At 390 million years after the Big Bang, it isn’t quite as old as initially estimated.
Will Shanklin
·Contributing Reporter
Tue, August 15, 2023
NASA / STScI / CEERS / TACC / The University of Texas at Austin / S. Finkelstein / M. Bagley
Astronomers have used advanced instruments to calculate a more accurate age of Maisie’s galaxy, discovered by the James Webb Space Telescope (JWST) in June 2022. Although the star system isn’t quite as old as initially estimated, it’s still one of the oldest recorded, from 390 million years after the Big Bang — making it about 13.4 billion years old. That’s a mere 70 million years younger than JADES-GS-z13-0, the (current) oldest-known system.
A team led by the University of Texas at Austin astronomer Steven Finkelstein discovered the system last summer. (The name “Maisie’s galaxy” is an ode to his daughter because they spotted it on her birthday.) The group initially estimated that it was only 290 million years after the Big Bang, but analyzing the galaxy with more advanced equipment revealed it’s about 100 million years older than that. “The exciting thing about Maisie’s galaxy is that it was one of the first distant galaxies identified by JWST, and of that set, it’s the first to actually be spectroscopically confirmed,” said Finkelstein.
The spectroscopic confirmation came courtesy of the JWST’s Near InfraRed Spectrograph (NIRSpec) conducted by the Cosmic Evolution Early Release Science Survey (CEERS). The NIRSpec “splits an object’s light into many different narrow frequencies to more accurately identify its chemical makeup, heat output, intrinsic brightness and relative motion.” Redshift — the movement of light towards longer (redder) wavelengths to indicate motion away from the observer — held the key to more accurate dating than the original photometry-based estimate. The advanced tools assigned a redshift of z=11.4 to Maisie’s galaxy, helping the researchers settle on the revised estimate of 390 million years after the Big Bang.
James Webb Space Telescope
The astronomers also examined CEERS-93316, a galaxy initially estimated at 235 million years pre-Big Bang — which would have made it astonishingly old. After studying this system, it revealed a redshift of z=4.9, which places it at a mere one billion years after the Big Bang. The first faulty estimate about CEERS-93316 was understandable: The galaxy emitted an unusual amount of light in narrow frequency bands associated with oxygen and hydrogen, making it appear bluer than it was.
Finkelstein chalks up the miss to bad luck. “This was a kind of weird case,” he said. “Of the many tens of high redshift candidates that have been observed spectroscopically, this is the only instance of the true redshift being much less than our initial guess.” Finkelstein added, “It would have been really challenging to explain how the universe could create such a massive galaxy so soon. So, I think this was probably always the most likely outcome, because it was so extreme, so bright, at such an apparent high redshift.”
The CEERS team is now evaluating about 10 more systems that could be older than Maisie’s galaxy
·Contributing Reporter
Tue, August 15, 2023
NASA / STScI / CEERS / TACC / The University of Texas at Austin / S. Finkelstein / M. Bagley
Astronomers have used advanced instruments to calculate a more accurate age of Maisie’s galaxy, discovered by the James Webb Space Telescope (JWST) in June 2022. Although the star system isn’t quite as old as initially estimated, it’s still one of the oldest recorded, from 390 million years after the Big Bang — making it about 13.4 billion years old. That’s a mere 70 million years younger than JADES-GS-z13-0, the (current) oldest-known system.
A team led by the University of Texas at Austin astronomer Steven Finkelstein discovered the system last summer. (The name “Maisie’s galaxy” is an ode to his daughter because they spotted it on her birthday.) The group initially estimated that it was only 290 million years after the Big Bang, but analyzing the galaxy with more advanced equipment revealed it’s about 100 million years older than that. “The exciting thing about Maisie’s galaxy is that it was one of the first distant galaxies identified by JWST, and of that set, it’s the first to actually be spectroscopically confirmed,” said Finkelstein.
The spectroscopic confirmation came courtesy of the JWST’s Near InfraRed Spectrograph (NIRSpec) conducted by the Cosmic Evolution Early Release Science Survey (CEERS). The NIRSpec “splits an object’s light into many different narrow frequencies to more accurately identify its chemical makeup, heat output, intrinsic brightness and relative motion.” Redshift — the movement of light towards longer (redder) wavelengths to indicate motion away from the observer — held the key to more accurate dating than the original photometry-based estimate. The advanced tools assigned a redshift of z=11.4 to Maisie’s galaxy, helping the researchers settle on the revised estimate of 390 million years after the Big Bang.
