The Scientific Start Of The James Webb Space Telescope Promises Answers To The World’s Greatest Mysteries And, Most Fascinating Of All, Surprising Discoveries We Never Expected.
The James Webb Space Telescope started a new era in the world of astronomy with the release of its first scientific images at the end of last month. After years of delays, a delayed launch, and months of testing, the most powerful space telescope is finally ready to gather new clues about questions that were only a dream with previous-generation telescopes.
Thanks to a unique combination of capabilities, NASA’s new space telescope will allow us to peer further into the universe’s distant past. As an infrared telescope with a giant mirror orbiting beyond the Moon’s orbit, James Webb can collect the glow of the faintest and most distant stars and galaxies; The light that has been stretched to infrared wavelengths after traveling billions of years in the expanding space.
The telescope sees these objects in great detail thanks to its unprecedented angular resolution. James Webb’s infrared spectrometer will also allow us to identify molecules hidden in the atmospheres of potentially habitable exoplanets.
Data from the James Webb Space Telescope is helping us unravel some of the universe’s greatest mysteries, from how the first stars and galaxies formed and how fast the universe is expanding to possible extraterrestrial life. This article examines seven big questions that James Webb is expected to shed new light on in his first cycle of observations and transform our understanding of the universe.
When and where were the first stars formed?
After the big bang came the cosmic dark age. Then, the gas began to mix over several hundred million years, and the lights turned on as stars formed. The matter at this stage was either neutral helium and hydrogen gas or dark matter that neither emitted nor reflected light.
The radiation from these early stars ionized the neutral gas around them. When this period of so-called bayonization ended, the universe had transformed from a primordial homogeneous soup into a highly structured entity with galaxies, stars, and possibly planets. We know this happened, But we have a few observations to show how it happens.
Jehan Kartaltepe, an astrophysicist at the Rochester Institute of Technology in New York, has 256 hours of observation time with James Webb, one of the most extended periods in the telescope’s first observation cycle to answer a wide range of questions about the aforementioned cosmic dawn. What were the first stars? In which type of galaxies were formed? When did deionization occur, and how long did it last?
“Detecting [an early galaxy] with the Hubble Space Telescope is just a speck in the picture, and you can just tell how bright it is,” Kartaltepe said. [But] we will now be able to measure their stellar mass and solve the puzzle of structure; As a result, we will learn much more about physics.”
The Kartaltepe project will give us a comprehensive view of gameization. He says: “This process did not happen all at once. “It started in small areas and then spread to these bazionization bubbles.”
Meanwhile, Rohan Naidu, an astronomer at Harvard University, believes he has identified one of these tiny regions as the site of the cosmic dawn, and now he can finally look at it. “We think these are among the earliest galaxies that probably formed,” he says.
We measure the distance of objects in deep space by looking at “redshift,”; A phenomenon that represents the stretching of their light into the infrared part of the electromagnetic spectrum resulting from billions of years of travel in the expanding universe. The redshift number indicates how much light has been shifted to the red part, and the larger it is, the older the mass.
Cosmic dawn is thought to have started around redshift 10 When the universe was approximately 500 million years old. But Naidu says we can find evidence that the first stars formed in the ionized bubble we now see at redshift 9. He says: “This section is considered an extraordinary place; Because that tiny patch of sky contains a quarter of all known high-redshift candidate galaxies. What we know about structure formation in the universe suggests that the first stars grew in such a place. I am very excited to see these highly redshifted galaxies. “Maybe we can see the first stars.”
What is the origin of supermassive black holes?
Black holes are regions of space-time with such high density, curvature, and gravity that even light cannot escape. We have stellar black holes formed when massive stars with masses ranging from a few to hundreds of times that of the Sun collapse. On the other hand, supermassive black holes with hundreds of thousands to tens of billions of the Sun exist in the center of most galaxies. These monsters shape the evolution of galaxies by merging or accumulating mass and throwing out powerful fountains that can shatter everything around them.
One of the most astonishing observations in astrophysics is the sight of supermassive black holes that had billions of times the Sun’s mass when the universe was less than a billion years old. Even if these black holes were growing exponentially by swallowing stars and gas, they must have started their lives with the mass of thousands of suns, and according to our current models of how black holes form and grow, we have no idea how they came into being.
Theorists have proposed two paths for the formation of these massive black holes. The first way is the collapse of a vast gas cloud that either directly forms a black hole or first forms a gigantic star that later collapses into a black hole.
