Wobbling Galaxies: New Evidence For Dark Matter Makes It Even More Exotic

Using the NASA/ESA Hubble Space Telescope, astronomers have discovered that the brightest galaxies within galaxy clusters “wobble” relative to the cluster’s centre of mass. This unexpected result is inconsistent with predictions made by the current standard model of dark matter. With further analysis it may provide insights into the nature of dark matter, perhaps even indicating that new physics is at work.

Dark matter constitutes just over 25 percent of all matter in the Universe but cannot be directly observed, making it one of the biggest mysteries in modern astronomy. Invisible halos of elusive dark matter enclose galaxies and galaxy clusters alike. The latter are massive groupings of up to a thousand galaxies immersed in hot intergalactic gas. Such clusters have very dense cores, each containing a massive galaxy called the “brightest cluster galaxy” (BCG).

The standard model of dark matter (cold dark matter model) predicts that once a galaxy cluster has returned to a “relaxed” state after experiencing the turbulence of a merging event, the BCG does not move from the cluster’s centre. It is held in place by the enormous gravitational influence of dark matter.

But now, a team of Swiss, French, and British astronomers have analysed ten galaxy clusters observed with the NASA/ESA Hubble Space Telescope, and found that their BCGs are not fixed at the centre as expected.

The Hubble data indicate that they are “wobbling” around the centre of mass of each cluster long after the galaxy cluster has returned to a relaxed state following a merger. In other words, the centre of the visible parts of each galaxy cluster and the centre of the total mass of the cluster — including its dark matter halo — are offset, by as much as 40,000 light-years.

“We found that the BCGs wobble around centre of the halos,” explains David Harvey, astronomer at EPFL, Switzerland, and lead author of the paper. “This indicates that, rather than a dense region in the centre of the galaxy cluster, as predicted by the cold dark matter model, there is a much shallower central density. This is a striking signal of exotic forms of dark matter right at the heart of galaxy clusters.”

The wobbling of the BCGs could only be analysed as the galaxy clusters studied also act as gravitational lenses. They are so massive that they warp spacetime enough to distort light from more distant objects behind them. This effect, called strong gravitational lensing, can be used to make a map of the dark matter associated with the cluster, enabling astronomers to work out the exact position of the centre of mass and then measure the offset of the BCG from this centre.

If this “wobbling” is not an unknown astrophysical phenomenon and in fact the result of the behaviour of dark matter, then it is inconsistent with the standard model of dark matter and can only be explained if dark matter particles can interact with each other — a strong contradiction to the current understanding of dark matter. This may indicate that new fundamental physics is required to solve the mystery of dark matter.

Co-author Frederic Courbin, also at EPFL, concludes: “We’re looking forward to larger surveys — such as the Euclid survey — that will extend our dataset. Then we can determine whether the wobbling of BGCs is the result of a novel astrophysical phenomenon or new fundamental physics. Both of which would be exciting!”

Scientists Detect Comets Outside Our Solar System

Scientists from MIT and other institutions, working closely with amateur astronomers, have spotted the dusty tails of six exocomets — comets outside our solar system — orbiting a faint star 800 light years from Earth.

These cosmic balls of ice and dust, which were about the size of Halley’s Comet and traveled about 100,000 miles per hour before they ultimately vaporized, are some of the smallest objects yet found outside our own solar system.

The discovery marks the first time that an object as small as a comet has been detected using transit photometry, a technique by which astronomers observe a star’s light for telltale dips in intensity. Such dips signal potential transits, or crossings of planets or other objects in front of a star, which momentarily block a small fraction of its light.

In the case of this new detection, the researchers were able to pick out the comet’s tail, or trail of gas and dust, which blocked about one-tenth of 1 percent of the star’s light as the comet streaked by.

“It’s amazing that something several orders of magnitude smaller than the Earth can be detected just by the fact that it’s emitting a lot of debris,” says Saul Rappaport, professor emeritus of physics in MIT’s Kavli Institute for Astrophysics and Space Research. “It’s pretty impressive to be able to see something so small, so far away.”

Rappaport and his team have published their results this week in the Monthly Notices of the Royal Astronomical Society. The paper’s co-authors are Andrew Vanderburg of the Harvard-Smithsonian Center for Astrophysics; several amateur astronomers including Thomas Jacobs of Bellevue, Washington; and researchers from the University of Texas at Austin, NASA’s Ames Research Center, and Northeastern University.

