James Webb captures dramatic image of newborn star | Digital Trends
A new image of a Herbig-Haro object captured by the James Webb Space Telescope shows the dramatic outflows from a young star. These luminous flares are created when stellar winds shoot off in opposite directions from newborn stars, as the jets of gas slam into nearby dust and gas at tremendous speed. These objects can be huge, up to several light-years across, and they glow brightly in the infrared wavelengths in which James Webb operates.
This image shows Herbig-Haro object HH 797, which is located close to the IC 348 star cluster, and is also nearby to another Herbig-Haro object that Webb captured recently: HH 211.
The image was taken using Webb’s Near-Infrared Camera (NIRCam) instrument, which is particularly suited to investigating young stars, Webb scientists explain in a statement, : “Infrared imaging is a powerful way to study newborn stars and their outflows, because the youngest stars are invariably still embedded within the gas and dust from which they are formed. The infrared emission of the star’s outflows penetrates the obscuring gas and dust, making Herbig-Haro objects ideal for observation with Webb’s sensitive infrared instruments.
“Molecules excited by the turbulent conditions, including molecular hydrogen and carbon monoxide, emit infrared light that Webb can collect to visualize the structure of the outflows. NIRCam is particularly good at observing the hot (thousands of degree Celsius) molecules that are excited as a result of shocks.”
This particular Herbig-Haro object is unusual in that scientists originally believed that it was created from a single young star, as most such objects are. But these detailed observations reveal that there are actually two sets of outflows, coming from a pair of stars at the center.
In addition to the bright ripples of the Herbig-Haro object in the lower half of the image, there are also thought to be more new stars being born in the upper half of the image. The bright smudge in shades of yellow and green is believed to host two young protostars.
Rocky planets could form in extreme radiation environment | Digital Trends
It takes a particular confluence of conditions for rocky planets like Earth to form, as not all stars in the universe are conducive to planet formation. Stars give off ultraviolet light, and the hotter the star burns, the more UV light it gives off. This radiation can be so significant that it prevents planets from forming from nearby dust and gas. However, the James Webb Space Telescope recently investigated a disk around a star thatseems like it could be forming rocky planets, even though nearby massive stars are pumping out huge amounts of radiation.
The disk of material around the star, called a protoplanetary disk, is located in the Lobster Nebula, one of the most extreme environments in our galaxy. This region hosts massive stars that give off so much radiation that they can eat through a disk in as little as a million years, dispersing the material needed for planets to form. But the recently observed disk, named XUE 1, seems to be an exception.
The researchers used James Webb’s Mid-Infrared Instrument (MIRI) to identify water, carbon monoxide, carbon dioxide, hydrogen cyanide, and acetylene in the disk. Those are some of the building blocks for rocky planets and show that the disk is similar to other planet-forming disks, despite the high amount of UV radiation.
“We were surprised and excited because this is the first time that these molecules have been detected under these extreme conditions,” said one of the authors, Lars Cuijpers of Radboud University, in a statement.
The problem for this disk is that there are a number of nearby massive stars, so the disk is being bombarded by UV radiation from several sources. The disk does seem to be a bit smaller than expected, but it still appears that it could be capable of forming rocky planets. That means that rocky planets could form even in very extreme environments, if this particular disk is not an outlier.
“XUE 1 shows us that the conditions to form rocky planets are there, so the next step is to check how common that is,” said lead researcher María Claudia Ramírez-Tannus of the Max Planck Institute for Astronomy. “We will observe other disks in the same region to determine the frequency with which these conditions can be observed.”
James Webb detects methane in the atmosphere of an exoplanet | Digital Trends
One of the amazing abilities of the James Webb Space Telescope is not just detecting the presence of far-off planets, but also being able to peer into their atmospheres to see what they are composed of. With previous telescopes, this was extremely difficult to do because they lacked the powerful instruments needed for this kind of analysis, but scientists using Webb recently announced they had made a rare detection of methane in an exoplanet atmosphere.
Scientists studied the planet WASP-80 b using Webb’s NIRCam instrument, which is best known as a camera but also has a slitless spectroscopy mode which allows it to split incoming light into different wavelengths. By looking at which wavelengths are missing because they have been absorbed by the target, researchers can tell what an object — in this case, a planetary atmosphere — is composed of.