The second hypothesis is that they are made up of dense clusters of stars that merge, grow more extensive, and eventually form a black hole.
Astronomer Shawy Fan from the University of Arizona wants to observe distant quasars to learn more about supermassive black holes. Super-luminous objects are formed when gas is trapped at extremely high speeds by these black holes, spewing out massive eruptions of particles and radiation.
Looking closely at three examples of the most distant quasars we know, Fan and his colleagues measure the speed of the gas and dust pellets that fall into the black hole, thereby directly discovering their mass.
By combining these with the luminosity, we can get the rate at which the black hole is accreting matter. These details give the researchers the most accurate values about the initial mass of the black hole and when it formed in the young universe.
Fan observations cannot rule out ideas about how supermassive black holes form. However, it should reveal how they grow and their growth’s effect on galaxies’ evolution. We know that the most massive black holes are in the most massive galaxies, But which one emerged first and whether one is responsible for the other or not is considered a cosmic chicken-and-egg puzzle.
With James Webb’s unique sensitivity, we will see starlight from the galaxies that host these black holes for the first time. Infrared observations mean we can determine their age and thus when star and galaxy formation occurred relative to the black hole’s growth.
Waiting for the unexpected
Even if astronomers who get telescope time during James Webb’s first observing cycle know what they will be looking at, they’re still excited by the prospect of seeing something unexpected. “Hopefully, we’ll discover something we don’t expect,” says Wendy Friedman, an astronomer at the University of Chicago.
“I’m most excited about the questions that we don’t know enough to ask,” says Kristen McQueen, an astrophysicist at Rutgers University in New Jersey. He points to the Hubble space probe; This image was taken in 2004 after the Hubble Space Telescope pointed at a small unpromising part of the sky.
Many expected that nothing but blackness would be recorded in the photo, But long exposures revealed thousands of twinkling stars and galaxies that were older than anyone thought. This fascinating picture transformed the field of cosmology, just as the accidental discovery of photons left over from the Big Bang, or the cosmic background radiation, in the 1960s.
“Whenever a new instrument opens a new observational window, it creates a world of possibilities,” Friedman says, and the James Webb Space Telescope is no exception. “Almost all fields of astronomy are going to learn something new,” he adds. Then there will be discoveries that no one expects, and they are sometimes the most enjoyable.”
Is dark matter cold?
Dark matter is a mysterious form of matter whose existence can only be inferred from its gravitational effects. It is thought that this substance constitutes approximately 85% of all matter in the universe, But we don’t know what kind of particles dark matter is made of if it is. We think dark matter is “cold”; That is, it moves slowly, and this low speed allows small masses to come together due to their gravity and become larger structures called “halos.” In our current best picture of how the universe evolved, dark matter helped shape the universe; Because the halos absorbed gas that accumulated and collapsed to form stars and galaxies.
Dark matter halos range in size from a quadrillion the mass of the Sun to as small as the mass of the Earth. Based on our understanding of cosmic evolution, they exist as small invisible clumps of dark matter, so we are probably surrounded by many more minor haloes. When haloes are lighter than 10 million solar masses, they cannot absorb enough gas to form galaxies.
Ana Nirenberg, a physicist at the University of California, Merced, and her colleagues will test this hypothesis by looking at quasars and, by extension, the idea that dark matter is cold and slow.
In this case, the light emitted from the quasars is bent and turned into a lens due to the gravity of the slight halo without the dark matter galaxy. As a result, the light is refracted to create duplicate images in the telescope, Which is what Nirenberg and his colleagues did.
He says that detecting minor haloes would be a significant breakthrough for the current model. On the other hand, “the absence of these halos would mean that dark matter cannot be cold but must be more unfamiliar.”
How do massive stars turn into supernovae?
The Crab Nebula from the Hubble Space Telescope.
When stars like the Sun die, they go out relatively quietly. But more massive stars reach the end of their lives by entering a stage of intense and stunning explosions called “core annihilator supernovae.” These cosmic fireworks inject large amounts of energy into their surroundings. As the shock waves from the explosion heat and ionize the interstellar material, they cause the formation of new generations of stars. The supernova also enriches the gas clouds that form planets like ours by releasing chemical elements.
At some point, the star’s core can no longer support the weight of its outer layers, which causes the star to collapse and explode. We don’t know the mechanisms of this explosion or, in other words, how exactly massive stars explode in this way. We see supernovas all the time, and we know that stars with at least eight times the mass of the Sun will end their lives in these explosions.
