Highest-resolution observations yet from the surface of Earth

The Event Horizon Telescope (EHT) Collaboration has conducted test observations, using the Atacama Large Millimeter/submillimeter Array (ALMA) and other facilities, that achieved the highest resolution ever obtained from the surface of Earth. They managed this feat by detecting light from distant galaxies at a frequency of around 345 GHz, equivalent to a wavelength of 0.87 mm. The Collaboration estimates that in future they will be able to make black hole images that are 50% more detailed than was possible before, bringing the region immediately outside the boundary of nearby supermassive black holes into sharper focus. They will also be able to image more black holes than they have done so far. The new detections, part of a pilot experiment, were published today in The Astronomical Journal.

The EHT Collaboration released images of M87*, the supermassive black hole at the centre of the M87 galaxy, in 2019, and of Sgr A*, the black hole at the heart of our Milky Way galaxy, in 2022. These images were obtained by linking together multiple radio observatories across the planet, using a technique called very long baseline interferometry (VLBI), to form a single 'Earth-sized' virtual telescope.

To get higher-resolution images, astronomers typically rely on bigger telescopes -- or a larger separation between observatories working as part of an interferometer. But since the EHT was already the size of Earth, increasing the resolution of their ground-based observations called for a different approach. Another way to increase the resolution of a telescope is to observe light of a shorter wavelength -- and that's what the EHT Collaboration has now done.

"With the EHT, we saw the first images of black holes using the 1.3-mm wavelength observations, but the bright ring we saw, formed by light bending in the black hole's gravity, still looked blurry because we were at the absolute limits of how sharp we could make the images," said the study's co-lead Alexander Raymond, previously a postdoctoral scholar at the Center for Astrophysics | Harvard & Smithsonian (CfA), and now at the Jet Propulsion Laboratory, both in the United States. "At 0.87 mm, our images will be sharper and more detailed, which in turn will likely reveal new properties, both those that were previously predicted and maybe some that weren't."

To show that they could make detections at 0.87 mm, the Collaboration conducted test observations of distant, bright galaxies at this wavelength. Rather than using the full EHT array, they employed two smaller subarrays, both of which included ALMA and the Atacama Pathfinder EXperiment (APEX) in the Atacama Desert in Chile. The European Southern Observatory (ESO) is a partner in ALMA and co-hosts and co-operates APEX. Other facilities used include the IRAM 30-meter telescope in Spain and the NOrthern Extended Millimeter Array (NOEMA) in France, as well as the Greenland Telescope and the Submillimeter Array in Hawai'i.

In this pilot experiment, the Collaboration achieved observations with detail as fine as 19 microarcseconds, meaning they observed at the highest-ever resolution from the surface of Earth. They have not been able to obtain images yet, though: while they made robust detections of light from several distant galaxies, not enough antennas were used to be able to accurately reconstruct an image from the data.

This technical test has opened up a new window to study black holes. With the full array, the EHT could see details as small as 13 microarcseconds, equivalent to seeing a bottle cap on the Moon from Earth. This means that, at 0.87 mm, they will be able to get images with a resolution about 50% higher than that of previously released M87* and SgrA* 1.3-mm images. In addition, there's potential to observe more distant, smaller and fainter black holes than the two the Collaboration has imaged thus far.

EHT Founding Director Sheperd "Shep" Doeleman, an astrophysicist at the CfA and study co-lead, says: "Looking at changes in the surrounding gas at different wavelengths will help us solve the mystery of how black holes attract and accrete matter, and how they can launch powerful jets that stream over galactic distances."

This is the first time that the VLBI technique has been successfully used at the 0.87 mm wavelength. While the ability to observe the night sky at 0.87 mm existed before the new detections, using the VLBI technique at this wavelength has always presented challenges that took time and technological advances to overcome. For example, water vapour in the atmosphere absorbs waves at 0.87 mm much more than it does at 1.3 mm, making it more difficult for radio telescopes to receive signals from black holes at the shorter wavelength. Combined with increasingly pronounced atmospheric turbulence and noise buildup at shorter wavelengths, and an inability to control global weather conditions during atmospherically sensitive observations, progress to shorter wavelengths for VLBI -- especially those that cross the barrier into the submillimetre regime -- has been slow. But with these new detections, that's all changed.

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Dark matter could have helped make supermassive black holes in the early universe

Supermassive black holes typically take billions of years to form. But the James Webb Space Telescope is finding them not that long after the Big Bang -- before they should have had time to form.

It takes a long time for supermassive black holes, like the one at the center of our Milky Way galaxy, to form. Typically, the birth of a black hole requires a giant star with the mass of at least 50 of our suns to burn out -- a process that can take a billion years -- and its core to collapse in on itself.

Even so, at only about 10 solar masses, the resulting black hole is a far cry from the 4 million-solar-masses black hole, Sagittarius A*, found in our Milky Way galaxy, or the billion-solar-mass supermassive black holes found in other galaxies. Such gigantic black holes can form from smaller black holes by accretion of gas and stars, and by mergers with other black holes, which take billions of years.

Why, then, is the James Webb Space Telescope discovering supermassive black holes near the beginning of time itself, eons before they should have been able to form? UCLA astrophysicists have an answer as mysterious as the black holes themselves: Dark matter kept hydrogen from cooling long enough for gravity to condense it into clouds big and dense enough to turn into black holes instead of stars. The finding is published in the journal Physical Review Letters.

"How surprising it has been to find a supermassive black hole with a billion solar mass when the universe itself is only half a billion years old," said senior author Alexander Kusenko, a professor of physics and astronomy at UCLA. "It's like finding a modern car among dinosaur bones and wondering who built that car in the prehistoric times."

Some astrophysicists have posited that a large cloud of gas could collapse to make a supermassive black hole directly, bypassing the long history of stellar burning, accretion and mergers. But there's a catch: Gravity will, indeed, pull a large cloud of gas together, but not into one large cloud. Instead, it gathers sections of the gas into little halos that float near each other but don't form a black hole.

The reason is because the gas cloud cools too quickly. As long as the gas is hot, its pressure can counter gravity. However, if the gas cools, pressure decreases, and gravity can prevail in many small regions, which collapse into dense objects before gravity has a chance to pull the entire cloud into a single black hole.

"How quickly the gas cools has a lot to do with the amount of molecular hydrogen," said first author and doctoral student Yifan Lu. "Hydrogen atoms bonded together in a molecule dissipate energy when they encounter a loose hydrogen atom. The hydrogen molecules become cooling agents as they absorb thermal energy and radiate it away. Hydrogen clouds in the early universe had too much molecular hydrogen, and the gas cooled quickly and formed small halos instead of large clouds."

Lu and postdoctoral researcher Zachary Picker wrote code to calculate all possible processes of this scenario and discovered that additional radiation can heat the gas and dissociate the hydrogen molecules, altering how the gas cools.

"If you add radiation in a certain energy range, it destroys molecular hydrogen and creates conditions that prevent fragmentation of large clouds," Lu said.

But where does the radiation come from?

Only a very tiny portion of matter in the universe is the kind that makes up our bodies, our planet, the stars and everything else we can observe. The vast majority of matter, detected by its gravitational effects on stellar objects and by the bending of light rays from distant sources, is made of some new particles, which scientists have not yet identified.

The forms and properties of dark matter are therefore a mystery that remains to be solved. While we don't know what dark matter is, particle theorists have long speculated that it could contain unstable particles which can decay into photons, the particles of light. Including such dark matter in the simulations provided the radiation needed for the gas to remain in a large cloud while it is collapsing into a black hole.

Dark matter could be made of particles that slowly decay, or it could be made of more than one particle species: some stable and some that decay at early times. In either case, the product of decay could be radiation in the form of photons, which break up molecular hydrogen and prevent hydrogen clouds from cooling too quickly. Even very mild decay of dark matter yielded enough radiation to prevent cooling, forming large clouds and, eventually, supermassive black holes.

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Astrophysicists uncover supermassive blackhole/dark matter connection in solving the 'final parsec problem'

Researchers have found a link between some of the largest and smallest objects in the cosmos: supermassive black holes and dark matter particles.

Their new calculations reveal that pairs of supermassive black holes (SMBHs) can merge into a single larger black hole because of previously overlooked behaviour of dark matter particles, proposing a solution to the longstanding "final parsec problem" in astronomy.

The research is described in Self-interacting dark matter solves the final parsec problem of supermassive black hole mergers published this month in the journal Physical Review Letters.

In 2023, astrophysicists announced the detection of a "hum" of gravitational waves permeating the universe. They hypothesized that this background signal emanated from millions of merging pairs of SMBHs each billions of times more massive than our Sun.