Even with Webb’s sensitive instruments, it’s still difficult to detect an exoplanet though. That’s because planets are so much smaller and dimmer than stars, which makes them almost impossible to view directly. Instead, researchers often detect them by observing the stars around which they orbit, using techniques like the transit method which measures the dip in a star’s brightness that occurs when a planet moves in front of it.
“Using the transit method, we observed the system when the planet moved in front of its star from our perspective, causing the starlight we see to dim a bit,” one of the study’s authors, Luis Welbanks of Arizona State University, explained in a statement. “It’s kind of like when someone passes in front of a lamp and the light dims. During this time, a thin ring of the planet’s atmosphere around the planet’s day/night boundary is lit up by the star, and at certain colors of light where the molecules in the planet’s atmosphere absorb light, the atmosphere looks thicker and blocks more starlight, causing a deeper dimming compared (with) other wavelengths where the atmosphere appears transparent. This method helps scientists like us understand what the planet’s atmosphere is made of by seeing which colors of light are being blocked.”
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When the authors used this method on WASP-80b, they found evidence of both water and methane in the planet’s atmosphere. Planets in our solar system like Jupiter and Saturn have methane in their atmospheres too, but this planet is much warmer, with a temperature of over 1,000 degrees Fahrenheit. Finding methane in a planet of this type, called a warm Jupiter, is exciting because it can help scientists learn about planetary atmospheres and also because despite it being commonly found in planetary atmospheres in our solar system, it is rarely detected in exoplanet atmospheres.
It could also be relevant for the hunt for life beyond our planet. “Not only is methane an important gas in tracing atmospheric composition and chemistry in giant planets, it is also hypothesized to be, in combination with oxygen, a possible signature of biology,” Wellbanks said. “One of the key goals of the Habitable Worlds Observatory, the next NASA flagship mission after JWST and Roman, is to look for gases like oxygen and methane in Earth-like planets around sun-like stars.”
Stunning James Webb image shows the heart of our Milky Way | Digital Trends
A new image from the James Webb Space Telescope shows the heart of our galaxy, in a region close to the supermassive black hole at the center of the Milky Way, Sagittarius A*. The image shows a star-forming region where filaments of dust and gas are clumping together to give birth to new baby stars.
The image was captured using Webb’s NIRCam instrument, a camera that looks in the near-infrared portion of the electromagnetic spectrum with shorter wavelengths shown in blue and cyan and longer wavelengths shown in yellow and red.
This region is called Sagittarius C, and is located around 300 light-years away from the supermassive black hole Sagittarius A*. For reference, Earth is located much further away from the galactic center, at a distance of around 26,000 light years from Sagittarius A*.
There are thought to be as many as 500,000 stars in the Sagittarius C region, including many young protostars, some of which will go on to become main-sequence stars like our sun. As stars form, they give off powerful stellar winds which blow away nearby material and prevent more stars from forming very close to them.
These outflows are illuminated in the infrared wavelength, and the cyan-colored patches in the image are created by ionized gas. The young stars give off a great deal of energy, which ionizes the hydrogen gas around them and makes them glow in the infrared.
However, there are actually even more stars in this area than can be seen in the image. The pockets of darkness scattered throughout the image aren’t blank but are dense clouds that are dark in the infrared, including a large dense area in the heart of the region.
There are still some surprises to be found in the image too, with some features that scientists need to study in more depth. “Researchers say they have only begun to dig into the wealth of unprecedented high-resolution data that Webb has provided on this region, and many features bear detailed study,” Webb scientists write. “This includes the rose-colored clouds on the right side of the image, which have never been seen in such detail.”
Why can’t we measure how fast the universe is expanding? | Digital Trends
Something very strange is going on in the universe. The science of cosmology, which studies the universe on a grand scale, is in a state of crisis. Over the last century, scientists have found mountains of evidence that the universe is expanding over time, as they observed that the further away from Earth a galaxy is, the faster it is moving away from us.
The problem is that no one is sure how fast this expansion is happening. Two different ways of measuring this value, called the Hubble constant, produce two different results. The last decades have seen the best theories and experiments that humanity can come up with struggle to explain how this could be so.
