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Astronomers are using NASA’s James Webb Space Telescope to peer deeper into the universe and farther back in time than ever before.
Already, the team has discovered hundreds of galaxies that existed when the universe was less than 600 million years old—just 4% of its current age.
The Webb Telescope, or JWST, also has observed galaxies sparkling with a multitude of young, hot stars formed during what researchers call “surprisingly episodic bursts of star formation.”
They made the observations as part of the JWST Advanced Deep Extragalactic Survey, or JADES, which is dedicated to uncovering and studying extremely faint, distant galaxies. Thirty-two days of observing time have been devoted to JADES, which is one of the largest observing programs in Webb’s first year of science.
The key to JWST’s ability to sniff out the extremely faint signatures of distant objects is its large, light-gathering mirror and infrared sensitivity.
“With JADES, we want to answer questions such as, ‘How did the earliest galaxies assemble themselves? How fast did they form stars? Why do some galaxies stop forming stars?'” says Marcia Rieke, a professor of astronomy at the University of Arizona Steward Observatory and a co-lead of the JADES program.
During his doctoral research at Steward Observatory, JADES team member Ryan Endsley, who is now a postdoctoral fellow at the University of Texas at Austin, led an investigation into galaxies that existed 500 to 850 million years after the Big Bang, a crucial time known as the “Epoch of Reionization.”
“Star formation in the early universe is much more complicated than we thought.”
For hundreds of millions of years, the young universe was filled with a gaseous fog that made it opaque to energetic light such as ultraviolet light or X-rays. About 1 billion years after the Big Bang, the fog had cleared and the universe became transparent during a process known as reionization.
Scientists have debated whether active, supermassive black holes or galaxies full of hot, young stars were the primary cause of reionization. As part of the JADES program, Endsley and his colleagues studied these galaxies specifically to look for signatures of star formation—and found them in abundance.
“Almost every single galaxy that we are finding shows these unusually strong emission line signatures indicating intense recent star formation,” Endsley says. “These early galaxies were very good at creating hot, massive stars.”
These bright, massive stars pumped out torrents of ultraviolet light, which transformed surrounding gas from opaque to transparent by ionizing atoms, unbinding their electrons from the nuclei. Since these early galaxies had such a large population of hot, massive stars, they may have been the main driver of the reionization process. The later reuniting of the electrons and nuclei produces the distinctively strong emission lines.
Endsley and his colleagues also found evidence that these young galaxies underwent periods of rapid star formation interspersed with quiet periods during which fewer stars formed. These fits and starts may have occurred as galaxies captured clumps of the gaseous raw materials needed to form stars. Alternatively, since massive stars are short-lived before they explode, they may have injected energy into the surrounding environment periodically, preventing gas from condensing to form new stars.
Another element of the JADES program involves the search for the earliest galaxies that existed when the universe was less than 400 million years old. By studying these galaxies, astronomers can explore how star formation in the early years after the Big Bang was different from today. The light from faraway galaxies is stretched to longer wavelengths and redder colors by the expansion of the universe—a phenomenon called redshift. By measuring a galaxy’s redshift, astronomers can learn how far away it is and, therefore, at what time it existed in the early universe.
“Before JWST, there were only a few dozen galaxies observed above a redshift of 8, when the universe was younger than 650 million years old, but JADES is now uncovering nearly a thousand of these extremely distant galaxies,” Rieke says.
The JADES team identified more than 700 candidate galaxies above redshift 8, which will completely overhaul astronomers’ understanding of early galaxy formation. The sheer number of these sources far exceeded predictions based on observations made before the launch of JWST. Webb’s fine resolution and sensitivity allow astronomers to get an unprecedented view of these distant galaxies.
“Previously, the earliest galaxies we could see just looked like little smudges,” says JADES team member Kevin Hainline, an assistant research professor at Steward Observatory. “And yet those smudges represent millions, or even billions, of stars at the beginning of the universe. Now, we can see, incredibly, that some of them are actually groupings of stars being born only a few hundred million years after the beginning of time.”
“What all this tells us,” Rieke says, “is that star formation in the early universe is much more complicated than we thought.”
