientists speculated that unseen errors in the measurement may grow and become visible as we look deeper into the universe. In particular, stellar crowding could affect brightness measurements of more distant stars in a systematic way.
The SH0ES (Supernova H0 for the Equation of State of Dark Energy) team, led by Riess, obtained additional observations with Webb of objects that are critical cosmic milepost markers, known as Cepheid variable stars, which now can be correlated with the Hubble data.
“We’ve now spanned the whole range of what Hubble observed, and we can rule out a measurement error as the cause of the Hubble Tension with very high confidence,” Riess said.
The team’s first few Webb observations in 2023 were successful in showing Hubble was on the right track in firmly establishing the fidelity of the first rungs of the so-called cosmic distance ladder.
Astronomers use various methods to measure relative distances in the universe, depending upon the object being observed. Collectively these techniques are known as the cosmic distance ladder – each rung or measurement technique relies upon the previous step for calibration.
But some astronomers suggested that, moving outward along the “second rung,” the cosmic distance ladder might get shaky if the Cepheid measurements become less accurate with distance. Such inaccuracies could occur because the light of a Cepheid could blend with that of an adjacent star – an effect that could become more pronounced with distance as stars crowd together and become harder to distinguish from one another.
The observational challenge is that past Hubble images of these more distant Cepheid variables look more huddled and overlapping with neighboring stars at ever farther distances between us and their host galaxies, requiring careful accounting for this effect. Intervening dust further complicates the certainty of the measurements in visible light. Webb slices though the dust and naturally isolates the Cepheids from neighboring stars because its vision is sharper than Hubble’s at infrared wavelengths.
“Combining Webb and Hubble gives us the best of both worlds. We find that the Hubble measurements remain reliable as we climb farther along the cosmic distance ladder,” said Riess.
The new Webb observations include five host galaxies of eight Type Ia supernovae containing a total of 1,000 Cepheids, and reach out to the farthest galaxy where Cepheids have been well measured – NGC 5468 – at a distance of 130 million light-years. “This spans the full range where we made measurements with Hubble. So, we've gone to the end of the second rung of the cosmic distance ladder,” said co-author Gagandeep Anand of the Space Telescope Science Institute in Baltimore, which operates the Webb and Hubble telescopes for NASA.
Hubble and Webb’s further confirmation of the Hubble Tension sets up other observatories to possibly settle the mystery. NASA’s upcoming Nancy Grace Roman Space Telescope will do wide celestial surveys to study the influence of dark energy, the mysterious energy that is causing the expansion of the universe to accelerate. ESA's Euclid observatory, with NASA contributions, is pursuing a similar task.
At present it’s as though the distance ladder observed by Hubble and Webb has firmly set an anchor point on one shoreline of a river, and the afterglow of the big bang observed by Planck’s measurement from the beginning of the universe is set firmly on the other side. How the universe’s expansion was changing in the billions of years between these two endpoints has yet to be directly observed. “We need to find out if we are missing something on how to connect the beginning of the universe and the present day,” said Riess.
The Hubble Space Telescope has been operating for over three decades and continues to make ground-breaking discoveries that shape our fundamental understanding of the universe. Hubble is a project of international cooperation between NASA and ESA. NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. Goddard also conducts mission operations with Lockheed Martin Space in Denver, Colorado. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble and Webb science operations for NASA.
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.
At the center of these side-by-side images is a special class of star used as a milepost marker for measuring the universe’s rate of expansion – a Cepheid variable star. The two images are very pixelated because they are a very zoomed-in view of a distant galaxy. Each of the pixels represents one or more stars. The image from the James Webb Space Telescope is significantly sharper at near-infrared wavelengths than Hubble (which is primarily a visible-ultraviolet light telescope). By reducing the clutter with Webb’s crisper vision, the Cepheid stands out more clearly, eliminating any potential confusion. Webb was used to look at a sample of Cepheids and confirmed the accuracy of the previous Hubble observations that are fundamental to precisely measuring the universe’s expansion rate and age.