However, theoretical simulations showed that as pairs of these mammoth celestial objects spiral closer together, their approach stalls when they are roughly a parsec apart -- a distance of about three light years -- thereby preventing a merger.

Not only did this "final parsec problem" conflict with the theory that merging SMBHs were the source of the gravitational wave background, it was also at odds with the theory that SMBHs grow from the merger of less massive black holes.

"We show that including the previously overlooked effect of dark matter can help supermassive black holes overcome this final parsec of separation and coalesce," says paper co-author Gonzalo Alonso-Álvarez, a postdoctoral fellow in the Department of Physics at the University of Toronto and the Department of Physics and Trottier Space Institute at McGill University. "Our calculations explain how that can occur, in contrast to what was previously thought."

The paper's co-authors include Professor James Cline from McGill University and the CERN Theoretical Physics Department in Switzerland and Caitlyn Dewar, a master of science student in physics at McGill.

SMBHs are thought to lie in the centres of most galaxies and when two galaxies collide, the SMBHs fall into orbit around each other. As they revolve around each other, the gravitational pull of nearby stars tugs at them and slows them down. As a result, the SMBHs spiral inward toward a merger.

Previous merger models showed that when the SMBHs approached to within roughly a parsec, they begin to interact with the dark matter cloud or halo in which they are embedded. They indicated that the gravity of the spiraling SMBHs throws dark matter particles clear of the system and the resulting sparsity of dark matter means that energy is not drawn from the pair and their mutual orbits no longer shrink.

While those models dismissed the impact of dark matter on the SMBH's orbits, the new model from Alonso-Álvarez and his colleagues reveals that dark matter particles interact with each other in such a way that they are not dispersed. The density of the dark matter halo remains high enough that interactions between the particles and the SMBHs continue to degrade the SMBH's orbits, clearing a path to a merger.

"The possibility that dark matter particles interact with each other is an assumption that we made, an extra ingredient that not all dark matter models contain," says Alonso-Álvarez. "Our argument is that only models with that ingredient can solve the final parsec problem."

The background hum generated by these colossal cosmic collisions is made up of gravitational waves of much longer wavelength than those first detected in 2015 by astrophysicists operating the Laser Interferometer Gravitational-Wave Observatory (LIGO). Those gravitational waves were generated by the merger of two black holes, both some 30 times the mass of the Sun.

The background hum has been detected in recent years by scientists operating the Pulsar Timing Array. The array reveals gravitational waves by measuring minute variations in signals from pulsars, rapidly rotating neutron stars that emit strong radio pulses.

"A prediction of our proposal is that the spectrum of gravitational waves observed by pulsar timing arrays should be softened at low frequencies," says Cline. "The current data already hint at this behavior, and new data may be able to confirm it in the next few years."

In addition to providing insight into SBMH mergers and the gravitational wave background signal, the new result also provides a window into the nature of dark matter.

"Our work is a new way to help us understand the particle nature of dark matter," says Alonso-Álvarez. "We found that the evolution of black hole orbits is very sensitive to the microphysics of dark matter and that means we can use observations of supermassive black hole mergers to better understand these particles."

For example, the researchers found that the interactions between dark matter particles they modeled also explains the shapes of galactic dark matter halos.

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Stellar collisions produce strange, zombie-like survivors

Despite their ancient ages, some stars orbiting the Milky Way's central supermassive black hole appear deceptively youthful. But unlike humans, who might appear rejuvenated from a fresh round of collagen injections, these stars look young for a much darker reason.

They ate their neighbors.

This is just one of the more peculiar findings from new Northwestern University research. Using a new model, astrophysicists traced the violent journeys of 1,000 simulated stars orbiting our galaxy's central supermassive black hole, Sagittarius A* (Sgr A*).

So densely packed with stars, the region commonly experiences brutal stellar collisions. By simulating the effects of these intense collisions, the new work finds that collision survivors can lose mass to become stripped down, low-mass stars or can merge with other stars to become massive and rejuvenated in appearance.

"The region around the central black hole is dense with stars moving at extremely high speeds," said Northwestern's Sanaea C. Rose, who led the research. "It's a bit like running through an incredibly crowded subway station in New York City during rush hour. If you aren't colliding into other people, then you are passing very closely by them. For stars, these near collisions still cause them to interact gravitationally. We wanted to explore what these collisions and interactions mean for the stellar population and characterize their outcomes."

Rose will present this research at the American Physical Society's (APS) April meeting in Sacramento, California. "Stellar Collisions in the Galactic Center" will take place on Thursday (April 4) as part of the session "Particle Astrophysics and the Galactic Center."

Rose is the Lindheimer Postdoctoral Fellow at Northwestern's Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA). She began this work as a Ph.D. candidate at UCLA.

Destined to collide

The center of our Milky Way is a strange and wild place. The gravitational pull of Sgr A* accelerates stars to whip around their orbits at terrifying speeds. And the sheer number of stars packed into the galaxy's center is upwards of a million. The densely packed cluster plus the lightning-fast speeds equal a high-speed demolition derby. In the innermost region -- within 0.1 parsecs of the black hole -- few stars escape unscathed.

"The closest star to our sun is about four light-years away," Rose explained. "Within that same distance near the supermassive black hole, there are more than a million stars. It's an incredibly crowded neighborhood. On top of that, the supermassive black hole has a really strong gravitational pull. As they orbit the black hole, stars can move at thousands of kilometers per second."

Within this tight, hectic neighborhood, stars can collide with other stars. And the closer stars live to the supermassive black hole, the likelihood of collision increases. Curious of the outcomes of these collisions, Rose and her collaborators developed a simulation to trace the fates of stellar populations in the galactic center. The simulation takes several factors into account: density of the stellar cluster, mass of the stars, orbit speed, gravity and distances from the Sgr A*.

From 'violent high fives' to total mergers

In her research, Rose pinpointed one factor that is most likely to determine a star's fate: its distance from the supermassive black hole.

Within 0.01 parsecs from the black hole, stars -- moving at speeds reaching thousands of kilometers per second -- constantly bump into one another. It's rarely a head-on collision and more like a "violent high five," as Rose describes it. The impacts are not strong enough to smash the stars completely. Instead, they shed their outer layers and continue speeding along the collision course.

"They whack into each other and keep going," Rose said. "They just graze each other as though they are exchanging a very violent high five. This causes the stars to eject some material and lose their outer layers. Depending on how fast they are moving and how much they overlap when they collide, they might lose quite a bit of their outer layers. These destructive collisions result in a population of strange, stripped down, low-mass stars."

Outside of 0.01 parsecs, stars move at a more relaxed pace -- hundreds of kilometers per second as opposed to thousands. Because of the slower speeds, these stars collide with one another but then don't have enough energy to escape. Instead, they merge to become more massive. In some cases, they might even merge multiple times to become 10 times more massive than our sun.

"A few stars win the collision lottery," Rose said. "Through collisions and mergers, these stars collect more hydrogen. Although they were formed from an older population, they masquerade as rejuvenated, young-looking stars. They are like zombie stars; they eat their neighbors."

But the youthful appearance comes at the cost of a shorter life expectancy.

"They die very quickly," Rose said. "Massive stars are sort of like giant, gas-guzzling cars. They start with a lot of hydrogen, but they burn through it very, very fast."

Extreme environment 'unlike any other'

Although Rose finds simple joy in studying the bizarre, extreme region near our galactic center, her work also can reveal information about the history of the Milky Way. And because the central cluster is extremely difficult to observe, her team's simulations can illuminate otherwise hidden processes.

"It's an environment unlike any other," Rose said. "Stars, which are under the influence of a supermassive black hole in a very crowded region, are unlike anything we will ever see in our own solar neighborhood. But if we can learn about these stellar populations, then we might be able to learn something new about how the galactic center was assembled. At the very least, it certainly provides a point of contrast for the neighborhood where we live."

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Sleeping supermassive black holes awakened briefly by shredded stars

A new investigation into an obscure class of galaxies known as Compact Symmetric Objects, or CSOs, has revealed that these objects are not entirely what they seem. CSOs are active galaxies that host supermassive black holes at their cores. Out of these monstrous black holes spring two jets traveling in opposite directions at nearly the speed of light. But in comparison to other galaxies that boast fierce jets, these jets do not extend out to great distances -- they are much more compact. For many decades, astronomers suspected that CSOs were simply young and that their jets would eventually travel out to greater distances.

Now, reporting in three different papers in The Astrophysical Journal, a Caltech-led team of researchers has concluded that CSOs are not young but rather lead relatively short lives.

