Wednesday, August 30, 2023

JWST reveals surprising scarcity of supermassive black holes


A team of astronomers used the James Webb Space Telescope (JWST) to discover that the early universe was between 4 and 6 billion years old and had fewer supermassive black holes than previously believed.

The team used Webb to study a region of space known as the Extended Groth Strip, near the Big Dipper constellation. The well-known region contains an estimated 50,000 galaxies, and it is the first time it has been studied by an observatory as powerful as JWST.

Using Webb, they could peer behind dust clouds and shed new light on ancient black holes. They were also surprised to encounter far fewer in their observations than anticipated.


James Webb continues to peer further than ever before


In a press statement released by the University of Kansas, Allison Kirkpatrick, team leader, explained that "our observations were taken in last June and December, and we were aiming to characterize how galaxies looked during the heyday of star formation in the universe. This is a look back in time of 7 to 10 billion years in the past."

The team used Webb's Mid-Infrared Instrument (MIRI) instrument to peer behind dust in galaxies that existed up to 10 billion years ago. They published their findings in a new paper in preprint server ArXiv.

Surprisingly, the team found far fewer active galactic nuclei than they expected. An active galactic nucleus, or AGN, is a type of supermassive black hole that heats the surrounding material it is "eating", creating massive amounts of radiation. They are so bright they often outshine all the stars in their host galaxy.

As Webb can peer much further into the past, the team expected to find many new AGNs compared to previous surveys of the same region. Instead, they only discovered a handful of previously unobserved AGNs.

"The results looked completely different from what I had anticipated, leading to my first major surprise," Kirkpatrick explained. "One significant revelation was the scarcity of rapidly growing supermassive black holes. This finding was prompting questions about the whereabouts of these objects."

Kirkpatrick added that previous growth rates for supermassive black holes, based on observations of the region by the Spitzer Space Telescope, may have been overstated because the telescope only allowed astronomers to observe the brightest and fastest-growing examples.

Shedding new light on Sagittarius A*

The new findings suggest that the early universe may have been more stable than previously thought.

"The study's findings suggest that these black holes are not growing rapidly, absorbing limited material, and perhaps not significantly impacting their host galaxies," Kirkpatrick said. "This discovery opens up a whole new perspective on black-hole growth since our current understanding is largely based on the most massive black holes in the biggest galaxies, which have significant effects on their hosts, but the smaller black holes in these galaxies likely do not."

The researchers believe the new findings may also shed new light on the evolution of our galaxy, the Milky Way.

Astronomers have wondered whether it may have once had an AGN at its heart. The new research doesn't provide a conclusive answer, but it hints at the Milky Way's ancient past.

The black hole at the center of our galaxy, Sagittarius A*, is known to swallow surrounding matter at an incredibly slow pace.

"Our black hole seems quite uneventful, not displaying much activity. One significant question regarding the Milky Way is whether it was ever active or went through an AGN phase," Kirkpatrick continued. "If most galaxies, like ours, lack detectable AGN, it could imply that our black hole was never more active in the past.

"Ultimately, this knowledge will help constrain and measure black hole masses, shedding light on the origins of black holes growing, which remain an unanswered question," she added.

7th Edition of International Conference on Gravitational Waves


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Tuesday, August 29, 2023

Chandrayaan-3 moon landing Highlights: Rover, lander very healthy, giving ‘beautiful’ data, says ISRO chief

 Chandrayaan-3 Moon Landing Successful:

India took a giant leap on Wednesday evening as the ISRO's mooncraft, Chandrayaan-3 soft landed on Moon's south polar region, making it the first country to achieve this milestone. Moreover, India became the fourth country – after the US, China, and Russia – to have successfully landed on the moon’s surface.

ISRO has continued to share videos and images of the moon Vikram lander and Pragyan rover of Chandrayaan-3 frequently on social media platforms. The Pragyan Rover has rolled over the surface of the moon for a distance of eight meters, ISRO said in its latest update. Yesterday, ISRO released a video of the Pragyan rover rolling out of Chandrayaan-3 Vikram lander from a two-segment ramp as well as the deployment of the ramp and solar panel prior to the rolldown of the rover.

Prime Minister Narendra on Saturday met the ingenious scientists of ISRO, including chairman S Somnath who were involved in the Chandrayaan-3 mission.

The mission began more than a month ago at an estimated cost of over ₹600 crore. ISRO Chairman S Somnath said that India would next attempt a manned lunar mission.

On 23 August, at 6:04 PM (IST), the Chandrayaan-3's lander touched down close to the center of the 4.5-kilometer-wide area that had been targeted for the landing. The lander landed within 300 meters (985 feet) of that point. As per ISRO chairman, rover Pragyan was on the move, and working "very well,"

Chandrayan-3 Rover would conduct experiments over 14 days, including an analysis of the mineral composition of the lunar surface.