The team presented their latest observations at the 242nd meeting of the American Astronomical Society in Albuquerque, New Mexico.
Source: University of Arizona
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In a scientific first, researchers have detected neutrinos created by a particle collider.
The discovery promises to deepen scientists’ understanding of the subatomic particles, which were first spotted in 1956 and play a key role in the process that makes stars burn.
The work could also shed light on cosmic neutrinos that travel large distances and collide with the Earth, providing a window on distant parts of the universe.
It’s the latest result from the Forward Search Experiment, or FASER, a particle detector designed and built by an international group of physicists and installed at CERN, the European Council for Nuclear Research in Geneva, Switzerland. There, FASER detects particles produced by CERN’s Large Hadron Collider.
“We’ve discovered neutrinos from a brand-new source—particle colliders—where you have two beams of particles smash together at extremely high energy,” says Jonathan Feng, a particle physicist at the University of California, Irvine, and a co-spokesperson for the FASER Collaboration.
Neutrinos, which were co-discovered nearly 70 years ago by the late physicist and Nobel laureate Frederick Reines, are the most abundant particle in the cosmos and “were very important for establishing the standard model of particle physics,” says FASER co-spokesperson Jamie Boyd, a particle physicist at CERN. “But no neutrino produced at a collider had ever been detected by an experiment.”
Since the groundbreaking work of Reines and others like Hank Sobel, professor of physics and astronomy, the majority of neutrinos studied by physicists have been low-energy neutrinos. But the neutrinos detected by FASER are the highest energy ever produced in a lab and are similar to the neutrinos found when deep-space particles trigger dramatic particle showers in our atmosphere.
“They can tell us about deep space in ways we can’t learn otherwise,” says Boyd. “These very high-energy neutrinos in the LHC are important for understanding really exciting observations in particle astrophysics.”
FASER itself is new and unique among particle-detecting experiments. In contrast to other detectors at CERN, such as ATLAS, which stands several stories tall and weighs thousands of tons, FASER is about one ton and fits neatly inside a small side tunnel at CERN. And it took only a few years to design and construct using spare parts from other experiments.
“Neutrinos are the only known particles that the much larger experiments at the Large Hadron Collider are unable to directly detect, so FASER’s successful observation means the collider’s full physics potential is finally being exploited,” says Dave Casper, an experimental physicist.
Beyond neutrinos, one of FASER’s other chief objectives is to help identify the particles that make up dark matter, which physicists think comprises most of the matter in the universe, but which they’ve never directly observed.
FASER has yet to find signs of dark matter, but with the LHC set to begin a new round of particle collisions in a few months, the detector stands ready to record any that appear.
“We’re hoping to see some exciting signals,” says Boyd.
Brian Petersen, a particle physicist at CERN, announced the results at the 57th Rencontres de Moriond Electroweak Interactions and Unified Theories conference in Italy.
Source: UC Irvine
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Extraterrestrial life has the potential to exist on distant exoplanets inside special areas called “terminator zones,” according to a new study.
The terminator zone is a ring on planets that have one side that always faces its star and one side that is always dark.
“These planets have a permanent day side and a permanent night side,” says lead author Ana Lobo, a postdoctoral researcher in the physics and astronomy department at the University of California, Irvine.
Such planets are particularly common because they exist around stars that make up about 70% of the stars seen in the night sky—so-called M-dwarf stars, which are relatively dimmer than our sun, Lobo says.
The terminator is the dividing line between the day and night sides of the planet. Terminator zones could exist in that “just right” temperature zone between too hot and too cold.
“You want a planet that’s in the sweet spot of just the right temperature for having liquid water,” says Lobo, because liquid water, as far as scientists know, is an essential ingredient for life.
On the dark sides of terminator planets, perpetual night would yield plummeting temperatures that could cause any water to be frozen in ice. The side of the planet always facing its star could be too hot for water to remain in the open for long.
“These new and exotic habitability states our team is uncovering are no longer the stuff of science fiction.”
“This is a planet where the dayside can be scorching hot, well beyond habitability, and the night side is going to be freezing, potentially covered in ice. You could have large glaciers on the night side,” Lobo says.