"These CSOs are not young," explains Anthony (Tony) Readhead, the Robinson Professor of Astronomy, Emeritus, who led the investigation. "You wouldn't call a 12-year-old dog young even though it has lived a shorter life than an adult human. These objects are a distinct species all of their own that live and die out in thousands of years rather than the millions of years that are common in galaxies with bigger jets."

In the new studies, the team reviewed literature and past observations of more than 3,000 CSO candidates, verifying 64 as real and identifying an additional 15 CSOs. All these objects had been previously observed by the National Radio Astronomy Observatory's Very Long Baseline Array (VLBA), funded by the National Science Foundation (NSF), and some had been observed by other high-resolution radio telescopes. "The VLBA observations are the most detailed in astronomy, providing images with details equivalent to measuring the width of a human hair at a distance of 100 miles," Readhead says.

The team's analysis concludes that CSOs expel jets for 5,000 years or less and then die out. "The CSO jets are very energetic jets but they seem to shut off," says Vikram Ravi, assistant professor of astronomy at Caltech and a co-author of one of the studies. "The jets stop flowing from the source."

As for what is fueling the short-lived jets, the scientists believe the cause is a tidal disruption event (TDE), which occurs when a single star wanders too close to a supermassive black hole and is devoured.

"We think that a single star gets ripped apart, and then all that energy is channeled into jets along the axis the black hole is spinning around," Readhead says. "The giant black hole starts out invisible to us, and then when it consumes a star, boom! The black hole has fuel, and we can see it."

Readhead first suspected that CSOs might be fueled by TDEs back in the 1990s, but he says the idea went largely unnoticed by the scientific community. "The hypothesis was all but forgotten because years went by before observational evidence began to mount for TDEs," he says. At the time of his original hypothesis, only three CSOs had been found.

Fast forward to 2020. Readhead, who had paused his studies of CSOs to delve into different problems in radio astronomy, decided it was time to revisit the topic. He gathered some of his colleagues together on Zoom, and they decided to comb through literature and weed out objects that had been misclassified as CSOs. Over the next two years, the team investigated more than 3,000 CSO candidates, narrowing the group down to only dozens that had the criteria to be real CSOs.

Ultimately, a picture began to emerge of CSOs as an entirely distinct family with jets that die out much sooner than their gigantic brethren, such as those of the extremely powerful Cygnus A, a galaxy that shoots out extremely powerful jets that glow brightly at radio wavelengths. These jets stretch to distances of about 230,000 light-years in each direction and last tens of millions of years. In contrast, the CSO jets extend to about 1,500 light-years at most and die out by about 5,000 years.

According to the astronomers, the CSO jets likely form when a supermassive black hole snacks on not just any star, but a substantial one.

"The TDEs we've previously seen only lasted for a few years," Ravi says. "We think that the remarkable TDEs powering CSOs last far longer because the disrupted stars are very large in size, very massive, or both."

By analyzing the varied collection of CSO radio images, the researchers say they can trace how the objects age over time, almost like looking at a photo album of a CSO's life to observe how its jets evolve. The younger CSOs have shorter jets that are closer to the black holes, while the older objects have jets that extend further out from their black hole. Though most of the jets die out, the scientists estimate that one in 100 will go onto to become long-lived like those of Cygnus A. In those rare cases, the galaxies are likely merging with other galaxies, a turbulent process that provides a large quantity of fuel.

If the discoveries of Readhead and his team are confirmed with additional observations, the CSOs will provide a whole new avenue for studying how massive stars at the centers of galaxies interact with supermassive black holes.

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Baby quasars: Growing supermassive black holes

The James Webb Space Telescope makes one of the most unexpected findings within its first year of service: A high number of faint little red dots in the distant Universe could change the way we understand the genesis of supermassive black holes. The research, led by Jorryt Matthee, Assistant Professor in astrophysics at the Institute of Science and Technology Austria (ISTA), is now published in The Astrophysical Journal.

A bunch of little red dots found in a tiny region of our night sky might be an unexpected breakthrough for the James Webb Space Telescope (JWST) within its first year of service. These objects were indistinguishable from normal galaxies through the 'eyes' of the older Hubble Space Telescope. "Without having been developed for this specific purpose, the JWST helped us determine that faint little red dots-found very far away in the Universe's distant past-are small versions of extremely massive black holes. These special objects could change the way we think about the genesis of black holes," says Jorryt Matthee, Assistant Professor at the Institute of Science and Technology Austria (ISTA), and lead author of the study. "The present findings could bring us one step closer to answering one of the greatest dilemmas in astronomy: According to the current models, some supermassive black holes in the early Universe have simply grown 'too fast'. Then how did they form?"

The cosmic points of no return

Scientists have long considered black holes a mathematical curiosity until their existence became increasingly evident. These strange cosmic bottomless pits could have such compact masses and strong gravities that nothing can escape their force of attraction-they suck in anything, including cosmic dust, planets, and stars, and deform the space and time around them such that even light cannot escape. The general theory of relativity, published by Albert Einstein over a century ago, predicted that black holes could have any mass. Some of the most intriguing black holes are the supermassive black holes (SMBHs), which could reach millions to billions of times the mass of the Sun. Astrophysicists agree that there is an SMBH at the center of almost every large galaxy. The proof that Sagittarius A* is an SMBH in the center of our Galaxy with over four million times the Sun's mass, earned the 2020 Nobel Prize in Physics.

Too massive to be there

However, not all SMBHs are the same. While Sagittarius A* could be compared to a sleeping volcano, some SMBHs grow extremely rapidly by engulfing astronomic amounts of matter. Thus, they become so luminous that they can be observed until the edge of the ever-expanding Universe. These SMBHs are called quasars and are among the brightest objects in the Universe. "One issue with quasars is that some of them seem to be overly massive, too massive given the age of the Universe at which the quasars are observed. We call them the 'problematic quasars,'" says Matthee. "If we consider that quasars originate from the explosions of massive stars-and that we know their maximum growth rate from the general laws of physics, some of them look like they have grown faster than is possible. It's like looking at a five-year-old child that is two meters tall. Something doesn't add up," he explains. Could SMBHs perhaps grow even faster than we originally thought? Or do they form differently?

Small versions of giant cosmic monsters

Now, Matthee and his colleagues identify a population of objects that appear as little red dots in JWST images. Also, they demonstrate that these objects are SMBHs, but not overly massive ones. Central in determining that these objects are SMBHs was the detection of Hα spectral emission lines with wide line profiles. Hα lines are spectral lines in the deep-red region of visible light that are emitted when hydrogen atoms are heated. The width of the spectra traces the motion of the gas. "The wider the base of the Hα lines, the higher the gas velocity. Thus, these spectra tell us that we are looking at a very small gas cloud that moves extremely rapidly and orbits something very massive like an SMBH," says Matthee. However, the little red dots are not the giant cosmic monsters found in overly massive SMBHs. "While the 'problematic quasars' are blue, extremely bright, and reach billions of times the mass of the Sun, the little red dots are more like 'baby quasars.' Their masses lie between ten and a hundred million solar masses. Also, they appear red because they are dusty. The dust obscures the black holes and reddens the colors," says Matthee. But eventually, the outflow of gas from the black holes will puncture the dust cocoon, and giants will evolve from these little red dots. Thus, the ISTA astrophysicist and his team suggest that the little red dots are small, red versions of giant blue SMBHs in the phase that predates the problematic quasars. "Studying baby versions of the overly massive SMBHs in more detail will allow us to better understand how problematic quasars come to exist."

A "breakthrough" technology

Matthee and his team could find the baby quasars thanks to the datasets acquired by the EIGER (Emission-line galaxies and Intergalactic Gas in the Epoch of Reionization) and FRESCO (First Reionization Epoch Spectroscopically Complete Observations) collaborations. These are a large and a medium JWST program in which Matthee was involved. Last December, the Physics World magazine listed EIGER among the top 10 breakthroughs of the year for 2023. "EIGER was designed to study specifically the rare blue supermassive quasars and their environments. It was not designed to find the little red dots. But we found them by chance in the same dataset. This is because, by using the JWST's Near Infrared Camera, EIGER acquires emission spectra of all objects in the Universe," says Matthee. "If you raise your index finger and extend your arm completely, the region of the night sky we explored corresponds to roughly a twentieth of the surface of your nail. So far, we have probably only scratched the surface."

