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.
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 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.
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).
The incredibly distant galaxy JADES-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 & CSA, JADES Collaboration, J. Witstok, P. Jakobsen, A. Pagan (STScI), M. Zamani (ESA/Webb)
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.
Webb finds candidates for first young brown dwarfs outside the Milky Way, in the star cluster NGC 602
An international team of astronomers has used the NASA/ESA/CSA James Webb Space Telescope to detect the first rich population of brown dwarf candidates outside the Milky Way in the star cluster NGC 602.
Near the outskirts of the Small Magellanic Cloud, a satellite galaxy roughly 200 000 light-years from Earth, lies the young star cluster NGC 602. The local environment of this cluster is a close analogue of what existed in the early Universe, with very low abundances of elements heavier than hydrogen and helium. The existence of dark clouds of dense dust and the fact that the cluster is rich in ionised gas also suggest the presence of ongoing star formation processes. Together with its associated HII [1] region N90, which contains clouds of ionised atomic hydrogen, this cluster provides a valuable opportunity to examine star formation scenarios under dramatically different conditions from those in the solar neighbourhood.
An international team of astronomers, including Peter Zeidler, Elena Sabbi, Elena Manjavacas and Antonella Nota, used Webb to observe NGC 602 and they detected candidates for the first young brown dwarfs outside our Milky Way.
“Only with the incredible sensitivity and spatial resolution in the correct wavelength regime is it possible to detect these objects at such great distances,” shared lead author Peter Zeidler of AURA/STScI for the European Space Agency. “This has never been possible before and also will remain impossible from the ground for the foreseeable future.”
Brown dwarfs are the more massive cousins of giant gas planets (typically ranging from roughly 13 to 75 Jupiter masses, and sometimes lower). They are free-floating, meaning that they are not gravitationally bound to a star as exoplanets are. However, some of them share characteristics with exoplanets, like their atmospheric composition and storm patterns.
“Until now, we’ve known of about 3000 brown dwarfs, but they all live inside our own galaxy,” added team member Elena Manjavacas of AURA/STScI for the European Space Agency.
“This discovery highlights the power of using both Hubble and Webb to study young stellar clusters,” explained team member Antonella Nota, executive director of the International Space Science Institute in Switzerland and the previous Webb Project Scientist for ESA. “Hubble showed that NGC602 harbors very young low mass stars, but only with Webb we can finally see the extent and the significance of the substellar mass formation in this cluster. Hubble and Webb are an amazingly powerful telescope duo!”
“Our results fit very well with the theory that the mass distribution of bodies below the hydrogen burning limit is simply a continuation of the stellar distribution,” shared Zeidler. “It seems they form in the same way, they just don’t accrete enough mass to become a fully fledged star.”
The team’s data include a new image from Webb’s Near-InfraRed Camera (NIRCam) of NGC 602, which highlights the cluster stars, the young stellar objects, and the surrounding gas and dust ridges, as well as the gas and dust itself, while also showing the significant contamination by background galaxies and other stars in the Small Magellanic Cloud. These observations were made in April 2023.
“By studying the young metal-poor brown dwarfs newly discovered in NGC602, we are getting closer to unlocking the secrets of how stars and planets formed in the harsh conditions of the early Universe,“ added team member Elena Sabbi of NSF’s NOIRLab, the University of Arizona, and the Space Telescope Science Institute.
“These are the first substellar objects outside the Milky Way” added Manjavacas. “We need to be ready for new ground-breaking discoveries in these new objects!”
These observations were made as part of the JWST GO programme #2662 (PI: P. Zeidler). The results have been published in The Astrophysical Journal.
Near the outskirts of the Small Magellanic Cloud, a satellite galaxy roughly 200 000 light-years from Earth, lies the young star cluster NGC 602, which is featured in this new image from the NASA/ESA/CSA James Webb Space Telescope. This image includes data from Webb’s NIRCam (Near-InfraRed Camera) and MIRI (Mid-InfraRed Instrument). The local environment of this cluster is a close analogue of what existed in the early Universe, with very low abundances of elements heavier than hydrogen and helium. The existence of dark clouds of dense dust and the fact that the cluster is rich in ionised gas also suggest the presence of ongoing star formation processes. This cluster provides a valuable opportunity to examine star formation scenarios under dramatically different conditions from those in the solar neighbourhood. An international team of astronomers, including Peter Zeidler, Elena Sabbi, and Antonella Nota, used Webb to observe NGC 602 and detected candidates for the first young brown dwarfs outside our Milky Way. Credit: ESA/Webb, NASA & CSA, P. Zeidler, E. Sabbi, A. Nota, M. Zamani (ESA/Webb)
Notes
[1] Some of the most beautiful extended objects that we can see are known as HII regions, also called diffuse or emission nebulae. They contain mostly ionised hydrogen and are found throughout the interstellar medium in the Milky Way and in other galaxies.
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.
This image highlights the location of the galaxy JADES-GS-z6 in a portion of an area of the sky known as GOODS-South, which was observed as part of the JWST Advanced Deep Extragalactic Survey, or JADES. This galaxy, along with others in this region, were part of a Webb study by 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. The team’s research indicates that this particular galaxy showed significant dust obscuration and has undergone substantial metal enrichment relative to galaxies with similar mass at the same redshift. The team also believes the galaxy’s visible colour gradient may indicate a peculiar geometrical alignment of stars and dust. 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. The galaxy is shown zoomed in on a region measuring roughly 1×1 arcseconds, which is a measure of angular distance on the sky. One arcsecond is equal to 1/3600 of one degree of arc (the full Moon has an angular diameter of about 0.5 degrees). The actual size of an object that covers one arcsecond on the sky depends on its distance from the telescope. 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)
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 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.