James Webb Space Telescope
The astronomers also examined CEERS-93316, a galaxy initially estimated at 235 million years pre-Big Bang — which would have made it astonishingly old. After studying this system, it revealed a redshift of z=4.9, which places it at a mere one billion years after the Big Bang. The first faulty estimate about CEERS-93316 was understandable: The galaxy emitted an unusual amount of light in narrow frequency bands associated with oxygen and hydrogen, making it appear bluer than it was.
Finkelstein chalks up the miss to bad luck. “This was a kind of weird case,” he said. “Of the many tens of high redshift candidates that have been observed spectroscopically, this is the only instance of the true redshift being much less than our initial guess.” Finkelstein added, “It would have been really challenging to explain how the universe could create such a massive galaxy so soon. So, I think this was probably always the most likely outcome, because it was so extreme, so bright, at such an apparent high redshift.”
The CEERS team is now evaluating about 10 more systems that could be older than Maisie’s galaxy
Looking back toward cosmic dawn − astronomers confirm the faintest galaxy ever seen
Guido Roberts-Borsani, Postdoctoral Researcher in Astrophysics, University of California, Los Angeles
Tue, August 15, 2023
The early universe was filled with a fog made up of hydrogen atoms until the first stars and galaxies burned it away. NASA/JPL-Caltech, CC BY
The intense ultraviolet light from the first generations of stars and galaxies is thought to have burned through the hydrogen fog, transforming the universe into what we see today. While previous generations of telescopes lacked the ability to study those early cosmic objects, astronomers are now using the James Webb Space Telescope’s superior technology to study the stars and galaxies that formed in the immediate aftermath of the Big Bang.
I’m an astronomer who studies the farthest galaxies in the universe using the world’s foremost ground- and space-based telescopes. Using new observations from the Webb telescope and a phenomenon called gravitational lensing, my team confirmed the existence of the faintest galaxy currently known in the early universe. The galaxy, called JD1, is seen as it was when the universe was only 480 million years old, or 4% of its present age.
A brief history of the early universe
The first billion years of the universe’s life were a crucial period in its evolution. In the first moments after the Big Bang, matter and light were bound to each other in a hot, dense “soup” of fundamental particles.
However, a fraction of a second after the Big Bang, the universe expanded extremely rapidly. This expansion eventually allowed the universe to cool enough for light and matter to separate out of their “soup” and – some 380,000 years later – form hydrogen atoms. The hydrogen atoms appeared as an intergalactic fog, and with no light from stars and galaxies, the universe was dark. This period is known as the cosmic dark ages.
The arrival of the first generations of stars and galaxies several hundred million years after the Big Bang bathed the universe in extremely hot UV light, which burned – or ionized – the hydrogen fog. This process yielded the transparent, complex and beautiful universe we see today.
Astronomers like me call the first billion years of the universe – when this hydrogen fog was burning away – the epoch of reionization. To fully understand this time period, we study when the first stars and galaxies formed, what their main properties were and whether they were able to produce enough UV light to burn through all the hydrogen.
The search for faint galaxies in the early universe
The first step toward understanding the epoch of reionization is finding and confirming the distances to galaxies that astronomers think might be responsible for this process. Since light travels at a finite speed, it takes time to arrive to our telescopes, so astronomers see objects as they were in the past.
For example, light from the center of our galaxy, the Milky Way, takes about 27,000 years to reach us on Earth, so we see it as it was 27,000 years in the past. That means that if we want to see back to the very first instants after the Big Bang (the universe is 13.8 billion years old), we have to look for objects at extreme distances.
Because galaxies residing in this time period are so far away, they appear extremely faint and small to our telescopes and emit most of their light in the infrared. This means astronomers need powerful infrared telescopes like Webb to find them. Prior to Webb, virtually all of the distant galaxies found by astronomers were exceptionally bright and large, simply because our telescopes weren’t sensitive enough to see the fainter, smaller galaxies.
However, it’s the latter population that are far more numerous, representative and likely to be the main drivers to the reionization process, not the bright ones. So, these faint galaxies are the ones astronomers need to study in greater detail. It’s like trying to understand the evolution of humans by studying entire populations rather than a few very tall people. By allowing us to see faint galaxies, Webb is opening a new window into studying the early universe.
It was written by: Guido Roberts-Borsani, University of California, Los Angeles.
Read more:
A subtle symphony of ripples in spacetime – astronomers use dead stars to measure gravitational waves produced by ancient black holes
How the James Webb Space Telescope has revealed a surprisingly bright, complex and element-filled early universe – podcast
The most powerful space telescope ever built will look back in time to the Dark Ages of the universe
This work is based on observations made with the NASA/ESA/CSA JWST. The data were obtained from the Mikulski Archive for Space Telescopes at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-03127 for JWST. These observations are associated with program JWST-ERS-1324, and the authors acknowledge financial support from NASA through grant JWST-ERS-1324.