Usually, when there’s a discrepancy like this, newer technologies enable more accurate experimental data which helps to solve the mystery. But in the case of this puzzle, called the Hubble tension, the more we learn, the harder it is to explain the discrepancy.
The cosmological distance ladder
When the Hubble Space Telescope was launched in 1990, one of its main aims was to investigate the expansion of the universe. The debate over the rate of this expansion was raging, and scientists were keen to pin down an answer more precisely — because this information was crucial to understanding the age of the universe, and at this time that age could have been as little as 8 billion years old or as much as 20 billion years.
By the late 2000s, scientists had honed in on a figure by looking at stars that brightened in a particular rhythm, called Cepheid variables, and a particular type of supernova called Type Ia supernovae. Both of these objects have a predictable level of brightness, which means they can be used to measure distance — Cephids for closer galaxies and Type Ia supernovae for more distant ones — so they are used as “standard candles” for astronomical measurements.
With these accurate distance measurements, the value Hubble scientists came up with for the expansion of the universe was 72 kilometers per second per megaparsec. That’s a measurement of the amount of expansion by time by distance, because the further away from us galaxies are, the faster they are moving. A parsec is 3.26 light-years, and a megaparsec is one million parsecs. So if we look at a galaxy 3.26 million light-years away, it will be moving away from us at around 70 kilometers per second, or around 150,000 mph.
That measurement was an enormous scientific step forward, but it still had a potential error of around 10%. Subsequent research managed to chip away at reducing this error, honing in on a recent figure of 73.2km/s/Mpc with an error rate of under 2%, but they were bumping up against the physical limitations of the telescope.
A new telescope in the toolkit
While one group of astronomers was busy with data from the Hubble Space Telescope, another was looking in quite a different place, by examining the Cosmic Microwave Background, or CMB. This is the leftover energy remaining from the Big Bang and it’s seen everywhere as a constant very slight background hum. When calculating the Hubble constant based on this data, researchers found quite a different figure: 67 km/s/Mpc. That difference might seem small, but it’s stubborn: The more accurately each group made its measurements, the more entrenched the divide seemed.
But when the James Webb Space Telescope was launched in 2021, researchers had a new and even more accurate tool for their measurements. A group of researchers including Richard Anderson of the Swiss Federal Institute of Technology Lausanne got to work double-checking Hubble’s measurements using this new technology. Perhaps the Hubble Space Telescope’s measurements had been inaccurate due to the limitations of the telescope, which might explain the different figures, and this new tool could help to show if that was the case.
The advantage James Webb has over Hubble in this context is greater spatial resolution when looking at Cephids. “Previously, when you had lower resolution you needed to statistically correct for the light of sources that blend together,” Anderson explained to Digital Trends. And this statistical correction introduced a nugget of doubt into the Hubble data. Perhaps the rate of expansion measured by Hubble was inaccurate, some argued, because the statistical tools used for this correction were inaccurate.
With the better spatial resolution of new Webb data, though, that statistical correction is much smaller. “So if you don’t have to correct so much, you add less error, and your measurement becomes more precise,” Anderson said. Not only does the Webb data agree with the previous Hubble measurements, but it increases the precision of that measurement too.
The evidence is in, and it’s clear: Hubble’s measurements of the rate of expansion are correct. Of course, nothing this complex can be proved beyond any shadow of doubt, but the measurements are as accurate as we can practically make them.
A sticky problem
So if the Hubble telescope data is correct, maybe the problem is with the other measurement. Maybe it’s the Cosmic Microwave Background data that is wrong?
That’s tough too, however. Because just as researchers were refining the figure from Hubble data, so too the CMB researchers were making their own figure more and more accurate. The biggest step forward in this field was the launch of the European Space Agency’s Planck space observatory in 2009. This mission was specifically designed to measure the CMB and it acquired the most accurate data yet of the small variations in temperature across the CMB. That’s important because although the CMB is at a consistent temperature almost everywhere, there are tiny variations in this temperature of 1 part in 100,000.