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Brightest and fastest-growing: Astronomers identify record-breaking quasar

Using the European Southern Observatory's (ESO) Very Large Telescope (VLT), astronomers have characterised a bright quasar, finding it to be not only the brightest of its kind, but also the most luminous object ever observed. Quasars are the bright cores of distant galaxies and they are powered by supermassive black holes. The black hole in this record-breaking quasar is growing in mass by the equivalent of one Sun per day, making it the fastest-growing black hole to date.

The black holes powering quasars collect matter from their surroundings in a process so energetic that it emits vast amounts of light.

So much so that quasars are some of the brightest objects in our sky, meaning even distant ones are visible from Earth.

As a general rule, the most luminous quasars indicate the fastest-growing supermassive black holes.

"We have discovered the fastest-growing black hole known to date. It has a mass of 17 billion Suns, and eats just over a Sun per day. This makes it the most luminous object in the known Universe," says Christian Wolf, an astronomer at the Australian National University (ANU) and lead author of the study published today in Nature Astronomy. The quasar, called J0529-4351, is so far away from Earth that its light took over 12 billion years to reach us.

The matter being pulled in toward this black hole, in the form of a disc, emits so much energy that J0529-4351 is over 500 trillion times more luminous than the Sun.

"All this light comes from a hot accretion disc that measures seven light-years in diameter -- this must be the largest accretion disc in the Universe," says ANU PhD student and co-author Samuel Lai.

Seven light-years is about 15,000 times the distance from the Sun to the orbit of Neptune.

And, remarkably, this record-breaking quasar was hiding in plain sight.

"It is a surprise that it has remained unknown until today, when we already know about a million less impressive quasars. It has literally been staring us in the face until now," says co-author Christopher Onken, an astronomer at ANU.

He added that this object showed up in images from the ESO Schmidt Southern Sky Survey dating back to 1980, but it was not recognised as a quasar until decades later.

Finding quasars requires precise observational data from large areas of the sky.

The resulting datasets are so large, researchers often use machine-learning models to analyse them and tell quasars apart from other celestial objects.

However, these models are trained on existing data, which limits the potential candidates to objects similar to those already known.

If a new quasar is more luminous than any other previously observed, the programme might reject it and classify it instead as a star not too distant from Earth.

An automated analysis of data from the European Space Agency's Gaia satellite passed over J0529-4351 for being too bright to be a quasar, suggesting it to be a star instead.

The researchers identified it as a distant quasar last year using observations from the ANU 2.3-metre telescope at the Siding Spring Observatory in Australia.

Discovering that it was the most luminous quasar ever observed, however, required a larger telescope and measurements from a more precise instrument.

The X-shooter spectrograph on ESO's VLT in the Chilean Atacama Desert provided the crucial data.

The fastest-growing black hole ever observed will also be a perfect target for the GRAVITY+ upgrade on ESO's VLT Interferometer (VLTI), which is designed to accurately measure the mass of black holes, including those far away from Earth.

Additionally, ESO's Extremely Large Telescope (ELT), a 39-metre telescope under construction in the Chilean Atacama Desert, will make identifying and characterising such elusive objects even more feasible.

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Black hole at center of the Milky Way resembles a football

The supermassive black hole in the center of the Milky Way is spinning so quickly it is warping the spacetime surrounding it into a shape that can look like a football, according to a new study using data from NASA's Chandra X-ray Observatory and the U.S. National Science Foundation's Karl G. Jansky Very Large Array (VLA). That football shape suggests the black hole is spinning at a substantial speed, which researchers estimated to be about 60% of its potential limit.

The work, led by Penn State Berks Professor of Physics Ruth Daly, was published in the Monthly Notices of the Royal Astronomical Society.

Astronomers call this giant black hole Sagittarius A* (Sgr A*). It is located about 26,000 light-years away from Earth in the center of the galaxy. To determine how quickly Sgr A* is spinning -- one of its fundamental properties, along with mass -- the researchers applied a method that uses X-ray and radio data to assess how material is flowing towards and away from the black hole. The method was developed and published by Daly in 2019 in The Astrophysical Journal.

"Our work may help settle the question of how fast our galaxy's supermassive black hole is spinning," Daly said. "Our results indicate that Sgr A* is spinning very rapidly, which is interesting and has far-reaching implications."

The team found the angular velocity -- the number of revolutions per second -- of Sgr A*'s spin is about 60% of the maximum possible value, a limit set because material cannot travel faster than the speed of light.

Past estimations of Sgr A*'s speed have been made with different techniques and by other astronomers, with results ranging from no rotation at all to spinning at almost the maximum rate.

"This work, however, shows that this could change if the amount of material in the vicinity of Sgr A* increases," Daly said.

As a black hole rotates, it pulls "spacetime" -- the combination of time and the three dimensions of space -- and nearby matter. The gravitational pull also squashes the spacetime, altering its shape depending on how it's observed. Spacetime appears circular if the black hole is viewed from the top. From the side, however, the spacetime is shaped like a football. The faster the spin, the flatter the football.

The spin can also serve as an energy source, Daly said, if matter -- such as gas or the remnants of a star that wanders too close -- exists in the vicinity of the black hole. As the black hole spins, matter can escape in the form of narrow jets called collimated outflows. However, Sgr A* currently has limited nearby matter, so the black hole has been relatively quiet, with weakly collimated outflows, in recent millennia.

"A spinning black hole is like a rocket on the launch pad," said Biny Sebastian, a co-author from the University of Manitoba in Winnipeg, Canada. "Once material gets close enough, it's like someone has fueled the rocket and hit the 'launch' button."

This means that in the future, if the properties of the matter and the magnetic field strength close to the black hole change, part of the enormous energy of the black hole's spin could drive more powerful outflows. This source material could come from gas or from the remnants of a star torn apart by the black hole's gravity if that star wanders too close to Sgr A*.

"Jets powered and collimated by a galaxy's spinning central black hole can profoundly affect the gas supply for an entire galaxy, which affects how quickly and even whether stars can form," said co-author Megan Donahue from Michigan State University. "The 'Fermi bubbles' seen in X-rays and gamma rays around our Milky Way's black hole show the black hole was probably active in the past. Measuring the spin of our black hole is an important test of this scenario."

Fermi bubbles refer to structures that emit gamma rays above and below the black hole that researchers have theorized resulted from prior massive outflows.

The researchers used the outflow method to determine the spin of Sgr A*. Daly's approach incorporates consideration of the relationship between the spin of the black hole and its mass, the properties of the matter near the black hole and the outflow properties. The collimated outflow produces the radio waves, while the disk of gas surrounding the black hole emits X-rays. The researchers combined observational data from Chandra and the VLA with an independent estimate of the black hole's mass from other telescopes to inform the outflow method and determine the black hole's spin.

"We have a special view of Sgr A* because it is the nearest supermassive black hole to us," said co-author Anan Lu from McGill University in Montreal, Canada. "Although it's quiet right now, our work shows that in the future it will give an incredibly powerful kick to surrounding matter. That might happen in a thousand or a million years, or it could happen in our lifetimes."

Read more at Science Daily

Gas on the run -- ALMA spots the shadow of a molecular outflow from a quasar when the Universe was less than one billion years old

Theoretical predictions have been confirmed with the discovery of an outflow of molecular gas from a quasar when the Universe was less than a billion years old.

A quasar is a compact region powered by a supermassive black hole located in the center of a massive galaxy.

They are extremely luminous, with a point-like appearance similar to stars, and are extremely distant from Earth.

Owing to their distance and brightness, they provide a peek into conditions of the early Universe, when it was less than 1 billion years old.

A team of researchers led by Assistant Professor Dragan Salak at Hokkaido University, Assistant Professor Takuya Hashimoto at the University of Tsukuba, and Professor Akio Inoue at Waseda University, has discovered the first evidence of suppression of star formation driven by an outflow of molecular gas in a quasar-host galaxy in the early Universe.

Their findings, based on observations they made using the Atacama Large Millimeter/submillimeter Array (ALMA), in Chile, were published in The Astrophysical Journal.

Molecular gas is vital to the formation of stars. As the primary fuel of star formation, the ubiquity and high concentrations of molecular gas within a galaxy would lead to a vast number of stars being formed.

By ejecting this gas into intergalactic space faster than it could be consumed by star formation, molecular outflows effectively suppress the formation of stars in galaxies that host quasars.

"Theoretical work suggests that molecular gas outflows play an important role in the formation and evolution of galaxies from an early age, because they can regulate star formation," Salak explains.

"Quasars are especially energetic sources, so we expected that they may be able to generate powerful outflows."

The quasar the researchers observed, J2054-0005, has a very high redshift -- it and the Earth are apparently moving away from each other very fast.