The lander and the rover are very healthy: ISRO chief

On Chandrayaan-3, ISRO Chairman S Somanath said, “Everything is working very well. Chandrayaan-3, the lander, the rover is very healthy and all the five instruments on board have been switched on. And it's giving beautiful data now."

“So we are hoping that in the days to come next another ten more days remaining before 3rd September, we should be able to complete all the experiments with its full capability of various modes. There are different modes for which it has to be tested... So we have the best picture ever of the Moon," he said.

Nothing wrong in naming touchdown point as ‘Shiv Shakti’, says ISRO chief


On the naming of the Chandrayaan-3 lander touchdown point as ‘Shiv Shakti’, ISRO chief S Somanath said there is nothing wrong with the naming of it. “PM narrated the meaning of it in a manner that suits all of us. I think there is nothing wrong with that. And also he gave the next name to Tiranga and both are Indian-sounding names. See, we must have a significance of doing what we are doing. And he has a prerogative of naming it being the Prime Minister of the country," he said.

‘India’s space missions are designed in…’: Jitendra Singh 


Union Minister of State for Space Jitendra Singh said India’s space missions are designed in such a way that it is cost-effective. India, he said, has learned to compensate for costs through skills.

Chandrayaan symbol of spirit of new India that knows how to win in any situation: PM Modi


Mission Chandrayaan has become a symbol of the spirit of 'New India' which wants to ensure victory and knows how to win in any situation, Prime Minister Narendra Modi said on Sunday and asserted that the lunar programme was also a living example of women power.

In his monthly 'Mann Ki Baat' programme, Modi said the daughters of India are now challenging even space which is considered infinite. "When the daughters of a country become so ambitious, who can stop that country from becoming developed," he said.

Dawn of revolution lit up dark side of moon: PM Modi hails Chandrayaan - 3 in 'Mann Ki Baat'


Mission 'Chandrayaan-3' has emerged as the symbol of the spirit of a 'New India', which wants to emerge victorious under any circumstances, Prime Minister Narendra Modi said in the latest edition of his monthly radio broadcast — 'Mann Ki Baat' — on Sunday.

India entered record books as the first country to successfully place a lander on the moon's uncharted South Police on Wednesday, last week.

Chandrayaan-3 proved India's cost-effective space mission capability: Jitendra Singh


Chandrayaan-3 has proved India's capability for cost-effective space missions, said Union Minister of State for Space Jitendra Singh.

Speaking at an interactive meet of intellectuals, prominent citizens and media persons in Indore on Saturday, “The Russian moon mission, that was unsuccessful, cost ₹16,000 crore, and our (Chandrayaan-3) mission cost just around ₹600 crore. Consider, Hollywood films based on moon and space Missions cost over ₹600 crore."

'Chandrayaan is also a living example of women's power', says PM Modi


During his 104th episode of Mann Ki Baat, Prime Minister Narendra Modi said, “From the Red Fort I had said that we have to strengthen women-led development as a national character. Where the capability of women's power is added impossible is made possible. Mission Chandrayaan is also a living example of women's power. In this mission, many women scientists & engineers were directly involved in it."

7th Edition of International Conference on Gravitational Waves


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Monday, August 28, 2023

International Space Station: Live updates


The International Space Station has been orbiting Earth since 1998, serving as a research platform for NASA astronauts and its international partners: the Russian Space Agency Roscosmos, the European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA).

Expedition 67, the 67th and current long-duration mission to the International Space Station, began in March 2022 and will last about six months. Here we'll provide live updates on what the Expedition 67 crew has been up to, from visiting vehicles to spacewalks and more.

 


SpaceX's Crew-7 astronaut launch to the International Space Station has been pushed back to Saturday (Aug. 26), roughly 24 hours past its first attempt at Florida's Kennedy Space Center.

"NASA and SpaceX are standing down from the Friday, Aug. 25, launch opportunity for the agency's Crew-7 mission to the International Space Station," NASA officials said in an emailed statement Thursday night (Aug. 24). "Launch now is targeted at 3:27 a.m. Saturday, Aug. 26, for SpaceX's seventh crew rotation mission to the microgravity laboratory for NASA. More to come."

SpaceX Crew-7 passed its flight readiness review with no major issues, NASA officials said in a late-night update Thursday (Aug. 24). Weather conditions also are positive, according to Patrick Space Force Base, which manages the airspace in the region of the launch site at NASA's Kennedy Space Center in Florida.

The Crew-7 mission will launch to the International Space Station no earlier than Friday (Aug. 25) at 3:50 a.m. EDT (0750 GMT) and you can watch live here at Space.com, via a feed from NASA Television. The broadcast will begin at Thursday (Aug. 24) at 11:45 p.m. EDT (0345 GMT Friday, Aug. 25).