About 1,300 light years away from Earth, there lies a massive stellar nursery named NGC 604, which is home to nearly 200 stars. Recently, NASA’s James Webb telescope captured two detailed images of this cosmic wonder, revealing many surprising details.
NGC 604 is inside Messier 33 (M33), a galaxy located within the peculiar triangle-shaped Triangulum constellation.
Compared to our Milky Way galaxy, it is 50 percent smaller in size.
However, its NGC 604 region, which appears like a bright blue patch, is one of the most massive star-forming regions.
The recent images taken by Webb’s Mid-Infrared Instrument (MIRI) and Near-infrared camera (NIRCam) reveal never-before-seen cosmic bubbles, stars, and gaseous structures branching out of NGC 604.
The image from the MIRI has fewer stars including some reg supergiants. The latter could be a million times brighter and a hundred times bigger than our Sun.
It also highlights blue tendril-like formations that suggest the presence of polycyclic aromatic hydrocarbons (PAH), according to NASA. PAH is an important cosmic ingredient as it plays a key role in developing planets and stars.
However, the MIRI image doesn’t reveal hot stars because it doesn’t capture the wavelength emitted by them. This is where the NIRCam image proves to be very useful.
The image captured by NIRCam confirms the presence of two young stars located above the central nebula (clouds of cosmic gas and dust). Interestingly, the Hubble Telescope previously identified these stars as irregular spots.
It also contains bright red bubble-like structures within the nebula. According to NASA, these bubbles are formed by the activity of winds originating from the hottest and brightest stars of NGC 604.
Moreover, the tendrils that appeared in the MIRI image are also actually extensions branching out from the bubbles.
To a normal person, the images of NGC 604 may appear like a painting or an ordinary photo of cosmic clouds and stars. However, for astronomers, stellar nurseries and the details they hold are of great significance.
This is because vast star-forming regions like NGC 604 comprise a variety of organic molecules that can reveal information not just about the development of planets and stars, but also about the origin of life.
“In these cold molecular clouds, you’re creating the first building blocks that will, in the end, form stars and planets,” Jordy Bouwman, an expert on chemistry and space physics at CU Boulder, said in a press release.
Thanks to James Webb, for the first time, researchers are able to produce such high-resolution and detailed images of NGC 604.
Hopefully, the insights from these images will increase our understanding of the cosmos, and help us decode several other mysteries linked to this star nursery. You can read the press release from NASA here.
Scientists Surprised to Realize Red Dots in James Webb Images Are Black Holes
"These special objects could change the way we think about the genesis of black holes."
Image by Getty Images
NASA's James Webb Space Telescope has made one of its "most unexpected" discoveries to date: tiny red dots in some of the oldest corners of the universe, which turned out to be "baby" life stages of supermassive black holes.
After studying observations by the groundbreaking observatory, the team concluded that "faint little red dots very far away in the universe's distant past are small versions of extremely massive black holes," as team lead Jorryt Matthee, astrophysics assistant professor at the Institute of Science and Technology Austria and lead author of a new paper published in The Astrophysical Journal, explained in a statement.
"These special objects could change the way we think about the genesis of black holes," he added.
The team is hoping to hone in on how these early-stage supermassive black holes, which often lurk at the center of large galaxies including our own, came to be and how they change over billions of years.
"The present findings could bring us one step closer to answering one of the greatest dilemmas in astronomy: According to the current models, some supermassive black holes in the early universe have simply grown 'too fast,'" Matthee explained. "Then how did they form?"
As their name suggests, supermassive black holes can reach epic proportions, anywhere from millions to billions of times the mass of our Sun. While scientists believe they can grow by merging with other black holes, their origin remains an active field of study.
Over the last couple of years, scientists have found evidence of one hiding at the center of the Milky Way dubbed Sagittarius A*, which is roughly 4.3 million times the mass of the Sun.
Some types of supermassive black holes, called quasars, are extremely luminous galactic cores that light up as gas and dust fall into them. They're some of the brightest objects in the universe, emitting thousands of times more light than our entire galaxy.
Matthee and his colleagues believe the little red dots in the JWST images are quasars — except that they're far smaller than their counterparts elsewhere.
