Category Archives: Space Science

ESO: Record-breaking quasar identified

A new report from the European Southern Observatory (ESO):

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

This artist’s impression shows the record-breaking quasar J059-4351, the bright core of a distant galaxy that is powered by a supermassive black hole. Using ESO’s Very Large Telescope (VLT) in Chile, this quasar has been found to be the most luminous object known in the Universe to date. The supermassive black hole, seen here pulling in surrounding matter, has a mass 17 billion times that of the Sun and is growing in mass by the equivalent of another Sun per day, making it the fastest-growing black hole ever known.

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 [1].

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.

Finding and studying distant supermassive black holes could shed light on some of the mysteries of the early Universe, including how they and their host galaxies formed and evolved. But that’s not the only reason why Wolf searches for them.

“Personally, I simply like the chase,” he says. “For a few minutes a day, I get to feel like a child again, playing treasure hunt, and now I bring everything to the table that I have learned since.”

Notes

[1] A few years ago, NASA and the European Space Agency reported that the Hubble Space Telescope had discovered a quasar, J043947.08+163415.7, as bright as 600 trillion Suns. However, that quasar’s brightness was magnified by a ‘lensing’ galaxy, located between us and the distant quasar. The actual luminosity of J043947.08+163415.7 is estimated to be equivalent to about 11 trillion Suns (1 trillion is a million million: 1 000 000 000 000 or 1012).

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ESO: Observation of supernova producing compact object (black hole or neutron star)

A new report from the European Southern Observatory (ESO):

Missing link found:
Supernovae give rise to black holes or neutron stars

This artist’s impression is based on the aftermath of a supernova explosion as seen by two teams of astronomers with both ESO’s Very Large Telescope (VLT) and ESO’s New Technology Telescope (NTT). The supernova observed, SN 2022jli, occurred when a massive star died in a fiery explosion, leaving behind a compact object — a neutron star or a black hole. This dying star, however, had a companion which was able to survive this violent event. The periodic interactions between the compact object and its companion left periodic signals in the data, which revealed that the supernova explosion had indeed resulted in a compact object.

Astronomers have found a direct link between the explosive deaths of massive stars and the formation of the most compact and enigmatic objects in the Universe — black holes and neutron stars. With the help of the European Southern Observatory’s Very Large Telescope (ESO’s VLT) and ESO’s New Technology Telescope (NTT), two teams were able to observe the aftermath of a supernova explosion in a nearby galaxy, finding evidence for the mysterious compact object it left behind.

When massive stars reach the end of their lives, they collapse under their own gravity so rapidly that a violent explosion known as a supernova ensues. Astronomers believe that, after all the excitement of the explosion, what is left is the ultra-dense core, or compact remnant, of the star. Depending on how massive the star is, the compact remnant will be either a neutron star — an object so dense that a teaspoon of its material would weigh around a trillion kilograms here on Earth — or a black hole — an object from which nothing, not even light, can escape.

Astronomers have found many clues hinting at this chain of events in the past, such as finding a neutron star within the Crab Nebula, the gas cloud left behind when a star exploded nearly a thousand years ago. But they had never before seen this process happen in real time, meaning that direct evidence of a supernova leaving behind a compact remnant has remained elusive.

In our work, we establish such a direct link

says Ping Chen, a researcher at the Weizmann Institute of Science, Israel, and lead author of a study published today in Nature and presented at the 243rd American Astronomical Society meeting in New Orleans, USA.

The researchers’ lucky break came in May 2022, when South African amateur astronomer Berto Monard discovered the supernova SN 2022jli in the spiral arm of the nearby galaxy NGC 157, located 75 million light-years away. Two separate teams turned their attention to the aftermath of this explosion and found it to have a unique behaviour.

This artist’s impression shows the process by which a massive star within a binary system becomes a supernova. This series of events occurred in the supernova SN 2022jli, and was revealed to researchers through observations with ESO’s Very Large Telescope (VLT) and New Technology Telescope (NTT). After a massive star exploded as a supernova, it left behind a compact object — a neutron star or a black hole. The companion star survived the explosion, but its atmosphere became puffier as a result. The compact object and its companion star continued to orbit one another, with the compact object regularly stealing matter from the other’s puffy atmosphere. This accretion of matter was seen in the researchers’ data as regular fluctuations of brightness, as well as periodic movements of hydrogen gas.

After the explosion, the brightness of most supernovae simply fades away with time; astronomers see a smooth, gradual decline in the explosion’s ‘light curve’. But SN 2022jli’s behaviour is very peculiar: as the overall brightness declines, it doesn’t do so smoothly, but instead oscillates up and down every 12 days or so.