As small as these temperature variations are, they are important because they represent variations that were present when the universe was forming. Looking at the variations as they exist now, researchers can roll back the clock to understand what the universe must have looked like in its earliest stages.
When researchers use this Planck data to estimate the expansion of the universe, based on our understanding of the universe as it existed when it was young, they honed in on a figure for the constant of 67.4 km/s/Mpc with an error of less than 1%. There’s no crossover between the uncertainties of the two figures anymore — they’re both solid, and they don’t agree.
A history of expansion
Scientists have been studying the CMB since the 1960s, and in that time the research has progressed to a degree of precision that makes its specialists confident in their findings. When it comes to modeling the inflation of the universe in its early stages, they have gotten about as accurate as possible according to Jamie Bock of Caltech, PI for NASA’s upcoming SPHEREx mission to investigate the CMB.
“The microwave background is very close to hitting cosmological limits on those measures,” Bock said. “In other words, you can’t build a better experiment. You’re just limited on how much of the universe you can see.”
SPHEREx will be a space-based mission that won’t take direct measurements of the Hubble constant. But it will help researchers learn about the history of the universe’s expansion, by investigating a period of the early universe called inflation when the universe expanded rapidly. In this very early period, the universe was much, much smaller, hotter, and denser, and that affected the way in which it expanded. Over its lifetime, the most significant driving factors of the universe’s expansion have changed as it has grown, cooled, and become less dense. We know that today, a hypothesized form of energy called dark energy is the main force pushing the universe to expand. But at other times in the universe’s history, other factors such as the presence of dark matter have been more significant.
“The trajectory of the universe is set by the type of matter and energy that are dominant at that time,” Bock explained. Dark energy, for example, “has only started to dominate the expansion of the universe in the latter half of the age of the universe. Prior to that, it would have been dark matter that would drive the evolution of the universe.”
One popular theory for the difference in the two measurements is that dark energy could be the culprit. Perhaps there was more dark energy in the early universe than is currently believed, which would make it expand faster. We might learn more about this possibility with new missions like ESA’s Euclid, which launched recently and aims to map a huge chunk of the universe in 3D to study dark matter and dark energy.
A thermometer for our understanding of the universe
You can think of the two values of the Hubble constant as measuring from the universe as we see it now, called the late universe, compared to measuring from the universe as it was when it was young, called the early universe. When the two different rates were calculated using less accurate methods, it was possible that the two could actually be in agreement but just appeared further apart due to overlapping errors.
But as scientists have reduced these errors down and down, that explanation can’t work anymore. Either one of the measurements is wrong — always possible, but increasingly unlikely given the mountain of data on each — or there’s something fundamental about the universe that we just don’t understand yet.
“The thermometer tells us that we have a fever.”
“What we have here is like a thermometer of how good our understanding is of the cosmos at this time,” Anderson said. “And I think the thermometer tells us that we have a fever, and we have a problem.”
And bear in mind, the Hubble constant isn’t a minor issue. It’s a fundamental measurement, arguably the most important number in cosmology. And the more accurate our measurements of it get, the more the mystery deepens.
Searching for independent verification
This is another way of measuring the universe as we see it now, and that’s by looking at gravitational waves. When massive enough objects collide, such as two black holes merging, the enormous forces create ripples in spacetime called gravitational waves, which can be detected from billions of light-years away.
These ripples can be detected on Earth by specialized facilities like LIGO (the Laser Interferometer Gravitational-Wave Observatory) and can be used to determine how far away a source is, which means they can theoretically be used to measure the rate of expansion as well.
This is a late universe measurement, but it’s also completely independent of the Cephids and supernovas used in other research. That means that if measurements of the expansion rate appear similar based on gravitational wave data, we could be even more confident that the higher figure is correct — and if they don’t, then we’d know better where the problem is.
The advantage of using gravitational waves for this type of measurement is that the signature is very clean — “the only thing that affects it is very heavy masses,” said gravitational wave expert Stefan Ballmer of Syracuse University. And when black holes merge, their dynamic behavior is very consistent, no matter their size. That makes them ideal standard candles for measuring distances — “about as good as it gets,” according to Ballmer.