"One issue with quasars is that some of them seem to be overly massive, too massive given the age of the universe at which the quasars are observed," Matthee said in the statement. "If we consider that quasars originate from the explosions of massive stars and that we know their maximum growth rate from the general laws of physics, some of them look like they have grown faster than is possible."
As a result, the astrophysicist suggests the "little red dots are more like 'baby quasars,'" with masses somewhere between "ten and a hundred million solar masses." They likely predate the stage of these "problematic quasars,"as Matthee puts it, which are more massive than they should be.
As for why they're red, Matthee has a simple answer: "Because they are dusty. The dust obscures black holes and reddens the colors" in the observations.
The "baby quasars" are destined to balloon into much larger supermassive black holes, eventually turning into ones that appear blue thanks to the bright disc of matter that orbits and feeds them.
"Studying baby versions of the overly massive SMBHs in more detail will allow us to better understand how problematic quasars come to exist," Matthee concluded.
The team used datasets acquired by the EIGER (Emission-line galaxies and Intergalactic Gas in the Epoch of Reionization) experiment to come to their conclusion.
While EIGER wasn't designed to find the little red dots in particular, the team "found them by chance in the same dataset," Matthee explained.
But mysteries linger, and more research will be needed.
"So far, we have probably only scratched the surface," Matthee said.
Webb’s Historic Discovery: The Farthest Active Supermassive Black Hole Ever Found
BySPACE TELESCOPE SCIENCE INSTITUTEMARCH 10, 2024
Researchers using the James Webb Space Telescope have made groundbreaking discoveries in galaxy GN-z11, which is one of the most distant and luminous galaxies known. They identified a supermassive black hole responsible for the galaxy’s brightness and found a pristine gas clump that may lead to the discovery of the universe’s first stars, providing significant insights into cosmic evolution. (Artist’s concept.) Credit: SciTechDaily.com
The enigmatic galaxy GN-z11 is one of the youngest ever observed.
Delivering on its promise to transform our understanding of the early universe, the James Webb Space Telescope is probing galaxies near the dawn of time. One of these is the exceptionally luminous galaxy GN-z11, which existed when the universe was just a tiny fraction of its current age. One of the youngest and most distant galaxies ever observed, it is also one of the most enigmatic. Why is it so bright? Webb appears to have found the answer.
Scientists using Webb to study GN-z11 have also uncovered some tantalizing evidence for the existence of Population III stars nestled in the outskirts of this remote galaxy. These elusive stars — the first to bring light to the universe — are purely made of hydrogen and helium. No definitive detection of such stars has ever been made, but scientists know they must exist. Now, with Webb, their discovery seems closer than ever before.
This image from Webb’s NIRCam (Near-Infrared Camera) instrument shows a portion of the GOODS-North field of galaxies. At lower right, a pullout highlights the galaxy GN-z11, which is seen at a time just 430 million years after the big bang. The image reveals an extended component, tracing the GN-z11 host galaxy, and a central source whose colors are consistent with those of an accretion disk surrounding a black hole. Credit: NASA, ESA, CSA, STScI, Brant Robertson (UC Santa Cruz), Ben Johnson (CfA), Sandro Tacchella (Cambridge), Marcia Rieke (University of Arizona), Daniel Eisenstein (CfA)
Webb Unlocks Secrets of One of the Most Distant Galaxies Ever Seen
Looking deeply into space and time, two teams using NASA’s James Webb Space Telescope have studied the exceptionally luminous galaxy GN-z11, which existed when our 13.8 billion-year-old universe was only about 430 million years old.
Initially detected with NASA’s Hubble Space Telescope, this galaxy — one of the youngest and most distant ever observed — is so bright that it is challenging scientists to understand why. Now, GN-z11 is giving up some of its secrets.
Vigorous Black Hole Is Most Distant Ever Found
A team studying GN-z11 with Webb found the first clear evidence that the galaxy is hosting a central, supermassive black hole that is rapidly accreting matter. Their finding makes this the farthest active supermassive black hole spotted to date.
