Astronomers from McGill University in Canada and the Indian Institute of Science (IISc) have used data from the Giant Metrewave Radio Telescope (GMRT), in Pune, to detect a radio signal originating from atomic hydrogen in an extremely distant galaxy.
The IISc said on Monday that the astronomical distance over which the signal has been picked up is “the largest so far by a large margin”.
The findings have been published in the Monthly Notices of the Royal Astronomical Society.
While detection of radio waves with 21 cm wavelength, emitted by atomic hydrogen, is possible through low-frequency radio telescopes like GMRT, the “extremely weak” nature of the radio signal makes it nearly impossible to detect emissions from a distant galaxy.
The most distant galaxy detected through the 21-cm emission, so far, was at redshift z=0.376.
The value denotes the look-back time, or the time elapsed between the detection and the original emission; in this case, 4.1 billion years.
Arnab Chakraborty, postdoctoral researcher at the Department of Physics and Trottier Space Institute of McGill University, and Nirupam Roy, associate professor, department of Physics, IISc, used data from GMRT to detect a radio signal from atomic hydrogen in a distant galaxy at redshift z=1.29.
IISc said in an official statement that the signal was emitted when the universe was only 4.9 billion years old, which translated to a look-back time of 8.8 billion years.
Atomic hydrogen – formed when hot ionised gas from the surrounding medium of a galaxy falls onto the galaxy, and cools – and its subsequent change into molecular hydrogen leads to the formation of stars. Studying the evolution of neutral gas, therefore, becomes critical in understanding the evolution of galaxies.
The GMRT was built and is operated by National Centre for Radio Astrophysics – Tata Institute of Fundamental Research, Pune. The research was funded by McGill and IISc.
The astronomers traced the detection to a phenomenon called gravitational lensing, which causes the light emitted by the source to bend due to the presence of another massive body, “such as an early type elliptical galaxy,” between the observer and the target galaxy, resulting in a signal that is magnified. “In this specific case, the magnification of the signal was about a factor of 30, allowing us to see through the high redshift universe,” Roy said.
The detection significantly increases possibilities in observing atomic gas from galaxies at cosmological distances and studying the cosmic evolution of neutral gas with low-frequency radio telescopes.
Yashwant Gupta, Centre Director at NCRA, called detection of neutral hydrogen in emission from the distant universe one of GMRT’s “key science goals”.
What takes over 20,000 engineers and hundreds of scientists to build? A space telescope — specifically, the James Webb Space Telescope.
Thankfully, the effort was well worthwhile, with a plethora of incredible results from NASA’s newest observatory in its first six months of science operations. But what comes next? John Mather, a Nobel-winning astronomer and a leading force behind the James Webb Space Telescope (Webb or JWST), shared his visions of what all those engineers and scientists may tackle next on Thursday (Jan. 12), the final day of the 241st meeting of the American Astronomical Society held in Seattle and virtually.
Mather’s involvement in astronomy traces back to before even the Hubble Space Telescope‘s launch in 1990, when the first ideas for the Next Generation Space Telescope (which later became JWST) were thrown around in the 1980s. To make a dream like JWST come true required decades of innovation by countless scientists and engineers, including inventing “new flavors of detectors” for the telescope to make the observations they hoped for.
Related: James Webb Space Telescope’s best images of all time (gallery)
And the next big astronomical goals will require similar dedication and creativity, Mather said. JWST “is a demonstration that we can do hard things,” he said in his speech at the convention. “And we’re going to continue to do hard things.”
Some goals are closer than others, and there are so many out there swirling in the minds of astronomers. “I cannot possibly tell you all the wonderful things that are coming, so I’ll tell you the ones that interest me the most,” Mather said.
There are a number of exciting new observatories coming online in the coming months and years, including the European mission Euclid and NASA’s Nancy Grace Roman Space Telescope that will both search for clues in the long-standing mysteries of dark matter and dark energy. The Vera Rubin Observatory, a giant project currently under construction in the high deserts of Chile, will survey the whole sky looking for small changes, known as transients. Astronomers think the observatory will spot millions of points of interest each night — so many that it’ll be a challenge to sift through them all. “Maybe that ChatGPT thing will help,” Mather joked.
A view of the Vera Rubin Observatory in Cerro Pachón, Chile, in 2020; the telescope is due to begin observations later this year. (Image credit: Rubin Observatory/NSF/AURA)
Looking a bit further down the road, the next hugely ambitious project is the so-called “Habitable Worlds Observatory” — the mega-successor to Hubble and JWST, recommended by an important committee known as the Astro2020 Decadal Survey.
Mather said that he thinks this project is well within reach, and could even be easier to complete than JWST, which notoriously struggled to meet budgets and deadlines. Because rocket technology is continually improving — and getting cheaper — he suggested it may even be possible to assemble the Habitable Worlds Observatory and other next-generation telescopes in space instead of on the ground.
And it’s not all about space telescopes. Mather said he’s looking forward to seeing how giant telescopes around 98 feet (30 meters) in diameter revolutionize astronomy here on the ground, too.
And he’s dreaming even bigger than the official NASA plans: Maybe someday these ground-based behemoths will even work in tandem with space observatories in what Mather calls “hybrid space-ground” setups. For example, one key technique of ground-based astronomers relies on little contraptions called coronagraphs that block out stars and reveal faint nearby planets. Perhaps someday, Mather posited, we could fly a giant starshade in orbit and match it up with the telescope on the ground.
Where such ambitions might take us isn’t clear, but to date, every time our technology has improved, we’ve learned leaps and bounds about the universe — often finding something completely unknown. Mather ended his talk by rhetorically asking what we’ll see with all this new technology. “I don’t know,” he said, “but a whole lot more details and a whole lot further away than you can now.”
