Astronomy

Webb discovers the incredibly distant galaxy JADES-GS-z13-1

By ScientifiCult 26 March 2025

Webb discovers the incredibly distant galaxy JADES-GS-z13-1 in mysteriously clearing fog of early Universe

Using the unique infrared sensitivity of the NASA/ESA/CSA James Webb Space Telescope, researchers can examine ancient galaxies to probe secrets of the early universe. Now, an international team of astronomers has identified bright hydrogen emission from a galaxy in an unexpectedly early time in the Universe’s history. The surprise finding is challenging researchers to explain how this light could have pierced the thick fog of neutral hydrogen that filled space at that time.

A small, zoomed-in area of deep space. Numerous galaxies in various shapes are visible, most of them small, but two are quite large and glow brightly. In the very centre is a small red dot, an extremely faraway galaxy. Two lines of light enter the left side: these are diffraction spikes, visual artefacts, caused by a nearby bright star just out of view. — The incredibly distant galaxy GS-z13-1, observed just 330 million years after the Big Bang, was initially discovered with deep imaging from the NASA/ESA/CSA James Webb Space Telescope. Now, an international team of astronomers has definitively identified powerful hydrogen emission from this galaxy at an unexpectedly early period in the Universe’s history, a probable sign that we are seeing some of the first hot stars from the dawn of the Universe. This image shows the galaxy GS-z13-1 (the red dot at centre), imaged with Webb’s Near-Infrared Camera (NIRCam) as part of the JWST Advanced Deep Extragalactic Survey (JADES) programme. These data from NIRCam allowed researchers to identify GS-z13-1 as an incredibly distant galaxy, and to put an estimate on its redshift value. Webb’s unique infrared sensitivity is necessary to observe galaxies at this extreme distance, whose light has been redshifted into infrared wavelengths during its long journey across the cosmos.
To confirm the galaxy’s redshift, the team turned to Webb’s Near-Infrared Spectrograph (NIRSpec) instrument. With new observations permitting advanced spectroscopy of the galaxy’s emitted light, the team not only confirmed GS-z13-1’s redshift of 13.0, they also revealed the strong presence of a type of ultraviolet radiation called Lyman-α emission. This is a telltale sign of the presence of newly forming stars, or a possible active galactic nucleus in the galaxy, but at a much earlier time than astronomers had thought possible. The result holds great implications for our understanding of the Universe.
Credit: ESA/Webb, NASA, STScI, CSA, JADES Collaboration, Brant Robertson (UC Santa Cruz), Ben Johnson (CfA), Sandro Tacchella (Cambridge), Phill Cargile (CfA), J. Witstok, P. Jakobsen, A. Pagan (STScI), M. Zamani (ESA/Webb)

A key science goal of the NASA/ESA/CSA James Webb Space Telescope has been to see further than ever before into the distant past of our Universe, when the first galaxies were forming after the Big Bang. This search has already yielded record-breaking galaxies, in observing programmes such as the JWST Advanced Deep Extragalactic Survey (JADES). Webb’s extraordinary sensitivity to infrared light also opens entirely new avenues of research into when and how such galaxies formed, and their effects on the Universe at the time known as cosmic dawn. Researchers studying one of those very early galaxies have now made a discovery in the spectrum of its light, that challenges our established understanding of the Universe’s early history.

Webb discovered the incredibly distant galaxy JADES-GS-z13-1, observed to be at just 330 million years after the Big Bang, in images taken by Webb’s NIRCam (Near-Infrared Camera) as part of the JADES programme. Researchers used the galaxy’s brightness in different infrared filters to estimate its redshift, which measures a galaxy’s distance from Earth based on how its light has been stretched out during its journey through expanding space.

The spectrum of light from the distant galaxy JADES-GS-z13-1 is graphed as a line from left (lower wavelengths) to right (higher wavelengths). The line rises where a wavelength in the spectrum is brighter, and falls where it is dimmer. A vertical red line labelled “Lyman-alpha emission z=13.05” marks a wavelength in the spectrum where there is a noticeable spike in brightness. The graph is labelled “NIRSpec | PRISM”. — The incredibly distant galaxy GS-z13-1, observed just 330 million years after the Big Bang, was initially discovered with deep imaging from the NASA/ESA/CSA James Webb Space Telescope. Now, an international team of astronomers has definitively identified powerful hydrogen emission from this galaxy at an unexpectedly early period in the Universe’s history, a probable sign that we are seeing some of the first hot stars from the dawn of the Universe. Data from NIRCam allowed researchers to identify GS-z13-1 as an incredibly distant galaxy, and to put an estimate on its redshift value. Webb’s unique infrared sensitivity is necessary to observe galaxies at this extreme distance, whose light has been redshifted into infrared wavelengths during its long journey across the cosmos.
To confirm the galaxy’s redshift, the team turned to Webb’s Near-Infrared Spectrograph (NIRSpec) instrument. This graphic shows the light from galaxy GS-z13-1, dispersed by NIRSpec into its component near-infrared wavelengths. This graphic indicates very bright Lyman-α emission from the galaxy, which has been redshifted to an infrared wavelength. Not only does this emission in GS-z13-1’s spectrum confirm the galaxy’s extreme redshift, it is a telltale sign of the presence of newly forming stars, or a possible active galactic nucleus in the galaxy. Appearing at a much earlier time than astronomers had thought possible, the discovery of this Lyman-α emission holds great implications for our understanding of the Universe.
Credit: ESA/Webb, NASA, CSA, STScI, J. Olmsted (STScI), S. Carniani (Scuola Normale Superiore), P. Jakobsen

The NIRCam imaging yielded an initial redshift estimate of 12.9. Seeking to confirm its extreme redshift, an international team led by Joris Witstok of the University of Cambridge in the United Kingdom as well as the Cosmic Dawn Center and the University of Copenhagen in Denmark, then observed the galaxy using Webb’s Near-Infrared Spectrograph (NIRSpec) instrument.

An area of deep space is covered by a scattering of galaxies in many shapes and in colours ranging from blue to whitish to orange, as well as a few nearby stars. A very small square is shown zoomed in, in a box to the left. In the centre a red dot, a faraway galaxy, is marked out by lines and labelled “Redshift (z)=13”, signifying its extreme distance. Two much larger galaxies are labelled “z=0.63” and “z=0.70”. The box is titled “JADES-GS-z13-1”. — The incredibly distant galaxy GS-z13-1, observed just 330 million years after the Big Bang, was initially discovered with deep imaging from the NASA/ESA/CSA James Webb Space Telescope. Now, an international team of astronomers has definitively identified powerful hydrogen emission from this galaxy at an unexpectedly early period in the Universe’s history, a probable sign that we are seeing some of the first hot stars from the dawn of the Universe. This image shows the location of the galaxy GS-z13-1 in the GOODS-S field, as well as the galaxy itself, imaged with Webb’s Near-Infrared Camera (NIRCam) as part of the JWST Advanced Deep Extragalactic Survey (JADES) programme. These data from NIRCam allowed researchers to identify GS-z13-1 as an incredibly distant galaxy, and to put an estimate on its redshift value. Webb’s unique infrared sensitivity is necessary to observe galaxies at this extreme distance, whose light has been redshifted into infrared wavelengths during its long journey across the cosmos.
To confirm the galaxy’s redshift, the team turned to Webb’s Near-Infrared Spectrograph (NIRSpec) instrument. With new observations permitting advanced spectroscopy of the galaxy’s emitted light, the team not only confirmed GS-z13-1’s redshift of 13.0, they also revealed the strong presence of a type of ultraviolet radiation called Lyman-α emission. This is a telltale sign of the presence of newly forming stars, or a possible active galactic nucleus in the galaxy, but at a much earlier time than astronomers had thought possible. The result holds great implications for our understanding of the Universe.
Credit: ESA/Webb, NASA, STScI, CSA, JADES Collaboration, Brant Robertson (UC Santa Cruz), Ben Johnson (CfA), Sandro Tacchella (Cambridge), Phill Cargile (CfA), J. Witstok, P. Jakobsen, A. Pagan (STScI), M. Zamani (ESA/Webb)

In the resulting spectrum, the redshift was confirmed to be 13.0. This equates to a galaxy seen just 330 million years after the Big Bang, a small fraction of the Universe’s present age of 13.8 billion years old. But an unexpected feature stood out as well: one specific, distinctly bright wavelength of light, identified as the Lyman-α emission radiated by hydrogen atoms.[1] This emission was far stronger than astronomers thought possible at this early stage in the Universe’s development.