Guido Roberts-Borsani, Postdoctoral Researcher in Astrophysics, University of California, Los Angeles
Tue, August 15, 2023
THE CONVERSATION
A phenomenon called gravitational lensing can help astronomers observe faint, hard-to-see galaxies. NASA/STScI
The universe we live in is a transparent one, where light from stars and galaxies shines bright against a clear, dark backdrop. But this wasn’t always the case – in its early years, the universe was filled with a fog of hydrogen atoms that obscured light from the earliest stars and galaxies.
A phenomenon called gravitational lensing can help astronomers observe faint, hard-to-see galaxies. NASA/STScI
The universe we live in is a transparent one, where light from stars and galaxies shines bright against a clear, dark backdrop. But this wasn’t always the case – in its early years, the universe was filled with a fog of hydrogen atoms that obscured light from the earliest stars and galaxies.
The early universe was filled with a fog made up of hydrogen atoms until the first stars and galaxies burned it away. NASA/JPL-Caltech, CC BY
The intense ultraviolet light from the first generations of stars and galaxies is thought to have burned through the hydrogen fog, transforming the universe into what we see today. While previous generations of telescopes lacked the ability to study those early cosmic objects, astronomers are now using the James Webb Space Telescope’s superior technology to study the stars and galaxies that formed in the immediate aftermath of the Big Bang.
I’m an astronomer who studies the farthest galaxies in the universe using the world’s foremost ground- and space-based telescopes. Using new observations from the Webb telescope and a phenomenon called gravitational lensing, my team confirmed the existence of the faintest galaxy currently known in the early universe. The galaxy, called JD1, is seen as it was when the universe was only 480 million years old, or 4% of its present age.
A brief history of the early universe
The first billion years of the universe’s life were a crucial period in its evolution. In the first moments after the Big Bang, matter and light were bound to each other in a hot, dense “soup” of fundamental particles.
However, a fraction of a second after the Big Bang, the universe expanded extremely rapidly. This expansion eventually allowed the universe to cool enough for light and matter to separate out of their “soup” and – some 380,000 years later – form hydrogen atoms. The hydrogen atoms appeared as an intergalactic fog, and with no light from stars and galaxies, the universe was dark. This period is known as the cosmic dark ages.
The arrival of the first generations of stars and galaxies several hundred million years after the Big Bang bathed the universe in extremely hot UV light, which burned – or ionized – the hydrogen fog. This process yielded the transparent, complex and beautiful universe we see today.
Astronomers like me call the first billion years of the universe – when this hydrogen fog was burning away – the epoch of reionization. To fully understand this time period, we study when the first stars and galaxies formed, what their main properties were and whether they were able to produce enough UV light to burn through all the hydrogen.
The search for faint galaxies in the early universe
The first step toward understanding the epoch of reionization is finding and confirming the distances to galaxies that astronomers think might be responsible for this process. Since light travels at a finite speed, it takes time to arrive to our telescopes, so astronomers see objects as they were in the past.
For example, light from the center of our galaxy, the Milky Way, takes about 27,000 years to reach us on Earth, so we see it as it was 27,000 years in the past. That means that if we want to see back to the very first instants after the Big Bang (the universe is 13.8 billion years old), we have to look for objects at extreme distances.
Because galaxies residing in this time period are so far away, they appear extremely faint and small to our telescopes and emit most of their light in the infrared. This means astronomers need powerful infrared telescopes like Webb to find them. Prior to Webb, virtually all of the distant galaxies found by astronomers were exceptionally bright and large, simply because our telescopes weren’t sensitive enough to see the fainter, smaller galaxies.
However, it’s the latter population that are far more numerous, representative and likely to be the main drivers to the reionization process, not the bright ones. So, these faint galaxies are the ones astronomers need to study in greater detail. It’s like trying to understand the evolution of humans by studying entire populations rather than a few very tall people. By allowing us to see faint galaxies, Webb is opening a new window into studying the early universe.
A typical early galaxy
JD1 is one such “typical” faint galaxy. It was discovered in 2014 with the Hubble Space Telescope as a suspect distant galaxy. But Hubble didn’t have the capabilities or sensitivity to confirm its distance – it could make only an educated guess.