"J2054-0005 is one of the brightest quasars in the distant Universe, so we decided to target this object as an excellent candidate to study powerful outflows," Hashimoto says.

The researchers used ALMA to observe the outflow of molecular gas from the quasar.

As the only telescope in the world that has the sensitivity and frequency coverage to detect molecular gas outflows in the early Universe, ALMA was key to this study.

Speaking about the method used in the study, Salak comments: "The outflowing molecular (OH) gas was discovered in absorption. This means we did not observe microwave radiation coming directly from the OH molecules; instead, we observed the radiation coming from the bright quasar -- and absorption means that OH molecules happened to absorb a part of the radiation from the quasar. So, it was like revealing the presence of a gas by seeing the 'shadow' it cast in front of the light source."

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Origin of intense light in supermassive black holes and tidal disruption events revealed

Anew study by Hebrew University is a significant breakthrough in understanding Tidal Disruption Events (TDEs) involving supermassive black holes. The new simulations, for the first time ever, accurately replicate the entire sequence of a TDE from stellar disruption to the peak luminosity of the resulting flare. This study has unveiled a previously unknown type of shockwave within TDEs, settling a longstanding debate about the energy source of the brightest phases in these events. It confirms that shock dissipation powers the brightest weeks of a TDE flare, opening doors for future studies to utilize TDE observations as a means to measure essential properties of black holes and potentially test Einstein's predictions in extreme gravitational environments.

The mysteries of supermassive black holes have long captivated astronomers, offering a glimpse into the deepest corners of our universe.

Now, a new study led by Dr. Elad Steinberg and Dr. Nicholas C. Stone at the Racah Institute of Physics, The Hebrew University, sheds new light on these enigmatic cosmic entities.

Supermassive black holes, ranging from millions to billions of times the mass of our Sun, have remained elusive despite their pivotal role in shaping galaxies.

Their extreme gravitational pull warps spacetime, creating an environment that defies conventional understanding and presents a challenge for observational astronomers.

Enter Tidal Disruption Events (TDEs), a dramatic phenomenon that occurs when ill-fated stars venture too close to a black hole's event horizon, and are torn apart into thin streams of plasma.

As this plasma returns towards the black hole, a series of shockwaves heat it up, leading to an extraordinary display of luminosity -- a flare that surpasses the collective brightness of an entire galaxy for weeks or even months.

The study conducted by Steinberg and Stone represents a significant leap forward in understanding these cosmic events.

For the first time, their simulations have recreated a realistic TDE, capturing the complete sequence from the initial star disruption to the peak of the ensuing luminous flare, all made possible by pioneering radiation-hydrodynamics simulation software developed by Steinberg at The Hebrew University.

This research has uncovered a previously unexplored type of shockwave within TDEs, revealing that these events dissipate their energy at a faster rate than previously understood.

By clarifying this aspect, the study resolves a long-standing theoretical debate, confirming that the brightest phases of a TDE flare are powered by shock dissipation -- a revelation that sets the stage for comprehensive exploration by observational astronomers.

These findings pave the way for translating TDE observations into precise measurements of crucial black hole properties, including mass and spin.

Moreover, these cosmic occurrences could serve as a litmus test for validating Einstein's predictions in extreme gravitational environments.

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NASA's Webb reveals new features in heart of Milky Way

The latest image from NASA's James Webb Space Telescope shows a portion of the dense center of our galaxy in unprecedented detail, including never-before-seen features astronomers have yet to explain. The star-forming region, named Sagittarius C (Sgr C), is about 300 light-years from the Milky Way's central supermassive black hole, Sagittarius A*.

"There's never been any infrared data on this region with the level of resolution and sensitivity we get with Webb, so we are seeing lots of features here for the first time," said the observation team's principal investigator Samuel Crowe, an undergraduate student at the University of Virginia in Charlottesville.

"Webb reveals an incredible amount of detail, allowing us to study star formation in this sort of environment in a way that wasn't possible previously."

"The galactic center is the most extreme environment in our Milky Way galaxy, where current theories of star formation can be put to their most rigorous test," added professor Jonathan Tan, one of Crowe's advisors at the University of Virginia.

Protostars

Amid the estimated 500,000 stars in the image is a cluster of protostars -- stars that are still forming and gaining mass -- producing outflows that glow like a bonfire in the midst of an infrared-dark cloud.

At the heart of this young cluster is a previously known, massive protostar over 30 times the mass of our Sun.

The cloud the protostars are emerging from is so dense that the light from stars behind it cannot reach Webb, making it appear less crowded when in fact it is one of the most densely packed areas of the image.

Smaller infrared-dark clouds dot the image, looking like holes in the starfield.

That's where future stars are forming.

Webb's NIRCam (Near-Infrared Camera) instrument also captured large-scale emission from ionized hydrogen surrounding the lower side of the dark cloud, shown cyan-colored in the image.

Typically, Crowe says, this is the result of energetic photons being emitted by young massive stars, but the vast extent of the region shown by Webb is something of a surprise that bears further investigation.

Another feature of the region that Crowe plans to examine further is the needle-like structures in the ionized hydrogen, which appear oriented chaotically in many directions.

"The galactic center is a crowded, tumultuous place. There are turbulent, magnetized gas clouds that are forming stars, which then impact the surrounding gas with their outflowing winds, jets, and radiation," said Rubén Fedriani, a co-investigator of the project at the Instituto Astrofísica de Andalucía in Spain.

"Webb has provided us with a ton of data on this extreme environment, and we are just starting to dig into it."

Around 25,000 light-years from Earth, the galactic center is close enough to study individual stars with the Webb telescope, allowing astronomers to gather unprecedented information on how stars form, and how this process may depend on the cosmic environment, especially compared to other regions of the galaxy.

For example, are more massive stars formed in the center of the Milky Way, as opposed to the edges of its spiral arms?

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Mystery resolved: Black hole feeding and feedback at the center of an active galaxy

An international research team led by Takuma Izumi, an assistant professor at the National Astronomical Observatory of Japan, has observed in high resolution (approximately 1 light year) the active galactic nucleus of the Circinus Galaxy -- one of the closest major galaxies to the Milky Way. The observation was made possible by the Atacama Large Millimeter/Submillimeter Array (ALMA) astronomical observatory in Chile.

This breakthrough marks the world's first quantitative measurement at this scale of gas flows and their structures of a nearby supermassive black hole in all phase gases, including plasma, atomic, and molecular. Such high resolution allowed the team to team to capture the accretion flow heading towards the supermassive black hole, revealing that this accretion flow is generated by a physical mechanism known as 'gravitational instability.' Furthermore, the team also found that a significant portion of this accretion flow does not contribute to the growth of the black hole. Instead, most of the gas is expelled from the vicinity of the black hole as atomic or molecular outflows, and returns to the gas disk to participate again into an accretion flow towards the black hole, much like how water gets recycled in a water fountain. These findings represent a crucial advancement towards a greater understanding of the growth mechanisms of supermassive black holes.

These observation results were published in Science on November 2, 2023.

'Supermassive black holes,' with masses exceeding a million times that of the Sun, exist at the centers of many galaxies. But astronomers have long pondered the mechanisms responsible their formation. One proposed mechanism, as outlined in previous research, suggests that gas accretes onto the black hole as it gravitates towards the center of the host galaxy.

As gas approaches the supermassive black holes, the intense gravitational pull of the black hole causes the gas to accelerate. The resulting increase in friction between gas particles leads to the gas heating up to temperatures as high as several million degrees and results in the emission of brilliant light. Known as an active galactic nucleus (AGN), the brightness can at times surpass the combined light of all the stars in the galaxy. Interestingly, a portion of the gas that falls towards the black hole (accretion flow) is thought to be blown away by the immense energy of this active galactic nucleus, leading to outflows.

Previous theoretical and observational studies have provided detailed insights into gas accretion mechanisms from the 100,000 light-years scale down to a scale of a few hundred light-years at the center. However, gas accretion occurs a few dozen light-years from the galactic center. This limited spacial scale has hindered further understanding of the accretion process. For instance, to comprehend quantitatively the growth of black holes, it is necessary to measure the accretion flow rate (how much gas is flowing in) and to determine the amounts and types of gases (plasma, atomic gas, molecular gas) that are expelled as outflows at that small scale. Unfortunately, observational understanding has not progressed significantly until now.

"Observations of multiphase gases can provide a more comprehensive and thorough understanding of the distribution and dynamics of matter around a black hole and our observation marks the highest resolution ever achieved for multiphase gas observations in an active galactic nucleus," points out Izumi.