“The early Universe was bathed in a thick fog of neutral hydrogen,” explained Roberto Maiolino, a team member from the University of Cambridge and University College London. “Most of this haze was lifted in a process called reionisation, which was completed about one billion years after the Big Bang. GS-z13-1 is seen when the Universe was only 330 million years old, yet it shows a surprisingly clear, telltale signature of Lyman-α emission that can only be seen once the surrounding fog has fully lifted. This result was totally unexpected by theories of early galaxy formation and has caught astronomers by surprise.”

Before and during the epoch of reionisation [2], the immense amounts of neutral hydrogen fog surrounding galaxies blocked any energetic ultraviolet light they emitted, much like the filtering effect of coloured glass. Until enough stars had formed and were able to ionise the hydrogen gas, no such light — including Lyman-α emission — could escape from these fledgling galaxies to reach Earth. The confirmation of Lyman-α radiation from this galaxy, therefore, has great implications for our understanding of the early Universe. Team member Kevin Hainline of the University of Arizona in the United States, says

“We really shouldn’t have found a galaxy like this, given our understanding of the way the Universe has evolved. We could think of the early Universe as shrouded with a thick fog that would make it exceedingly difficult to find even powerful lighthouses peeking through, yet here we see the beam of light from this galaxy piercing the veil. This fascinating emission line has huge ramifications for how and when the Universe reionised.”

The source of the Lyman-α radiation from this galaxy is not yet known, but it is may include the first light from the earliest generation of stars to form in the Universe. Witstok elaborates:

“The large bubble of ionised hydrogen surrounding this galaxy might have been created by a peculiar population of stars — much more massive, hotter and more luminous than stars formed at later epochs, and possibly representative of the first generation of stars”.

A powerful active galactic nucleus (AGN) [3], driven by one of the first supermassive black holes, is another possibility identified by the team.

The new results could not have been obtained without the incredible near-infrared sensitivity of Webb, necessary not only to find such distant galaxies but also to examine their spectra in fine detail. Former NIRSpec Project Scientist, Peter Jakobsen of the Cosmic Dawn Center and the University of Copenhagen in Denmark, recalls:

“Following in the footsteps of the Hubble Space Telescope, it was clear Webb would be capable of finding ever more distant galaxies. As demonstrated by the case of GS-z13-1, however, it was always going to be a surprise what it might reveal about the nature of the nascent stars and black holes that are formed at the brink of cosmic time.”

The team plans further follow-up observations of GS-z13-1, aiming to obtain more information about the nature of this galaxy and origin of its strong Lyman-α radiation. Whatever the galaxy is concealing, it is certain to illuminate a new frontier in cosmology.

This new research has been published today in Nature. The data for this result were captured as part of JADES under JWST programmes #1180 (PI: D. J. Eisenstein), #1210, #1286 and #1287 (PI: N. Luetzgendorf), and the JADES Origin Field programme #3215 (PIs: Eisenstein and R. Maiolino).

Notes

[1] The name comes from the fact that a hydrogen atom emits a characteristic wavelength of light, known as “Lyman-alpha” radiation, that is produced when its electron drops from the second-lowest to the lowest orbit around the nucleus (energy level).

[2] The epoch of reionisation was a very early stage in the Universe’s history that took place after recombination (the first stage following the Big Bang). During recombination, the Universe cooled enough that electrons and protons began to combine to form neutral hydrogen atoms. Reionisation began when denser clouds of gas started to form, creating stars and eventually entire galaxies. They produced large amounts of ultraviolet photons, which gradually reionised the hydrogen gas. As neutral hydrogen gas is opaque to energetic ultraviolet light, we can only see galaxies during this epoch at longer wavelengths until they create a “bubble” of ionised gas around them, so that their ultraviolet light can escape through it and reach us.

[3] An active galactic nucleus is a region of extremely strong radiation at the centre of a galaxy. It is fuelled by an accretion disc, made of material orbiting and falling into a central supermassive black hole. The material crashes together as it spins around the black hole, heating to such extreme temperatures that it radiates highly energetic ultraviolet light and even X-rays, rivalling the brightness of the whole galaxy surrounding it.

Press release from ESA Webb.

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Massive black hole in the early universe is lying dormant in its host galaxy, GN-1001830

By ScientifiCult 18 December 2024

Massive black hole in the early universe spotted taking a ‘nap’ after overeating, and lying dormant in its host galaxy, GN-1001830

JWST buco nero dormiente GN-1001830 Illustrazione artistica che rappresenta l'aspetto potenziale del buco nero supermassiccio scoperto dal team di ricerca durante la sua fase di intensa attività super-Eddington. Crediti: Jiarong Gu — A study in *Nature* finds that black holes in the early Universe go through short periods of ultra-fast growth, followed by long periods of dormancy. Picture credits: Jiarong Gu

Scientists have spotted a massive black hole in the early universe that is ‘napping’ after stuffing itself with too much food.

Like a bear gorging itself on salmon before hibernating for the winter, or a much-needed nap after Christmas dinner, this black hole has overeaten to the point that it is lying dormant in its host galaxy, GN-1001830.

An international team of astronomers, led by the University of Cambridge, used the NASA/ESA/CSA James Webb Space Telescope to detect this black hole in the early universe, just 800 million years after the Big Bang.

The black hole is huge – 400 million times the mass of our Sun – making it one of the most massive black holes discovered by Webb at this point in the universe’s development. The black hole is so enormous that it makes up roughly 40% of the total mass of its host galaxy: in comparison, most black holes in the local universe are roughly 0.1% of their host galaxy mass.

However, despite its gigantic size, this black hole is eating, or accreting, the gas it needs to grow at a very low rate – about 100 times below its theoretical maximum limit – making it essentially dormant.

Such an over-massive black hole so early in the universe, but one that isn’t growing, challenges existing models of how black holes develop. However, the researchers say that the most likely scenario is that black holes go through short periods of ultra-fast growth, followed by long periods of dormancy. Their results are reported in the journal Nature.

When black holes are ‘napping’, they are far less luminous, making them more difficult to spot, even with highly-sensitive telescopes such as Webb. Black holes cannot be directly observed, but instead they are detected by the tell-tale glow of a swirling accretion disc, which forms near the black hole’s edges. The gas in the accretion disc becomes extremely hot and starts to glow and radiate energy in the ultraviolet range.

“Even though this black hole is dormant, its enormous size made it possible for us to detect,” said lead author Ignas Juodžbalis from Cambridge’s Kavli Institute for Cosmology. “Its dormant state allowed us to learn about the mass of the host galaxy as well. The early universe managed to produce some absolute monsters, even in relatively tiny galaxies.”

According to standard models, black holes form from the collapsed remnants of dead stars and accrete matter up to a predicted limit, known as the Eddington limit, where the pressure of radiation on matter overcomes the gravitational pull of the black hole. However, the sheer size of this black hole suggests that standard models may not adequately explain how these monsters form and grow.

“It’s possible that black holes are ‘born big’, which could explain why Webb has spotted huge black holes in the early universe,” said co-author Professor Roberto Maiolino, from the Kavli Institute and Cambridge’s Cavendish Laboratory. “But another possibility is they go through periods of hyperactivity, followed by long periods of dormancy.”