Small and faint nearby galaxies can sometimes be mistaken as distant ones, so astronomers need to be sure of their distances before we can make claims about their properties. Distant galaxies therefore remain “candidates” until they are confirmed. The Webb telescope finally has the capabilities to confirm these, and JD1 was one of the first major confirmations by Webb of an extremely distant galaxy candidate found by Hubble. This confirmation ranks it as the faintest galaxy yet seen in the early universe.
To confirm JD1, an international team of astronomers and I used Webb’s near-infrared spectrograph, NIRSpec, to obtain an infrared spectrum of the galaxy. The spectrum allowed us to pinpoint the distance from Earth and determine its age, the number of young stars it formed and the amount of dust and heavy elements that it produced.
A sky full of galaxies and a few stars. JD1, pictured in a zoomed-in box, is the faintest galaxy yet found in the early universe.
JD1 is one such “typical” faint galaxy. It was discovered in 2014 with the Hubble Space Telescope as a suspect distant galaxy. But Hubble didn’t have the capabilities or sensitivity to confirm its distance – it could make only an educated guess.
Small and faint nearby galaxies can sometimes be mistaken as distant ones, so astronomers need to be sure of their distances before we can make claims about their properties. Distant galaxies therefore remain “candidates” until they are confirmed. The Webb telescope finally has the capabilities to confirm these, and JD1 was one of the first major confirmations by Webb of an extremely distant galaxy candidate found by Hubble. This confirmation ranks it as the faintest galaxy yet seen in the early universe.
To confirm JD1, an international team of astronomers and I used Webb’s near-infrared spectrograph, NIRSpec, to obtain an infrared spectrum of the galaxy. The spectrum allowed us to pinpoint the distance from Earth and determine its age, the number of young stars it formed and the amount of dust and heavy elements that it produced.
A sky full of galaxies and a few stars. JD1, pictured in a zoomed-in box, is the faintest galaxy yet found in the early universe.
Guido Roberts-Borsani/UCLA; original images: NASA, ESA, CSA, Swinburne University of Technology, University of Pittsburgh, STScI
Gravitational lensing, nature’s magnifying glass
Even for Webb, JD1 would be impossible to see without a helping hand from nature. JD1 is located behind a large cluster of nearby galaxies, called Abell 2744, whose combined gravitational strength bends and amplifies the light from JD1. This effect, known as gravitational lensing, makes JD1 appear larger and 13 times brighter than it ordinarily would.
Without gravitational lensing, astronomers would not have seen JD1, even with Webb. The combination of JD1’s gravitational magnification and new images from another one of Webb’s near-infrared instruments, NIRCam, made it possible for our team to study the galaxy’s structure in unprecedented detail and resolution.
Not only does this mean we as astronomers can study the inner regions of early galaxies, it also means we can start determining whether such early galaxies were small, compact and isolated sources, or if they were merging and interacting with nearby galaxies. By studying these galaxies, we are tracing back to the building blocks that shaped the universe and gave rise to our cosmic home.
This article is republished from The Conversation, a nonprofit news site dedicated to sharing ideas from academic experts.
Gravitational lensing, nature’s magnifying glass
Even for Webb, JD1 would be impossible to see without a helping hand from nature. JD1 is located behind a large cluster of nearby galaxies, called Abell 2744, whose combined gravitational strength bends and amplifies the light from JD1. This effect, known as gravitational lensing, makes JD1 appear larger and 13 times brighter than it ordinarily would.
Without gravitational lensing, astronomers would not have seen JD1, even with Webb. The combination of JD1’s gravitational magnification and new images from another one of Webb’s near-infrared instruments, NIRCam, made it possible for our team to study the galaxy’s structure in unprecedented detail and resolution.
Not only does this mean we as astronomers can study the inner regions of early galaxies, it also means we can start determining whether such early galaxies were small, compact and isolated sources, or if they were merging and interacting with nearby galaxies. By studying these galaxies, we are tracing back to the building blocks that shaped the universe and gave rise to our cosmic home.
This article is republished from The Conversation, a nonprofit news site dedicated to sharing ideas from academic experts.
It was written by: Guido Roberts-Borsani, University of California, Los Angeles.
Read more:
A subtle symphony of ripples in spacetime – astronomers use dead stars to measure gravitational waves produced by ancient black holes
How the James Webb Space Telescope has revealed a surprisingly bright, complex and element-filled early universe – podcast
The most powerful space telescope ever built will look back in time to the Dark Ages of the universe
This work is based on observations made with the NASA/ESA/CSA JWST. The data were obtained from the Mikulski Archive for Space Telescopes at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-03127 for JWST. These observations are associated with program JWST-ERS-1324, and the authors acknowledge financial support from NASA through grant JWST-ERS-1324.
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