Webb spots swirling, gritty clouds on VHS 1256 b, a remote planet
Researchers observing with the NASA/ESA/CSA James Webb Space Telescope have pinpointed silicate cloud features in a distant planet’s atmosphere. The atmosphere is constantly rising, mixing, and moving during its 22-hour day, bringing hotter material up and pushing colder material down. The resulting brightness changes are so dramatic that it is the most variable planetary-mass object known to date. The science team also made extraordinarily clear detections of water, methane and carbon monoxide with Webb’s data, and found evidence of carbon dioxide. This is the largest number of molecules ever identified all at once on a planet outside our Solar System.
This illustration conceptualises the swirling clouds identified by the James Webb Space Telescope in the atmosphere of the exoplanet VHS 1256 b. The planet is about 40 light-years away and orbits two stars that are locked in their own tight rotation. Its clouds, which are filled with silicate dust, are constantly rising, mixing, and moving during its 22-hour day. Credit: NASA, ESA, CSA, J. Olmsted (STScI)
Catalogued as VHS 1256 b, the planet is about 40 light-years away and orbits not one, but two stars over a 10 000-year period.
“VHS 1256 b is about four times farther from its stars than Pluto is from our Sun, which makes it a great target for Webb,” said science team lead Brittany Miles of the University of Arizona. “That means the planet’s light is not mixed with light from its stars.” Higher up in its atmosphere, where the silicate clouds are churning, temperatures reach a scorching 830 degrees Celsius.
Within those clouds, Webb detected both larger and smaller silicate dust grains, which are shown on a spectrum.
“The finer silicate grains in its atmosphere may be more like tiny particles in smoke,” noted co-author Beth Biller of the University of Edinburgh in the United Kingdom. “The larger grains might be more like very hot, very small sand particles.”
VHS 1256 b has low gravity compared to more massive brown dwarfs [1], which means that its silicate clouds can appear and remain higher in its atmosphere where Webb can detect them. Another reason its skies are so turbulent is the planet’s age. In astronomical terms, it’s quite young. Only 150 million years have passed since it formed — and it will continue to change and cool over billions of years.
A research team led by Brittany Miles of the University of Arizona used two instruments known as spectrographs aboard the James Webb Space Telescope, one on its Near Infrared Spectrograph (NIRSpec) and another on its Mid-Infrared Instrument (MIRI), to observe a vast section of near- to mid-infrared light emitted by the planet VHS 1256 b. They plotted the light on the spectrum, identifying signatures of silicate clouds, water, methane and carbon monoxide. They also found evidence of carbon dioxide. Credit: NASA, ESA, CSA, J. Olmsted (STScI), B. Miles (University of Arizona), S. Hinkley (University of Exeter), B. Biller (University of Edinburgh), A. Skemer (University of California, Santa Cruz)
In many ways, the team considers these findings to be the first ‘coins’ pulled out of a spectrum that researchers view as a treasure chest of data. In many ways, they’ve only begun identifying its contents.
“We’ve identified silicates, but a better understanding of which grain sizes and shapes match specific types of clouds is going to take a lot of additional work,” Miles said. “This is not the final word on this planet — it is the beginning of a large-scale modelling effort to fit Webb’s complex data.”
Although all of the features the team observed have been spotted on other planets elsewhere in the Milky Way by other telescopes, other research teams typically identified only one at a time.
“No other telescope has identified so many features at once for a single target,” said co-author Andrew Skemer of the University of California, Santa Cruz. “We’re seeing a lot of molecules in a single spectrum from Webb that detail the planet’s dynamic cloud and weather systems.”
The team came to these conclusions by analysing data known as spectra gathered by two instruments aboard Webb, the Near-Infrared Spectrograph (NIRSpec) and the Mid-Infrared Instrument (MIRI). Since the planet orbits at such a great distance from its stars, the researchers were able to observe it directly, rather than using the transit technique [2] or a coronagraph [3] to take this data.
There will be plenty more to learn about VHS 1256 b in the months and years to come as this team — and others — continue to sift through Webb’s high-resolution infrared data. “There’s a huge return on a very modest amount of telescope time,” Biller added. “With only a few hours of observations, we have what feels like unending potential for additional discoveries.”
What might become of this planet billions of years from now? Since it’s so far from its stars, it will become colder over time, and its skies may transition from cloudy to clear.
The researchers observed VHS 1256 b as part of Webb’s Early Release Science program, which is designed to help transform the astronomical community’s ability to characterise planets and the discs from which they form.
The team’s paper, entitled “The JWST Early Release Science Program for Direct Observations of Exoplanetary Systems II: A 1 to 20 Micron Spectrum of the Planetary-Mass Companion VHS 1256-1257 b,” will be published in The Astrophysical Journal Letters on 22 March.
Crushed, Zapped, Boiled, Baked And More: Nature Used 57 Recipes To Create Earth’s 10,500+ “Mineral Kinds”
Washington, DC—A 15-year study led by Carnegie’s Robert Hazen and Shaunna Morrison details the origins and diversity of every known mineral on Earth, a landmark body of work that will help reconstruct the history of life on our planet, guide the search for new minerals and ore deposits, predict possible characteristics of future life, and aid the search for habitable exoplanets and extraterrestrial life.