“Where few have traveled”

The detection was made using data from NASA’s Kepler Space Telescope, a stellar observatory that was launched into space in 2009. For four years, the spacecraft monitored about 200,000 stars for dips in starlight caused by transiting exoplanets.

To date, the mission has identified and confirmed more than 2,400 exoplanets, mostly orbiting stars in the constellation Cygnus, with the help of automated algorithms that quickly sift through Kepler’s data, looking for characteristic dips in starlight.

The smallest exoplanets detected thus far measure about one-third the size of the Earth. Comets, in comparison, span just several football fields, or a small city at their largest, making them incredibly difficult to spot.

However, on March 18, Jacobs, an amateur astronomer who has made it his hobby to comb through Kepler’s data, was able to pick out several curious light patterns amid the noise.

Jacobs, who works as an employment consultant for people with intellectual disabilities by day, is a member of the Planet Hunters — a citizen scientist project first established by Yale University to enlist amateur astronomers in the search for exoplanets. Members were given access to Kepler’s data in hopes that they might spot something of interest that a computer might miss.

In January, Jacobs set out to scan the entire four years of Kepler’s data taken during the main mission, comprising over 200,000 stars, each with individual light curves, or graphs of light intensity tracked over time. Jacobs spent five months sifting by eye through the data, often before and after his day job, and through the weekends.

“Looking for objects of interest in the Kepler data requires patience, persistence, and perseverance,” Jacobs says. “For me it is a form of treasure hunting, knowing that there is an interesting event waiting to be discovered. It is all about exploration and being on the hunt where few have traveled before.”

“Something we’ve seen before”

Jacobs’ goal was to look for anything out of the ordinary that computer algorithms may have passed over. In particular, he was searching for single transits — dips in starlight that happen only once, meaning they are not periodic like planets orbiting a star multiple times.

In his search, he spotted three such single transits around KIC 3542116, a faint star located 800 light years from Earth (the other three transits were found later by the team). He flagged the events and alerted Rappaport and Vanderburg, with whom he had collaborated in the past to interpret his findings.

“We sat on this for a month, because we didn’t know what it was — planet transits don’t look like this,” Rappaport recalls. “Then it occurred to me that, ‘Hey, these look like something we’ve seen before.'”

In a typical planetary transit, the resulting light curve resembles a “U,” with a sharp dip, then an equally sharp rise, as a result of a planet first blocking a little, then a lot, then a little of the light as it moves across the star. However, the light curves that Jacobs identified appeared asymmetric, with a sharp dip, followed by a more gradual rise.

Rappaport realized that the asymmetry in the light curves resembled disintegrating planets, with long trails of debris that would continue to block a bit of light as the planet moves away from the star. However, such disintegrating planets orbit their star, transiting repeatedly. In contrast, Jacobs had observed no such periodic pattern in the transits he identified.

“We thought, the only kind of body that could do the same thing and not repeat is one that probably gets destroyed in the end,” Rappaport says.

In other words, instead of orbiting around and around the star, the objects must have transited, then ultimately flown too close to the star, and vaporized.

“The only thing that fits the bill, and has a small enough mass to get destroyed, is a comet,” Rappaport says.

The researchers calculated that each comet blocked about one-tenth of 1 percent of the star’s light. To do this for several months before disappearing, the comet likely disintegrated entirely, creating a dust trail thick enough to block out that amount of starlight.

Vanderburg says the fact that these six exocomets appear to have transited very close to their star in the past four years raises some intriguing questions, the answers to which could reveal some truths about our own solar system.

“Why are there so many comets in the inner parts of these solar systems?” Vanderburg says. “Is this an extreme bombardment era in these systems? That was a really important part of our own solar system formation and may have brought water to Earth. Maybe studying exocomets and figuring out why they are found around this type of star … could give us some insight into how bombardment happens in other solar systems.”

The researchers say that in the future, the MIT-led Transiting Exoplanet Survey Satellite (TESS) mission will continue the type of research done by Kepler.

Apart from contributing to the fields of astrophysics and astronomy, Rappaport says, the new detection speaks to the perseverence and discernment of citizen scientists.

“I could name 10 types of things these people have found in the Kepler data that algorithms could not find, because of the pattern-recognition capability in the human eye,” Rappaport says. “You could now write a computer algorithm to find this kind of comet shape. But they were missed in earlier searches. They were deep enough but didn’t have the right shape that was programmed into algorithms. I think it’s fair to say this would never have been found by any algorithm.”