Working with colleagues from Italy, the Cambridge researchers conducted a range of computer simulations to model how this dormant black hole could have grown to such a massive size so early in the universe. They found that the most likely scenario is that black holes can exceed the Eddington limit for short periods, during which they grow very rapidly, followed by long periods of inactivity: the researchers say that black holes such as this one likely eat for five to ten million years, and sleep for about 100 million years.

“It sounds counterintuitive to explain a dormant black hole with periods of hyperactivity, but these short bursts allow it to grow quickly while spending most of its time napping,” said Maiolino.

Because the periods of dormancy are much longer than the periods of ultra-fast growth, it is in these periods that astronomers are most likely to detect black holes.

“This was the first result I had as part of my PhD, and it took me a little while to appreciate just how remarkable it was,” said Juodžbalis. “It wasn’t until I started speaking with my colleagues on the theoretical side of astronomy that I was able to see the true significance of this black hole.”

Due to their low luminosities, dormant black holes are more challenging for astronomers to detect, but the researchers say this black hole is almost certainly the tip of a much larger iceberg, if black holes in the early universe spend most of their time in a dormant state.

“It’s likely that the vast majority of black holes out there are in this dormant state – I’m surprised we found this one, but I’m excited to think that there are so many more we could find,” said Maiolino.

The observations were obtained as part of the JWST Advanced Deep Extragalactic Survey (JADES). The research was supported in part by the European Research Council and the Science and Technology Facilities Council (STFC), part of UK Research and Innovation (UKRI).

Bibliographic Information:

“A dormant, overmassive black hole in the early Universe”, by Ignas Juodžbalis, Roberto Maiolino, William M. Baker, Sandro Tacchella, Jan Scholtz, Francesco D’Eugenio, Raffaella Schneider, Alessandro Trinca, Rosa Valiante, Christa DeCoursey, Mirko Curti, Stefano Carniani, Jacopo Chevallard, Anna de Graaff, Santiago Arribas, Jake S. Bennett, Martin A. Bourne, Andrew J. Bunker, Stephane Charlot, Brian Jiang, Sophie Koudmani, Michele Perna, Brant Robertson, Debora Sijacki, Hannah Ubler, Christina C. Williams, Chris Willott, Joris Witstok, has been published on Nature (18-Dec-2024).

Press release from the University of Cambridge

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Astronomy

Webb detects most distant black hole merger to date in the ZS7 galaxy system

By ScientifiCult 16 May 2024

Webb detects most distant black hole merger to date in the ZS7 galaxy system

An international team of astronomers have used the NASA/ESA/CSA James Webb Space Telescope to find evidence for an ongoing merger of two galaxies and their massive black holes when the Universe was only 740 million years old. This marks the most distant detection of a black hole merger ever obtained and the first time that this phenomenon has been detected so early in the Universe.

Three panels are shown showing an increasingly small area of the PRIMER galaxy field. The first image shows a large field of galaxies on the black background of space. The second image shows a smaller region from this field, revealing the galaxies in closer detail, appearing in a variety of shapes and colours. The final image shows the ZS7 galaxy system, revealing the ionised hydrogen emission in orange and the doubly ionised oxygen emission in dark red. — This image shows the location of the galaxy system ZS7 from the JWST PRIMER programme (PI: J. Dunlop). New research using the NIRSpec instrument on the NASA/ESA/CSA James Webb Space Telescope have determined the system to be evidence of an ongoing merger of two galaxies and their massive black holes when the Universe was only 740 million years old. This marks the most distant detection of a black hole merger ever obtained and the first time that this phenomenon has been detected so early in the Universe.
The team has found evidence for very dense gas with fast motions in the vicinity of the black hole, as well as hot and highly ionised gas illuminated by the energetic radiation typically produced by black holes in their accretion episodes. Webb also allowed the team to spatially separate the two black holes and determined that one of the two black holes has a mass that is 50 million times the mass of the Sun. The mass of the other black hole is likely similar, although it is harder to measure because this second black hole is buried in dense gas.
In this Webb NIRCam image, the ionised hydrogen (Hβ) emission in the ZS7 system is identified by the orange region and the doubly ionised oxygen (OIII) emission is visible in dark red (right image).
Credit: ESA/Webb, NASA, CSA, J. Dunlop, D. Magee, P. G. Pérez-González, H. Übler, R. Maiolino, et al.

Astronomers have found supermassive black holes with masses of millions to billions times that of the Sun in most massive galaxies in the local Universe, including in our Milky Way galaxy. These black holes have likely had a major impact on the evolution of the galaxies they reside in. However, scientists still don’t fully understand how these objects grew to become so massive. The finding of gargantuan black holes already in place in the first billion years after the Big Bang indicates that such growth must have happened very rapidly, and very early. Now, the James Webb Space Telescope is shedding new light on the growth of black holes in the early Universe.

The new Webb observations have provided evidence for an ongoing merger of two galaxies and their massive black holes when the Universe was just 740 million years old. The system is known as ZS7.

Massive black holes that are actively accreting matter have distinctive spectrographic features that allow astronomers to identify them. For very distant galaxies, like those in this study, these signatures are inaccessible from the ground and can only be seen with Webb.

“We found evidence for very dense gas with fast motions in the vicinity of the black hole, as well as hot and highly ionised gas illuminated by the energetic radiation typically produced by black holes in their accretion episodes,” explained lead author Hannah Übler of the University of Cambridge in the United Kingdom. “Thanks to the unprecedented sharpness of its imaging capabilities, Webb also allowed our team to spatially separate the two black holes.”

The team found that one of the two black holes has a mass that is 50 million times the mass of the Sun.

“The mass of the other black hole is likely similar, although it is much harder to measure because this second black hole is buried in dense gas,”

explained team member Roberto Maiolino of the University of Cambridge and University College London in the United Kingdom.

“Our findings suggest that merging is an important route through which black holes can rapidly grow, even at cosmic dawn,” explained Übler. “Together with other Webb findings of active, massive black holes in the distant Universe, our results also show that massive black holes have been shaping the evolution of galaxies from the very beginning.”

“The stellar mass of the system we studied is similar to that of our neighbor the Large Magellanic Cloud,” shared team member Pablo G. Pérez-González of the Centro de Astrobiología (CAB), CSIC/INTA, in Spain. “We can try to imagine how the evolution of merging galaxies could be affected if each galaxy had one super massive black hole as large or larger than the one we have in the Milky Way”.

This image features the ZS7 galaxy system, showing a large field of hundreds of galaxies on the black background of space. — This image shows the environment of the galaxy system ZS7 from the JWST PRIMER programme (PI: J. Dunlop) as seen by Webb’s NIRCam instrument.
New research using the NIRSpec instrument on the NASA/ESA/CSA James Webb Space Telescope has determined the system to be evidence of an ongoing merger of two galaxies and their massive black holes when the Universe was only 740 million years old. This marks the most distant detection of a black hole merger ever obtained and the first time that this phenomenon has been detected so early in the Universe.
The team has found evidence for very dense gas with fast motions in the vicinity of the black hole, as well as hot and highly ionised gas illuminated by the energetic radiation typically produced by black holes in their accretion episodes. Webb also allowed the team to spatially separate the two black holes and determined that one of the two black holes has a mass that is 50 million times the mass of the Sun. The mass of the other black hole is likely similar, although it is harder to measure because this second black hole is buried in dense gas.
Credit: ESA/Webb, NASA, CSA, J. Dunlop, D. Magee, P. G. Pérez-González, H. Übler, R. Maiolino, et al.

The team also notes that once the two black holes merge, they will also generate gravitational waves [1]. Events like this will be detectable with the next generation of gravitational wave observatories, such as the upcoming Laser Interferometer Space Antenna (LISA) mission, which was recently approved by the European Space Agency and will be the first space-based observatory dedicated to studying gravitational waves.