For the study, which appears in The Astrophysical Journal, Lobo and Aomawa Shields, an associate professor of physics and astronomy, modeled the climate of terminator planets using software typically used to model our own planet’s climate, but with a few adjustments, including slowing down planetary rotation.
It’s believed to be the first time astronomers have been able to show that such planets can sustain habitable climates confined to this terminator region.
Historically, researchers have mostly studied ocean-covered exoplanets in their search for candidates for habitability. But now that Lobo and her team have shown that terminator planets are also viable refuges for life, it increases the options life-hunting astronomers have to choose from.
“We are trying to draw attention to more water-limited planets, which despite not having widespread oceans, could have lakes or other smaller bodies of liquid water, and these climates could actually be very promising,” Lobo says.
One key to the finding, Lobo adds, was pinpointing exactly what kind of terminator zone planet can retain liquid water. If the planet is mostly covered in water, then the water facing the star, the team found, would likely evaporate and cover the entire planet in a thick layer of vapor.
But if there’s land, this effect shouldn’t occur.
“Ana has shown if there’s a lot of land on the planet, the scenario we call ‘terminator habitability’ can exist a lot more easily,” says Shields. “These new and exotic habitability states our team is uncovering are no longer the stuff of science fiction—Ana has done the work to show that such states can be climatically stable.”
Recognizing terminator zones as potential harbors for life also means that astronomers will need to adjust the way they study exoplanet climates for signs of life, because the biosignatures life creates may only be present in specific parts of the planet’s atmosphere.
The work will also help inform future efforts by teams using telescopes like the James Webb Space Telescope or the Large Ultraviolet Optical Infrared Surveyor telescope currently in development at NASA as they search for planets that may host extraterrestrial life.
“By exploring these exotic climate states, we increase our chances of finding and properly identifying a habitable planet in the near future,” says Lobo.
Source: UC Irvine
The post Could ‘terminator zones’ on far off planets harbor life? appeared first on Futurity.
When neutron stars collide they produce an explosion that, contrary to what was believed until recently, is shaped like a perfect sphere, researchers report.
Although how this is possible is still a mystery, the discovery may provide a new key to fundamental physics and to measuring the age of the universe.
An article about the discovery appears in the journal Nature.
Kilonovae—the giant explosions that occur when two neutron stars orbit each other and finally collide—are responsible for creating both great and small things in the universe, from black holes to the atoms in the gold ring on your finger and the iodine in our bodies. They give rise to the most extreme physical conditions in the universe, and it is under these extreme conditions that the universe creates the heaviest elements of the periodic table, such as gold, platinum, and uranium.
But there is still a great deal we do not know about this violent phenomenon. When a kilonova was detected at 140 million light-years away in 2017, it was the first time scientists could gather detailed data. Scientists around the world are still interpreting the data from this colossal explosion, including Albert Sneppen and Darach Watson from the University of Copenhagen, who made a surprising discovery.
“You have two super-compact stars that orbit each other 100 times a second before collapsing. Our intuition, and all previous models, say that the explosion cloud created by the collision must have a flattened and rather asymmetrical shape,” says Sneppen, a PhD student at the Niels Bohr Institute and first author of the new study.
This is why he and his research colleagues are surprised to find that this is not the case at all for the kilonova from 2017. It is completely symmetrical and has a shape close to a perfect sphere.
“No one expected the explosion to look like this. It makes no sense that it is spherical, like a ball. But our calculations clearly show that it is. This probably means that the theories and simulations of kilonovae that we have been considering over the past 25 years lack important physics,” says Watson, associate professor at the Niels Bohr Institute and second author on the study.
How the kilonova can be spherical is a real mystery. According to the researchers, there must be unexpected physics at play.
“The most likely way to make the explosion spherical is if a huge amount of energy blows out from the center of the explosion and smooths out a shape that would otherwise be asymmetrical. So the spherical shape tells us that there is probably a lot of energy in the core of the collision, which was unforeseen,” says Sneppen.