This research made use of data collected by the Kepler mission, funded by the NASA Science Mission directorate.

Oldest Recorded Solar Eclipse Helps Date The Egyptian Pharaohs

Researchers have pinpointed the date of what could be the oldest solar eclipse yet recorded. The event, which occurred on 30 October 1207 BC, is mentioned in the Bible, and could have consequences for the chronology of the ancient world.

Using a combination of the biblical text and an ancient Egyptian text, the researchers were then able to refine the dates of the Egyptian pharaohs, in particular the dates of the reign of Ramesses the Great. The results are published in the Royal Astronomical Society journal Astronomy & Geophysics.

The biblical text in question comes from the Old Testament book of Joshua and has puzzled biblical scholars for centuries. It records that after Joshua led the people of Israel into Canaan — a region of the ancient Near East that covered modern-day Israel and Palestine — he prayed: “Sun, stand still at Gibeon, and Moon, in the Valley of Aijalon. And the Sun stood still, and the Moon stopped, until the nation took vengeance on their enemies.”

“If these words are describing a real observation, then a major astronomical event was taking place — the question for us to figure out is what the text actually means,” said paper co-author Professor Sir Colin Humphreys from the University of Cambridge’s Department of Materials Science & Metallurgy, who is also interested in relating scientific knowledge to the Bible.

“Modern English translations, which follow the King James translation of 1611, usually interpret this text to mean that the sun and moon stopped moving,” said Humphreys, who is also a Fellow of Selwyn College. “But going back to the original Hebrew text, we determined that an alternative meaning could be that the sun and moon just stopped doing what they normally do: they stopped shining. In this context, the Hebrew words could be referring to a solar eclipse, when the moon passes between the earth and the sun, and the sun appears to stop shining. This interpretation is supported by the fact that the Hebrew word translated ‘stand still’ has the same root as a Babylonian word used in ancient astronomical texts to describe eclipses.”

Humphreys and his co-author, Graeme Waddington, are not the first to suggest that the biblical text may refer to an eclipse, however, earlier historians claimed that it was not possible to investigate this possibility further due to the laborious calculations that would have been required.

Independent evidence that the Israelites were in Canaan between 1500 and 1050 BC can be found in the Merneptah Stele, an Egyptian text dating from the reign of the Pharaoh Merneptah, son of the well-known Ramesses the Great. The large granite block, held in the Egyptian Museum in Cairo, says that it was carved in the fifth year of Merneptah’s reign and mentions a campaign in Canaan in which he defeated the people of Israel.

Earlier historians have used these two texts to try to date the possible eclipse, but were not successful as they were only looking at total eclipses, in which the disc of the sun appears to be completely covered by the moon as the moon passes directly between the earth and the sun. What the earlier historians failed to consider was that it was instead an annular eclipse, in which the moon passes directly in front of the sun, but is too far away to cover the disc completely, leading to the characteristic ‘ring of fire’ appearance. In the ancient world the same word was used for both total and annular eclipses.

The researchers developed a new eclipse code, which takes into account variations in the Earth’s rotation over time. From their calculations, they determined that the only annular eclipse visible from Canaan between 1500 and 1050 BC was on 30 October 1207 BC, in the afternoon. If their arguments are accepted, it would not only be the oldest solar eclipse yet recorded, it would also enable researchers to date the reigns of Ramesses the Great and his son Merneptah to within a year.

“Solar eclipses are often used as a fixed point to date events in the ancient world,” said Humphreys. Using these new calculations, the reign of Merneptah began in 1210 or 1209 BC. As it is known from Egyptian texts how long he and his father reigned for, it would mean that Ramesses the Great reigned from 1276-1210 BC, with a precision of plus or minus one year, the most accurate dates available. The precise dates of the pharaohs have been subject to some uncertainty among Egyptologists, but this new calculation, if accepted, could lead to an adjustment in the dates of several of their reigns and enable us to date them precisely.

Minor Merger Kicks Supermassive Black Hole Into High Gear

The galaxy Messier 77 (M77) is famous for its super-active nucleus that releases enormous energy across the electromagnetic spectrum, ranging from x-ray to radio wavelengths. Yet, despite its highly active core, the galaxy looks like any normal quiet spiral. There’s no visual sign of what is causing its central region to radiate so extensively. It has long been a mystery why only the center of M77 is so active. Astronomers suspect a long-ago event involving a sinking black hole, which could have kicked the core into high gear.