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The Hubble Space Telescope has spotted a star being stripped and stretched into a doughnut shape as a black hole devours it.
The supermassive black hole, located 300 million light-years from Earth at the core of the galaxy ESO 583-G004, snared and shredded the star after it wandered too close, sending out a powerful beam of ultraviolet light that astronomers used to locate the violent encounter.
When a black hole feeds, its immense gravity exerts powerful tidal forces on the unfortunate star. As the star is reeled ever closer to the black hole’s maw, the gravity affecting the regions of the star closer to the black hole is far stronger than that acting on the star’s farside. This disparity “spaghettifies” the star into a long, noodle-like string that gets tightly wound around the black hole layer by layer — like spaghetti around a fork.
This sequence of artist’s illustrations shows how a black hole can devour a bypassing star. 1. A normal star passes near a supermassive black hole in the center of a galaxy. 2. The star’s outer gasses are pulled into the black hole’s gravitational field. 3. The star is shredded as tidal forces pull it apart. 4. The stellar remnants are pulled into a donut-shaped ring around the black hole, and will eventually fall into the black hole, unleashing a tremendous amount of light and high-energy radiation. (Image credit: NASA, ESA, Leah Hustak (STScI))
This doughnut of hot plasma quickly accelerates around the black hole and spins out into an enormous jet of energy and matter, which produces a distinctive bright flash that optical, X-ray and radio-wave telescopes can detect.
The exceptional brightness of this particular black hole feeding session allowed astronomers to study it over a longer time period than is typical for tidal disruption events. This could yield exciting new insights about the unfortunate star’s final moments, the researchers said.
Related: Wormhole simulated in quantum computer could bolster theory that the universe is a hologram
“We’re looking somewhere on the edge of that donut,” Peter Maksym, an astronomer at the Harvard-Smithsonian Center for Astrophysics, said in a NASA statement (opens in new tab). “We’re seeing a stellar wind from the black hole sweeping over the surface that’s being projected towards us at speeds of 20 million miles per hour (three percent the speed of light). We really are still getting our heads around the event.”
For a star, spaghettification is a dramatic process. The outer atmospheric layers of the star are stripped first. Then, they circle the black hole to form the tight yarn ball the researchers observed. The remainder of the star soon follows, accelerating around the black hole. Despite black holes’ reputation as voracious eaters, most of the star’s matter will escape; only 1% of a typical star ever gets swallowed by a black hole, Live Science previously reported.
The results were reported at the 241st meeting of the American Astronomical Society, held in Seattle this week.
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Two supermassive black holes have been spotted feasting on cosmic materials as two galaxies in distant space merge — and are the closest to colliding black holes astronomers have ever observed.
Astronomers spotted the pair while using the Atacama Large Millimeter/Submillimeter Array of telescopes, or ALMA, in northern Chile’s Atacama Desert, to observe two merging galaxies about 500 million light-years from Earth.
The two black holes were growing in tandem near the center of the coalescing galaxy resulting from the merger. They met when their host galaxies, known as UGC 4211, collided.
One is 200 million times the mass of our sun, while the other is 125 million times the mass of our sun.
While the black holes themselves aren’t directly visible, both were surrounded by bright clusters of stars and warm, glowing gas — all of which is being tugged by the holes’ gravitational pull.
Over time, they will start circling one another in orbit, eventually crashing into one another and creating one black hole.
After observing them across multiple wavelengths of light, the black holes are located the closest together scientists have ever seen — only about 750 light-years apart, which is relatively close, astronomically speaking.
The results were shared at the 241st meeting of the American Astronomical Society being held this week in Seattle, and published Monday in The Astrophysical Journal Letters.
The distance between the black holes “is fairly close to the limit of what we can detect, which is why this is so exciting,” said study coauthor Chiara Mingarelli, an associate research scientist at the Flatiron Institute’s Center for Computational Astrophysics in New York City, in a statement.
Galactic mergers are more common in the distant universe, which makes them harder to see using Earth-based telescopes. But ALMA’s sensitivity was able to observe even their active galactic nuclei — the bright, compact regions in galaxies where matter swirls around black holes. Astronomers were surprised to find a binary pair of black holes, rather than a single black hole, dining on the gas and dust stirred up by the galactic merger.
“Our study has identified one of the closest pairs of black holes in a galaxy merger, and because we know that galaxy mergers are much more common in the distant Universe, these black hole binaries too may be much more common than previously thought,” said lead study author Michael Koss, a senior research scientist at the Eureka Scientific research institute in Oakland, California, in a statement.
“What we’ve just studied is a source in the very final stage of collision, so what we’re seeing presages that merger and also gives us insight into the connection between black holes merging and growing and eventually producing gravitational waves,” Koss said.
If pairs of black holes — as well as merging galaxies that lead to their creation — are more common in the universe than previously thought, they could have implications for future gravitational wave research. Gravitational waves, or ripples in space time, are created when black holes collide.
It will still take a few hundred million years for this particular pair of black holes to collide, but the insights gained from this observation could help scientists better estimate how many pairs of black holes are close to colliding in the universe.
“There might be many pairs of growing supermassive black holes in the centers of galaxies that we have not been able to identify so far,” said study coauthor Ezequiel Treister, an astronomer at Universidad Católica de Chile in Santiago, Chile, in a statement. “If this is the case, in the near future we will be observing frequent gravitational wave events caused by the mergers of these objects across the Universe.”
Space-based telescopes like Hubble and the Chandra X-ray Observatory and ground-based telescopes like the European Southern Observatory’s Very Large Telescope, also in the Atacama Desert, and the W.M. Keck telescope in Hawaii have also observed UGC 4211 across different wavelengths of light to provide a more detailed overview and differentiate between the two black holes.