Two models for massive stars at the lower end of the mass range can lead to supernovae. In the “electron trapping” model, the star has a core composed of oxygen, neon, and magnesium, which is held together by the pressure of electrons from these atoms. This pressure results from a quantum mechanics law that states that all those particles cannot have the same energy state.
However, if the core becomes too dense, the neon and magnesium atoms’ nuclei can absorb their electrons in a reaction called electron capture.
This process reduces the pressure and leads to the gravitational collapse of the star’s outer layers and the explosion.
Another hypothesis is the iron core collapse model. It is impossible to observe what happens inside the star at the moment of explosion; Because the outer layers prevent the core from being seen. In this situation, an iron nucleus is formed. Since iron is a very stable element, it cannot combine with other ingredients and release energy; As a result, nuclear reactions can no longer balance gravity and eventually collapse, and combustion follow.
But Princeton University astrophysicist T Tamim will use the James Webb Telescope to take a closer look at the Crab Nebula to see the remnants of a stellar supernova explosion in the 8 to 10 mass range of the Sun. This supernova, recorded by astronomers in 1054, is considered one of the most studied astronomical objects of all time.
“[The Crab Nebula] has a very complex ionization structure,” says Tamim. Only the James Webb Space Telescope has enough resolution to distinguish two possible signs of a star explosion in the nebula. However, if we take a closer look, we may be able to understand how it explodes; Because each of the two possible explosion mechanisms leaves its signature: a different ratio of stable iron to nickel in each case and a different distribution of iron in the material ejected by the star.
Where did Earth-like planets get their water?
We are lucky that our planet is a green world full of lakes, rivers, and waterfalls. However, our current understanding of the solar system’s history shows that our pale blue spot was not blue at all when it formed. When the Earth began from a vortex of gas and dust approximately 4.5 billion years ago, it was inside the Sun’s “ice line,”; A region far from the Sun whose low temperature causes all water to freeze.
Also, at that time, the Sun was emitting more energy than today, and this radiation pressure could push all the water vapor close to the Earth behind the ice line. All this means that, as far as we know, the Earth’s constituents did not contain any water. As a result, according to Isabel Rebolido, an astrophysicist at the Space Telescope Science Institute, “Earth’s water must have come from somewhere else.”
Planetary scientists believe that water probably reached Earth later in a period called the “Late Heavy Bombardment” by asteroids or comets. Indirect effects of the motion of gas giant planets in the outer reaches of the solar system are thought to have driven water to Earth by pushing ice-containing debris inward, creating many craters on the Moon in the process.
Rebolledo will use the James Webb Space Telescope to study five planetary systems at a similar stage of evolution. That is when gas giants are formed, and their movements disturb the surrounding material. “One possible explanation for the gas detected in the inner regions of planetary systems is the evaporation of solid and icy bodies sent from the outer regions,” says Rebolledo.
The goal is simple: look for water in the middle area. If water is there, it follows that icy bodies could reach rocky planets within the ice line from the solar system’s outer regions, allowing barren worlds to become pale blue spots.
Could the most promising exoplanets harbor life?
The prospect of life on planets beyond Earth has fascinated us for centuries. Thanks to the James Webb Space Telescope, we can now search for alien life by looking for “traces” in the atmospheres of exoplanets. If certain combinations of molecules, such as methane and carbon dioxide, are present in the atmosphere, it is a sign of life there. But to begin with, the planet must have an atmosphere.
We characterize the chemical composition of exoplanet atmospheres using the transit technique. When a planet passes in front of its host star, various molecules in the atmosphere interact with the star’s light and emit infrared radiation at specific wavelengths that make up the fingerprint of those molecules. They attract The James Webb Telescope spectrometer is sensitive to these fingerprints; This means that it can detect which molecules are present.
“The James Webb telescope is going to be revolutionary,” says Megan Mansfield, an astronomer at the University of Arizona. Because the Hubble and Spitzer telescopes had a relatively limited wavelength range, and as a result, they could not measure many elements in the planets’ atmospheres.
For the transition method to work, the signal from the planet’s atmosphere must be distinguishable against the star’s much brighter motion. Even with James Webb’s unprecedented capabilities, finding life traces will probably only be possible for planets orbiting excellent, low-mass stars known as M dwarfs. Fortunately, a group of fascinating exoplanets is within our reach. For example, the Trappist 1 system, a group of seven rocky planets discovered in 2016, hosts worlds that are better able to retain liquid water than any other known system.