“We found extremely dense gas that is common in the vicinity of supermassive black holes accreting gas,” explained principal investigator Roberto Maiolino of the Cavendish Laboratory and the Kavli Institute of Cosmology at the University of Cambridge in the United Kingdom. “These were the first clear signatures that GN-z11 is hosting a black hole that is gobbling matter.”
Using Webb, the team also found indications of ionized chemical elements typically observed near accreting supermassive black holes. Additionally, they discovered a very powerful wind being expelled by the galaxy. Such high-velocity winds are typically driven by processes associated with vigorously accreting supermassive black holes.
“Webb’s NIRCam (Near-Infrared Camera) has revealed an extended component, tracing the host galaxy, and a central, compact source whose colors are consistent with those of an accretion disk surrounding a black hole,” said investigator Hannah Ãœbler, also of the Cavendish Laboratory and the Kavli Institute.
Together, this evidence shows that GN-z11 hosts a 2-million-solar-mass, supermassive black hole in a very active phase of consuming matter, which is why it’s so luminous.
Pristine Gas Clump in GN-z11’s Halo Intrigues Researchers
A second team, also led by Maiolino, used Webb’s NIRSpec (Near-Infrared Spectrograph) to find a gaseous clump of helium in the halo surrounding GN-z11.
“The fact that we don’t see anything else beyond helium suggests that this clump must be fairly pristine,” said Maiolino. “This is something that was expected by theory and simulations in the vicinity of particularly massive galaxies from these epochs — that there should be pockets of pristine gas surviving in the halo, and these may collapse and form Population III star clusters.”
Finding the never-before-seen Population III stars — the first generation of stars formed almost entirely from hydrogen and helium — is one of the most important goals of modern astrophysics. These stars are anticipated to be very massive, very luminous, and very hot. Their expected signature is the presence of ionized helium and the absence of chemical elements heavier than helium.
The formation of the first stars and galaxies marks a fundamental shift in cosmic history, during which the universe evolved from a dark and relatively simple state into the highly structured and complex environment we see today.
In future Webb observations, Maiolino, Ãœbler, and their team will explore GN-z11 in greater depth, and they hope to strengthen the case for the Population III stars that may be forming in its halo.
The research on the pristine gas clump in GN-z11’s halo has been accepted for publication by Astronomy & Astrophysics. The results of the study of GN-z11’s black hole were published in the journal Nature on January 17, 2024. The data was obtained as part of the JWST Advanced Deep Extragalactic Survey (JADES), a joint project between the NIRCam and NIRSpec teams.
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.
'Baby quasars': James Webb Space Telescope spots little giants in the deep past
Giant quasar and little red dots. A NASA/ESA/CSA James Webb Space Telescope (JWST) NIRCam picture of the luminous quasar J1148+5251, an extremely rare active supermassive black hole of 10 billion solar masses. The quasar's light, the orange star-like source with six clear diffraction spikes, was emitted 13 billion years ago. The existence of such massive black holes in the young Universe poses an important challenge to black hole and galaxy formation theories. Simultaneously, the image captured small, point-like red objects, the so-called little red dots. Several such objects appear in virtually every deep JWST image. Like the quasar J1148+5251, the light from these objects (that in these cases was emitted 12.5 billion years ago) is also powered by supermassive black holes. However, these black holes are a factor of hundred to a thousand lower in mass and heavily obscured by dust (making them appear red). The little red dots could represent galaxies that are in an evolutionary phase that predates the luminous quasar phase, and therefore help researchers understand the formation and role of supermassive black holes in distant galaxies. Credit: NASA, ESA, CSA, J. Matthee (ISTA), R. Mackenzie (ETH Zurich), D. Kashino (National Observatory of Japan), S. Lilly (ETH Zurich)
The James Webb Space Telescope has made one of the most unexpected findings within its first year of service: A high number of faint little red dots in the distant universe could change the way we understand the genesis of supermassive black holes.
The research, led by Jorryt Matthee, Assistant Professor in astrophysics at the Institute of Science and Technology Austria (ISTA), is now published in The Astrophysical Journal.