Izumi and his colleagues initially captured, for the first time, the accretion flow heading towards the supermassive black hole within the high-density gas disk that extends over several light-years from the galactic center. Identifying this accretion flow had long been a challenge due to the small scale of the region and the complex motions of gas near the galactic center. However, the research team pinpointed the location where the foreground molecular gas was absorbing the light from the active galactic nucleus shining brightly in the background. Detailed analysis revealed that this absorbing material is moving away from Earth. As the absorbing material consistently resides between the active galactic nucleus and Earth, this indicates that the team has successfully captured the accretion flow heading toward the active galactic nucleus.

The study also elucidated the physical mechanism responsible for inducing this gas accretion. The observed gas disk exhibited a gravitational force so substantial that it could not be sustained by the pressure calculated from the gas disk's motion. When this situation occurs, the gas disk collapses under its own weight, forming complex structures and losing its ability to maintain stable motion at the galactic center. Consequently, the gas rapidly falls towards the central black hole, A phenomenon known as "gravitational instability" at the heart of the galaxy.

Furthermore, the study advanced quantitative understanding of gas flows around the active galactic nucleus. By considering the density of the observed gas and the velocity of the accretion flow, the researchers were able to calculate the rate at which gas is supplied to the black hole. Surprisingly, this rate was found to be 30 times greater than what is needed to sustain the active galactic nucleus. In other words, the majority of the accretion flow at the 1-light-year scale around the galactic center was not contributing to the growth of the black hole.

So, where did this surplus gas go? High-sensitivity observations of all phase gases with ALMA detected outflows from the active galactic nucleus. Quantitative analysis revealed that the majority of the gas flowing towards the black hole was expelled as atomic or molecular outflows. However, due to their slow velocities, they couldn't escape the gravitational pull of the black hole and eventually returned to the gas disk. There, they were recycled into an accretion flow toward the black hole, completing a fascinating gas recycling process at the galactic center.

Read more at Science Daily

Black holes are messy eaters

New observations down to light-year scale of the gas flows around a supermassive black hole have successfully detected dense gas inflows and shown that only a small portion (about 3 percent) of the gas flowing towards the black hole is eaten by the black hole. The remainder is ejected and recycled back into the host galaxy.

Not all of the matter which falls towards a black hole is absorbed, some of it is ejected as outflows. But the ratio of the matter that the black hole "eats," and the amount "dropped" has been difficult to measure.

An international research team led by Takuma Izumi, an assistant professor at the National Astronomical Observatory of Japan, used the Atacama Large Millimeter/submillimeter Array (ALMA) to observe the supermassive black hole in the Circinus Galaxy, located 14 million light-years away in the direction of the constellation Circinus. This black hole is known to be actively feeding.

Thanks to ALMA's high resolution, the team was the first in the world to measure the amount of inflow and outflow down to a scale of a few light-years around the black hole. By measuring the flows of gasses in different states (molecular, atomic, and plasma) the team was able to determine the overall efficiency of black hole feeding, and found that it was only about 3 precent. The team also confirmed that gravitational instability is driving the inflow. Analysis also showed that the bulk of the expelled outflows are not fast enough to escape the galaxy and be lost. They are recycled back into the circumnuclear regions around the black hole, and start to slowly fall towards the black hole again.

Read more at Science Daily

Dark matter halos measured around ancient quasars

At the center of every galaxy is a supermassive black hole. Beyond a certain size, these become active, emitting huge amounts of radiation, and are then called quasars. It is thought these are activated by the presence of massive dark matter halos (DMH) surrounding the galaxy, directing matter towards the center, feeding the black hole. A team including researchers from the University of Tokyo have, for the first time, surveyed hundreds of ancient quasars and found this behavior is very consistent throughout history. This is surprising, as many large-scale processes show variation throughout the life of the universe, so the mechanism of quasar activation could have implications for the evolution of the entire universe.

Measuring the mass of DMHs is not easy; it's famously a very elusive substance, if substance is even the right word to use, given the actual nature of dark matter is unknown. We only know it exists at all due to its gravitational impact on large structures such as galaxies. Thus, dark matter can only be measured by making observations about its gravitational effects on things. This includes the way it might pull on something or affect its movement, or through the lensing (bending of light) of objects behind a suspected area of dark matter.

The challenge becomes greater at large distances, given how weak the light from more distant, and therefore ancient, phenomena can be. But this did not stop Professor Nobunari Kashikawa from the Department of Astronomy, and his team, from trying to answer a long-standing question in astronomy: How are black holes born, and how do they grow? The researchers are especially keen to explore this in relation to supermassive black holes, the largest kind, which exist in the heart of every galaxy. These would be very difficult to study were it not for the fact that some grow so massive they begin to output incredibly powerful jets of matter or spheres of radiation that in either case become what we call quasars. These are so powerful that even at large distances, we can now observe them using modern techniques.

"We measured for the first time the typical mass for dark matter halos surrounding an active black hole in the universe about 13 billion years ago," said Kashikawa. "We find the DMH mass of quasars is pretty constant at about 10 trillion times the mass of our sun. Such measurements have been made for more recent DMH around quasars, and those measurements are strikingly similar to what we see for more ancient quasars. This is interesting because it suggests there is a characteristic DMH mass which seems to activate a quasar, regardless of whether it happened billions of years ago or right now."

Quasars at great distances appear faint, as the light which left them long ago has spread out, was absorbed by intervening matter, and has been stretched into nearly invisible infrared wavelengths due to the universe expanding over time. So Kashikawa and his team, whose project began in 2016, used multiple surveys of the sky which incorporated a range of different instruments, the main one being Japan's Subaru Telescope, located in U.S. state of Hawaii.

Read more at Science Daily

VERA unveils surroundings of rapidly growing black holes

An international team of astronomers used the state-of-the-art capability of VERA, a Japanese network of radio telescopes operated by NAOJ, to uncover valuable clues about how rapidly growing "young" supermassive black holes form, grow, and possibly evolve into more powerful quasars.

It is now widely accepted that nearly every active galaxy harbors a supermassive black hole at its core, with masses ranging from millions to billions of times that of the Sun. The growth history by which these black holes have gained such huge masses, however, remains an open question.

Led by Mieko Takamura, a graduate student at the University of Tokyo, an international team focused on a distinct category of active galaxies known as Narrow-line Seyfert 1 (NLS1) galaxies. These galaxies are suspected to contain relatively small yet rapidly growing massive black holes, thus offering a potential opportunity to study an early evolutionary stage of these cosmic monsters. To gain a deeper understanding of the immediate surroundings of these peculiar black holes, the team observed the cores of six nearby active NLS1 galaxies using VERA -- a radio telescope network with an eyesight over 100,000 times more powerful than the human eye. In particular, the team leveraged the newly enhanced ultra-wideband recording capability of VERA, enabling them to detect faint "polarized" radio waves emanating from the core of these galaxies with unprecedented precision.

A portion of radio waves emitted near supermassive black holes is known to exhibit polarization. As this polarized emission propagates through the magnetized gas surrounding the black hole, the plane of polarization gradually rotates, causing an effect known as Faraday rotation. The extent of this rotation (at a given wavelength) is proportional to the gas density and the strength of the magnetic field within the propagating medium. Therefore, polarization and Faraday rotation provide valuable insights into the immediate environment surrounding a central black hole.

Read more at Science Daily

Webb Telescope detects most distant active supermassive black hole

Researchers have discovered the most distant active supermassive black hole to date with the James Webb Space Telescope (JWST). The galaxy, CEERS 1019, existed about 570 million years after the big bang, and its black hole is less massive than any other yet identified in the early universe.

In addition to the black hole in CEERS 1019, the researchers identified two more black holes that are on the smaller side and existed 1 billion and 1.1 billion years after the big bang. JWST also identified eleven galaxies that existed when the universe was 470 million to 675 million years old. The evidence was provided by JWST's Cosmic Evolution Early Release Science (CEERS) Survey, led by Steven Finkelstein, a professor of astronomy at The University of Texas at Austin. The program combines JWST's highly detailed near- and mid-infrared images and data known as spectra, all of which were used to make these discoveries.

"Looking at this distant object with this telescope is a lot like looking at data from black holes that exist in galaxies near our own," said Rebecca Larson, a recent Ph.D. graduate at UT Austin, who led the study. "There are so many spectral lines to analyze!"

The team has published these results in several initial papers in a special edition of The Astrophysical Journal Letters.

CEERS 1019 is notable not only for how long ago it existed, but also how relatively little its black hole weighs. It clocks in around 9 million solar masses, far less than other black holes that also existed in the early universe and were detected by other telescopes. Those behemoths typically contain more than 1 billion times the mass of the sun -- and they are easier to detect because they are much brighter. The black hole within CEERS 1019 is more like the black hole at the center of our Milky Way galaxy, which is 4.6 million times the mass of the sun.