“Webb’s results are telling us that lighter systems detectable by LISA should be far more frequent than previously assumed,” shared LISA Lead Project Scientist Nora Luetzgendorf of the European Space Agency in the Netherlands. “It will most likely make us adjust our models for LISA rates in this mass range. This is just the tip of the iceberg.”

This discovery was from observations made as part of the Galaxy Assembly with NIRSpec Integral Field Spectroscopy programme. The team has recently been awarded a new Large Programme in Webb’s Cycle 3 of observations, to study in detail the relationship between massive black holes and their host galaxies in the first billion years. An important component of this programme will be to systematically search for and characterise black hole mergers. This effort will determine the rate at which black hole merging occurs at early cosmic epochs and will assess the role of merging in the early growth of black holes and the rate at which gravitational waves are produced from the dawn of time.

These results have been published in the Monthly Notices of the Royal Astronomical Society.

Notes

[1] Gravitational waves are invisible ripples in the fabric of spacetime. Spacetime is a four-dimensional quantity, described by Einstein’s general theory of relativity, which fuses three-dimensional space with time. Mass warps spacetime, and gravity is actually the result of spacetime being curved by an object’s mass. Ripples through spacetime are created by the movement of any object with mass, and these are known as gravitational waves. Gravitational waves are constantly passing unnoticed through Earth and they are caused by some of the most violent and energetic events in the Universe. These include colliding black holes, collapsing stellar cores, merging neutron stars or white dwarf stars, the wobble of neutron stars that are not perfect spheres and possibly even the remnants of gravitational radiation created at the birth of the Universe.

Press release from ESA Webb.

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Webb unlocks secrets of GN-z11, one of the most distant galaxies ever seen

By ScientifiCult 4 March 2024

Webb unlocks secrets of GN-z11, one of the most distant galaxies ever seen

Looking deep into space and time, two teams using the NASA/ESA/CSA James Webb Space Telescope have studied the exceptionally luminous galaxy GN-z11, which existed when our 13.8 billion-year-old Universe was only about 430 million years old.

A rectangular image with thousands of galaxies of various shapes and colours on the black background of space. Some are noticeably spirals, either face-on or edge-on, while others are blobby ellipticals. Many are too small to discern any structure. One prominent foreground star at top centre features Webb’s signature eight-point diffraction spikes. — This image from Webb’s NIRCam (Near-Infrared Camera) instrument shows a portion of the GOODS-North field of galaxies.
Credit: NASA, ESA, CSA, B. Robertson (UC Santa Cruz), B. Johnson (CfA), S. Tacchella (Cambridge), M. Rieke (University of Arizona), D. Eisenstein (CfA)

Delivering on its promise to transform our understanding of the early Universe, the James Webb Space Telescope is probing galaxies near the dawn of time. One of these is the exceptionally luminous galaxy GN-z11, which existed when the Universe was just a tiny fraction of its current age. Initially detected with the NASA/ESA Hubble Space Telescope, it is one of the youngest and most distant galaxies ever observed, and it is also one of the most enigmatic. Why is it so bright? Webb appears to have found the answer.

A team studying GN-z11 with Webb found the first clear evidence that the galaxy is hosting a central, supermassive black hole that is rapidly accreting matter. Their finding makes this the most distant active supermassive black hole spotted to date.

“We found extremely dense gas that is common in the vicinity of supermassive black holes accreting gas,” explained principal investigator Roberto Maiolino of the Cavendish Laboratory and the Kavli Institute of Cosmology at the University of Cambridge in the United Kingdom. “These were the first clear signatures that GN-z11 is hosting a black hole that is gobbling matter.”

Using Webb, the team also found indications of ionised chemical elements typically observed near accreting supermassive black holes. Additionally, they discovered that the galaxy is expelling a very powerful wind. Such high-velocity winds are typically driven by processes associated with vigorously accreting supermassive black holes.

“Webb’s NIRCam (Near-Infrared Camera) has revealed an extended component, tracing the host galaxy, and a central, compact source whose colours are consistent with those of an accretion disc surrounding a black hole,” said investigator Hannah Übler, also of the Cavendish Laboratory and the Kavli Institute.

Together, this evidence shows that GN-z11 hosts a two-million-solar-mass, supermassive black hole in a very active phase of consuming matter, which is why it’s so luminous.

A second team, also led by Maiolino, used Webb’s NIRSpec (Near-Infrared Spectrograph) to find a gaseous clump of helium in the halo surrounding GN-z11.

“The fact that we don’t see anything else beyond helium suggests that this clump must be fairly pristine,” said Maiolino. “This is something that was expected by theory and simulations in the vicinity of particularly massive galaxies from these epochs — that there should be pockets of pristine gas surviving in the halo, and these may collapse and form Population III star clusters.”

A graphic labelled Galaxy GN-z11, Pristine Gas Clump Near GN-z11. The graphic is divided into two sections. The top half of the graphic features a rectangular image of a field of galaxies with two pullouts, the second of them labelled Helium Two Detected. The bottom half shows a single line graph. — This two-part graphic shows evidence of a gaseous clump of helium in the halo surrounding the galaxy GN-z11. In the top portion, at the far right, a small box identifies GN-z11 in a field of galaxies. The middle box shows a zoomed-in image of the galaxy. The box at the far left displays a map of the helium gas in the halo of GN-z11, including a clump that does not appear in the infrared colours shown in the middle panel. In the lower half of the graphic, a spectrum shows the distinct ‘fingerprint’ of helium in the halo. The full spectrum shows no evidence of other elements and so suggests that the helium clump must be fairly pristine, made almost entirely of hydrogen and helium gas left over from the Big Bang, without much contamination from heavier elements produced by stars. Theory and simulations in the vicinity of particularly massive galaxies from these epochs predict that there should be pockets of pristine gas surviving in the halo, and these may collapse and form Population III star clusters.
Credit: NASA, ESA, CSA, Ralf Crawford (STScI)

Finding the so far unseen Population III stars [1] — the first generation of stars formed almost entirely from hydrogen and helium — is one of the most important goals of modern astrophysics. These stars are expected to be very massive, very luminous, and very hot. Their signature would be the presence of ionised helium and the absence of chemical elements heavier than helium.

The formation of the first stars and galaxies marks a fundamental shift in cosmic history, during which the Universe evolved from a dark and relatively simple state into the highly structured and complex environment we see today.

In future Webb observations, Maiolino, Übler, and their team will explore GN-z11 in greater depth, and they hope to strengthen the case for the Population III stars that may be forming in its halo.

The research on the pristine gas clump in GN-z11’s halo has been accepted for publication in Astronomy & Astrophysics. The results of the study of GN-z11’s black hole were published in the journal Nature on 17 January 2024. The data was obtained as part of the JWST Advanced Deep Extragalactic Survey (JADES), a joint project between the NIRCam and NIRSpec teams.

Notes

[1] The name Population III arose because astronomers had already classified the stars of the Milky Way as Population I (stars like the Sun, which are rich in heavier elements) and Population II (older stars with a low heavy-element content, found in the Milky Way bulge and halo, and in globular star clusters).

A rectangular image shows thousands of galaxies of various shapes and colours on the black background of space. The pullout features a galaxy labelled GN-z11, seen as a fuzzy yellow dot. Above it is another galaxy, seen as a fuzzy red oval. To the left of the small box, a scale bar is labelled 60 arcseconds. It extends about one tenth of the way across the image. Below the image, a list of NIRCam filters show what colours were used to make the image. Filters shown in blue are F090W, F115W, and F150W. Filters shown in green are F200W, F277W, and F335M. Filters shown in red are F356W, F410M, and F444W. — This image of the GOODS-North field, captured by Webb’s Near-Infrared Camera (NIRCam), shows compass arrows, a scale bar, and a colour key for reference.
The north and east compass arrows show the orientation of the image on the sky. Note that the relationship between north and east on the sky (as seen from below) is flipped relative to direction arrows on a map of the ground (as seen from above).
The scale bar is labelled in angular distance on the sky, where one arcsecond is one 3600th of a degree. The scale bar is 60 arcseconds long.
This image shows invisible near-infrared wavelengths of light that have been translated into visible-light colours. The colour key shows which NIRCam filters were used when collecting the light. The colour of each filter name is the visible light colour used to represent the infrared light that passes through that filter.
Credit: NASA, ESA, CSA, B. Robertson (UC Santa Cruz), B. Johnson (CfA), S. Tacchella (Cambridge), M. Rieke (University of Arizona), D. Eisenstein (CfA)

Press release from ESA Webb.