For more than a century, thousands of mineralogists from around the globe have carefully documented “mineral species” based on their unique combinations of chemical composition and crystal structure. Carnegie scientists Robert Hazen and Shaunna Morrison took a different approach, emphasizing how and when each kind of mineral appeared through more than 4.5 billion years of Earth history.
In twin papers published by American Mineralogist, Hazen, Morrison, and their collaborators detail how they used extensive database analysis to cluster kindred species of minerals together and distinguish new mineral species based on when and how they originated, rather than solely on their chemical and physical characteristics.
Their work indicates that the number of “mineral kinds”—a term coined in 2020 by Hazen and Morrison—totals more than 10,500. In comparison, the International Mineralogical Association recognizes about 6,000 mineral species on the basis of crystal structure and chemical composition alone.
Nature Used 57 Recipes To Create Earth’s 10,500+ “Mineral Kinds”: Pyrite forms in 21 different ways, the most of any mineral. Pyrite is so stable that it forms both at high temperature and low, both with and without water, and both with the help of microbes and in harsh environments where life plays no role whatsoever. These examples formed by the gradual precipitation of crystals from a solution rich in iron and sulfur. The large cubes are wonders of nature. Credit: ARKENSTONE/Rob Lavinsky
“This work fundamentally changes our view of the diversity of minerals on the planet,” Hazen explained. “For example, more than 80 percent of Earth’s minerals were mediated by water, which is, therefore, fundamentally important to mineral diversity on this planet. By extension, it explains one of the key reasons why the Moon and Mercury and even Mars have far fewer mineral species than Earth.”
“It also tells us something very profound about the role of biology,” he added. “One third of Earth’s minerals could not have formed without biology—shells and bones and teeth, or microbes, for example—or the vital indirect role of biology—importantly by creating an oxygen-rich atmosphere that led to 2,000 minerals that wouldn’t have formed otherwise. Each mineral specimen has a history. Each tells a story. Each is a time capsule that reveals Earth’s past as nothing else can.”
According to Hazen and Morrison—along with collaborators Sergey Krivovichev of the Russian Academy of Sciences and Robert Downs of the University of Arizona—nature created 40 percent of Earth’s mineral species by more than one method—for example, many minerals arose both abiotically and with a helping hand from living organisms—and in several cases more than 15 different “recipes” produced the same crystal structure and chemical composition.
Of the 5,659 mineral species surveyed by Hazen and colleagues, nine arose via 15 or more origin pathways, each incorporating various combinations of physical, chemical, and biological processes—everything from near-instantaneous formation by lightning or meteor strikes, to changes caused by water-rock interactions or high-pressure, high-temperature transformations that took place over hundreds of millions of years.
And, as if to demonstrate a sense of humor, nature has used 21 different ways over the last 4.56 billion years to create pyrite, also known as Fool’s Gold—the most origin stories of any mineral. Pyrite, composed of one part iron to two parts sulfide, is so stable that it forms under a huge variety of circumstances, including meteorites, volcanos, hydrothermal deposits, by pressure between layers of rock, near-surface rock weathering, in microbially-precipitated deposits, and via several mining-associated processes.
To reach their conclusions, Hazen and Morrison built a database of every known process of formation of every known mineral. Relying on large, open-access mineral databases, amplified by thousands of primary research articles on the geology of mineral localities around the world, they identified 10,556 different combinations of minerals and modes of formation.
“No one has undertaken this huge task before,” said Hazen, who honored last year by the IMA with its medal for his outstanding achievements in mineral crystal chemistry, particularly in the field of mineral evolution. “In these twin papers, we are putting forward our best effort to lay the groundwork for a new approach to recognizing different kinds of minerals. We welcome the insights, additions, and future versions of the mineralogical community.”
The papers’ groundbreaking observations and conclusions include:
Water has played a dominant role in the mineral diversity of Earth, was involved in the formation of more than 80 percent of mineral species.
Life played a direct or indirect role in the formation of almost half of known mineral species while a third of known minerals—more than 1,900 species—formed exclusively as a consequence of biological activities.
Rare elements play a disproportionate role in Earth’s mineral diversity. Just 41 elements—together constituting less than 5 parts per million of Earth’s crust—are essential constituents in some 2,400 (more than 42 percent) of Earth’s minerals. The 41 elements include arsenic, cadmium, gold, mercury, silver, titanium, tin, uranium, and tungsten.
Much of Earth’s mineral diversity was established within the planet’s first 250 million years
Some 296 known minerals are thought to pre-date Earth itself, of which 97 are known only from meteorites, with the age of some individual mineral grains estimated at 7 billion years—which was billions of years before the origin of our Solar System.
The oldest known minerals are tiny, durable zircon crystals that are almost 4.4 billion years old.
More than 600 minerals have derived from human activities, including more than 500 minerals caused by mining, 234 of them formed by coal mine fires.
Hazen, Morrison, and their colleagues propose that, complementary to the IMA-approved mineral list, new categorizations and groupings be created on the basis of a mineral’s genesis. For example, science can group 400 minerals formed by condensation at volcanic fumaroles—the openings in the Earth’s surface that emit steam and volcanic gasses.
Their papers detail other considerations in the clustering and classification of minerals, such as the eon in which they formed. For example, Earth’s so-called Great Oxidation Event about 2.3 billion years ago led new minerals to form at the planet’s near-surface. And about 4.45 billion years ago, when water first appeared, the earliest water-rock interactions may have produced as many as 350 minerals in near-surface marine and terrestrial environments.