“Each wavelength tells a different part of the story,” Treister said. “All of these data together have given us a clearer picture of how galaxies such as our own turned out to be the way they are, and what they will become in the future.”
Understanding more about the end stages of galaxy mergers could provide more insight about what will happen when our Milky Way galaxy collides with the Andromeda galaxy in about 4.5 billion years.
Scientists just announced that they’ve detected what might be some of the earliest galaxies to form in the universe, a tantalizing discovery made thanks to NASA’s new flagship James Webb Space Telescope.
“This is the first large sample of candidate galaxies beyond the reach of the Hubble Space Telescope,” astronomer Haojing Yan said yesterday at a press conference at the American Astronomical Society meeting in Seattle. Yan, who is at the University of Missouri, led the newly published study. Because the more sensitive JWST can see further into deep space than its predecessor Hubble does, it essentially sees further back in time. In the new catalog of 87 galaxies astronomers have spotted using it, some could date back to about 13.6 billion years ago, just 200 million years after the Big Bang. That’s when the galaxies emitted the light that we’re seeing today—although those systems of stars, gas, and dust would have changed dramatically since then, if they still exist at all.
While scientists have studied other faraway galaxies that date back to when the universe was still young, the discoveries by Yan and his colleagues could break those records by a few hundred million years or so. But at this point, they are all still considered “candidate galaxies,” which means that their birthdates still need confirmation.
Dating a galaxy can be a challenging matter: It involves measuring its “redshift,” how much the light it emits is stretched toward longer red wavelengths, which tells astronomers how fast the galaxy is moving away from us in the quickly expanding universe. That, in turn, tells astronomers the galaxy’s distance from Earth—or more exactly, the distance that the photons from its stars had to travel at the speed of light before reaching a space telescope near the Earth, like JWST. Light from stars in the most distant galaxy in this collection may have been emitted 13.6 billion years ago, likely fairly soon after the young galaxy came together.
These newly estimated distances will have to be confirmed with spectra, which means measuring the light the galaxies emit across the electromagnetic spectrum and pinpointing its unique signatures. Still, Yan expects many of them to be correctly dated to the early days of the cosmos: “I’ll bet $20 and a tall beer that the success rate will be higher than 50 percent,” he said.
Yan’s team imaged these galaxies with JWST’s NIRCam at six near-infrared wavelengths. To estimate their distances, the astronomers used a standard “dropout” technique: Hydrogen gas surrounding galaxies absorbs light at a particular wavelength, so the wavelengths at which an object can or can’t be seen puts a limit on how far away it is likely to be. These 87 candidate galaxies mostly look like blobs that can only be detected in the longer (and therefore redder) near-infrared wavelengths detectable by NIRCam, which could mean they’re very distant, and therefore very old.
However, it’s possible that some of them could be much closer than expected—which would mean they aren’t so old after all. For example, it could be that their light is just too faint to be detected at some wavelengths. Until Yan can collect more detailed data, he won’t know for sure.
This illustration shows the Milky Way galaxy’s inner and outer halos. A halo is a spherical cloud of stars surrounding a galaxy. Credit: NASA, ESA, and A. Feild (STScI)
Astronomers have discovered more than 200 distant variable stars known as RR Lyrae stars in the Milky Way’s stellar halo. The most distant of these stars is more than a million light years from Earth, almost half the distance to our neighboring galaxy, Andromeda, which is about 2.5 million light years away.
The characteristic pulsations and brightness of RR Lyrae stars make them excellent “standard candles” for measuring galactic distances. These new observations have allowed the researchers to trace the outer limits of the Milky Way’s halo.
“This study is redefining what constitutes the outer limits of our galaxy,” said Raja GuhaThakurta, professor and chair of astronomy and astrophysics at UC Santa Cruz. “Our galaxy and Andromeda are both so big, there’s hardly any space between the two galaxies.”
GuhaThakurta explained that the stellar halo component of our galaxy is much bigger than the disk, which is about 100,000 light years across. Our solar system resides in one of the spiral arms of the disk. In the middle of the disk is a central bulge, and surrounding it is the halo, which contains the oldest stars in the galaxy and extends for hundreds of thousands of light years in every direction.
“The halo is the hardest part to study because the outer limits are so far away,” GuhaThakurta said. “The stars are very sparse compared to the high stellar densities of the disk and the bulge, but the halo is dominated by dark matter and actually contains most of the mass of the galaxy.”
Yuting Feng, a doctoral student working with GuhaThakurta at UCSC, led the new study and is presenting their findings in two talks at the American Astronomical Society meeting in Seattle on January 9 and 11.
According to Feng, previous modeling studies had calculated that the stellar halo should extend out to around 300 kiloparsecs or 1 million light years from the galactic center. (Astronomers measure galactic distances in kiloparsecs; one kiloparsec is equal to 3,260 light years.) The 208 RR Lyrae stars detected by Feng and his colleagues ranged in distance from about 20 to 320 kiloparsecs.
“We were able to use these variable stars as reliable tracers to pin down the distances,” Feng said. “Our observations confirm the theoretical estimates of the size of the halo, so that’s an important result.”
The findings are based on data from the Next Generation Virgo Cluster Survey (NGVS), a program using the Canada-France-Hawaii Telescope (CFHT) to study a cluster of galaxies well beyond the Milky Way. The survey was not designed to detect RR Lyrae stars, so the researchers had to dig them out of the dataset. The Virgo Cluster is a large cluster of galaxies that includes the giant elliptical galaxy M87.
“To get a deep exposure of M87 and the galaxies around it, the telescope also captured the foreground stars in the same field, so the data we used are sort of a by-product of that survey,” Feng explained.
According to GuhaThakurta, the excellent quality of the NGVS data enabled the team to obtain the most reliable and precise characterization of RR Lyrae at these distances. RR Lyrae are old stars with very specific physical properties that cause them to expand and contract in a regularly repeating cycle.