Though smaller, this black hole existed so much earlier that it is still difficult to explain how it formed so soon after the universe began. Researchers have long known that smaller black holes must have existed earlier in the universe, but it wasn't until JWST began observing that they were able to make definitive detections.

Not only could the team untangle which emissions in the spectrum are from the black hole and which are from its host galaxy, they could also pinpoint how much gas the black hole is ingesting and determine its galaxy's star-formation rate.

The team found this galaxy is ingesting as much gas as it can while also churning out new stars. They turned to the images to explore why that might be. Visually, CEERS 1019 appears as three bright clumps, not a single circular disk.

"We're not used to seeing so much structure in images at these distances," said CEERS team member Jeyhan Kartaltepe, an associate professor of astronomy at the Rochester Institute of Technology in New York. "A galaxy merger could be partly responsible for fueling the activity in this galaxy's black hole, and that could also lead to increased star formation."

These are only the first groundbreaking findings from the CEERS Survey.

"Until now, research about objects in the early universe was largely theoretical," Finkelstein said. "With Webb, not only can we see black holes and galaxies at extreme distances, we can now start to accurately measure them. That's the tremendous power of this telescope."

In the future, it's possible JWST's data may also be used to explain how early black holes formed, revising researchers' models of how black holes grew and evolved in the first several hundred million years of the universe's history.

The James Webb Space Telescope is an international program led by NASA with its partners, the European Space Agency and the Canadian Space Agency.

More Extremely Distant Black Holes and Galaxies

The CEERS Survey is expansive, and there is much more to explore. Team member Dale Kocevski of Colby College in Waterville, Maine, and the team quickly spotted another pair of small black holes in the data. The first, within galaxy CEERS 2782, was easiest to pick out. There isn't any dust obscuring JWST's view of it, so researchers could immediately determine when its black hole existed in the history of the universe -- only 1.1 billion years after the big bang. The second black hole, in galaxy CEERS 746, existed slightly earlier, 1 billion years after the big bang. Its bright accretion disk, a ring made up of gas and dust that encircles its supermassive black hole, is still partially clouded by dust.

"The central black hole is visible, but the presence of dust suggests it might lie within a galaxy that is also furiously pumping out stars," Kocevski explained.

Like the one in CEERS 1019, the two other newly described black holes (in galaxies CEERS 2782 and CEERS 746) are also "light weights" -- at least when compared with previously known supermassive black holes at these distances. They are only about 10 million times the mass of the sun.

"Researchers have long known that there must be lower mass black holes in the early universe. Webb is the first observatory that can capture them so clearly," Kocevski said. "Now we think that lower mass black holes might be all over the place, waiting to be discovered."

Before JWST, all three black holes were too faint to be detected.

"With other telescopes, these targets look like ordinary star-forming galaxies, not active supermassive black holes," Finkelstein added.

JWST's sensitive spectra also allowed these researchers to measure precise distances to, and therefore the ages of, galaxies in the early universe. Team members Pablo Arrabal Haro of the National Science Foundation's NOIRLab and Seiji Fujimoto, a postdoctoral researcher and Hubble fellow at UT Austin, identified 11 galaxies that existed 470 million to 675 million years after the big bang. Not only are they extremely distant, the fact that so many bright galaxies were detected is notable. Researchers theorized that JWST would detect fewer galaxies than are being found at these distances.

"I am overwhelmed by the amount of highly detailed spectra of remote galaxies Webb returned," Arrabal Haro said. "These data are absolutely incredible."

Read more at Science Daily

Earliest strands of the cosmic web

Galaxies are not scattered randomly across the universe. They gather together not only into clusters, but into vast interconnected filamentary structures with gigantic barren voids in between. This "cosmic web" started out tenuous and became more distinct over time as gravity drew matter together.

Astronomers using NASA's James Webb Space Telescope have discovered a thread-like arrangement of 10 galaxies that existed just 830 million years after the big bang. The 3 million light-year-long structure is anchored by a luminous quasar -- a galaxy with an active, supermassive black hole at its core. The team believes the filament will eventually evolve into a massive cluster of galaxies, much like the well-known Coma Cluster in the nearby universe.

"I was surprised by how long and how narrow this filament is," said team member Xiaohui Fan of the University of Arizona in Tucson. "I expected to find something, but I didn't expect such a long, distinctly thin structure."

"This is one of the earliest filamentary structures that people have ever found associated with a distant quasar," added Feige Wang of the University of Arizona in Tucson, the principal investigator of this program.

This discovery is from the ASPIRE project (A SPectroscopic survey of biased halos In the Reionization Era), whose main goal is to study the cosmic environments of the earliest black holes. In total, the program will observe 25 quasars that existed within the first billion years after the big bang, a time known as the Epoch of Reionization.

"The last two decades of cosmology research have given us a robust understanding of how the cosmic web forms and evolves. ASPIRE aims to understand how to incorporate the emergence of the earliest massive black holes into our current story of the formation of cosmic structure," explained team member Joseph Hennawi of the University of California, Santa Barbara.

Growing Monsters

Another part of the study investigates the properties of eight quasars in the young universe. The team confirmed that their central black holes, which existed less than a billion years after the big bang, range in mass from 600 million to 2 billion times the mass of our Sun. Astronomers continue seeking evidence to explain how these black holes could grow so large so fast.

"To form these supermassive black holes in such a short time, two criteria must be satisfied. First, you need to start growing from a massive 'seed' black hole. Second, even if this seed starts with a mass equivalent to a thousand Suns, it still needs to accrete a million times more matter at the maximum possible rate for its entire lifetime," explained Wang.

"These unprecedented observations are providing important clues about how black holes are assembled. We have learned that these black holes are situated in massive young galaxies that provide the reservoir of fuel for their growth," said Jinyi Yang of the University of Arizona, who is leading the study of black holes with ASPIRE.

Webb also provided the best evidence yet of how early supermassive black holes potentially regulate the formation of stars in their galaxies. While supermassive black holes accrete matter, they also can power tremendous outflows of material. These winds can extend far beyond the black hole itself, on a galactic scale, and can have a significant impact on the formation of stars.

"Strong winds from black holes can suppress the formation of stars in the host galaxy. Such winds have been observed in the nearby universe but have never been directly observed in the Epoch of Reionization," said Yang. "The scale of the wind is related to the structure of the quasar. In the Webb observations, we are seeing that such winds existed in the early universe."

Read more at Science Daily

Mysterious dashes revealed in Milky Way's center

An international team of astrophysicists has discovered something wholly new, hidden in the center of the Milky Way galaxy.

In the early 1980s, Northwestern University's Farhad Yusef-Zadeh discovered gigantic, one-dimensional filaments dangling vertically near Sagittarius A*, our galaxy's central supermassive black hole. Now, Yusef-Zadeh and his collaborators have discovered a new population of filaments -- but these threads are much shorter and lie horizontally or radially, spreading out like spokes on a wheel from the black hole.

Although the two populations of filaments share several similarities, Yusef-Zadeh assumes they have different origins. While the vertical filaments sweep through the galaxy, towering up to 150 light-years high, the horizontal filaments look more like the dots and dashes of Morse code, punctuating only one side of Sagittarius A*.

The study will be published on Friday (June 2) in The Astrophysical Journal Letters.

"It was a surprise to suddenly find a new population of structures that seem to be pointing in the direction of the black hole," Yusef-Zadeh said. "I was actually stunned when I saw these. We had to do a lot of work to establish that we weren't fooling ourselves. And we found that these filaments are not random but appear to be tied to the outflow of our black hole. By studying them, we could learn more about the black hole's spin and accretion disk orientation. It is satisfying when one finds order in a middle of a chaotic field of the nucleus of our galaxy."

An expert in radio astronomy, Yusef-Zadeh is a professor of physics and astronomy at Northwestern's Weinberg College of Arts and Sciences and member of CIERA.

Decades in the making

The new discovery may come as a surprise, but Yusef-Zadeh is no stranger to uncovering mysteries at the center of our galaxy, located 25,000 light-years from Earth. The latest study builds on four decades of his research. After first discovering the vertical filaments in 1984 with Mark Morris and Don Chance, Yusef-Zadeh along with Ian Heywood and their collaborators later uncovered two gigantic radio-emitting bubbles near Sagittarius A*. Then, in a series of publications in 2022, Yusef-Zadeh (in collaborations with Heywood, Richard Arent and Mark Wardle) revealed nearly 1,000 vertical filaments, which appeared in pairs and clusters, often stacked equally spaced or side by side like strings on a harp.