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Galaxy mergers are the solution to the early Universe mystery concerning the Lyman-α emission

By ScientifiCult 18 January 2024

Webb reveals that galaxy mergers are the solution to the early Universe mystery concerning the Lyman-α emission

One of the key missions of the NASA/ESA/CSA James Webb Space Telescope is to probe the early Universe. Now, the unmatched resolution and sensitivity of Webb’s NIRCam instrument have revealed, for the first time, what lies in the local environment of galaxies in the very early Universe. This has solved one of the most puzzling mysteries in astronomy — why astronomers detect light from hydrogen atoms which should have been entirely blocked by the pristine gas that formed after the Big-Bang. These new Webb observations have found small, faint objects surrounding the very galaxies that show the ‘inexplicable’ hydrogen emission. In conjunction with state-of-the-art simulations of galaxies in the early Universe, the observations have shown that the chaotic merging of these neighbouring galaxies is the source of this hydrogen emission.

A close-in view of three neighbouring galaxies. They appear as coloured blobs with bright, distinct cores. The image is mostly black, with a few unrelated galaxies visible nearby. — This image shows the galaxy EGSY8p7, a bright galaxy in the early Universe where light emission is seen from, among other things, excited hydrogen atoms — Lyman-α emission. Webb’s high sensitivity picks out this distant galaxy along with its two companion galaxies, where previous observations saw only one larger galaxy in its place.
This discovery of a cluster of interacting galaxies sheds light on the mystery of why the hydrogen emission from EGSY8p7, shrouded in neutral gas formed after the Big Bang, should be visible at all. Astronomers have concluded that the intense star-forming activity within these interacting galaxies energised hydrogen emission and cleared swathes of gas from their surroundings, allowing the unexpected hydrogen emission to escape.
This close-up view of EGSY8p7 has been newly processed, making use of NIRCam data captured with seven different near-infrared filters.
Credit: ESA/Webb, NASA & CSA, C. Witten, M. Zamani (ESA/Webb)

Light travels at a finite speed (300 000 kilometres per second), which means that the further away a galaxy is, the longer it has taken the light from it to reach our Solar System. As a result, not only do observations of the most distant galaxies probe the far reaches of the Universe, but they also allow us to study the Universe as it was in the past. In order to study the very early Universe, astronomers require exceptionally powerful telescopes that are capable of observing very distant — and therefore very faint — galaxies. One of Webb’s key capabilities is its ability to observe those very distant galaxies, and hence to probe the early history of the Universe. An international team of astronomers have put Webb’s amazing capacity to excellent use in solving a long-standing mystery in astronomy.

The very earliest galaxies were sites of vigorous and active star formation, and as such were rich sources of a type of light emitted by hydrogen atoms called Lyman-α emission [1]. However, during the epoch of reionisation [2] an immense amount of neutral hydrogen gas surrounded these areas of active star formation (also known as stellar nurseries). Furthermore, the space between galaxies was filled by more of this neutral gas than is the case today. The gas can very effectively absorb and scatter this kind of hydrogen emission [3], so astronomers have long predicted that the abundant Lyman-α emission released in the very early Universe should not be observable today. This theory has not always stood up to scrutiny, however, as examples of very early hydrogen emission have previously been observed by astronomers. This has presented a mystery: how is it that this hydrogen emission — that should have long since been absorbed or scattered — is being observed? Researcher at the University of Cambridge and principal investigator on the new study Callum Witten elaborates:

“One of the most puzzling issues that previous observations presented was the detection of light from hydrogen atoms in the very early Universe, which should have been entirely blocked by the pristine neutral gas that was formed after the Big-Bang. Many hypotheses have previously been suggested to explain the great escape of this ‘inexplicable’ emission.”

A graphic with three images. The top image, labelled “CEERS survey”, shows many square images of stars and galaxies, stitched together according to their locations in the sky. One square is highlighted, and a cutout on the bottom left shows it enlarged, labelled “Webb/ NIRCam”. A tiny spot is shown zoomed-in to the right, labelled “EGSY8p7” with a scale marker of “0.5 arcsec”. Here it can be seen that the spot is three neighbouring galaxies, appearing as coloured blobs with bright, distinct cores. — This image shows the galaxy EGSY8p7, a bright galaxy in the early Universe where light emission is seen from, among other things, excited hydrogen atoms — Lyman-α emission. The galaxy was identified in a field of young galaxies studied by Webb in the CEERS survey. In the bottom two panels, Webb’s high sensitivity picks out this distant galaxy along with its two companion galaxies, where previous observations saw only one larger galaxy in its place.
This discovery of a cluster of interacting galaxies sheds light on the mystery of why the hydrogen emission from EGSY8p7, shrouded in neutral gas formed after the Big Bang, should be visible at all. Astronomers have concluded that the intense star-forming activity within these interacting galaxies energised hydrogen emission and cleared swathes of gas from their surroundings, allowing the unexpected hydrogen emission to escape.
This graphic is assembled from multiple images captured by Webb’s NIRCam instrument as part of the CEERS survey. The close-up view of EGSY8p7 was newly processed for this image, making use of NIRCam data captured with seven different near-infrared filters.
Credit: ESA/Webb, NASA & CSA, S. Finkelstein (UT Austin), M. Bagley (UT Austin), R. Larson (UT Austin), A. Pagan (STScI), C. Witten, M. Zamani (ESA/Webb)

The team’s breakthrough came thanks to Webb’s extraordinary combination of angular resolution and sensitivity. The observations with Webb’s NIRCam instrument were able to resolve smaller, fainter galaxies that surround the bright galaxies from which the ‘inexplicable’ hydrogen emission had been detected. In other words, the surroundings of these galaxies appear to be a much busier place than we previously thought, filled with small, faint galaxies. Crucially, these smaller galaxies were interacting and merging with one another, and Webb has revealed that galaxy mergers play an important role in explaining the mystery emission from the earliest galaxies. Sergio Martin-Alvarez, team member from Stanford University, adds:

“Where Hubble was seeing only a large galaxy, Webb sees a cluster of smaller interacting galaxies, and this revelation has had a huge impact on our understanding of the unexpected hydrogen emission from some of the first galaxies.”

The team then used state-of-the-art computer simulations to explore the physical processes that might explain their results. They found that the rapid build-up of stellar mass through galaxy mergers both drove strong hydrogen emission and facilitated the escape of that radiation via channels cleared of the abundant neutral gas. So the high merger rate of the previously unobserved smaller galaxies presented a compelling solution to the long-standing puzzle of the ‘inexplicable’ early hydrogen emission.

The team are planning follow up observations with galaxies at various stages of merging, in order to continue to develop their understanding of how the hydrogen emission is ejected from these changing systems. Ultimately, this will enable them to improve our understanding of galaxy evolution.

These findings have been published today in Nature Astronomy.

Notes

[1] Lyman-α emission is light emitted at a wavelength of 121.567 nanometres when the electron in an excited hydrogen atom drops from an excited state in the n = 2 orbital down to its ground state n = 1 (the lowest energy state the atom can have). Quantum physics dictates that electrons can only exist in very specific energy states, and this means that certain energy transitions — such as when the electron in a hydrogen atom drops from orbital n = 2 to n = 1 — can be identified by the wavelength of the light emitted during that transition. Lyman-α emission is important in many branches of astronomy, partly because hydrogen is so abundant in the Universe, and also because hydrogen is typically excited by energetic processes such as ongoing active star formation. Accordingly, Lyman-α emission can be used as a sign that active star formation is taking place.