“The way their brightness varies looks like an EKG—they’re like the heartbeats of the galaxy—so the brightness goes up quickly and comes down slowly, and the cycle repeats perfectly with this very characteristic shape,” GuhaThakurta said. “In addition, if you measure their average brightness, it is the same from star to star. This combination is fantastic for studying the structure of the galaxy.”
The sky is full of stars, some brighter than others, but a star may look bright because it is very luminous or because it is very close, and it can be hard to tell the difference. Astronomers can identify an RR Lyrae star from its characteristic pulsations, then use its observed brightness to calculate how far away it is. The procedures are not simple, however. More distant objects, such as quasars, can masquerade as RR Lyrae stars.
“Only astronomers know how painful it is to get reliable tracers of these distances,” Feng said. “This robust sample of distant RR Lyrae stars gives us a very powerful tool for studying the halo and testing our current models of the size and mass of our galaxy.”
This study is based on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/IRFU, at the Canada-France-Hawaii Telescope (CFHT), which is operated by the National Research Council (NRC) of Canada, the Institut National des Sciences de l’Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii.
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The Andromeda Galaxy captured by the NASA Galaxy Evolution Mapper in 2012.Image: NASA/JPL-Caltech
In the quest to find the outer limits of our galaxy, astronomers have discovered over 200 stars that form the Milky Way’s edge, the most distant of which is over one million light-years away—nearly halfway to the Andromeda galaxy.
The 208 stars the researchers identified are known as RR Lyrae stars, which are stars with a brightness that can change as viewed from Earth. These stars are typically old and brighten and dim at regular intervals, which is a mechanism that allows scientists to calculate how far away they are. By calculating the distance to these RR Lyrae stars, the team found that the farthest of the bunch was located about halfway between the Milky Way and the Andromeda galaxy, one of our cosmic next-door neighbors.
“This study is redefining what constitutes the outer limits of our galaxy,” said Raja GuhaThakurta in a press release. GuhaThakurta is professor and chair of astronomy and astrophysics at the University of California Santa Cruz. “Our galaxy and Andromeda are both so big, there’s hardly any space between the two galaxies.”
Illustration: NASA, ESA, AND A. FEILD (STSCI)
The Milky Way galaxy consists of a few different parts, the primary of which is a thin, spiral disk about 100,000 light-years across. Our home solar system sits on one of the arms of this disk. An inner and outer halo surround the disk, and these halos contain some of the oldest stars in our galaxy.
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Previous studies have placed the edge of the outer halo at 1 million light-years from the Milky Way’s center, but based on the new work, the edge of this halo should be about 1.04 million light-years from the galactic center. Yuting Feng, a doctoral student at the university working with GuhaThakurta, led the study and is presenting the findings this week at the American Astronomical Society meeting in Seattle.
“We were able to use these variable stars as reliable tracers to pin down the distances,” said Yuting Feng, a doctoral student at the university working with GuhaThakurta. “Our observations confirm the theoretical estimates of the size of the halo, so that’s an important result.”
Space is vast and lonely—but we can feel a bit cozier knowing that our galactic neighbor is closer than we thought.
When the Fermi Gamma-Ray Space Telescope entered low-Earth orbit in 2008, it opened our eyes to a whole new Universe of high-energy radiation.
One of its more curious discoveries was the Fermi Bubbles: giant, symmetrical blobs extending above and below the galactic plane, 25,000 light-years on each side from the Milky Way’s center, glowing in gamma-ray light – the highest energy wavelength ranges on the electromagnetic spectrum.
Then, in 2020, an X-ray telescope named eROSITA found another surprise: even bigger bubbles extending over 45,000 light-years on each side of the galactic plane, this time emitting less energetic X-rays.
Scientists have since concluded that both sets of bubbles are probably the result of some sort of outburst or outbursts from the galactic center and the supermassive black hole therein. The mechanism producing the gamma- and X-radiation, however, has been a little harder to pin down.
Now, using simulations, physicist Yutaka Fujita from Tokyo Metropolitan University in Japan has come up with a single explanation that explains both sets of bubbles in one fell swoop.
The X-ray emission, he has found, is the product of a powerful, fast-moving wind that slams into the tenuous gas filling interstellar space, producing a shock wave that reverberates back through the plasma, causing it that energetic glow.
The supermassive black hole that powers the heart of the Milky Way – Sagittarius A* – is pretty quiet as far as black holes go. Its feeding activity is minimal; it’s classified as “quiescent”. It hasn’t always been that way, though. And an active black hole can have all sorts of effects on the space around it.
As material falls towards the black hole, it heats up and blazes with light. Some of the material gets channeled away along magnetic field lines outside the black hole, which act as a synchrotron to accelerate particles to near-light speed. These are launched as powerful jets of ionized plasma from the black hole’s poles, punching out into space for up to millions of light-years.
In addition, there are cosmic winds: streams of charged particles that are whipped up by the material orbiting the black hole that then blast out into space.
While Sagittarius A* may be quiet now, that hasn’t necessarily always been the case. Look hard enough, and relics of past activity, such as the Fermi bubbles, can be found lurking in the space around the galactic plane. By studying these relics we can understand when and how that activity took place.
Fujita’s foray into the Fermi bubbles is based on data from the now-retired Suzaku X-ray satellite, jointly operated by NASA and the Japanese Space Agency (JAXA). He took Suzaku observations of the X-ray structures associated with the bubbles and performed numerical simulations to try to reproduce them based on black hole feeding processes.
Schematic showing the structures surrounding the Fermi bubbles. (Y. Fujita, MNRAS, 2022)
“We show that a combination of the density, temperature, and shock age profiles of the X-ray gas can be used to distinguish the energy-injection mechanisms,” he writes in his paper.