It appears, too, that hundreds of different minerals may have formed on Earth prior to the giant impact that vaporized much of our planet’s crust and mantle and led to the Moon’s formation about 4.5 billion years ago. If so, those minerals were obliterated, only to reform as Earth cooled and solidified.
Beyond accidental mineral creations, humanity has manufactured countless thousands of mineral-like compounds that don’t qualify as minerals by the IMA standards, but do qualify as mineral kinds by Hazen and Morrison’s methodology. This includes building materials, semiconductors, laser crystals, specialty alloys, synthetic gemstones, plastic debris and the like—all “likely to persist for millions of years in the geologic record, providing a clear sedimentary horizon that marks the so-called “Anthropocene Epoch.”
Meanwhile, there are also 77 “biominerals,” that were formed by a variety of metabolic processes—this includes everything from minerals derived by corals, shells, and stinging nettles to minerals in bones, teeth, and kidney stones. Another 72 minerals originated directly or indirectly from the guano and urine of birds and bats.
The researchers noted that between the formation of oceans, the extensive development of continental crust, and perhaps even the initiation of some early form of the process that now drive plate tectonics, many important mineral-forming processes—and the origins of as many as 3,534 mineral species—took place in Earth’s first 250 million years. If so, then most of the geochemical and mineralogical environments invoked in models of life’s origins would have been present by 4.3 billion years ago.
If life is “a cosmic imperative that emerges on any mineral- and water-rich world,” the authors concluded, “then these findings support the hypothesis that life on Earth emerged rapidly, in concert with a vibrant, diverse Mineral Kingdom, in the earliest stages of planetary evolution.”
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The research was supported by the John Templeton Foundation, the NASA Astrobiology Institute ENIGMA team, and the Carnegie Institution for Science.
Bibliographic information:
On the paragenetic modes of minerals: A mineral evolution perspective, American Mineralogist (1-Jul-2022), DOI: 10.2138/am-2022-8099
Press release from Carnegie Science on the work about “mineral kinds”.
Astronomers reveal first image of the black hole at the heart of our galaxy
Today, at simultaneous press conferences around the world, including at the European Southern Observatory (ESO) headquarters in Germany, astronomers have unveiled the first image of the supermassive black hole at the centre of our own Milky Way galaxy. This result provides overwhelming evidence that the object is indeed a black hole and yields valuable clues about the workings of such giants, which are thought to reside at the centre of most galaxies. The image was produced by a global research team called the Event Horizon Telescope (EHT) Collaboration, using observations from a worldwide network of radio telescopes.
The black hole at the heart of our galaxy. This artist’s impression depicts a rapidly spinning supermassive black hole surrounded by an accretion disc. This thin disc of rotating material consists of the leftovers of a Sun-like star which was ripped apart by the tidal forces of the black hole. The black hole is labelled, showing the anatomy of this fascinating object. Credit:ESOThe black hole at the heart of our galaxy. This chart shows the location of the field of view within which Sagittarius A* resides — the black hole is marked with a red circle within the constellation of Sagittarius (The Archer). This map shows most of the stars visible to the unaided eye under good conditions. Credit:ESO, IAU and Sky & Telescope
The image is a long-anticipated look at the massive object that sits at the very centre of our galaxy. Scientists had previously seen stars orbiting around something invisible, compact, and very massive at the centre of the Milky Way. This strongly suggested that this object — known as Sagittarius A* (Sgr A*, pronounced “sadge-ay-star”) — is a black hole, and today’s image provides the first direct visual evidence of it.
The black hole at the heart of our galaxy. This is the first image of Sgr A*, the supermassive black hole at the centre of our galaxy. It’s the first direct visual evidence of the presence of this black hole. It was captured by the Event Horizon Telescope (EHT), an array which linked together eight existing radio observatories across the planet to form a single “Earth-sized” virtual telescope. The telescope is named after the event horizon, the boundary of the black hole beyond which no light can escape. Although we cannot see the event horizon itself, because it cannot emit light, glowing gas orbiting around the black hole reveals a telltale signature: a dark central region (called a shadow) surrounded by a bright ring-like structure. The new view captures light bent by the powerful gravity of the black hole, which is four million times more massive than our Sun. The image of the Sgr A* black hole is an average of the different images the EHT Collaboration has extracted from its 2017 observations. In addition to other facilities, the EHT network of radio observatories that made this image possible includes the Atacama Large Millimeter/submillimeter Array (ALMA) and the Atacama Pathfinder EXperiment (APEX) in the Atacama Desert in Chile, co-owned and co-operated by ESO is a partner on behalf of its member states in Europe. Credit: EHT Collaboration
Although we cannot see the black hole itself, because it is completely dark, glowing gas around it reveals a telltale signature: a dark central region (called a shadow) surrounded by a bright ring-like structure. The new view captures light bent by the powerful gravity of the black hole, which is four million times more massive than our Sun.
“We were stunned by how well the size of the ring agreed with predictions from Einstein’s Theory of General Relativity,” said EHT Project Scientist Geoffrey Bower from the Institute of Astronomy and Astrophysics, Academia Sinica, Taipei. “These unprecedented observations have greatly improved our understanding of what happens at the very centre of our galaxy, and offer new insights on how these giant black holes interact with their surroundings.” The EHT team’s results are being published today in a special issue of The Astrophysical Journal Letters.