An orbiting astronaut found out about Chandrayaan-3's successful landing on the moon today (Aug. 23) on social media.

It was "all over the news" during the lunch break of Sultan Al Neyadi, an International Space Station astronaut conducting the first long-duration orbital mission for the United Arab Emirates (UAE).

"It was really big," the SpaceX Crew-6 astronaut told Space.com from orbit during a press conference today. "I saw multiple clips of mission control in India ... it was really great watching that achievement, and, hopefully, as I've mentioned, many nations will follow the same footsteps of India."

The SpaceX Crew-7 astronauts arrived at NASA's Kennedy Space Center on Sunday (Aug. 20) for their International Space Station launch. They will head to space no earlier than Aug. 25, and you can watch the whole thing live here at Space.com, via NASA TV.

On board is Jasmin Moghbeli, the second Iranian-American to reach space on Crew-7, and joining her is a fully international crew: Japan Aerospace Exploration Agency (JAXA) astronaut Satoshi Furukawa, Roscosmos cosmonaut Konstantin Borisov and ESA (European Space Agency) astronaut Andreas Mogensen.

6th Edition of International Conference on Gravitational Waves


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Friday, August 25, 2023

New exoplanet discovery builds better understanding of planet formation


An international team of scientists has discovered an unusual Jupiter-sized planet orbiting a low-mass star called TOI-4860, located in the Corvus constellation.

The newly discovered gas giant, named TOI-4860 b, is an unusual planet for two reasons: Stars of such low mass are not expected to host planets like Jupiter, and the planet appears to be particularly enriched by heavy elements.


The study, led by University of Birmingham astronomers, is published today in a letter published within the Monthly Notices of the Royal Astronomical Society.

The planet was initially identified using NASA's Transiting Exoplanet Survey Satellite as a drop of brightness while transiting in front of its host star, but that data alone was insufficient to confirm that it was a planet.

The team used the SPECULOOS South Observatory, located in the Atacama Desert in Chile, to measure the planetary signal in several wavelengths and validated the planetary nature. The astronomers also observed the planet just before and after it disappeared behind its host star, noticing that there was no change in light, meaning the planet was not emitting any. Finally, the team collaborated with a Japanese group using the Subaru Telescope in Hawai'i. Together they measured the mass of the planet to fully confirm it.

Following this star and confirming its planet was the initiative of a group of Ph.D. students within the SPECULOOS project.

George Dransfield, one of those Ph.D. students, who recently submitted her thesis at the University of Birmingham, explains, "Under the canonical planet formation model, the less mass a star has, the less massive is the disc of material around that star.

"Since planets are created from that disc, high-mass planets like Jupiter, were widely expected not to form. However, we were curious about this and wanted to check planetary candidates to see if it was possible. TOI-4860 is our first confirmation and also the lowest mass star hosting such a high mass planet."

Amaury Triaud, Professor of Exoplanetology at the University of Birmingham who led the study, said, "I am ever thankful to the bright Ph.D. students of our team for proposing to observe systems like TOI-4860. Their work has really paid off since planets like TOI-4860 are vital to deepening our understanding of planet formation.

"A hint of what might have happened is hidden in the planetary properties, which appear particularly enriched in heavy elements. We have detected something similar in the host star too, so it is likely that an abundance of heavy elements catalyzed the planet formation process."

The new gas giant takes about 1.52 days to complete a full orbit around its host star, but because its host is a cold low mass star, the planet itself can be referred to as a "warm Jupiter." This is a subclass of planet that holds particular interest for astronomers looking to build on their initial observations and learn more about how these kinds of planets are formed.

Mathilde Timmermans, another student of the SPECULOOS project working at the University of Liege in Belgium, concludes, "Thanks to its very short orbital period, and to the properties of its host star, the discovery of TOI-4860 b provides a brilliant opportunity to study the atmospheric properties of a warm Jupiter and learn more about how gas giants are formed."

Recently the team has been awarded telescope time at the Very Large Telescope, in Chile, which they intend to use to confirm several more planets with similar properties.

6th Edition of International Conference on Gravitational Waves


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Wednesday, August 23, 2023

New study challenges Einstein and Newton's theories of gravity


Gravity is the force that attracts objects toward the Earth and maintains the orbital motion of planets around the Sun.

Our scientific understanding of gravity was established by Isaac Newton in 1687. Newton's theory of gravity stood the test of time for two centuries until Albert Einstein proposed his 'General Theory of Relativity,' filling in the gaps left by Newton's theory of gravity.

Despite the many successes of Einstein's theory of gravity, many phenomena, such as gravity inside a black hole and gravitational waves, can't be explained.