When the neutron stars collide, they are united, briefly as a single hypermassive neutron star, which then collapses to a black hole. The researchers speculate whether it is in this collapse that a large part of the secret is hidden.
“Perhaps a kind of ‘magnetic bomb’ is created at the moment when the energy from the hypermassive neutron star’s enormous magnetic field is released when the star collapses into a black hole. The release of magnetic energy could cause the matter in the explosion to be distributed more spherically. In that case, the birth of the black hole may be very energetic,” says Watson.
However, this theory does not explain another aspect of the researchers’ discovery. According to the previous models, while all elements produced are heavier than iron, the extremely heavy elements, such as gold or uranium, should be created in different places in the kilonova than the lighter elements such as strontium or krypton, and they should be expelled in different directions. The researchers, on the other hand, detect only the lighter elements, and they are distributed evenly in space.
They therefore believe that the enigmatic elementary particles, neutrinos, about which much is still unknown, also play a key role in the phenomenon.
“An alternative idea is that in the milliseconds that the hypermassive neutron star lives, it emits very powerfully, possibly including a huge number of neutrinos. Neutrinos can cause neutrons to convert into protons and electrons, and thus create more lighter elements overall. This idea also has shortcomings, but we believe that neutrinos play an even more important role than we thought,” says Sneppen.
The shape of the explosion is also interesting for an entirely different reason.
“Among astrophysicists there is a great deal of discussion about how fast the universe is expanding. The speed tells us, among other things, how old the universe is. And the two methods that exist to measure it disagree by about a billion years. Here we may have a third method that can complement and be tested against the other measurements,” says Sneppen.
The so-called “cosmic distance ladder” is the method used today to measure how fast the universe is growing. This is done simply by calculating the distance between different objects in the universe, which act as rungs on the ladder.
“If they are bright and mostly spherical, and if we know how far away they are, we can use kilonovae as a new way to measure the distance independently—a new kind of cosmic ruler,” says Watson.
“Knowing what the shape is, is crucial here, because if you have an object that is not spherical, it emits differently, depending on your sight angle,” Watson says. “A spherical explosion provide much greater precision in the measurement.”
He emphasizes that this requires data from more kilonovae. They expect that the LIGO observatories will detect many more kilonovae in the coming years.
The analyses have been carried out on data from the kilonova AT2017gfo from 2017. The researchers have analyzed data from the kilonova. Those data are the ultraviolet, optical, and infrared light from the X-shooter spectrograph on the Very Large Telescope at the European Southern Observatory, combined with previous analyses of gravitational waves, radio waves and data from the Hubble Space Telescope.
The study is an important early result of the HEAVYMETAL collaboration, which was recently awarded an ERC Synergy grant.
Additional researchers from the Cosmic Dawn Center/Niels Bohr Institute, University of Copenhagen; GSI Helmholtzzentrum für Schwerionenforschung, Germany; the University of Turku, Finland; Tel Aviv University, Israel; and Queen’s University Belfast, UK, contributed to the work.
Source: University of Copenhagen
The post Neutron star collisions make perfect explosions in space appeared first on Futurity.
As she navigates her mother’s fainting spells, and through the process of testing and diagnosis, Nona Fernández considers the similarities between stars in the sky and the busy neurons of her mother’s brain, lit up on the test screen by a happy memory.
An astronomer indicating different constellations with a laser pointer, explaining to a group of tourists and me that all those distant lights we see shining above our heads come from the past.
Depending how far away they are, we might be talking about billions of years. The glow from stars that may be dead or gone. Reports of their death have yet to reach us and what we see is the glimmer of a life possibly extinguished without our knowing it. Shafts of light freezing the past in our gaze, like family snapshots in a photograph album or the kaleidoscopic patterns of our own memory.
We exit the neurologist’s office and I look at my mother with new eyes. Now I know that she’s carrying the whole cosmos on her shoulders. I tell her what I saw on the doctor’s screen. I tell her how much her brain looks like the night sky. I tell her about the electrical patterns of her neurons, the glow of her memory, the constellation that lit up the moment she summoned it, the luminescent reflection of her own past. I ask which happy scene it was that I saw twinkling on the monitor in the doctor’s office and she smiles and says she was remembering the moment I was born.