In SN 2022jli’s data we see a repeating sequence of brightening and fading

says Thomas Moore, a doctoral student at Queen’s University Belfast, Northern Ireland, who led a study of the supernova published late last year in the Astrophysical Journal. Moore noted in his paper.

This is the first time that repeated periodic oscillations, over many cycles, have been detected in a supernova light curve

Both the Moore and Chen teams believe that the presence of more than one star in the SN 2022jli system could explain this behaviour. In fact, it’s not unusual for massive stars to be in orbit with a companion star in what is known as a binary system, and the star that caused SN 2022jli was no exception. What is remarkable about this system, however, is that the companion star appears to have survived the violent death of its partner and the two objects, the compact remnant and the companion, likely kept orbiting each other.

The data collected by the Moore team, which included observations with ESO’s NTT in Chile’s Atacama Desert, did not allow them to pin down exactly how the interaction between the two objects caused the highs and lows in the light curve. But the Chen team had additional observations. They found the same regular fluctuations in the system’s visible brightness that the Moore team had detected, and they also spotted periodic movements of hydrogen gas and bursts of gamma rays in the system. Their observations were made possible thanks to a fleet of instruments on the ground and in space, including X-shooter on ESO’s VLT, also located in Chile.

Putting all the clues together, the two teams generally agree that when the companion star interacted with the material thrown out during the supernova explosion, its hydrogen-rich atmosphere became puffier than usual. Then, as the compact object left behind after the explosion zipped through the companion’s atmosphere on its orbit, it would steal hydrogen gas, forming a hot disc of matter around itself. This periodic stealing of matter, or accretion, released lots of energy that was picked up as regular changes of brightness in the observations.

Even though the teams could not observe light coming from the compact object itself, they concluded that this energetic stealing can only be due to an unseen neutron star, or possibly a black hole, attracting matter from the companion star’s puffy atmosphere.

Our research is like solving a puzzle by gathering all possible evidence,” Chen says. “All these pieces lining up lead to the truth.

With the presence of a black hole or neutron star confirmed, there is still plenty to unravel about this enigmatic system, including the exact nature of the compact object or what end could await this binary system. Next-generation telescopes such as ESO’s Extremely Large Telescope, scheduled to begin operation later this decade, will help with this, allowing astronomers to reveal unprecedented details of this unique system.

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ESO: Disk detected around a star in another galaxy for the first time

A report from the European Southern Observatory (ESO):

Astronomers discover disc around star in another galaxy for the first time

This artist’s impression shows the HH 1177 system, which is located in the Large Magellanic Cloud, a neighbouring galaxy of our own. The young and massive stellar object glowing in the centre is collecting matter from a dusty disc while also expelling matter in powerful jets. Using the Atacama Large Millimeter/submillimeter Array (ALMA), in which ESO is a partner, a team of astronomers managed to find evidence for the presence of this disc by observing its rotation. This is the first time a disc around a young star — the type of disc identical to those forming planets in our own galaxy — has been discovered in another galaxy.

In a remarkable discovery, astronomers have found a disc around a young star in the Large Magellanic Cloud, a galaxy neighbouring ours. It’s the first time such a disc, identical to those forming planets in our own Milky Way, has ever been found outside our galaxy. The new observations reveal a massive young star, growing and accreting matter from its surroundings and forming a rotating disc. The detection was made using the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, in which the European Southern Observatory (ESO) is a partner.

“When I first saw evidence for a rotating structure in the ALMA data I could not believe that we had detected the first extragalactic accretion disc, it was a special moment,”

says Anna McLeod, an associate professor at Durham University in the UK and lead author of the study published today in Nature.

“We know discs are vital to forming stars and planets in our galaxy, and here, for the first time, we’re seeing direct evidence for this in another galaxy.”

This study follows up observations with the Multi Unit Spectroscopic Explorer (MUSE) instrument on ESO’s Very Large Telescope (VLT), which spotted a jet from a forming star — the system was named HH 1177 — deep inside a gas cloud in the Large Magellanic Cloud.

“We discovered a jet being launched from this young massive star, and its presence is a signpost for ongoing disc accretion,”

McLeod says. But to confirm that such a disc was indeed present, the team needed to measure the movement of the dense gas around the star.

With the combined capabilities of ESO’s Very Large Telescope (VLT) and the Atacama Large Millimeter/submillimeter Array (ALMA), in which ESO is a partner, a disc around a young massive star in another galaxy has been observed. Observations from the Multi Unit Spectroscopic Explorer (MUSE) on the VLT, left, show the parent cloud LHA 120-N 180B in which this system, dubbed HH 1177, was first observed. The image at the centre shows the jets that accompany it. The top part of the jet is aimed slightly towards us and thus blueshifted; the bottom one is receding from us and thus redshifted. Observations from ALMA, right, then revealed the rotating disc around the star, similarly with sides moving towards and away from us.