“By comparing the results of numerical simulations with observations, we indicate that the bubbles were created by a fast wind from the galactic center because it generates a strong reverse shock and reproduces the observed temperature peak there.”
The most likely scenario, he found, is a black hole wind blowing at a speed of 1,000 kilometers per second (621 miles) from a past feeding event that was metered out over the course of 10 million years and ended fairly recently. As the wind propagates outwards, the charged particles collide with the interstellar medium, producing a shock wave that bounces back into the bubble. These reverse shock waves heat the material inside the bubbles, causing it to glow.
The numerical simulations developed by Fujita accurately reproduced the temperature profile of the X-ray structure.
He also investigated the possibility of a single explosive eruption from the galactic center and was unable to reproduce the Fermi bubbles. This suggests that a slow, steady wind from the galactic center was the most likely progenitor of the mysterious structures. And the power of the wind can only be attributed to Sagittarius A*, not star formation – another phenomenon that produces cosmic winds.
“Thus,” he writes in his paper, “the wind may be the same as active galactic nuclei outflows often observed in other galaxies and thought to regulate the growth of galaxies and their central black holes.”
The paper has been published in the Monthly Notices of the Royal Astronomical Society.
ByColin Jacobs and Karl Glazebrook, Swinburne University of Technology December 29, 2022
What looks much like craggy mountains on a moonlit evening is actually the edge of a nearby, young, star-forming region NGC 3324 in the Carina Nebula. Captured in infrared light by the Near-Infrared Camera (NIRCam) on NASA’s James Webb Space Telescope, this image reveals previously obscured areas of star birth. Credit: NASA, ESA, CSA, STScI
It is no exaggeration to say the James Webb Space Telescope (JWST) represents a new era for modern astronomy.
Launched on December 25 last year and fully operational since July, the telescope offers glimpses of the universe that were inaccessible to us before. Like the
However, while Hubble is in orbit around Earth at an altitude of 335 miles (540 km), the JWST is 1 million miles (1.5 million kilometers) distant, far beyond the Moon. From this position, away from the interference of our planet’s reflected heat, it can collect light from across the universe far into the infrared portion of the electromagnetic spectrum.
This ability, when combined with the JWST’s larger mirror, state-of-the-art detectors, and many other technological advances, allows astronomers to look back to the universe’s earliest epochs.
As the universe expands, it stretches the wavelength of light traveling toward us, making more distant objects appear redder. At great enough distances, the light from a galaxy is shifted entirely out of the visible part of the electromagnetic spectrum to the infrared. The JWST is able to probe such sources of light right back to the earliest times, nearly 14 billion years ago.
The Hubble telescope continues to be a great scientific instrument and can see at optical wavelengths where the JWST cannot. But the Webb telescope can see much further into the infrared with greater sensitivity and sharpness.
Let’s have a look at ten images that have demonstrated the staggering power of this new window to the universe.
1. Mirror alignment complete
Left: The first publicly released alignment image from the JWST. Astronomers jumped on this image to compare it to previous images of the same part of sky like that on the right from the Dark Energy Camera on Earth. Credit: NASA/STScI/LegacySurvey/C. Jacobs
Despite years of testing on the ground, an observatory as complex as the JWST required extensive configuration and testing once deployed in the cold and dark of space.
One of the biggest tasks was getting the 18 hexagonal mirror segments unfolded and aligned to within a fraction of a wavelength of light. In March, NASA released the first image (centered on a star) from the fully aligned mirror. Although it was just a calibration image, astronomers immediately compared it to existing images of that patch of sky – with considerable excitement.
2. Spitzer vs MIRI
This image shows a portion of the ‘Pillars of Creation’ in the infrared (see below); on the left taken with the Spitzer Space Telescope, and JWST on the right. The contrast in depth and resolution is dramatic. Credit: NASA/JPL-Caltech (left), NASA/ESA/CSA/STScI (right)
This early image, taken while all the cameras were being focused, clearly demonstrates the step change in data quality that JWST brings over its predecessors.
On the left is an image from the Spitzer telescope, a space-based infrared observatory with an 85 cm mirror; the right, the same field from JWST’s mid-infrared MIRI camera and 6.5 m mirror. The resolution and ability to detect much fainter sources are on show here, with hundreds of galaxies visible that were lost in the noise of the Spitzer image. This is what a bigger mirror situated out in the deepest, coldest dark can do.
3. The first galaxy cluster image
SMACS 0723 galaxy cluster – from Hubble on the left, and JWST on the right. Hundreds more galaxies are visible in JWST’s infrared image. Credit: NASA/STSci
The galaxy cluster with the prosaic name of SMACS J0723.3–7327 was a good choice for the first color images released to the public from the JWST.
The field is crowded with galaxies of all shapes and colors. The combined mass of this enormous galaxy cluster, over 4 billion light years away, bends space in such a way that light from distant sources in the background is stretched and magnified, an effect known as gravitational lensing.
These distorted background galaxies can be clearly seen as lines and arcs throughout this image. The field is already spectacular in Hubble images (left), but the JWST near-infrared image (right) reveals a wealth of extra detail, including hundreds of distant galaxies too faint or too red to be detected by its predecessor.
4. Stephan’s Quintet
Hubble (left) and JWST (right) images of the group of galaxies known as ‘Stephan’s Quintet’. The inset shows a zoom-in on a distant background galaxy. Credit: NASA/STScI
These images depict a spectacular group of galaxies known as Stephan’s Quintet, a group that has long been of interest to astronomers studying the way colliding galaxies interact with one another gravitationally.
On the left we see the Hubble view, and the right the JWST mid-infrared view. The inset shows the power of the new telescope, with a zoom in on a small background galaxy. In the Hubble image we see some bright star-forming regions, but only with the JWST does the full structure of this and surrounding galaxies reveal itself.