Enlarge / A view of the business end of SpaceX's Super Heavy rocket. (credit: SpaceX)
Update, 4:45 pm ET: Well, they did it.
At around 3:15 pm local time in South Texas, SpaceX ignited its Super Heavy rocket for a "full duration" test of its Raptor engines. According to SpaceX founder Elon Musk, the launch team turned off one engine just prior to ignition, and another stopped itself. Still, he said 31 of 33 engines would have provided enough thrust to reach orbit. This is a huge milestone for SpaceX that potentially puts the company on track for an orbital test flight during the second half of March or possibly early April.
This is the most engines ignited on a rocket ever. The thrust output of these engines, too, was likely nearly double that of NASA's Saturn 5 rocket or Space Launch System. The good news for SpaceX is that, at least from early views, the launch infrastructure in South Texas looked mostly unscathed.
Enlarge / A fully stacked Starship launch system is seen on January 9, 2023. (credit: SpaceX)
After months of preparation, SpaceX is now approaching the critical test phase of its launch campaign for the massive Starship vehicle.
The company has evacuated nearby residents from the launch site in South Texas, near Boca Chica Beach, during the hours of 8 am CT (14:00 UTC) to 8 pm CT on Monday. If preparatory activities go well, the company will load both the Starship upper stage and Super Heavy booster with cryogenic methane and oxygen later today. The countdown will proceed toward liftoff but end just before the transfer of internal power to the launch vehicle.
There will be no engine ignition today. However, the upper stage of this vehicle, Ship 24, previously underwent a successful static fire test of its six Raptor rocket engines on September 8, 2022. The first stage, Booster 7, has seen as many as 14 of its 33 Raptor engines test fired during activity in November.
Astronomers have captured a radio signal from a distant galaxy at a specific wavelength known as the 21 cm line.
With the help of the Giant Metrewave Radio Telescope in India, this is the first time this type of radio signal has been detected at such a large distance.
How do stars form in distant galaxies? Astronomers have long been trying to answer this question by detecting radio signals emitted by nearby galaxies. However, these signals become weaker the further away a galaxy is from Earth, making it difficult for current radio telescopes to pick up.
“A galaxy emits different kinds of radio signals. Until now, it’s only been possible to capture this particular signal from a galaxy nearby, limiting our knowledge to those galaxies closer to Earth,” says Arnab Chakraborty, a postdoctoral researcher at McGill University under the supervision of Matt Dobbs, a professor in the physics department.
“But thanks to the help of a naturally occurring phenomenon called gravitational lensing, we can capture a faint signal from a record-breaking distance. This will help us understand the composition of galaxies at much greater distances from Earth.”
“It’s the equivalent to a look-back in time of 8.8 billion years.”
For the first time, the researchers were able to detect the signal from a distant star-forming galaxy known as SDSSJ0826+5630 and measure its gas composition. The researchers observed the atomic mass of the gas content of this particular galaxy is almost twice the mass of the stars visible to us.
The signal the team detected was emitted from this galaxy when the universe was only 4.9 billion years old, allowing the researchers to glimpse into the secrets of the early universe.
“It’s the equivalent to a look-back in time of 8.8 billion years,” says Chakraborty.
“Gravitational lensing magnifies the signal coming from a distant object to help us peer into the early universe. In this specific case, the signal is bent by the presence of another massive body, another galaxy, between the target and the observer.
“This effectively results in the magnification of the signal by a factor of 30, allowing the telescope to pick it up,” says coauthor Nirupam Roy, an associate professor in the physics department at the Indian Institute of Science.
According to the researchers, these results demonstrate the feasibility of observing faraway galaxies in similar situations with gravitational lensing. It also opens exciting new opportunities for probing the cosmic evolution of stars and galaxies with existing low-frequency radio telescopes.
The study appears in the Monthly Notices of the Royal Astronomical Society.
The Giant Metrewave Radio Telescope was built and is operated by NCRA-TIFR. The research was funded by McGill University and the Indian Institute of Science.
Source: McGill University
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