As matter is pulled towards a growing star, it cannot fall directly onto it; instead, it flattens into a spinning disc around the star. Closer to the centre, the disc rotates faster, and this difference in speed is the smoking gun that shows astronomers an accretion disc is present.

“The frequency of light changes depending on how fast the gas emitting the light is moving towards or away from us,”

explains Jonathan Henshaw, a research fellow at Liverpool John Moores University in the UK, and co-author of the study.

“This is precisely the same phenomenon that occurs when the pitch of an ambulance siren changes as it passes you and the frequency of the sound goes from higher to lower.”

The detailed frequency measurements from ALMA allowed the authors to distinguish the characteristic spin of a disc, confirming the detection of the first disc around an extragalactic young star.

Massive stars, like the one observed here, form much more quickly and live far shorter lives than low-mass stars like our Sun. In our galaxy, these massive stars are notoriously challenging to observe and are often obscured from view by the dusty material from which they form at the time a disc is shaping around them. However, in the Large Magellanic Cloud, a galaxy 160 000 light-years away, the material from which new stars are being born is fundamentally different from that in the Milky Way. Thanks to the lower dust content, HH 1177 is no longer cloaked in its natal cocoon, offering astronomers an unobstructed, if far away, view of star and planet formation.

“We are in an era of rapid technological advancement when it comes to astronomical facilities,” McLeod says. “Being able to study how stars form at such incredible distances and in a different galaxy is very exciting.”

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ESO: Observation of the most distant fast radio burst (FRB) to date

A new report from the European Southern Observatory (ESO):

Astronomers detect most distant fast radio burst to date

An international team has spotted a remote blast of cosmic radio waves lasting less than a millisecond. This ‘fast radio burst’ (FRB) is the most distant ever detected. Its source was pinned down by the European Southern Observatory’s (ESO) Very Large Telescope (VLT) in a galaxy so far away that its light took eight billion years to reach us. The FRB is also one of the most energetic ever observed; in a tiny fraction of a second it released the equivalent of our Sun’s total emission over 30 years.

The discovery of the burst, named FRB 20220610A, was made in June last year by the ASKAP radio telescope in Australia [1] and it smashed the team’s previous distance record by 50 percent.

“Using ASKAP’s array of dishes, we were able to determine precisely where the burst came from,”

says Stuart Ryder, an astronomer from Macquarie University in Australia and the co-lead author of the study published today in Science.

“Then we used [ESO’s VLT] in Chile to search for the source galaxy, [2] finding it to be older and further away than any other FRB source found to date and likely within a small group of merging galaxies.”

The discovery confirms that FRBs can be used to measure the ‘missing’ matter between galaxies, providing a new way to ‘weigh’ the Universe.

Current methods of estimating the mass of the Universe are giving conflicting answers and challenging the standard model of cosmology.

“If we count up the amount of normal matter in the Universe — the atoms that we are all made of — we find that more than half of what should be there today is missing,”

says Ryan Shannon, a professor at the Swinburne University of Technology in Australia, who also co-led the study.

“We think that the missing matter is hiding in the space between galaxies, but it may just be so hot and diffuse that it’s impossible to see using normal techniques.”

“Fast radio bursts sense this ionised material. Even in space that is nearly perfectly empty they can ‘see’ all the electrons, and that allows us to measure how much stuff is between the galaxies,”

Shannon says.

Finding distant FRBs is key to accurately measuring the Universe’s missing matter, as shown by the late Australian astronomer Jean-Pierre (‘J-P’) Macquart in 2020. “J-P showed that the further away a fast radio burst is, the more diffuse gas it reveals between the galaxies. This is now known as the Macquart relation. Some recent fast radio bursts appeared to break this relationship. Our measurements confirm the Macquart relation holds out to beyond half the known Universe,” says Ryder.

“While we still don’t know what causes these massive bursts of energy, the paper confirms that fast radio bursts are common events in the cosmos and that we will be able to use them to detect matter between galaxies, and better understand the structure of the Universe,”

says Shannon.

The result represents the limit of what is achievable with telescopes today, although astronomers will soon have the tools to detect even older and more distant bursts, pin down their source galaxies and measure the Universe’s missing matter. The international Square Kilometre Array Observatory is currently building two radio telescopes in South Africa and Australia that will be capable of finding thousands of FRBs, including very distant ones that cannot be detected with current facilities. ESO’s Extremely Large Telescope, a 39-metre telescope under construction in the Chilean Atacama Desert, will be one of the few telescopes able to study the source galaxies of bursts even further away than FRB 20220610A.