[2] The epoch of reionisation was a very early stage in the Universe’s history that took place after recombination (the first stage following the Big Bang). During recombination, the Universe cooled enough that electrons and protons began to combine to form neutral hydrogen atoms. During reionisation, denser clouds of gas started to form, creating stars and eventually entire galaxies whose light gradually reionised the hydrogen gas..

[3] Neutral hydrogen gas is made of hydrogen atoms that are in the lowest energy state they can be, each with their electron in orbital n = 1. Since the light emitted by a hydrogen atom during Lyman-α emission carries the energy of the atomic transition from orbital n = 2 down to n = 1, when it strikes a neutral hydrogen atom, it has exactly the right amount of energy to ionise the atom and take its electron up to the next available orbital. This means the neutral gas absorbs and blocks Lyman-α emission very easily.

Press release from ESA Webb.

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Webb discovers methane, carbon dioxide in atmosphere of K2-18 b

By ScientifiCult 11 September 2023

Webb discovers methane, carbon dioxide in atmosphere of K2-18 b

A new investigation by an international team of astronomers using data from the NASA/ESA/CSA James Webb Space Telescope into K2-18 b, an exoplanet 8.6 times as massive as Earth, has revealed the presence of carbon-bearing molecules including methane and carbon dioxide. The discovery adds to recent studies suggesting that K2-18 b could be a Hycean exoplanet, one which has the potential to possess a hydrogen-rich atmosphere and a water ocean-covered surface.

methane carbon dioxide K2-18 b — This artist’s concept shows what exoplanet K2-18 b could look like based on science data. K2-18 b, an exoplanet 8.6 times as massive as Earth, orbits the cool dwarf star K2-18 in the habitable zone and lies 120 light-years from Earth. A new investigation with the NASA/ESA/CSA James Webb Space Telescope into K2-18 b has revealed the presence of carbon-bearing molecules including methane and carbon dioxide. The abundance of methane and carbon dioxide, and shortage of ammonia, support the hypothesis that there may be an ocean underneath a hydrogen-rich atmosphere in K2-18 b.
Credit:
NASA, CSA, ESA, J. Olmstead (STScI), N. Madhusudhan (Cambridge University)

The first insight into the atmospheric properties of this habitable-zone exoplanet came from observations with the NASA/ESA Hubble Space Telescope, which prompted further studies that have since changed our understanding of the system.

K2-18 b orbits the cool dwarf star K2-18 in the habitable zone and lies 120 light-years from Earth in the constellation Leo. Exoplanets such as K2-18 b, which have sizes between those of Earth and Neptune, are unlike anything in our Solar System. This lack of equivalent nearby planets means that these ‘sub-Neptunes’ are poorly understood, and the nature of their atmospheres is a matter of active debate among astronomers. Exoplanets such as K2-18 b, which have sizes between those of Earth and Neptune, are unlike anything in our Solar System. This lack of analogous nearby planets means that these ‘sub-Neptunes’ are poorly understood and the nature of their atmospheres is a matter of active debate between astronomers. The suggestion that the sub-Neptune K2-18 b could be a Hycean exoplanet is intriguing, as some astronomers believe that these worlds are promising environments to search for evidence for life on exoplanets.

“Our findings underscore the importance of considering diverse habitable environments in the search for life elsewhere,”

explained Nikku Madhusudhan, an astronomer at the University of Cambridge and lead author of the paper announcing these results.

“Traditionally, the search for life on exoplanets has focused primarily on smaller rocky planets, but the larger Hycean worlds are significantly more conducive to atmospheric observations.“

The abundance of methane and carbon dioxide, and shortage of ammonia, support the hypothesis that there may be an ocean underneath a hydrogen-rich atmosphere on K2-18 b. These initial Webb observations also provided a possible detection of a molecule called dimethyl sulphide (DMS). On Earth, this is only produced by life. The bulk of the DMS in Earth’s atmosphere is emitted from phytoplankton in marine environments.

The inference of DMS is less robust and requires further validation.

“Upcoming Webb observations should be able to confirm if DMS is indeed present in the atmosphere of K2-18 b at significant levels,” explained Madhusudhan.

While K2-18 b lies in the habitable zone and is now known to harbour carbon-bearing molecules, this does not necessarily mean that the planet can support life. The planet’s large size — with a radius 2.6 times the radius of Earth — means that the planet’s interior likely contains a large mantle of high-pressure ice, like Neptune, but with a thinner hydrogen-rich atmosphere and an ocean surface. Hycean worlds are predicted to have oceans of water. However, it is also possible that the ocean is too hot to be habitable or be liquid.

“Although this kind of planet does not exist in our solar system, sub-Neptunes are the most common type of planet known so far in the galaxy,” explained team member Subhajit Sarkar of Cardiff University. “We have obtained the most detailed spectrum of a habitable-zone sub-Neptune to date, and this allowed us to work out the molecules that exist in its atmosphere.”

Characterising the atmospheres of exoplanets like K2-18 b — meaning identifying their gases and physical conditions — is a very active area in astronomy. However, these planets are outshone — literally — by the glare of their much larger parent stars, which makes exploring exoplanet atmospheres particularly challenging.

The team sidestepped this challenge by analysing light from K2-18 b’s parent star as it passed through the exoplanet’s atmosphere. K2-18 b is a transiting exoplanet, meaning that we can detect a drop in brightness as it passes across the face of its host star. This is how the exoplanet was first discovered. This means that during transits a tiny fraction of starlight will pass through the exoplanet’s atmosphere before reaching telescopes like Webb. The starlight’s passage through the exoplanet atmosphere leaves traces that astronomers can piece together to determine the gases of the exoplanet’s atmosphere.

“This result was only possible because of the extended wavelength range and unprecedented sensitivity of Webb, which enabled robust detection of spectral features with just two transits,” continued Madhusudhan. “For comparison, one transit observation with Webb provided comparable precision to eight observations with Hubble conducted over a few years and in a relatively narrow wavelength range.”

“These results are the product of just two observations of K2-18 b, with many more on the way,” explained team member Savvas Constantinou of the University of Cambridge. “This means our work here is but an early demonstration of what Webb can observe in habitable-zone exoplanets.”

The team now intends to conduct follow-up research with the telescope’s Mid-InfraRed Instrument (MIRI) spectrograph that they hope will further validate their findings and provide new insights into the environmental conditions on K2-18 b.

“Our ultimate goal is the identification of life on a habitable exoplanet, which would transform our understanding of our place in the Universe,” concluded Madhusudhan. “Our findings are a promising step towards a deeper understanding of Hycean worlds in this quest.”

Spectrum of K2-18 b, obtained with Webb’s NIRISS (Near-Infrared Imager and Slitless Spectrograph) and NIRSpec (Near-Infrared Spectrograph), displays an abundance of methane and carbon dioxide in the exoplanet’s atmosphere, as well as a possible detection of a molecule called dimethyl sulfide (DMS). The detection of methane and carbon dioxide, and shortage of ammonia, are consistent with the presence of an ocean underneath a hydrogen-rich atmosphere in K2-18 b. K2-18 b, 8.6 times as massive as Earth, orbits the cool dwarf star K2-18 in the habitable zone and lies 120 light-years from Earth.
Credit:
NASA, CSA, ESA, J. Olmstead (STScI), N. Madhusudhan (Cambridge University)

The team’s results are accepted for publication in The Astrophysical Journal Letters.

Notes

[1] The Habitable Zone is the region around a star where the conditions could potentially be suitable to sustain life on a planet within this region, for example allowing the presence of liquid water on its surface.