To test their ideas about why the central region of M77 beams massive amounts of radiation, a team of researchers at the National Astronomical Observatory of Japan and the Open University of Japan used the Subaru Telescope to study M77. The unprecedented deep image of the galaxy reveals evidence of a hidden minor merger billions of years ago. The discovery gives crucial evidence for the minor merger origin of active galactic nuclei.

The Mystery of Seyfert Galaxies

The galaxy Messier 77 (NGC 1068) is famous for harboring an active nucleus at its core that releases an enormous amount of energy. The existence of such active galaxies in the nearby universe was first noted by the American astronomer Carl Seyfert more than 70 years ago. Nowadays they are called the Seyfert galaxies. Astronomers think that the source of such powerful activity is the gravitational energy released from superheated matter falling onto a supermassive black hole (SMBH) that resides in the center of the host galaxy. The estimated mass of such a SMBH for M77 is about 10 million times that of the Sun.

It takes a massive amount of gas dumped on the galaxy’s central black hole to create such strong energies. That may sound like an easy task, but it’s actually very difficult. The gas in the galactic disk will circulate faster and faster as it spirals into the vicinity of the SMBH. Then, at some point the “centrifugal force” balances with the gravitational pull of the SMBH. That actually prevents the gas from falling into the center. The situation is similar to water draining out of a bathtub. Due to the centrifugal force, the rapidly rotating water will not drain out rapidly. So, how can the angular momentum be removed from the gas circling near an active galactic nucleus? Finding the answer to that question is one of the big challenges for researchers today.

A Prediction Posed 18 Years Ago

In 1999, Professor Yoshiaki Taniguchi (currently at the Open University of Japan), the team leader of the current Subaru study, published a paper about the driving mechanism of the active nucleus of Seyfert galaxies such as M 77. He pointed out that a past event — a “minor merger” where the host galaxy ate up its “satellite” galaxy (a small low-mass galaxy orbiting it) — would be the key to activating the Seyfert nucleus.

Usually, a minor merger event simply breaks up a low-mass satellite galaxy. The resulting debris is absorbed into the disk of the more massive host galaxy before it approaches the center. Therefore, it was not considered as the main driver of the nuclear activity. “However, the situation could be totally different if the satellite galaxy has a (smaller) SMBH in its center,” Professor Taniguchi suggests, “because the black hole can never be broken apart. If it exists, it should eventually sink into the center of the host galaxy.”

The sinking SMBH from the satellite galaxy would eventually create a disturbance in the rotating gas disk around the main galaxy’s SMBH. Then, the disturbed gas would eventually rush into the central SMBH while releasing enormous gravitational energy. “This must be the main ignition mechanism of the active Seyfert nuclei,” Taniguchi argued. “The idea can naturally explain the mystery about the morphology of the Seyfert galaxies,” said Professor Taniguchi, pointing out the advantage of the model of normal-looking galaxies also being very active at their cores.

Probing the Theory Using the Subaru Telescope

Recent advances in observational technique allow the detection of the extremely faint structure around galaxies, such as loops or debris that are likely made by dynamical interactions with satellite galaxies.. The outermost parts of galaxies are often considered as relatively “quiet” with a longer dynamical timescale than anywhere inside. Simulations show that the faint signature of a past minor merger can remain several billion years after the event. “Such a signature can be a key test for our minor merger hypothesis for Seyfert galaxies. Now it is time to revisit M77, ” said Taniguchi.

The team’s choice to look for ‘the past case’ was, of course, the Subaru Telescope and its powerful imaging camera, Hyper Suprime-Cam. The observing proposal was accepted and executed on Christmas night 2016. “The data was just amazing,” said Dr. Ichi Tanaka, the primary investigator of the project. “Luckily, we could also retrieve the other data that was taken in the past and just released from the Subaru Telescope’s data archive. Thus, the combined data we got finally is unprecedentedly deep.”

Subaru’s great photon-collecting power and the superb performance of the Hyper Suprime-Cam were crucial in the discovery of the extremely faint structures in M77. Their discovery reveals the normal-looking galaxy’s hidden violent past.. “Though people may sometimes make a lie, galaxies never do. The important thing is to listen to their small voices to understand the galaxies, ” said Professor Taniguchi.