Notes

[1] The ASKAP telescope is owned and operated by CSIRO, Australia’s national science agency, on Wajarri Yamaji Country in Western Australia.

[2] The team used data obtained with the FOcal Reducer and low dispersion Spectrograph 2 (FORS2), the X-shooter and the High Acuity Wide-field K-band Imager (HAWK-I) instruments on ESO’s VLT. Data from the Keck Observatory in Hawai’i, US, was also used in the study.

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ESO: Most distant galactic magnetic field detected

A new report from the European Southern Observatory (ESO). Note that the galaxy of interest was initially discovered by a citizen science project sponsored by the BBC’s Stargazing Live television program [1].

Furthest ever detection of a galaxy’s magnetic field

This image shows the orientation of the magnetic field in the distant 9io9 galaxy, seen here when the Universe was only 20% of its current age — the furthest ever detection of a galaxy’s magnetic field. The observations were done with the Atacama Large Millimeter/submillimeter Array (ALMA), in which ESO is a partner. Dust grains within 9io9 are somewhat aligned with the galaxy’s magnetic field, and due to this they emit polarised light, meaning that light waves oscillate along a preferred direction rather than randomly. ALMA detected this polarisation signal, from which astronomers could work out the orientation of the magnetic field, shown here as curved lines overlaid on the ALMA image. The polarised light signal emitted by the magnetically aligned dust in 9io9 was extremely faint, representing just one percent of the total brightness of the galaxy, so astronomers used a clever trick of nature to help them obtain this result. The team was helped by the fact that 9io9, although very distant from us, had been magnified via a process known as gravitational lensing. This occurs when light from a distant galaxy, in this case 9io9, appears brighter and distorted as it is bent by the gravity of a very large object in the foreground.

Using the Atacama Large Millimeter/submillimeter Array (ALMA), astronomers have detected the magnetic field of a galaxy so far away that its light has taken more than 11 billion years to reach us: we see it as it was when the Universe was just 2.5 billion years old. The result provides astronomers with vital clues about how the magnetic fields of galaxies like our own Milky Way came to be.

Lots of astronomical bodies in the Universe have magnetic fields, whether it be planets, stars or galaxies.

Many people might not be aware that our entire galaxy and other galaxies are laced with magnetic fields, spanning tens of thousands of light-years,”

says James Geach, a professor of astrophysics at the University of Hertfordshire, UK, and lead author of the study published today in Nature.

We actually know very little about how these fields form, despite their being quite fundamental to how galaxies evolve,”

adds Enrique Lopez Rodriguez, a researcher at Stanford University, USA, who also participated in the study. It is not clear how early in the lifetime of the Universe, and how quickly, magnetic fields in galaxies form because so far astronomers have only mapped magnetic fields in galaxies close to us.

Now, using ALMA, in which the European Southern Observatory (ESO) is a partner, Geach and his team have discovered a fully formed magnetic field in a distant galaxy, similar in structure to what is observed in nearby galaxies. The field is about 1000 times weaker than the Earth’s magnetic field, but extends over more than 16 000 light-years.

This discovery gives us new clues as to how galactic-scale magnetic fields are formed,

explains Geach. Observing a fully developed magnetic field this early in the history of the Universe indicates that magnetic fields spanning entire galaxies can form rapidly while young galaxies are still growing.

The team believes that intense star formation in the early Universe could have played a role in accelerating the development of the fields. Moreover, these fields can in turn influence how later generations of stars will form. Co-author and ESO astronomer Rob Ivison says that the discovery opens up

“a new window onto the inner workings of galaxies, because the magnetic fields are linked to the material that is forming new stars.”

To make this detection, the team searched for light emitted by dust grains in a distant galaxy, 9io9 [1]. Galaxies are packed full of dust grains and when a magnetic field is present, the grains tend to align and the light they emit becomes polarised. This means that the light waves oscillate along a preferred direction rather than randomly. When ALMA detected and mapped a polarised signal coming from 9io9, the presence of a magnetic field in a very distant galaxy was confirmed for the first time.

No other telescope could have achieved this,”

says Geach. The hope is that with this and future observations of distant magnetic fields the mystery of how these fundamental galactic features form will begin to unravel.

Notes

[1] 9io9 was discovered in the course of a citizen science project. The discovery was helped by viewers of the British BBC television programme Stargazing Live, when over three nights in 2014 the audience was asked to examine millions of images in the hunt for distant galaxies.

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