So measuring distance with gravitational waves is relatively simple. The challenge with using these measurements for calculating the expansion rate is finding the velocity. With supernovas, it’s easy to know the redshift (which gives you the velocity) but hard to know the absolute brightness (which gives you the distance). Whereas with gravitational waves it’s easy to know the distance but hard to know the velocity.
One way of approaching the velocity issue is to look for mergers happening in nearby galaxies, and then use the known redshift of those galaxies for your gravitational wave velocity. This only works when you can find the source of gravitational waves and pinpoint it to somewhere close by.
But in the future, once scientists observe enough of these gravitational wave events, they’ll be able to build up a picture of what the average event looks like and use that information to calculate the expansion rate on a large scale.
The next generation of facilities
For that, though, we’ll need hundreds of data points on gravitational wave events, compared to the handful we have now. This is a very new area of research, and our ability to detect gravitational waves is still limited to a small number of facilities. Currently, the uncertainties of the expansion rate measured using gravitational waves are still larger than the two other methods.
“Right now, our signal lies right in the middle between the two other results,” Ballmer said.
However, that could change in the future. With the next generation of gravitational wave detectors, being planned for construction in the next decades, these measurements could become more and more accurate.
The deepening of this puzzle might be a source of frustration, but it’s also given an impetus for new and better experiments as scientists from a wide range of fields tackle one of the great questions about the universe as we see it.
“The only way to really know is to make the experiment better,” Ballmer said. “That’s the world we live in.”
Webb investigates super puffy exoplanet where it rains sand | Digital Trends
Exoplanets come in many forms, from dense, rocky planets like Earth and Mars to gas giants like Jupiter and Saturn. But some planets discovered outside our solar system are even less dense than gas giants and are a type known informally as super-puff or cotton candy planets. One of the least dense exoplanets known, WASP-107b, was recently investigated using the James Webb Space Telescope (JWST) and the planet’s weather seems to be as strange as its puffiness.
The planet is more atmosphere than core, with a fluffy atmosphere in which Webb spotted water vapor and sulfur dioxide. Strangest of all, Webb also saw silicate sand clouds, suggesting that it would rain sand between the upper and lower layers of the atmosphere. The planet is almost as big as Jupiter but has a tiny mass similar to that of Neptune.
“JWST is revolutionizing exoplanet characterization, providing unprecedented insights at remarkable speed,“ says lead author of the study, Leen Decin of KU Leuven, in a statement. “The discovery of clouds of sand, water, and sulfur dioxide on this fluffy exoplanet by JWST’s MIRI instrument is a pivotal milestone. It reshapes our understanding of planetary formation and evolution, shedding new light on our own solar system.”
Understanding the planet’s formation and evolution is important because it seems impossible that it could have formed in its current location. It is thought to have formed further out in the star system and migrated inward over time. That could allow for its extremely low density. Its close orbit to its star means it has a very high temperature, with its outer atmosphere reaching 500 degrees Celsius. But those temperatures are not normally hot enough to form clouds of silicate, which would be expected to form in lower layers where the temperatures are higher.
The researchers theorize that the sand rain is evaporating in the lower, hotter layers and the silicate vapor moves upwards in the atmosphere before recondensing to form clouds and falling as rain, similar to the water cycle on Earth.
“The value of JWST cannot be overstated: wherever we look with this telescope, we always see something new and unexpected,” said fellow researcher Paul Mollière from the Max Planck Institute of Astronomy. “This latest result is no exception.”
The research will be published in the journal Nature.
The Hubble Telescope Just Sized Up an Earth-Sized Exoplanet
The Hubble Space Telescope just ogled an exoplanet passing in front of a star in a triple system, revealing the nearby world’s mass.
Webb Telescope Images the Pillars of Creation
The world is named LTT 1445Ac, and it was discovered in 2022 by NASA’s Transiting Exoplanet Survey Satellite (TESS). The world orbits a red dwarf star (one in a set of three) that is 22 light-years from Earth, in the constellation Eridanus. LTT 1445Ac shares its host star with two larger planets.
TESS doesn’t have the optical resolution necessary to determine the planet’s diameter accurately. Now, a team of researchers used the veteran Hubble telescope to certify the world’s size; their results are accepted for publication in The Astronomical Journal and are currently hosted on the preprint server arXiv.