The team will expand its study to more Seyfert galaxies using the Subaru Telescope. Dr. Masafumi Yagi, who leads the next phase of the project said, “We will discover more and more evidences of the satellite merger around Seyfert host galaxies. We expect that the project can provide a critical piece for the unified picture for the triggering mechanism for active galactic nuclei.”

Jupiter’s X-Ray Auroras Pulse Independently

Jupiter’s intense northern and southern lights pulse independently of each other according to new UCL-led research using ESA’s XMM-Newton and NASA’s Chandra X-ray observatories.

The study, published today in Nature Astronomy, found that very high-energy X-ray emissions at Jupiter’s south pole consistently pulse every 11 minutes. Meanwhile those at the north pole are erratic: increasing and decreasing in brightness, independent of the south pole.

This behaviour is distinct from Earth’s north and south auroras which broadly mirror each other in activity. Other similarly large planets, such as Saturn, do not produce any detectable X-ray aurora, which makes the findings at Jupiter particularly puzzling.

“We didn’t expect to see Jupiter’s X-ray hot spots pulsing independently as we thought their activity would be coordinated through the planet’s magnetic field. We need to study this further to develop ideas for how Jupiter produces its X-ray aurora and NASA’s Juno mission is really important for this,” explained lead author, William Dunn (UCL Mullard Space Science Laboratory, UK and the Harvard-Smithsonian Center for Astrophysics, USA).

Since arriving at Jupiter in 2016, the Juno mission has been re-writing much of what is known about the giant planet, but the spacecraft does not have an X-ray instrument on board. To understand how the X-ray aurora are produced, the team hope to combine the X-ray aurora information gathered using XMM-Newton and Chandra with data collected by Juno as it explores the regions producing Jupiter’s aurora.

“If we can start to connect the X-ray signatures with the physical processes that produce them, then we can use those signatures to understand other bodies across the Universe such as brown dwarfs, exoplanets or maybe even neutron stars. It is a very powerful and important step towards understanding X-rays throughout the Universe and one that we only have while Juno is conducting measurements simultaneously with Chandra and XMM-Newton,” said William Dunn.

One of the theories that Juno may help to prove or disprove is that Jupiter’s auroras form separately when the planet’s magnetic field interacts with the solar wind. The team suspect that the magnetic field lines vibrate, producing waves that carry charged particles towards the poles and these change in speed and direction of travel until they collide with Jupiter’s atmosphere, generating X-ray pulses.

Using the XMM-Newton and Chandra X-ray observatories in May to June 2016 and March 2007, the authors produced maps of Jupiter’s X-ray emissions and identified an X-ray hot spot at each pole. Each hot spot covers an area much bigger than the surface of the earth. Studying each to identify patterns of behaviour, they found that the hot spots have very different characteristics.

“The behaviour of Jupiter’s X-ray hot spots raises important questions about what processes produce these auroras. We know that a combination of solar wind ions and ions of Oxygen and Sulphur, originally from volcanic explosions from Jupiter’s moon, Io, are involved. However, their relative importance in producing the X-ray emissions is unclear,” explained co-author Dr Licia Ray (Lancaster University).

“What I find particularly captivating in these observations, especially at the time when Juno is making measurements in situ, is the fact that we are able to see both of Jupiter’s poles at once, a rare opportunity that last occurred ten years ago. Comparing the behaviours at the two poles allows us to learn much more of the complex magnetic interactions going on in the planet’s environment,” concluded co-author Professor Graziella Branduardi-Raymont (UCL Space & Climate Physics).

The team hopes to keep tracking the activity of Jupiter’s poles over the next two years using X-ray observing campaigns in conjunction with Juno to see if this previously unreported behaviour is commonplace.

Mystery Of Raging Black Hole Beams Penetrated

They are nature’s very own Death Star beams — ultra-powerful jets of energy that shoot out from the vicinity of black holes like deadly rays from the Star Wars super-weapon.

Now a team of scientists led by the University of Southampton has moved a step closer to understanding these mysterious cosmic phenomena — known as relativistic jets — by measuring how quickly they ‘switch on’ and start shining brightly once they are launched.

How these jets form is still a puzzle. One theory suggests that they develop within the ‘accretion disc’ — the matter sucked into the orbit of a growing black hole. Extreme gravity within the disc twists and stretches magnetic fields, squeezing hot, magnetised disc material called plasma until it erupts in the form of oppositely directed magnetic pillars along the black hole’s rotational axis.