Press release from ESA Webb

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Webb sees carbon-rich dust grains at redshift, in the first billion years of cosmic time

By ScientifiCult 19 July 2023

Webb sees carbon-rich dust grains at redshift, in the first billion years of cosmic time

For the first time, the NASA/ESA/CSA James Webb Space Telescope has observed the chemical signature of carbon-rich dust grains at redshift ~ 7 [1], which is roughly equivalent to one billion years after the birth of the Universe [2]. Similar observational signatures have been observed in the much more recent Universe, attributed to complex, carbon-based molecules known as polycyclic aromatic hydrocarbons (PAHs). It is not thought likely, however, that PAHs would have developed within the first billion years of cosmic time. Therefore, this observation suggests the exciting possibility that Webb may have observed a different species of carbon-based molecule: possibly minuscule graphite- or diamond-like grains produced by the earliest stars or supernovae. This observation suggests exciting avenues of investigation into both the production of cosmic dust and the earliest stellar populations in our Universe, and was made possible by Webb’s unprecedented sensitivity.

The seemingly empty spaces in our Universe are in reality often not empty at all, but occupied by clouds of gas and cosmic dust. This dust consists of grains of various sizes and compositions that are formed and ejected into space in a variety of ways, including by supernova events. This material is crucial to the evolution of the Universe, as dust clouds ultimately form the birthplaces for new stars and planets. However, it can also be a hindrance to astronomers: the dust absorbs stellar light at certain wavelengths, making some regions of space very challenging to observe. An upside, however, is that certain molecules will very consistently absorb or otherwise interact with specific wavelengths of light. This means that astronomers can acquire information about the cosmic dust’s composition by observing the wavelengths of light that it blocks. An international team of astronomers used this technique, combined with Webb’s extraordinary sensitivity, to detect the presence of carbon-rich dust grains only a billion years after the birth of the Universe.

Joris Witstok of the University of Cambridge, the lead author of this work, elaborates: “Carbon-rich dust grains can be particularly efficient at absorbing ultraviolet light with a wavelength around 217.5 nanometres, which for the first time we have directly observed in the spectra of very early galaxies.”

This prominent 217.5-nanometre feature has previously been observed in the much more recent and local Universe, both within our own Milky Way galaxy, and in galaxies up to redshift ~ 3 [1]. It has been attributed to two different types of carbon-based species: polycyclic aromatic hydrocarbons (PAHs) or nano-sized graphitic grains. PAHs are complex molecules, and modern models predict that it should take several hundreds of millions of years before they form. It would be surprising, therefore, if the team had observed the chemical signature of a mixture of dust grains that include species that were unlikely to have formed yet. However, according to the science team, this result is the earliest and most distant direct signature for this particular type of carbon-rich dust grain.

The answer may lie in the details of what was observed. As already stated, the feature associated with the cosmic dust mixture of PAHs and tiny graphitic grains is at 217.5 nanometres. However, the feature observed by the team actually peaked at 226.3 nanometres. A nanometre is a millionth of a millimetre, and this discrepancy of less than ten nanometres could be accounted for by measurement error [3]. Equally, it could also indicate a difference in the composition of the early-Universe cosmic dust mixture that the team detected.

“This slight shift in wavelength of where the absorption is strongest suggests we may be seeing a different mix of grains, for example graphite- or diamond-like grains,” adds Witstok. “This could also potentially be produced on short timescales by Wolf-Rayet stars or supernova ejecta.”

The detection of this feature in the early Universe is surprising, and allows astronomers to postulate about the mechanisms that could create such a mix of dust grains. This involves drawing on existing knowledge from observations and models. Witstok suggests diamond grains formed in supernova ejecta because models have previously suggested that nano-diamonds could be formed this way. Wolf-Rayet stars are suggested because they are exceptionally hot towards the end of their lives, and very hot stars tend to live fast and die young; giving enough time for generations of stars to have been born, lived, and died, to distribute carbon-rich grains into the surrounding cosmic dust in under a billion years. Models have also shown that carbon-rich grains can be produced by certain types of Wolf-Rayet stars, and just as importantly that those grains can survive the violent deaths of those stars. However, it is still a challenge to fully explain these results with the existing understanding of the early formation of cosmic dust. These results will therefore go on to inform the development of improved models and future observations.

Before Webb, the observations of multiple galaxies had to be combined in order to get signals strong enough to make deductions about the stellar populations in the galaxies, and to learn about how their light was affected by dust absorption. Importantly, astronomers were restricted to studying relatively old and mature galaxies that had had a long time to form stars as well as dust. This limited their ability to really pin down the key sources of cosmic dust. With the advent of Webb, astronomers are now able to make very detailed observations of the light from individual dwarf galaxies, seen in the first billion years of cosmic time. Webb finally permits the study of the origin of cosmic dust and its role in the crucial first stages of galaxy evolution.

“This discovery was made possible by the unparalleled sensitivity improvement in near-infrared spectroscopy provided by Webb, and specifically its Near-Infrared Spectrograph (NIRSpec),” noted team member Roberto Maiolino of the University of Cambridge and University College London. “The increase in sensitivity provided by Webb is equivalent, in the visibile, to instantaneously upgrading Galileo’s 37-millimetre telescope to the 8-metre Very Large Telescope (one of the most powerful modern optical telescopes).”

NIRSpec was built for the European Space Agency by a consortium of European companies led by Airbus Defence and Space (ADS) with NASA’s Goddard Space Flight Centre providing its detector and micro-shutter subsystems. The primary goal of NIRSpec is to enable large spectroscopic surveys of astronomical objects such as stars or distant galaxies. This is made possible by its powerful multi-object spectroscopy mode, which makes use of microshutters. This mode is capable of obtaining spectra of up to nearly 200 objects simultaneously, over a 3.6 × 3.4 arcminute field of view — the first time this capability has been provided from space. This mode makes for very efficient use of Webb’s valuable observing time.

The team is also planning further research into the data and this result.

“We are planning to work further with theorists who model dust production and growth in galaxies,” shares team member Irene Shivaei of the University of Arizona/Centro de Astrobiología (CAB). “This will shed light on the origin of dust and heavy elements in the early Universe.”

These observations were made as part of the JWST Advanced Deep Extragalactic Survey, or JADES, which devoted about 32 days of telescope time to uncovering and characterising faint, distant galaxies. This programme has facilitated the discovery of hundreds of galaxies that existed when the Universe was less than 600 million years old, including some of the farthest galaxies known to date. The sheer number and maturity of these galaxies was far beyond predictions from observations made before Webb’s launch. This new result of early-Universe dust grains contributes to our growing and evolving understanding of the evolution of stellar populations and galaxies during the first billion years of cosmic time.

“This discovery implies that infant galaxies in the early Universe develop much faster than we ever anticipated,” adds team member Renske Smit of the Liverpool John Moores University in the United Kingdom. “Webb shows us a complexity of the earliest birth-places of stars (and planets) that models are yet to explain.“

The results have been published today in Nature.