“There was a chance that this system has an unlucky geometry and if that’s the case, we wouldn’t measure the right size,” said Emily Pass, an astronomer at the Center for Astrophysics | Harvard & Smithsonian, and the study’s lead author, in a NASA release. “But with Hubble’s capabilities, we nailed its diameter.”
Though the Webb Space Telescope—Hubble’s nominal successor as NASA’s marquee space observatory—has been operational for over a year, work for the older telescope hasn’t slowed. Webb takes in light at infrared and near-infrared wavelengths, meaning some observations (namely those at visible and ultraviolet wavelengths) are still the domain of Hubble.
The Hubble observations revealed that LTT 1445Ac has a diameter 1.07 times that of Earth, meaning it’s a rocky world with roughly the same gravity as our own. The similarities stop there, though: LTT 1445Ac has a surface temperature of 500° Fahrenheit (260° Celsius), piping hot—and unsuitable for life—compared to our relatively balmy planet.
“Transiting planets are exciting since we can characterize their atmospheres with spectroscopy, not only with Hubble but also with the James Webb Space Telescope,” Pass said. “Our measurement is important because it tells us that this is likely a very nearby terrestrial planet. We are looking forward to follow-on observations that will allow us to better understand the diversity of planets around other stars.”
NASA’s Voyager 1 spacecraft captured this view of Earth—appearing as a speck of light—on February 14, 1980, at a distance of roughly 3.2 billion miles (6 billion km) from the Sun—beyond the orbit of Neptune. The words of Carl Sagan, as featured in his 1994 book, Pale Blue Dot: A Vision of a Human Future in Space, best describes the significance of this ultra-famous image:
… Look again at that dot. That’s here. That’s home. That’s us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every “superstar,” every “supreme leader,” every saint and sinner in the history of our species lived there – on a mote of dust suspended in a sunbeam.
The Earth is a very small stage in a vast cosmic arena. Think of the rivers of blood spilled by all those generals and emperors, so that, in glory and triumph, they could become the momentary masters of a fraction of a dot. Think of the endless cruelties visited by the inhabitants of one corner of this pixel on the scarcely distinguishable inhabitants of some other corner, how frequent their misunderstandings, how eager they are to kill one another, how fervent their hatreds. Our posturings, our imagined self-importance, the delusion that we have some privileged position in the Universe, are challenged by this point of pale light.
Our planet is a lonely speck in the great enveloping cosmic dark. In our obscurity, in all this vastness, there is no hint that help will come from elsewhere to save us from ourselves.
The Earth is the only world known so far to harbor life. There is nowhere else, at least in the near future, to which our species could migrate. Visit, yes. Settle, not yet. Like it or not, for the moment the Earth is where we make our stand.
It has been said that astronomy is a humbling and character building experience. There is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world. To me, it underscores our responsibility to deal more kindly with one another, and to preserve and cherish the pale blue dot, the only home we’ve ever known.
These goosebump-inducing words, so potent 30 years ago, resonate even more powerfully today.
Webb and Hubble image the Christmas Tree Galaxy Cluster | Digital Trends
Different telescopes work at different wavelengths, meaning they can observe different objects in the sky — and when data from various telescopes is combined, it can make for stunning views that would be impossible to get from any one instrument. That’s the case with a beautiful new image of a cluster of thousands of galaxies that combines data from both the Hubble Space Telescope and the James Webb Space Telescope to create a stunning and colorful view.
Hubble looks in the optical wavelength, like the human eye, and the galaxies that it detected are mostly shown in blue and cyan. James Webb, however, looks beyond the range of human vision in the infrared wavelength, and the galaxies it viewed are shown mostly in yellow and red. There’s some crossover in the green parts of the image, which represent portions of the spectrum visible to both telescopes.
The huge MACS0416 cluster is actually a pair of galaxy clusters that are in the process of colliding, and which will eventually form one enormous cluster. This cluster was studied by Hubble over the last decade to look for some of the furthest galaxies that had been detected at that time — work that has now been taken up by Webb.
“We are building on Hubble’s legacy by pushing to greater distances and fainter objects,” said lead researcher Rogier Windhorst of Arizona State University in a statement.