Plasma travels along these focused jets and gains tremendous speed, shooting across vast stretches of space. At some point, the plasma begins to shine brightly, but how and where this occurs in the jet has been debated by scientists.

In a new study published today [Monday, October 30] in Nature Astronomy, an international team of scientists led by Dr Poshak Gandhi show how they used precise multi-wavelength observations of a binary system called V404 Cygni — consisting of a star and a black hole closely orbiting each other, with the black hole feeding off matter from the star that falls through the disc — to throw light on this hotly debated phenomenon.

V404 Cygni is located about 7,800 light years away in the constellation of Cygnus, and weighs as much as about nine of our Suns put together. Dr Gandhi and his collaborators captured the data in June 2015, when V404 Cygni was observed radiating one of the brightest ‘outbursts’ of light from a black hole ever seen — bright enough to be visible to small telescopes used by amateur astronomers, and energetic enough to tear apart an Earth-like planet if properly focused.

Using telescopes on Earth and in space observing at exactly the same time, they captured a 0.1-second delay between X-ray flares emitted from near the black hole, where the jet forms, and the appearance of visible light flashes, marking the moment when accelerated jet plasma begins to shine.

This ‘blink of an eye’ delay was calculated to represent a maximum distance of 19,000 miles (30,000 km), impossible to resolve at the distance of V404 with any current telescope.

Dr Gandhi, of the University of Southampton, said: “Scientists have been observing jets for decades, but are far from understanding how nature creates these mind-bogglingly vast and energetic structures.

“Now, for the first time, we have captured the time delay between the appearance of X-rays and the appearance of optical light in a stellar-mass black hole at the moment jet plasma is activated. This lays to rest the controversy regarding the origin of the optical flashes, and also gives us a critical distance over which jet plasma must have been strongly accelerated to speeds approaching that of light.”

In Star Wars terms, the key measurement of this study can roughly be likened to measuring the distance between the surface of the Death Star, where multiple rays of light shoot out, and the point where they converge into a single bright beam.

“But the physics of black hole jets has nothing to do with lasers or the fictional Kyber crystals that power the Death Star. Nature has found other ways to power jets,” said Dr Gandhi. “Gravity and magnetic fields play the key roles here, and this is the mechanism we are trying to unravel.”

The study also creates a link between V404 Cygni and supermassive black holes, which lie at the centre of massive galaxies and which weigh billions of times more than stellar-mass black holes. Similar jet physics may apply to all black holes.

Dr Gandhi said: “This is an exciting and important discovery which can be fed back into theory about relativistic jets, and contributes to our ever-growing understanding of black holes.”

The X-ray emission, representing the accretion disc ‘feeding’ the jet at its base, was captured from Earth orbit by NASA’s NuSTAR telescope, while the moment the jet became visible as optical light was caught by the ULTRACAM high-speed camera, mounted on the William Herschel Telescope on La Palma, in the Canary Islands.

Professor Vik Dhillon, of the University of Sheffield, the principal investigator behind ULTRACAM, commented: “This discovery was made possible thanks to our camera gathering 28 frames per second. It demonstrates the untapped potential of studying astrophysical phenomena at high speeds.”

At the same time, radio waves from the extended portions of the jet plasma were observed by a team of Professor Rob Fender, of the University of Oxford, using the AMI-LA radio telescope, in Cambridge, UK.

Professor Fender said: “These observations are another major step towards understanding exactly how relativistic jets are formed by black holes. Radio detections come from the outer jet and are the key unambiguous indicator of ongoing jet activity. The optical, X-rays and radio were also crucial for that discovery.”

Magnitude 7.0 Undersea Quake Hits Near New Caledonia, No Tsunami Trigger

A major undersea earthquake of magnitude 7.0 struck close to New Caledonia in the South Pacific on Tuesday, the US Geological Survey said.

The quake, which was at a shallow depth of 9.3 miles (15 km)below the seabed, did not trigger a tsunami, according to the Pacific Tsunami Warning Center in Hawaii and the Joint Australian Tsunami Warning Centre.

The epicenter was located 73 miles (117.48 km) east of the town of Tadine, on the Loyalty Islands, part of France’s New Caledonia territory.

There were no immediate reports of injuries or damage.

A spokesman for the government in Noumea, the New Caledonia capital, and staff of two hotels contacted by Reuters said they did not feel the quake.