Because the black hole is about 27 000 light-years away from Earth, it appears to us to have about the same size in the sky as a doughnut on the Moon. To image it, the team created the powerful EHT, which linked together eight existing radio observatories across the planet to form a single “Earth-sized” virtual telescope [1]. The EHT observed Sgr A* on multiple nights in 2017, collecting data for many hours in a row, similar to using a long exposure time on a camera.
The black hole at the heart of our galaxy. The Event Horizon Telescope (EHT) Collaboration has created a single image (top frame) of the supermassive black hole at the centre of our galaxy, called Sagittarius A*, or Sgr A* for short, by combining images extracted from the EHT observations. The main image was produced by averaging together thousands of images created using different computational methods — all of which accurately fit the EHT data. This averaged image retains features more commonly seen in the varied images, and suppresses features that appear infrequently. The images can also be clustered into four groups based on similar features. An averaged, representative image for each of the four clusters is shown in the bottom row. Three of the clusters show a ring structure but, with differently distributed brightness around the ring. The fourth cluster contains images that also fit the data but do not appear ring-like. The bar graphs show the relative number of images belonging to each cluster. Thousands of images fell into each of the first three clusters, while the fourth and smallest cluster contains only hundreds of images. The heights of the bars indicate the relative “weights,” or contributions, of each cluster to the averaged image at top. In addition to other facilities, the EHT network of radio observatories that made this image possible includes the Atacama Large Millimeter/submillimeter Array (ALMA) and the Atacama Pathfinder EXperiment (APEX) in the Atacama Desert in Chile, co-owned and co-operated by ESO is a partner on behalf of its member states in Europe. Credit: EHT Collaboration
In addition to other facilities, the EHT network of radio observatories includes the Atacama Large Millimeter/submillimeter Array (ALMA) and the Atacama Pathfinder EXperiment (APEX) in the Atacama Desert in Chile, co-owned and co-operated by ESO on behalf of its member states in Europe. Europe also contributes to the EHT observations with other radio observatories — the IRAM 30-meter telescope in Spain and, since 2018, the NOrthern Extended Millimeter Array (NOEMA) in France — as well as a supercomputer to combine EHT data hosted by the Max Planck Institute for Radio Astronomy in Germany. Moreover, Europe contributed with funding to the EHT consortium project through grants by the European Research Council and by the Max Planck Society in Germany.
This image shows the Atacama Large Millimeter/submillimeter Array (ALMA) looking up at the Milky Way as well as the location of Sagittarius A*, the supermassive black hole at our galactic centre. Highlighted in the box is the image of Sagittarius A* taken by the Event Horizon Telescope (EHT) Collaboration. Located in the Atacama Desert in Chile, ALMA is the most sensitive of all the observatories in the EHT array, and ESO is a co-owner of ALMA on behalf of its European Member States. Credit: ESO/José Francisco Salgado (josefrancisco.org), EHT Collaboration
“It is very exciting for ESO to have been playing such an important role in unravelling the mysteries of black holes, and of Sgr A* in particular, over so many years,” commented ESO Director General Xavier Barcons. “ESO not only contributed to the EHT observations through the ALMA and APEX facilities but also enabled, with its other observatories in Chile, some of the previous breakthrough observations of the Galactic centre.” [2]
The EHT achievement follows the collaboration’s 2019 release of the first image of a black hole, called M87*, at the centre of the more distant Messier 87 galaxy.
These panels show the first two images ever taken of black holes. On the left is M87*, the supermassive black hole at the centre of the galaxy Messier 87 (M87), 55 million light-years away. On the right is Sagittarius A* (Sgr A*), the black hole at the centre of our Milky Way. The two images show the black holes as they would appear in the sky, with their bright rings appearing to be roughly the same size, despite M87* being around a thousand times larger than Sgr A*. The images were captured by the Event Horizon Telescope (EHT), a global network of radio telescopes including the Atacama Large Millimeter/submillimeter Array (ALMA) and Atacama Pathfinder EXperiment (APEX), in which ESO is co-owner. Credit: EHT Collaboration
The two black holes look remarkably similar, even though our galaxy’s black hole is more than a thousand times smaller and less massive than M87* [3].
“We have two completely different types of galaxies and two very different black hole masses, but close to the edge of these black holes they look amazingly similar,” says Sera Markoff, Co-Chair of the EHT Science Council and a professor of theoretical astrophysics at the University of Amsterdam, the Netherlands.
“This tells us that General Relativity governs these objects up close, and any differences we see further away must be due to differences in the material that surrounds the black holes.”
Size comparison of the two black holes imaged by the Event Horizon Telescope (EHT) Collaboration: M87*, at the heart of the galaxy Messier 87, and Sagittarius A* (Sgr A*), at the centre of the Milky Way. The image shows the scale of Sgr A* in comparison with both M87* and other elements of the Solar System such as the orbits of Pluto and Mercury. Also displayed is the Sun’s diameter and the current location of the Voyager 1 space probe, the furthest spacecraft from Earth. M87*, which lies 55 million light-years away, is one of the largest black holes known. While Sgr A*, 27 000 light-years away, has a mass roughly four million times the Sun’s mass, M87* is more than 1000 times more massive. Because of their relative distances from Earth, both black holes appear the same size in the sky. Credit: EHT collaboration (acknowledgment: Lia Medeiros, xkcd)
This achievement was considerably more difficult than for M87*, even though Sgr A* is much closer to us. EHT scientist Chi-kwan (‘CK’) Chan, from Steward Observatory and Department of Astronomy and the Data Science Institute of the University of Arizona, USA, explains:
“The gas in the vicinity of the black holes moves at the same speed — nearly as fast as light — around both Sgr A* and M87*. But where gas takes days to weeks to orbit the larger M87*, in the much smaller Sgr A* it completes an orbit in mere minutes. This means the brightness and pattern of the gas around Sgr A* were changing rapidly as the EHT Collaboration was observing it — a bit like trying to take a clear picture of a puppy quickly chasing its tail.”