The critical point, Mansfield says, is that we don’t know whether the Trappist planets or other worlds orbiting M dwarfs can maintain their atmospheres long enough to support life.
Because M dwarfs are much more active than stars like the Sun and emit large amounts of high-energy radiation, they can strip atmospheres from their planets.
One of the most valuable things the James Webb Space Telescope can do in the search for extraterrestrial life is to determine whether exoplanets around M-dwarfs have atmospheres. Kevin Stevenson, an astronomer at Johns Hopkins University in Maryland, will observe five exoplanets orbiting the nearest M dwarfs, including one world in the Trappist system.
The atmospheres of other Trappist planets will be observed as part of other James Webb projects. “If none of the five planets have atmospheres, we know that atmospheres are rare in planets around our dwarf, and we need to start looking for planets around other stars,” says Stevenson.
On the other hand, if we succeed in identifying the atmosphere, we will have good candidates for further investigations. Even so, whether or not we’ll be able to detect faint signs of alien life with James Webb. It will be unknown. “I don’t know if we’ll get there in 10 years,” Stevenson says. But we will try our best.”
Will the universe’s rate of expansion invalidate our best cosmological model?
As seen by the Hubble Space Telescope, RS Papis is one of the brightest Cepheus stars in the Milky Way.
We live in an expanding world, where galaxies are moving away from each other at speed called the Hubble constant. It can measure directly by determining distances to distant astronomical objects or indirectly by combining observations from the early universe with our best theory of how the galaxy evolved. But the problem is that these two measurements are inconsistent.
Our current cosmological model assumes that the universe is composed of radiation, matter (including cold dark matter), and dark energy; A mysterious form of energy is thought to be responsible for the expansion we observe. By recording data from radiation left over from the Big Bang, known as “cosmic background radiation,” cosmologists estimate that the universe is expanding at a rate of 67 kilometers per second per megaparsec. (A megaparsec is a distance equal to 3.26 million light-years.)
However, when astronomers measure Hubble’s constant from observations of distant objects, they arrive at a value of 73 km/s per megaparsec.
This discrepancy, known as the “Hubble tension,” could indicate that something is seriously wrong with our understanding of cosmic evolution. However, the cosmological standard model is very successful and includes all kinds of observations; Consequently, we will need a good reason to discard it.
The James Webb Space Telescope can finally solve the mystery. Astronomers use the “Cosmic Distance Ladder” to obtain the Hubble constant, A set of methods that include the use of stars called “Qifausi.” These stars, whose brightness fluctuates at a rate related to their absolute magnitude, allow us to measure their distance from us. We then move up the ladder using other “standard candles” such as supernovae to calculate distances to nearby galaxies and ultimately to the edge of the observable universe.
We must reduce the uncertainty at each step to ensure these measurements are accurate. To understand these uncertainties, Wendy Friedman, an astronomer from the University of Chicago, plans to measure the distance to similar galaxies using a variety of standard candles. For example, Cepheids are often surrounded by other young stars. The sharper images provided by the James Webb Space Telescope will help distinguish the measured light contributions of the Cepheids relative to their neighbors.
In addition, the higher sensitivity allows us to see Cepheids in more distant galaxies.
Friedman will combine the Cephasian measurements with other methods for measuring distances to other galaxies to understand better how accurate our Hubble constant calculations can be.
To address this issue, Sherry Soyo, an astrophysicist at the Technical University of Munich, is instead looking at the twinkling of quasars. When a massive object like another galaxy is between us and the quasar, its gravity can act like a lens, forming multiple images of the quasar in our telescopes.
There is a delay in the arrival of the quasar flash to different images; Because each of them has a different optical path due to the phenomenon of “gravitational convergence.”
These delays are related not only to the quasar distance but also to the gravitational potential of the lensing galaxy. By measuring the velocities of the stars in the lensed galaxy by James Webb, SOYO can understand its mass distribution and thus better refine the galaxy’s gravitational potential when estimating the Hubble constant from quasar blink time delays.
If these independent methods of determining the distance arrive at the same value for the Hubble constant, we will know that the astronomical measurement is robust. And if scientists agree with the Hubble value of the cosmological model, the Hubble tension disappears.
“If we can show that the standard model works, that would be a significant result,” Friedman says. However, what if the astronomical criteria differ from the cosmological model? “If this turns out to be new physics, it will be exciting,” Suyo says. “If that happens, I want to ensure we’re right.”