5. The Pillars of Creation
The ‘Pillars of Creation’, a star-forming region of our galaxy, as captured by Hubble (left) and JWST (right). Credit: NASA, ESA, CSA, STScI; Joseph DePasquale (STScI), Anton M. Koekemoer (STScI), Alyssa Pagan (STScI).
The so-called Pillars of Creation is one of the most famous images in all of astronomy, taken by Hubble in 1995. It demonstrated the extraordinary reach of a space-based telescope.
It depicts a star-forming region in the Eagle Nebula, where interstellar gas and dust provide the backdrop to a stellar nursery teeming with new stars. The image on the right, taken with the JWST’s near-infrared camera (NIRCam), demonstrates a further advantage of infrared astronomy: the ability to peer through the shroud of dust and see what lies within and behind.
6. The ‘Hourglass’ Protostar
The ‘hourglass protostar’, a star still in the process of accreting enough gas to begin fusing hydrogen. Inset: A much lower resolution view from Spitzer. Credit: NASA/STScI/JPL-Caltech/A. Tobin
This image depicts another act of galactic creation within the Milky Way. This hourglass-shaped structure is a cloud of dust and gas surrounding a star in the act of formation – a protostar called L1527.
Only visible in the infrared, an “accretion disk” of material falling in (the black band in the center) will eventually enable the protostar to gather enough mass to start fusing hydrogen, and a new star will be born.
In the meantime, light from the still-forming star illuminates the gas above and below the disk, making the hourglass shape. Our previous view of this came from Spitzer; the amount of detail is once again an enormous leap ahead.
7. Jupiter in infrared
An infrared view of Jupiter from the JWST. Note the auroral glow at the poles; this is caused by the interaction of charged particles from the sun with Jupiter’s magnetic field. Credit: NASA, ESA, CSA, Jupiter ERS Team; image processing by Judy Schmidt.
The Webb telescope’s mission includes imaging the most distant galaxies from the beginning of the universe, but it can look a little closer to home as well.
Although JWST cannot look at Earth or the inner Solar System planets – as it must always face away from the Sun – it can look outward at the more distant parts of our Solar System. This near-infrared image of Jupiter is a beautiful example, as we gaze deep into the structure of the gas giant’s clouds and storms. The glow of auroras at both the northern and southern poles is haunting.
This image was extremely difficult to achieve due to the fast motion of
Hubble visible light (left), JWST infrared (right), and combined (middle) images of the ‘Phantom Galaxy’ M74. The ability to combine visible light information about stars with infrared images of gas and dust allow us to probe such galaxies in exquisite detail. Credit: ESA/Webb, NASA & CSA, J. Lee and the PHANGS-JWST Team; ESA/Hubble & NASA, R. Chandar Acknowledgement: J. Schmidt
These images of the so-called Phantom Galaxy or M74 reveal the power of JWST not only as the latest and greatest of astronomical instruments, but as a valuable complement to other great tools. The middle panel here combines visible light from Hubble with infrared from Webb, allowing us to see how starlight (via Hubble) and gas and dust (via JWST) together shape this remarkable galaxy.
Much JWST science is designed to be combined with Hubble’s optical views and other imaging to leverage this principle.
9. A super-distant galaxy
A ‘zoom in’ on a galaxy from one of the universe’s earliest epochs, when the universe was only about 300 million years old (the small red source visible in the centre of the right panel). Galaxies at this distance are impossible to detect in visible light as their emitted radiation has been ‘redshifted’ far into the infrared. Credit: NASA/STScI/C. Jacobs
Although this galaxy – the small, red blob in the right image – is not among the most spectacularly picturesque our universe has to offer, it is just as interesting scientifically.
This snapshot is from when the universe was a mere 350 million years old, making this among the very first galaxies ever to have formed. Understanding the details of how such galaxies grow and merge to create galaxies like our own
An image of the galaxy cluster Abell 2744 created by combining many different JWST exposures. In this tiny part of the sky (a fraction of a full Moon) almost every one of the thousands of objects shown is a distant galaxy. Credit: Lukas Furtak (Ben-Gurion University of the Negev) from images from the GLASS/UNCOVER teams
This image is a mosaic (many individual images stitched together) centered on the giant Abell 2744 galaxy cluster, colloquially known as “Pandora’s Cluster.” The sheer number and variety of sources that the JWST can detect is mind-boggling; with the exception of a handful of foreground stars, every spot of light represents an entire galaxy.
In a patch of dark sky no larger than a fraction of the full Moon there are umpteen thousands of galaxies, really bringing home the sheer scale of the universe we inhabit. Professional and amateur astronomers alike can spend hours scouring this image for oddities and mysteries.
Over the coming years, JWST’s ability to look so deep and far back into the universe will allow us to answer many questions about how we came to be. Just as exciting are the discoveries and questions we can not yet foresee. When you peel back the veil of time as only this new telescope can, these unknown unknowns are certain to be fascinating.
Written by:
Colin Jacobs – Postdoctoral Researcher in Astrophysics, Swinburne University of Technology
Karl Glazebrook – ARC Laureate Fellow & Distinguished Professor, Centre for Astrophysics & Supercomputing, Swinburne University of Technology
This article was first published in The Conversation.
Just one year after launch, the James Webb Space Telescope is exceeding all expectations, and astronomers are thrilled.
Launched on Dec. 25, 2021, the $10 billion infrared observatory was designed to learn how galaxies form and grow, to peer far back into the universe to the era of the first galaxies, to watch stars be born inside their nebulous embryos in unprecedented detail, and to probe the atmospheres of exoplanets and characterize some of the closest rocky worlds.