The researchers had to develop sophisticated new tools that accounted for the gas movement around Sgr A*. While M87* was an easier, steadier target, with nearly all images looking the same, that was not the case for Sgr A*. The image of the Sgr A* black hole is an average of the different images the team extracted, finally revealing the giant lurking at the centre of our galaxy for the first time.
The effort was made possible through the ingenuity of more than 300 researchers from 80 institutes around the world that together make up the EHT Collaboration. In addition to developing complex tools to overcome the challenges of imaging Sgr A*, the team worked rigorously for five years, using supercomputers to combine and analyse their data, all while compiling an unprecedented library of simulated black holes to compare with the observations.
Scientists are particularly excited to finally have images of two black holes of very different sizes, which offers the opportunity to understand how they compare and contrast. They have also begun to use the new data to test theories and models of how gas behaves around supermassive black holes. This process is not yet fully understood but is thought to play a key role in shaping the formation and evolution of galaxies.
“Now we can study the differences between these two supermassive black holes to gain valuable new clues about how this important process works,” said EHT scientist Keiichi Asada from the Institute of Astronomy and Astrophysics, Academia Sinica, Taipei. “We have images for two black holes — one at the large end and one at the small end of supermassive black holes in the Universe — so we can go a lot further in testing how gravity behaves in these extreme environments than ever before.”
Progress on the EHT continues: a major observation campaign in March 2022 included more telescopes than ever before. The ongoing expansion of the EHT network and significant technological upgrades will allow scientists to share even more impressive images as well as movies of black holes in the near future.
This visible light wide-field view shows the rich star clouds in the constellation of Sagittarius (the Archer) in the direction of the centre of our Milky Way galaxy. The entire image is filled with vast numbers of stars — but far more remain hidden behind clouds of dust and are only revealed in infrared images. This view was created from photographs in red and blue light and form part of the Digitized Sky Survey 2. The field of view is approximately 3.5 degrees x 3.6 degrees. Credit:ESO and Digitized Sky Survey 2. Acknowledgment: Davide De Martin and S. Guisard (www.eso.org/~sguisard)
The black hole at the heart of our galaxy
Notes
[1] The individual telescopes involved in the EHT in April 2017, when the observations were conducted, were: the Atacama Large Millimeter/submillimeter Array (ALMA), the Atacama Pathfinder EXperiment (APEX), the IRAM 30-meter Telescope, the James Clerk Maxwell Telescope (JCMT), the Large Millimeter Telescope Alfonso Serrano (LMT), the Submillimeter Array (SMA), the UArizona Submillimeter Telescope (SMT), the South Pole Telescope (SPT). Since then, the EHT has added the Greenland Telescope (GLT), the NOrthern Extended Millimeter Array (NOEMA) and the UArizona 12-meter Telescope on Kitt Peak to its network.
ALMA is a partnership of the European Southern Observatory (ESO; Europe, representing its member states), the U.S. National Science Foundation (NSF), and the National Institutes of Natural Sciences (NINS) of Japan, together with the National Research Council (Canada), the Ministry of Science and Technology (MOST; Taiwan), Academia Sinica Institute of Astronomy and Astrophysics (ASIAA; Taiwan), and Korea Astronomy and Space Science Institute (KASI; Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, the Associated Universities, Inc./National Radio Astronomy Observatory (AUI/NRAO) and the National Astronomical Observatory of Japan (NAOJ). APEX, a collaboration between the Max Planck Institute for Radio Astronomy (Germany), the Onsala Space Observatory (Sweden) and ESO, is operated by ESO. The 30-meter Telescope is operated by IRAM (the IRAM Partner Organizations are MPG [Germany], CNRS [France] and IGN [Spain]). The JCMT is operated by the East Asian Observatory on behalf of The National Astronomical Observatory of Japan; ASIAA; KASI; the National Astronomical Research Institute of Thailand; the Center for Astronomical Mega-Science and organisations in the United Kingdom and Canada. The LMT is operated by INAOE and UMass, the SMA is operated by Center for Astrophysics | Harvard & Smithsonian and ASIAA and the UArizona SMT is operated by the University of Arizona. The SPT is operated by the University of Chicago with specialised EHT instrumentation provided by the University of Arizona.
The Greenland Telescope (GLT) is operated by ASIAA and the Smithsonian Astrophysical Observatory (SAO). The GLT is part of the ALMA-Taiwan project, and is supported in part by the Academia Sinica (AS) and MOST. NOEMA is operated by IRAM and the UArizona 12-meter telescope at Kitt Peak is operated by the University of Arizona.