The infrared image shown here was taken as part of the JADES programme (the JWST Advanced Deep Extragalactic Survey) and shows a portion of an area of the sky known as GOODS-South.
This region was the focus area of Webb study for an international team of astronomers, who observed the chemical signature of carbon-rich dust grains at redshift ~7. This is roughly equivalent to one billion years after the birth of the Universe. Similar observational signatures have been observed in the much more recent Universe, attributed to complex, carbon-based molecules known as polycyclic aromatic hydrocarbons (PAHs). It is not thought likely, however, that PAHs would have developed within the first billion years of cosmic time. Therefore, this observation suggests the exciting possibility that Webb may have observed a different species of carbon-based molecule: possibly minuscule graphite- or diamond-like grains produced by the earliest stars or supernovae. This observation suggests exciting avenues of investigation into both the production of cosmic dust and the earliest stellar populations in our Universe, and was made possible by Webb’s unprecedented sensitivity.
In this image, blue, green, and red were assigned to Webb’s NIRCam (Near-Infrared Camera) data at 0.9, 1.15, and 1.5 microns; 2.0, 2.77, and 3.55 microns; and 3.56, 4.1, and 4.44 microns (F090W, F115W, and F150W; F200W, F277W, and F335M; and F356W, F410M, and F444W), respectively.
Credit:
ESA/Webb, NASA, ESA, CSA, B. Robertson (UC Santa Cruz), B. Johnson (Center for Astrophysics, Harvard & Smithsonian), S. Tacchella (University of Cambridge, M. Rieke (Univ. of Arizona), D. Eisenstein (Center for Astrophysics, Harvard & Smithsonian), A. Pagan (STScI)

Notes

[1] The Universe is expanding. The expansion is taking place at the fundamental spacetime level, which means that light travelling through the Universe is ‘stretched’ as the Universe expands. The earlier in the Universe the light originated, the more it will have been stretched by now. Practically speaking, this stretching of light means its wavelength becomes longer. This effect is known as cosmological redshift, because the colour red has the longest wavelength of all light visible to human eyes. Because of this, cosmological time is often not measured in years, but is indicated by the redshift of the observed light. The very local Universe — where the light we observe was emitted recently and has not been notably redshifted — has a low redshift. Conversely, redshift 7 corresponds to light that was emitted about 13 billion years ago, in the very early Universe.

[2] Astronomy fundamentally involves the study of light, and light travels at a finite speed (roughly 300 million kilometres per second). Objects can only be observed by humans once light from them has reached Earth. Whilst in some ways providing a limitation, this also provides a direct opportunity to study the early as well as the present Universe. Studying light from the early Universe necessarily entails the observation of regions very distant from Earth from which it takes a huge amount of time for light to travel to us. Thus, probing these early cosmological times (or high redshifts) requires very sensitive telescopes.

[3] All scientific measurements — including those from observations and those predicted by models — will have an associated error. This is because there will always be sources of uncertainty. If a measurement falls within the bounds of the expected error, it means that it could still be accurate: in this context, that means the 226.3 nanometre feature could still account for the same mix of cosmic dust as that represented by the 217.5 nanometre feature.

Press release from ESA Webb

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GJ 1132 b: Hubble sees new atmosphere forming on the rocky exoplanet

By ScientifiCult 13 March 2021

Hubble sees new atmosphere forming on a rocky exoplanet, GJ 1132 b

The planet GJ 1132 b appears to have begun life as a gaseous world with a thick blanket of atmosphere. Starting out at several times the radius of Earth, this so-called “sub-Neptune” quickly lost its primordial hydrogen and helium atmosphere, which was stripped away by the intense radiation from its hot, young star. In a short period of time, it was reduced to a bare core about the size of Earth.

To the surprise of astronomers, new observations from Hubble [1] have uncovered a secondary atmosphere that has replaced the planet’s first atmosphere. It is rich in hydrogen, hydrogen cyanide, methane and ammonia, and also has a hydrocarbon haze. Astronomers theorise that hydrogen from the original atmosphere was absorbed into the planet’s molten magma mantle and is now being slowly released by volcanism to form a new atmosphere. This second atmosphere, which continues to leak away into space, is continually being replenished from the reservoir of hydrogen in the mantle’s magma.

“This second atmosphere comes from the surface and interior of the planet, and so it is a window onto the geology of another world,” explained team member Paul Rimmer of the University of Cambridge, UK. “A lot more work needs to be done to properly look through it, but the discovery of this window is of great importance.”

Pictured here is the region around the host star of the exoplanet GJ 1132 b. Credit:
ESA/Hubble, Digitized Sky Survey 2, CC BY 4.0.
Acknowledgement: Davide De Martin

“We first thought that these highly radiated planets would be pretty boring because we believed that they lost their atmospheres,” said team member Raissa Estrela of the Jet Propulsion Laboratory at the California Institute of Technology in Pasadena, California, USA. But we looked at existing observations of this planet with Hubble and realised that there is an atmosphere there.”

“How many terrestrial planets don’t begin as terrestrials? Some may start as sub-Neptunes, and they become terrestrials through a mechanism whereby light evaporates the primordial atmosphere. This process works early in a planet’s life, when the star is hotter,” said team leader Mark Swain of the Jet Propulsion Laboratory. “Then the star cools down and the planet’s just sitting there. So you’ve got this mechanism that can cook off the atmosphere in the first 100 million years, and then things settle down. And if you can regenerate the atmosphere, maybe you can keep it.”

In some ways, GJ 1132 b has various parallels to Earth, but in some ways it is also very different. Both have similar densities, similar sizes, and similar ages, being about 4.5 billion years old. Both started with a hydrogen-dominated atmosphere, and both were hot before they cooled down. The team’s work even suggests that GJ 1132 b and Earth have similar atmospheric pressure at the surface.

This plot shows the spectrum of the atmosphere of an Earth sized rocky exoplanet, GJ 1132 b, which is overlaid on an artist’s impression of the planet. The orange line represents the model spectrum. In comparison, the observed spectrum is shown as blue dots representing averaged data points, along with their error bars. This analysis is consistent with GJ 1132 b being predominantly a hydrogen atmosphere with a mix of methane and hydrogen cyanide. The planet also has aerosols which cause scattering of light. This is the first time a so-called “secondary atmosphere,” which was replenished after the planet lost its primordial atmosphere, has been detected on a world outside of our solar system. Credit:
NASA, ESA, and P. Jeffries (STScI)

However, the planets’ formation histories are profoundly different. Earth is not believed to be the surviving core of a sub-Neptune. And Earth orbits at a comfortable distance from our yellow dwarf Sun. GJ 1132 b is so close to its host red dwarf star that it completes an orbit the star once every day and a half. This extremely close proximity keeps GJ 1132 b tidally locked, showing the same face to its star at all times — just as our moon keeps one hemisphere permanently facing Earth.

“The question is, what is keeping the mantle hot enough to remain liquid and power volcanism?” asked Swain. “This system is special because it has the opportunity for quite a lot of tidal heating.”

The phenomenon of tidal heating occurs through friction, when energy from a planet’s orbit and rotation is dispersed as heat inside the planet. GJ 1132 b is in an elliptical orbit, and the tidal forces acting on it are strongest when it is closest to or farthest from its host star. At least one other planet in the host star’s system also exerts a gravitational pull on the planet. The consequences are that the planet is squeezed or stretched by this gravitational “pumping.” That tidal heating keeps the mantle liquid for a long time. A nearby example in our own Solar System is the Jovian moon, Io, which has continuous volcanism as a result of a tidal tug-of-war between Jupiter and the neighbouring Jovian moons.

The team believes the crust of GJ 1132 b is extremely thin, perhaps only hundreds of feet thick. That’s much too feeble to support anything resembling volcanic mountains. Its flat terrain may also be cracked like an eggshell by tidal flexing. Hydrogen and other gases could be released through such cracks.

“This atmosphere, if it’s thin — meaning if it has a surface pressure similar to Earth — probably means you can see right down to the ground at infrared wavelengths. That means that if astronomers use the James Webb Space Telescope to observe this planet, there’s a possibility that they will see not the spectrum of the atmosphere, but rather the spectrum of the surface,” explained Swain. “And if there are magma pools or volcanism going on, those areas will be hotter. That will generate more emission, and so they’ll potentially be looking at the actual geological activity — which is exciting!”

This result is significant because it gives exoplanet scientists a way to figure out something about a planet’s geology from its atmosphere,” added Rimmer. “It is also important for understanding where the rocky planets in our own Solar System — Mercury, Venus, Earth and Mars, fit into the bigger picture of comparative planetology, in terms of the availability of hydrogen versus oxygen in the atmosphere.”

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Notes:

[1] The observations were conducted as part of the Hubble observing program #14758 (PI: Zach Berta-Thomson).

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