In addition to producing a stunning image, the Webb data is also helping to investigate objects that change their brightness over time, called transients. These could be supernovae events, when a star comes to the end of its life and explodes in a large, bright event that quickly dims, or they could be other types of object such as stars or galaxies that are briefly magnified due to the effect of gravitational lensing. There were 14 of these transient objects identified in the image.
“We’re calling MACS0416 the Christmas Tree Galaxy Cluster, both because it’s so colorful and because of these flickering lights we find within it. We can see transients everywhere,” said fellow researcher Haojing Yan of the University of Missouri.
The JWST Has Spotted Giant Black Holes All Over the Early Universe
Like any object, black holes take time to grow and form. And like a 6-foot-tall toddler, Fan’s supersize black holes were too big for their age—the universe wasn’t old enough for them to have accrued billions of suns of heft. To explain those overgrown toddlers, physicists were forced to consider two distasteful options.
The first was that Fan’s galaxies started off filled with standard, roughly stellar-mass black holes of the sort supernovas often leave behind. Those then grew both by merging and by swallowing up surrounding gas and dust. Normally, if a black hole feasts aggressively enough, an outpouring of radiation pushes away its morsels. That stops the feeding frenzy and sets a speed limit for black hole growth that scientists call the Eddington limit. But it’s a soft ceiling: A constant torrent of dust could conceivably overcome the outpouring of radiation. However, it’s hard to imagine sustaining such “super-Eddington” growth for long enough to explain Fan’s beasts—they would have had to bulk up unthinkably fast.
Or perhaps black holes can be born improbably large. Gas clouds in the early universe may have collapsed directly into black holes weighing many thousands of suns—producing objects called heavy seeds. This scenario is hard to stomach too, because such large, lumpy gas clouds should fracture into stars before forming a black hole.
One of JWST’s priorities is to evaluate these two scenarios by peering into the past and catching the fainter ancestors of Fan’s galaxies. These precursors wouldn’t quite be quasars, but galaxies with somewhat smaller black holes on their way to becoming quasars. With JWST, scientists have their best chance of spotting black holes that have barely started to grow—objects that are young enough and small enough for researchers to nail down their birth weight.
That’s one reason a group of astronomers with the Cosmic Evolution Early Release Science Survey, or CEERS, led by Dale Kocevski of Colby College, started working overtime when they first noticed signs of such young black holes popping up in the days following Christmas.
“It’s kind of impressive how many of these there are,” wrote Jeyhan Kartaltepe, an astronomer at the Rochester Institute of Technology, during a discussion on Slack.
“Lots of little hidden monsters,” Kocevski replied.
A Growing Crowd of Monsters
In the CEERS spectra, a few galaxies immediately leapt out as potentially hiding baby black holes—the little monsters. Unlike their more vanilla siblings, these galaxies emitted light that didn’t arrive with just one crisp shade for hydrogen. Instead, the hydrogen line was smeared, or broadened, into a range of hues, indicating that some light waves were squished as orbiting gas clouds accelerated toward JWST (just as an approaching ambulance emits a rising wail as its siren’s soundwaves are compressed) while other waves were stretched as clouds flew away. Kocevski and his colleagues knew that black holes were just about the only object capable of slinging hydrogen around like that.
“The only way to see the broad component of the gas orbiting the black hole is if you’re looking right down the barrel of the galaxy and right into the black hole,” Kocevski said.
By the end of January, the CEERS team had managed to crank out a preprint describing two of the “hidden little monsters,” as they called them. Then the group set out to systematically study a wider swath of the hundreds of galaxies collected by their program to see just how many black holes were out there. But they got scooped by another team, led by Yuichi Harikane of the University of Tokyo, just weeks later. Harikane’s group searched 185 of the most distant CEERS galaxies and found 10 with broad hydrogen lines—the likely work of million-solar-mass central black holes at redshifts between 4 and 7. Then in June, an analysis of two other surveys led by Jorryt Matthee of the Swiss Federal Institute of Technology Zurich identified 20 more “little red dots” with broad hydrogen lines: black holes churning around redshift 5. An analysis posted in early August announced another dozen, a few of which may even be in the process of growing by merging.