A bunch of little red dots found in a tiny region of our night sky might indeed be an unexpected breakthrough for the James Webb Space Telescope (JWST) during its first year of service. These objects were indistinguishable from normal galaxies through the "eyes" of the older Hubble Space Telescope.
"Without having been developed for this specific purpose, the JWST helped us determine that faint little red dots--found very far away in the universe's distant past--are small versions of extremely massive black holes. These special objects could change the way we think about the genesis of black holes," says Matthee, Assistant Professor at the Institute of Science and Technology Austria (ISTA), and lead author of the study.
"The present findings could bring us one step closer to answering one of the greatest dilemmas in astronomy: According to the current models, some supermassive black holes in the early universe have simply grown 'too fast.' Then how did they form?"
The cosmic points of no return
Scientists had long considered black holes a mathematical curiosity, until their existence became increasingly evident. These strange cosmic bottomless pits could have such compact masses and strong gravities that nothing can escape their force of attraction; they suck in anything, including cosmic dust, planets, and stars, and deform the space and time around them such that even light cannot escape.
The general theory of relativity, published by Albert Einstein over a century ago, predicted that black holes could have any mass. Some of the most intriguing black holes are the supermassive black holes (SMBHs), which could reach millions to billions of times the mass of the sun. Astrophysicists agree that there is an SMBH at the center of almost every large galaxy. The proof that Sagittarius A* is an SMBH in the center of our galaxy with over four million times the sun's mass, earned the 2020 Nobel Prize in Physics.
Too massive to be there
However, not all SMBHs are the same. While Sagittarius A* could be compared to a sleeping volcano, some SMBHs grow extremely rapidly by engulfing astronomic amounts of matter. Thus, they become so luminous that they can be observed until the edge of the ever-expanding universe. These SMBHs are called quasars, and are among the brightest objects in the universe.
"One issue with quasars is that some of them seem to be overly massive, too massive given the age of the universe at which the quasars are observed. We call them the 'problematic quasars,'" says Matthee.
"If we consider that quasars originate from the explosions of massive stars–and that we know their maximum growth rate from the general laws of physics, some of them look like they have grown faster than is possible. It's like looking at a five-year-old child that is two meters tall. Something doesn't add up," he explains.
Could SMBHs perhaps grow even faster than we originally thought? Or do they form differently?
Small versions of giant cosmic monsters
Now, Matthee and his colleagues identify a population of objects that appear as little red dots in JWST images. Also, they demonstrate that these objects are SMBHs, but not overly massive ones.
Central in determining that these objects are SMBHs was the detection of Hα spectral emission lines with wide line profiles. Hα lines are spectral lines in the deep-red region of visible light that are emitted when hydrogen atoms are heated. The width of the spectra traces the motion of the gas.
"The wider the base of the Hα lines, the higher the gas velocity. Thus, these spectra tell us that we are looking at a very small gas cloud that moves extremely rapidly and orbits something very massive like an SMBH," says Matthee.
However, the little red dots are not the giant cosmic monsters found in overly massive SMBHs.
"While the 'problematic quasars' are blue, extremely bright, and reach billions of times the mass of the sun, the little red dots are more like 'baby quasars.' Their masses lie between ten and a hundred million solar masses. Also, they appear red because they are dusty. The dust obscures the black holes and reddens the colors," says Matthee.
But eventually, the outflow of gas from the black holes will puncture the dust cocoon, and giants will evolve from these little red dots. Thus, the ISTA astrophysicist and his team suggest that the little red dots are small, red versions of giant blue SMBHs in the phase that predates the problematic quasars.
"Studying baby versions of the overly massive SMBHs in more detail will allow us to better understand how problematic quasars come to exist," Matthee explains.
A 'breakthrough' technology
Matthee and his team were able to find the baby quasars thanks to the datasets acquired by the EIGER (Emission-line galaxies and Intergalactic Gas in the Epoch of Reionization) and FRESCO (First Reionization Epoch Spectroscopically Complete Observations) collaborations. These are a large and a medium JWST program in which Matthee was involved. Last December, Physics World magazine listed EIGER among the top 10 breakthroughs of the year for 2023.