Yusef-Zadeh credits the flood of new discoveries to enhanced radio astronomy technology, particularly the South African Radio Astronomy Observatory's (SARAO) MeerKAT telescope. To pinpoint the filaments, Yusef-Zadeh's team used a technique to remove the background and smooth the noise from MeerKAT images in order to isolate the filaments from surrounding structures.

"The new MeerKAT observations have been a game changer," he said. "The advancement of technology and dedicated observing time have given us new information. It's really a technical achievement from radio astronomers."

Horizontal vs. vertical

After studying the vertical filaments for decades, Yusef-Zadeh was shocked to uncover their horizontal counterparts, which he estimates are about 6 million years old. "We have always been thinking about vertical filaments and their origin," he said. "I'm used to them being vertical. I never considered there might be others along the plane."

While both populations comprise one-dimensional filaments that can be viewed with radio waves and appear to be tied to activities in the galactic center, the similarities end there.

The vertical filaments are perpendicular to the galactic plane; the horizontal filaments are parallel to the plane but point radially toward the center of the galaxy where the black hole lies. The vertical filaments are magnetic and relativistic; the horizontal filaments appear to emit thermal radiation. The vertical filaments encompass particles moving at speeds near the speed of light; the horizontal filaments appear to accelerate thermal material in a molecular cloud. There are several hundred vertical filaments and just a few hundred horizontal filaments. And the vertical filaments, which measure up to 150 light-years high, far surpass the size of the horizontal filaments, which measure just 5 to 10 light-years in length. The vertical filaments also adorn space around the nucleus of the galaxy; the horizontal filaments appear to spread out to only one side, pointing toward the black hole.

"One of the most important implications of radial outflow that we have detected is the orientation of the accretion disk and the jet-driven outflow from Sagittarius A* along the galactic plane," Yusef-Zadeh said.

'Our work is never complete'

The new discovery is filled with unknowns, and Yusef-Zadeh's work to unravel its mysteries has just begun. For now, he can only consider a plausible explanation about the new population's mechanisms and origins.

"We think they must have originated with some kind of outflow from an activity that happened a few million years ago," Yusef-Zadeh said. "It seems to be the result of an interaction of that outflowing material with objects near it. Our work is never complete. We always need to make new observations and continually challenge our ideas and tighten up our analysis."

Read more at Science Daily

Hidden supermassive black holes brought to life by galaxies on collision course

Astronomers have found that supermassive black holes obscured by dust are more likely to grow and release tremendous amounts of energy when they are inside galaxies that are expected to collide with a neighbouring galaxy. The new work, led by researchers from Newcastle University, is published in Monthly Notices of the Royal Astronomical Society.

Galaxies, including our own Milky Way, contain supermassive black holes at their centres. They have masses equivalent to millions, or even billions, times that of our Sun. These black holes grow by ‘eating’ gas that falls on to them. However, what drives the gas close enough to the black holes for this to happen is an ongoing mystery.

One possibility is that when galaxies are close enough together, they are likely to be gravitationally pulled towards each other and ‘merge’ into one larger galaxy.

In the final stages of its journey into a black hole, gas lights up and produces a huge amount of energy. This energy is typically detected using visible light or X-rays. However, the astronomers conducting this study were only able to detect the growing black holes using infrared light. The team made use of data from many different telescopes, including the Hubble Space Telescope and infrared Spitzer Space Telescope.

The researchers developed a new technique to determine how likely it is that two galaxies are very close together and are expected to collide in the future. They applied this new method to hundreds of thousands of galaxies in the distant universe (looking at galaxies formed 2 to 6 billion years after the Big Bang) in an attempt to better understand the so-called ‘cosmic noon’, a time when most of the Universe’s galaxy and black hole growth is expected to have taken place.

Understanding how black holes grew during this time is fundamental in modern day galactic research, especially as it may give us an insight into the supermassive black hole situated inside the Milky Way, and how our galaxy evolved over time.

As they are so far away, only a small number of cosmic noon galaxies meet the required criteria to get precise measurements of their distances. This makes it very difficult to know with high precision if any two galaxies are very close to each other.

This study presents a new statistical method to overcome the previous limitations of measuring accurate distances of galaxies and supermassive black holes at cosmic noon. It applies a statistical approach to determine galaxy distances using images at different wavelengths and removes the need for spectroscopic distance measurements for individual galaxies.

Data arriving from the James Webb Space Telescope over the coming years is expected to revolutionise studies in the infrared and reveal even more secrets about how these dusty black holes grow.

Sean Dougherty, postgraduate student at Newcastle University and lead author of the paper, says, “Our novel approach looks at hundreds of thousands of distant galaxies with a statistical approach and asks how likely any two galaxies are to be close together and so likely to be on a collision course.”

Dr Chris Harrison, co-author of the study, “These supermassive black holes are very challenging to find because the X-ray light, which astronomers have typically used to find these growing black holes, is blocked, and not detected by our telescopes. But these same black holes can be found using infrared light, which is produced by the hot dust surrounding them.”

Read more at Science Daily

Astronomers reveal the largest cosmic explosion ever seen

A team of astronomers led by the University of Southampton have uncovered the largest cosmic explosion ever witnessed.

The explosion is more than ten times brighter than any known supernova (exploding star) and three times brighter than the brightest tidal disruption event, where a star falls into a supermassive black hole.

The explosion, known as AT2021lwx, has currently lasted over three years, compared to most supernovae which are only visibly bright for a few months. It took place nearly 8 billion light years away, when the universe was around 6 billion years old, and is still being detected by a network of telescopes.

The researchers believe that the explosion is a result of a vast cloud of gas, possibly thousands of times larger than our sun, that has been violently disrupted by a supermassive black hole. Fragments of the cloud would be swallowed up, sending shockwaves through its remnants, as well as into a large dusty 'doughnut' surrounding the black hole. Such events are very rare and nothing on this scale has been witnessed before.

Last year, astronomers witnessed the brightest explosion on record -- a gamma-ray burst known as GRB 221009A. While this was brighter than AT2021lwx, it lasted for just a fraction of the time, meaning the overall energy released by the AT2021lwx explosion is far greater.

The findings of the research have been published today [Friday, 12 May 2023] in Monthly Notices of the Royal Astronomical Society.

Discovery

AT2021lwx was first detected in 2020 by the Zwicky Transient Facility in California, and subsequently picked up by the Asteroid Terrestrial-impact Last Alert System (ATLAS) based in Hawaii. These facilities survey the night sky to detect transient objects that rapidly change in brightness indicating cosmic events such as supernovae, as well as finding asteroids and comets. Until now the scale of the explosion has been unknown.

"We came upon this by chance, as it was flagged by our search algorithm when we were searching for a type of supernova," says Dr Philip Wiseman, Research Fellow at the University of Southampton, who led the research. "Most supernovae and tidal disruption events only last for a couple of months before fading away. For something to be bright for two plus years was immediately very unusual."

The team investigated the object further with several different telescopes: the Neil Gehrels Swift Telescope (a collaboration between NASA, the UK and Italy), the New Technology Telescope (operated by the European Southern Observatory) in Chile, and the Gran Telescopio Canarias in La Palma, Spain.

Measuring the explosion

By analysing the spectrum of the light, splitting it up into different wavelengths and measuring the different absorption and emission features of the spectrum, the team were able to measure the distance to the object.

"Once you know the distance to the object and how bright it appears to us, you can calculate the brightness of the object at its source. Once we'd performed those calculations, we realised this is extremely bright," says Professor Sebastian Hönig from the University of Southampton, a co-author of the research.

The only things in the universe that are as bright as AT2021lwx are quasars -- supermassive black holes with a constant flow of gas falling onto them at high velocity.

Professor Mark Sullivan, also of the University of Southampton and another co-author of the paper, explains: "With a quasar, we see the brightness flickering up and down over time. But looking back over a decade there was no detection of AT2021lwx, then suddenly it appears with the brightness of the brightest things in the universe, which is unprecedented."

What caused the explosion?

There are different theories as to what could have caused such an explosion, but the Southampton-led team believe the most feasible explanation is an extremely large cloud of gas (mostly hydrogen) or dust that has come off course from its orbit around the black hole and been sent flying in.

The team are now setting out to collect more data on the explosion -- measuring different wavelengths, including X-rays which could reveal the object's surface and temperature, and what underlying processes are taking place. They will also carry out upgraded computational simulations to test if these match their theory of what caused the explosion.

Read more at Science Daily