A montage of the radio observatories that form the Event Horizon Telescope (EHT) network, used to image the Milky Way’s central black hole, Sagittarius A*. These include the Atacama Large Millimeter/submillimeter Array (ALMA), the Atacama Pathfinder EXperiment (APEX), IRAM 30-meter telescope, James Clark Maxwell Telescope (JCMT), Large Millimeter Telescope (LMT), Submillimeter Array (SMA), Submillimetere Telescope (SMT) and South Pole Telescope (SPT). The slightly transparent telescopes in the background, represent the three telescopes added to the EHT Collaboration after 2018: the Greenland Telescope, the NOrthern Extended Millimeter Array (NOEMA) in France, and the UArizona ARO 12-meter Telescope at Kitt Peak. These telescopes were added to the array after the 2017 observations of Sagittarius A*. Credit: ESO/M. Kornmesser. Images of individual telescopes: ALMA: ESO APEX: ESO LMT: INAOE Archives GLT: N. Patel JCMT: EAO-W. Montgomerie SMT: D. Harvey 30m: N. Billot SPT: Wikipedia SMA: S. R. Schimpf NOEMA: IRAM Kitt Peak: Wikipedia Milky Way: N. Risinger (skysurvey.org)A montage of the radio observatories that form the Event Horizon Telescope (EHT) network used to image the Milky Way’s central black hole, Sagittarius A*. These include the Atacama Large Millimeter/submillimeter Array (ALMA), the Atacama Pathfinder EXperiment (APEX), IRAM 30-meter telescope, James Clark Maxwell Telescope (JCMT), Large Millimeter Telescope (LMT), Submillimeter Array (SMA), Submillimeter Telescope (SMT) and South Pole Telescope (SPT). The slightly transparent telescopes in the background represent the three telescopes added to the EHT network after 2018: the Greenland Telescope, the NOrthern Extended Millimeter Array (NOEMA) in France, and the UArizona ARO 12-meter Telescope at Kitt Peak. These telescopes were added to the array after the 2017 observations of Sagittarius A*. Credit: ESO/M. Kornmesser. Images of individual telescopes: ALMA: ESO APEX: ESO LMT: INAOE Archives GLT: N. Patel JCMT: EAO-W. Montgomerie SMT: D. Harvey 30m: N. Billot SPT: Wikipedia SMA: S. R. Schimpf NOEMA: IRAM Kitt Peak: Wikipedia Milky Way: N. Risinger (skysurvey.org)
[2] A strong basis for the interpretation of this new image was provided by previous research carried out on Sgr A*. Astronomers have known the bright, dense radio source at the centre of the Milky Way in the direction of the constellation Sagittarius since the 1970s. By measuring the orbits of several stars very close to our galactic centre over a period of 30 years, teams led by Reinhard Genzel (Director at the Max –Planck Institute for Extraterrestrial Physics in Garching near Munich, Germany) and Andrea M. Ghez (Professor in the Department of Physics and Astronomy at the University of California, Los Angeles, USA) were able to conclude that the most likely explanation for an object of this mass and density is a supermassive black hole. ESO’s facilities (including the Very Large Telescope and the Very Large Telescope Interferometer) and the Keck Observatory were used to carry out this research, which shared the 2020 Nobel Prize in Physics.
[3] Black holes are the only objects we know of where mass scales with size. A black hole a thousand times smaller than another is also a thousand times less massive.
The black hole at the heart of our galaxy: more information
This research was presented in six papers published today in The Astrophysical Journal Letters.
A global map showing the radio observatories that form the Event Horizon Telescope (EHT) network used to image the Milky Way’s central black hole, Sagittarius A*. The telescopes highlighted in yellow were part of the EHT network during the observations of Sagittarius A* in 2017. These include the Atacama Large Millimeter/submillimeter Array (ALMA), the Atacama Pathfinder EXperiment (APEX), IRAM 30-meter telescope, James Clark Maxwell Telescope (JCMT), Large Millimeter Telescope (LMT), Submillimeter Array (SMA), Submillimetere Telescope (SMT) and South Pole Telescope (SPT). Highlighted in blue are the three telescopes added to the EHT Collaboration after 2018: the Greenland Telescope, the NOrthern Extended Millimeter Array (NOEMA) in France, and the UArizona ARO 12-meter Telescope at Kitt Peak. Credit:ESO/M. Kornmesser
The EHT collaboration involves more than 300 researchers from Africa, Asia, Europe, North and South America. The international collaboration aims to capture the most detailed black hole images ever obtained by creating a virtual Earth-sized telescope. Supported by considerable international efforts, the EHT links existing telescopes using novel techniques — creating a fundamentally new instrument with the highest angular resolving power that has yet been achieved.
This image shows the locations of some of the telescopes making up the EHT, as well as a representation of the long baselines between the telescopes. Credit:ESO/L. Calçada
The EHT consortium consists of 13 stakeholder institutes; the Academia Sinica Institute of Astronomy and Astrophysics, the University of Arizona, the Center for Astrophysics | Harvard & Smithsonian, the University of Chicago, the East Asian Observatory, Goethe-Universitaet Frankfurt, Institut de Radioastronomie Millimétrique, Large Millimeter Telescope, Max Planck Institute for Radio Astronomy, MIT Haystack Observatory, National Astronomical Observatory of Japan, Perimeter Institute for Theoretical Physics, and Radboud University.