"EIGER was designed to study specifically the rare blue supermassive quasars and their environments. It was not designed to find the little red dots. But we found them by chance in the same dataset. This is because by using the JWST's Near Infrared Camera, EIGER acquires emission spectra of all objects in the universe," says Matthee. "If you raise your index finger and extend your arm completely, the region of the night sky we explored corresponds to roughly a twentieth of the surface of your nail. So far, we have probably only scratched the surface."
Matthee is confident that the present study will open up many avenues and help answer some of the big questions about the universe.
"Black holes and SMBHs are possibly the most interesting things in the universe. It's hard to explain why they are there, but they are there. We hope that this work will help us lift one of the biggest veils of mystery about the universe," he concludes.
More information: Little Red Dots: An Abundant Population of Faint Active Galactic Nuclei (AGN) at z ~ 5 Revealed by the EIGER and FRESCO JWST Surveys, The Astrophysical Journal (2024). DOI: 10.3847/1538-4357/ad234
Astronomers using the James Webb Space Telescope have detected the oldest "dead" galaxy ever observed, at just 700 million years after the Big Bang. The stalled-out relic defies explanation by our current knowledge of the early cosmos.
An image from the James Webb Space Telescope highlighting JADES-GS-z7-01-QU, the oldest "dead" galaxy ever observed (Image credit: JADES Collaboration)
Astronomers using the James Webb Space Telescope (JWST) have discovered the oldest "dead" galaxy ever seen — but the cosmic corpse has left scientists puzzled as it defies explanation by our current knowledge of the early cosmos.
The galaxy suddenly and mysteriously halted star formation when the universe was just 700 million years old, when countless stars were birthing thanks to an abundance of pristine gas and dust elsewhere in the universe.
The galaxy, named JADES-GS-z7-01-QU and described in a paper published Wednesday (March 6) in the journal Nature, provides astronomers with a peek into the elusive underpinnings of galaxy evolution in a primordial universe, including why galaxies stop forming new stars and whether forces driving their starbursts alter across epochs.
"Galaxies need a rich supply of gas to form new stars, and the early universe was like an all-you-can-eat buffet," study lead author Tobias Looser, a researcher at the University of Cambridge's Kavli Institute for Cosmology, Cambridge (KICC), said in a statement.
Current models cannot explain how the newfound galaxy not only took shape in less than a billion years after the Big Bang, but also shut down its star factory so quickly. "It's only later in the universe that we [usually] start to see galaxies stop forming stars," study co-author Francesco D'Eugenio, also a researcher at KICC, said in the statement. In comparison, a handful of other "dead" galaxies found elsewhere appear to have paused forming new stars when the universe was about 3 billion years old, the researchers said.
"Everything seems to happen faster and more dramatically in the early universe," added Looser. "And that might include galaxies moving from a star-forming phase to dormant or quenched."
To discover JADES-GS-z7-01-QU, Looser and his colleagues used the JWST's powerful infrared vision to peer through the thick veil of dust obscuring the earliest objects in the universe. In addition to being the oldest "dead" or "quenched" galaxy spotted so far, the newfound galaxy is also many times lighter than other similarly quiescent galaxies previously found in the early universe.
JWST's data suggest the galaxy intensely formed stars for somewhere between 30 million to 90 million years before it rapidly shut off, although precisely what ended it is still unknown. Astronomers know of a couple different factors that can slow down or extinguish star formation. For instance, turbulence inside a galaxy, such as radiation emitted by a supermassive black hole, can push gas out of the galaxy and starve it of the gas reservoir it relies on to form stars. Another intriguing possibility is that the galaxy's surroundings at the time did not sufficiently replenish the gas reservoir being consumed by birthing stars, leading to a deficit in star-forming material.
However, "we're not sure if any of those scenarios can explain what we've now seen with Webb," study co-author Roberto Maiolino, an astrophysicist at KICC, said in the statement. Current models based on the modern universe are unable to explain the properties of JADES-GS-z7-01-QU, suggesting they "may need to be revisited," Maiolino said.