However, the complexity of the James Webb Space Telescope (Webb or JWST), including its fold-out, segmented 21-foot (6.5 meters) mirror and its delicate sun-shield the size of a tennis court, meant that astronomers were on tenterhooks as to whether the JWST would perform as hoped.
It turns out, they needn’t have worried. “I guess we really weren’t expecting the results to be this good,” Brenda Frye, an astronomy at Steward Observatory at the University of Arizona, told Space.com.
Related: James Webb Space Telescope’s best images of all time (gallery)
The James Webb Space Telescope launched atop an Ariane 5 rocket from French Guiana on Dec. 25, 2021. (Image credit: NASA/Bill Ingalls)
“It’s amazing,” Steve Longmore, an astrophysicist at Liverpool John Moores University in the U.K., told Space.com. “It’s delivering at least as well, and better in a lot of circumstances, than what we were expecting.”
And if it exceeds its own targets, it definitely surpasses those of its predecessors. “It’s leaps and bounds better than what we’ve been able to see before,” Susan Mullally, JWST’s deputy project scientist from the Space Telescope Science Institute (STScI) in Maryland, which operates the observatory, told Space.com, adding that she is “blown away by the imagery, honestly. The images are beautiful.”
The rings of Neptune
The main reason that JWST is performing so well is because of its superlative optics, which are able to achieve their maximum potential resolution for the majority of infrared wavelengths that the telescope observes in. This success means that JWST’s images have a clarity to them that were unobtainable by the likes of the Hubble Space Telescope and NASA’s retired Spitzer Space Telescope, or larger telescopes on the ground such as those at the Keck Observatory in Hawaii, whose vision is blurred by Earth’s atmosphere.
But with JWST, individual stars so close together they were once indistinguishable can now be resolved; the structures of very distant galaxies are now discernible; and even something close by such as the rings of Neptune pop with the most detail seen in decades.
The James Webb Space Telescope’s stunning view of Neptune, with its rings clearly visible. (Image credit: NASA/ESA/CSA/STScI)
“When the JWST’s images of Neptune first came out, both Heidi [Hammel, an interdisciplinary scientist on JWST and an expert on the outer planets of the solar system] and myself looked at them, and then at each other, and asked, ‘are we really looking at Neptune’?” Naomi Rowe-Gurney, an astronomer at NASA Goddard Space Flight Center in Maryland, told Space.com.
Although the Keck Observatory has imaged Neptune’s rings, our most impressive view before JWST came from Voyager 2‘s flyby in 1989. “Heidi had not seen the rings [this well] since Voyager 2, and I had never seen the rings like this because Voyager was before I was born!” Rowe-Gurney said.
Normally, faint details or features around a bright object, such as the dark and tenuous rings around blue Neptune, are difficult to see against the glare of the bright object. To counteract this, an instrument is required to have the characteristic of “high dynamic range” to take in both the faint and the bright at the same time.
“We didn’t realize that JWST would have this amazing dynamic range and be able to resolve really faint things like the rings of Neptune and the small moons and rings of Jupiter,” Rowe-Gurney said.
Alien atmospheres
It’s not only the planets of our solar system that JWST is scrutinizing. A key aim of the telescope is to detect the composition of exoplanets‘ atmospheres using a technique called transmission spectroscopy. As a planet transits its star, the star’s light shines through the planet’s atmosphere, but atoms and molecules within that atmosphere can block some of the light at characteristic wavelengths, which gives away the composition of the atmosphere.
The first exoplanet result released from JWST was the transmission spectrum of WASP-39b, which is a “hot Jupiter” exoplanet orbiting a sun-like star located 700 light-years away. JWST detected carbon dioxide in WASP-39b’s atmosphere, the first time the gas has ever been detected on an exoplanet. Other gases present included carbon monoxide, potassium, sodium, water vapor and sulfur dioxide, the last of which can only be created through photochemistry when atmospheric gases react with the ultraviolet light from the planet’s star — another exoplanet first.
The James Webb Space Telescope’s analysis of the atmospheric composition of WASP-39b. (Image credit: NASA/ESA/CSA/J. Olmsted (STScI))
“I keep being amazed by what we’re able to do with the exoplanet data, like the carbon dioxide and the photochemistry that was found in the atmosphere of WASP-39b,” Mullally said. “That was really cool, and I don’t remember people talking about [detecting photochemistry] ahead of time. I’m really looking forward to seeing what we can do with the terrestrial exoplanets orbiting the cool M-dwarfs and seeing what their atmospheres are made of.”
In particular, the TRAPPIST-1 planetary system of seven worlds orbiting an M-dwarf 40 light-years away is a key target of the JWST. Preliminary results, which failed to detect thick blankets of hydrogen surrounding some of the TRAPPIST-1 worlds, were released during a conference held at STScI in December, but we’ll have to be patient for more comprehensive results from these planets, of which up to four could reside in their star’s habitable zone.
WASP-39b was an easy first target because its star is bright and the planet’s signal is strong. M-dwarfs like TRAPPIST-1 are much fainter, despite being closer.
“We have to wait until we can get enough transits of these guys to build up the signal-to-noise, because you can’t do it with just one or two transits,” Mullally said. “I think we’re going to have to wait until at least the end of the cycle 1 observations [summer 2023] before anybody is going to be in a position to say if they’ve found anything really spectacular.”
Star formation near and far
Another aspect of JWST’s mission is to not only observe exoplanets, but to better understand how they, and their stars, form. Star formation in particular is a crucial process to understand it because it connects so many things in the universe both near and far.
Longmore is leading a study to use JWST to observe frantic star formation in a region at the center of our own Milky Way galaxy, called the central molecular zone, some 26,000 light-years from us. The center of our galaxy hosts the highest concentration of stars, and at our distance they all appear packed in — indistinguishable to the likes of the Hubble Space Telescope — while copious amounts of dust shroud most of them from view in optical light. Look with a large-aperture infrared telescope like JWST, however, and those two concerns are shoved aside.