This view shows several of the ALMA antennas and the central regions of the Milky Way above. In this wide field view, the zodiacal light is seen upper right and at lower left Mars is seen. Saturn is a bit higher in the sky towards the centre of the image. The image was taken during the ESO Ultra HD (UHD) Expedition. Credit:ESO/B. Tafreshi (twanight.org)
The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of ESO, the U.S. National Science Foundation (NSF) and the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Republic of Chile. ALMA is funded by ESO on behalf of its Member States, by NSF in cooperation with the National Research Council of Canada (NRC) and the Ministry of Science and Technology (MOST) and by NINS in cooperation with the Academia Sinica (AS) in Taiwan and the Korea Astronomy and Space Science Institute (KASI). ALMA construction and operations are led by ESO on behalf of its Member States; by the National Radio Astronomy Observatory (NRAO), managed by Associated Universities, Inc. (AUI), on behalf of North America; and by the National Astronomical Observatory of Japan (NAOJ) on behalf of East Asia. The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.
The slumbering Atacama Pathfinder Experiment (APEX) telescope sits beneath reddened skies amongst the snow covered Chajnantor landscape. Snow not only blankets the ground, but also the many peaks that encircle the Chilean plateau which also hosts the Atacama Large Millimeter/submillimeter Array (ALMA). Credit:Carlos A. Durán/ESO
APEX, Atacama Pathfinder EXperiment, is a 12-metre diameter telescope, operating at millimetre and submillimetre wavelengths — between infrared light and radio waves. ESO operates APEX at one of the highest observatory sites on Earth, at an elevation of 5100 metres, high on the Chajnantor plateau in Chile’s Atacama region. The telescope is a collaboration between the Max Planck Institute for Radio Astronomy (MPIfR), the Onsala Space Observatory (OSO), and ESO.
This image shows the dish of the Atacama Pathfinder Experiment (APEX) telescope seen perfectly from the side, including the starry sky. Credit:C. Duran/ESOESO Photo Ambassador Stéphane Guisard captured this astounding panorama from the site of ALMA, the Atacama Large Millimeter/submillimeter Array, in the Chilean Andes. The 5000-metre-high and extremely dry Chajnantor plateau offers the perfect place for this state-of-the-art telescope, which studies the Universe in millimetre- and submillimetre-wavelength light. Numerous giant antennas dominate the centre of the image. When ALMA is complete, it will have a total of 54 of these 12-metre-diameter dishes. Above the array, the arc of the Milky Way serves as a resplendent backdrop. When the panorama was taken, the Moon was lying close to the centre of the Milky Way in the sky, its light bathing the antennas in an eerie night-time glow. The Large and Small Magellanic Clouds, the biggest of the Milky Way’s dwarf satellite galaxies, appear as two luminous smudges in the sky on the left. A particularly bright meteor streak gleams near the Small Magellanic Cloud. On the right, some of ALMA’s smaller 7-metre antennas — twelve of which will be used to form the Atacama Compact Array — can be seen. Still further on the right shine the lights of the Array Operations Site Technical Building. And finally, looming behind this building is the dark, mountainous peak of Cerro Chajnantor. ALMA, an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA. Links ESO Photo Ambassadors More about ALMA at ESO The Joint ALMA Observatory. Links ESO Photo Ambassadors More about ALMA at ESO The Joint ALMA Observatory Credit:ESO/S. Guisard (www.eso.org/~sguisard)
The European Southern Observatory (ESO) enables scientists worldwide to discover the secrets of the Universe for the benefit of all. We design, build and operate world-class observatories on the ground — which astronomers use to tackle exciting questions and spread the fascination of astronomy — and promote international collaboration in astronomy. Established as an intergovernmental organisation in 1962, today ESO is supported by 16 Member States (Austria, Belgium, the Czech Republic, Denmark, France, Finland, Germany, Ireland, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom), along with the host state of Chile and with Australia as a Strategic Partner. ESO’s headquarters and its visitor centre and planetarium, the ESO Supernova, are located close to Munich in Germany, while the Chilean Atacama Desert, a marvellous place with unique conditions to observe the sky, hosts our telescopes. ESO operates three observing sites: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope and its Very Large Telescope Interferometer, as well as two survey telescopes, VISTA working in the infrared and the visible-light VLT Survey Telescope. Also at Paranal ESO will host and operate the Cherenkov Telescope Array South, the world’s largest and most sensitive gamma-ray observatory. Together with international partners, ESO operates APEX and ALMA on Chajnantor, two facilities that observe the skies in the millimetre and submillimetre range. At Cerro Armazones, near Paranal, we are building “the world’s biggest eye on the sky” — ESO’s Extremely Large Telescope. From our offices in Santiago, Chile we support our operations in the country and engage with Chilean partners and society.
The black hole at the heart of our galaxy. This is the first image of Sgr A*, the supermassive black hole at the centre of our galaxy, with an added black background to fit wider screens. It’s the first direct visual evidence of the presence of this black hole. It was captured by the Event Horizon Telescope (EHT), an array which linked together eight existing radio observatories across the planet to form a single “Earth-sized” virtual telescope. The telescope is named after the event horizon, the boundary of the black hole beyond which no light can escape. Although we cannot see the event horizon itself, because it cannot emit light, glowing gas orbiting around the black hole reveals a telltale signature: a dark central region (called a shadow) surrounded by a bright ring-like structure. The new view captures light bent by the powerful gravity of the black hole, which is four million times more massive than our Sun. The image of the Sgr A* black hole is an average of the different images the EHT Collaboration has extracted from its 2017 observations. In addition to other facilities, the EHT network of radio observatories that made this image possible includes the Atacama Large Millimeter/submillimeter Array (ALMA) and the Atacama Pathfinder EXperiment (APEX) in the Atacama Desert in Chile, co-owned and co-operated by ESO is a partner on behalf of its member states in Europe. Credit:EHT Collaboration