Another possible explanation for the new galaxy's dormancy could be that "galaxies in the early universe 'die' and then burst back to life," D'Eugenio said. However, previous research of "dead" galaxies from when the universe was around 3 billion years old — a time of its most prolific star birth — suggested such "dead" galaxies cannot rejuvenate even via mergers with nearby galaxies, which instead only serve to "puff" them up.
"We'll need more observations to help us figure that out," said D'Eugenio.
Oldest ‘dead’ galaxy spied by Webb may cause astronomers to revise their understanding of the early universe
By Ashley Strickland, CNN Wed March 6, 2024 A new image taken by the James Webb Space Telescope reveals a "dead" galaxy, named JADES-GS-z7-01-QU, in the distant universe. JADES Collaboration
Astronomers have spotted the oldest “dead” galaxy ever observed while studying the cosmos with the James Webb Space Telescope, and it’s one of the deepest views into the distant universe made with the observatory to date.
The galaxy existed when the universe was only about 700 million years into its current age of about 13.8 billion years. But something made the galaxy suddenly halt star formation almost as quickly as star birth had begun more than 13 billion years ago, and the researchers have yet to uncover the cause.
A report describing the discovery appeared Wednesday in the journal Nature. Studying the galaxy could reveal new insights about the early universe and the factors that affect star formation within galaxies, according to the authors.
“The first few hundred million years of the universe was a very active phase, with lots of gas clouds collapsing to form new stars,” said lead study author Tobias Looser, doctoral student in extragalactic astrophysics at the University of Cambridge’s Kavli Institute for Cosmology, in a statement. “Galaxies need a rich supply of gas to form new stars, and the early universe was like an all-you-can-eat buffet.”
The research team was surprised to find a so-called dead galaxy that essentially lived fast and died young so soon after the big bang that created the universe.
“It’s (usually) only later in the universe that we start to see galaxies stop forming stars, whether that’s due to a black hole or something else,” said study coauthor Dr. Francesco D’Eugenio, astrophysicist and postdoctoral research associate at the Kavli Institute for Cosmology, in a statement. What causes galaxies to die
Star formation ceases when environmental factors starve a galaxy of the gas needed to seed the birth of new stars.
Supermassive black holes or the violent interactions of stars can be the culprits that eject gas from galaxies, bringing star formation to a quick halt. Or, the act of star birth can consume so much gas that there isn’t time for enough to be replenished to ensure the process will continue in the future.
“We’re not sure if any of those scenarios can explain what we’ve now seen with Webb,” said study coauthor Roberto Maiolino, professor of experimental astrophysics at the Cavendish Laboratory and the Kavli Institute for Cosmology at the University of Cambridge, in a statement.
“Until now, to understand the early universe, we’ve used models based on the modern universe. But now that we can see so much further back in time, and observe that the star formation was quenched so rapidly in this galaxy, models based on the modern universe may need to be revisited,” Maiolino added.
The Webb observations revealed that the newly discovered galaxy, named JADES-GS-z7-01-QU, experienced a short, energetic burst of star formation that lasted between 30 million and 90 million years before star birth suddenly stopped.
“Everything seems to happen faster and more dramatically in the early universe, and that might include galaxies moving from a star-forming phase to dormant or quenched,” Looser said.
An unusual observation
The dead galaxy revealed by the study is not the first astronomers have come across, but it is the oldest one observed thus far.
What’s more, the galaxy also had a low mass, similar to a dwarf galaxy near the Milky Way known as the Small Magellanic Cloud — which is still forming new stars. Previously observed dead galaxies have been much larger, adding another quirk to the Webb discovery.
The newly found galaxy is billions of light-years away from Earth, and a light-year is how far a beam of light travels in a year, or over 5.88 trillion miles (9.46 trillion kilometers). So Webb is essentially observing the galaxy as it existed in the past — and astronomers have not ruled out the possibility that it may have essentially resurrected and begun star formation anew.
“We’re looking for other galaxies like this one in the early universe, which will help us place some constraints on how and why galaxies stop forming new stars,” D’Eugenio said. “It could be the case that galaxies in the early universe ‘die’ and then burst back to life — we’ll need more observations to help us figure that out.”