“These are the JWST’s two capabilities that are going to blow my field apart,” Longmore said. The telescope’s superb optics are able to resolve individual baby stars in the center of the galaxy, and infrared light will pass right through the dust to reach the observatory.
“Ordinarily, with Hubble, it’s like trying to point your telescope at a brick wall and see through it,” he added, “But the JWST is looking through a window in that wall and can count individual stars.”
The star-forming Pillars of Creation, imaged in mid-infrared by the JWST in what will surely become an iconic picture. (Image credit: NASA/ESA/CSA/STScI/J. DePasquale (STScI)/A. Pagan (STScI))
It’s taking longer to gather all the data from the center of the galaxy, but that’s because it’s such a complex environment, with bright, diffuse emission everywhere, and all that has to be disentangled from the relevant signal of star formation via determined and careful data processing.
“On all the projects I’m on, people are still fighting with calibration and things, but hopefully in the next six months that will change,” Longmore said. He added an amusing story of how one of his team’s observations had been blighted by a mysterious circle on the image. After deeper investigation, it turned out that this wasn’t some mysterious new phenomenon, but that JWST had previously been looking at bright Jupiter, and the giant planet’s after-image had not yet been properly flushed out of the instrument’s electronic sensors!
Longmore and his colleagues are targeting the central molecular zone because it is the region in our galaxy that most resembles star-forming conditions in the early universe, when the star-formation rate was high and dense clusters of stars formed. In the Central Molecular Zone, the astronomers intend to measure a property called the initial mass function (IMF), which describes the range of stellar masses in a star-forming nebula.
Currently, astronomers do not understand what determines why stars form with the masses that they have, only that low-mass stars are much more common than luminous high-mass stars, at least in the local universe. Was this still the case over 13 billion years ago in the first galaxies? Answering that question could help explain both how galaxies formed and what ended the universe’s dark ages.
Deep fields and the first galaxies
After she saw President Joe Biden reveal the first deep-field image from the JWST, of the galaxy cluster SMACS 0723, a “gravitational lens” whose massive gravity magnifies objects behind it, Frye and her student, Massimo Pascale at the University of California, Berkeley, raced to analyze the image.
“We didn’t sleep for three-and-a-half days, and our paper was one of the first two papers submitted on JWST data,” Frye said.
Together, they found 42 new gravitationally lensed images of 14 different high-redshift galaxies, galaxies located so far away that the expanding universe has stretched their light, making them appear redder. Further studies and more deep fields followed, and a host of high-redshift candidates were discovered by Frye’s team and others, including some galaxies at record-breaking redshifts of 12, 13 and above; these redshifts mean that we see the galaxies as they existed less than 300 million years after the Big Bang.
These high-redshift galaxies have proven something of a surprise, in that they appear more luminous than models of galaxy formation predicted they should be.
“One possible explanation is that they’re producing too many high-mass stars, that they have a top-heavy IMF,” Longmore said, noting the importance of measuring the IMF in the central molecular zone to understand stellar masses in young neighborhoods.
Why the IMF would be different over 13.5 billion years ago is not understood, but then again the early universe seems to have been a far more intense place than it is today. “In the present day, galaxies in general are not forming stars so actively, but many galaxies formed stars more actively in the early universe,” Frye said.
Frye is a member of the PEARLS (Prime Extragalactic Area for Reionization and Lensing Science) team. PEARLS is a JWST project to image a variety of deep fields, including two apparently sparse regions of sky and a number of galaxy clusters and proto-clusters, to observe the first few billion years of galaxy formation.
The PEARLS field looking toward the North Celestial Pole. Inset are numerous types of galaxy, from interacting galaxies to ruby-red dusty star-forming galaxies. (Image credit: NASA/ESA/CSA/Rolf A. Jansen, Jake Summers, Rosalia O’Brien, Rogier Windhorst (ASU)/Aaron Robotham (UWA)/Anton M. Koekemoer (STScI)/Christopher Willmer (University of Arizona)/JWST PEARLS Team)
In December, the PEARLs team released their first dataset, of an extraordinary field of distant galaxies close to the North Ecliptic Pole. This region is directly above the main plane of the Milky Way and so is constantly visible to JWST, and it’s also high above interfering features such as zodiacal dust.
Within the image are a whole host of galaxies. Some interact and some show a clear spiral structure; the collection exhibits a whole range of colors, from cobalt blue to ruby red. The latter are of great interest to Frye.
“We can now observe [in the PEARLS image] an abundance of red disk galaxies, which we think might be red spirals,” Frye said. “This type of galaxy is very interesting because they are analogs of what the Milky Way might have looked like when it was younger.”
The reddening is caused by huge amounts of dust in these galaxies; the dust is the result of rapid formation of massive stars that quickly die in supernova explosions and spill vast amounts of dust into space. Such galaxies are completely hidden from Hubble, but infrared light can pass through the dust and make the galaxies visible to JWST.
“The analogy is a New Year’s Eve fireworks display,” Frye said. “If you have a lot of fireworks going off then eventually they are obscured by dusty smoke.”
The JWST has impressed scientists in the six months that it has been gathering data since becoming fully operational in June, but the real fireworks are still to come with major discoveries awaiting us.
It’s slow going, requiring patience, Frye said. “There’s too much for any one person to be able to study or understand on really short timescales, it’s going to take us a long time to process all the data.”
The results, though, will be worth it.
“It’s going to completely change our understanding of our place in the universe, how the solar system formed and evolved, and how the very first stars and galaxies formed,” Mullally said. “We’ve made great headway with this telescope, and it’s going to do spectacular things.”
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