Recently, a new study has found direct evidence for a modified theory of gravity at low acceleration. Prof. Kyu-Hyun Chae carried out the study from Sejong University in Seoul, Korea. Chae observed the orbital behaviors of cosmic structures called wide binary stars from data collected by the European Space Agency's Gaia space telescope.



These findings are significant as they point towards a new theory of gravity, different from the Newton-Einstein theory.

Newton's & Einstein's theories of gravity 

Newton's theory of gravity was revolutionary at the time. It successfully explained the attraction between bodies on Earth and beyond, granting us a deeper understanding of planetary motion.

However, as the scope of technology expanded, Newton's framework revealed gaps in its ability to account for complex gravitational phenomena. Anomalies in Mercury's orbit were one of them, which puzzled astronomers and showed that the theory falls apart in explaining extreme gravitational conditions.

Then, in 1915, Einstein published his opus magnum, "The General Theory of Relativity." This transformative theory reimagined gravity as the curvature of spacetime itself, unifying mass and energy in a cosmic dance.

Einstein's theory bridged Mercury's orbit and explained the bending of starlight around massive bodies during a solar eclipse. However, even Einstein's visionary insights fell short in the face of the cosmic abyss—black holes, where gravity becomes infinitely intense.

To fill in these gaps, scientists proposed the concept of dark matter. This elusive form of matter is invisible as it doesn't interact with light, but its effects can be seen through its gravitational pull. It was postulated to explain the discrepancies between observed gravitational effects and predictions.

But we don't know what form dark matter takes and if it even exists.

MOND: Modified Newtonian dynamics

Although dark matter could potentially explain discrepancies, many scientists have been skeptical because of the lack of evidence. This has led to alternate theories.

Modified Newtonian dynamics, or MOND, was first proposed by Israeli scientist Mordehai Milgrom in 1983 and could explain these galactic anomalies, including the ones observed by Chae.

The basic premise of MOND is that Newtonian gravity, which works well for most everyday situations, might behave differently at extremely low accelerations.

This deviation from Newtonian physics is suggested to occur when the gravitational fields are weak. MOND suggests that at these low accelerations, the force of gravity no longer follows the familiar inverse square law but exhibits a different functional form.

It suggests that acceleration depends on masses and a scale-dependent function, which means that how gravity operates changes based on the size or scale of the system being studied, distinct from traditional gravity.

Wide binary star systems

Chae analyzed 26,500 comprehensive binary star systems within 650 lightyears from the data collected by the Gaia telescope.

Wide binary star systems consist of two stars in relatively distant orbits around each other. Chae's investigation into these systems revealed that at ultra-low accelerations, the observed accelerations were 30-40% higher than traditional predictions, suggesting a potential breakdown of standard gravity.

This unexpected acceleration boost is explained by A Quadratic Lagrangian (AQUAL), a MOND-influenced theory of gravity co-authored by Milgrom, marking direct evidence of standard gravity breakdown at weak acceleration.

In a press release, Chae explained why he chose to study these systems, "From the start, it seemed clear to me that gravity could be most directly and efficiently tested by calculating accelerations because the gravitational field itself is an acceleration."

"My recent research experiences with galactic rotation curves led me to this idea. Galactic disks and wide binaries share some similarity in their orbits, though wide binaries follow highly elongated orbits while hydrogen gas particles in a galactic disk follow nearly circular orbits," he said.

Chae's study does more than challenge the status quo; it lays the foundation for a broader exploration of gravity's mysteries. He hopes his results will be confirmed and refined using larger and better data sets.

The findings of the study are published in The Astrophysics Journal.

6th Edition of International Conference on Gravitational Waves
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A giant black hole tore apart a massive star


NASA’s Chandra X-ray Observatory and ESA’s XMM-Newton examined the amount of nitrogen and carbon close to a black hole known to have ripped apart a star. According to astronomers, these elements were produced inside the star before it was shattered as it approached the black hole.

“We can determine what kind of star perished by looking at the elements left behind,” astronomers noted.

Such events are generally known as ‘tidal disruption events,’ where the gravitational forces from a massive black hole destroy a star. This event, called ASASSN-14li, stands out for several reasons.

ASASSN-14li is one of the nearest tidal disruption events (TDE) ever discovered. Because of this proximity, ASASSN-14li has provided extraordinary detail about the destroyed star.



Astronomers used new theoretical models to make improved estimates of the amount of nitrogen and carbon around the black hole. The team’s discovery of a nitrogen-to-carbon ratio suggests that the material came from the interior of a dying star about three times as massive as the Sun.

It suggests that the star in ASASSN-14li was one of the most massive astronomers have seen ripped apart by a black hole.

Co-author Enrico Ramirez-Ruiz of the University of California, Santa Cruz, said, “ASASSN-14li is exciting because one of the hardest things with tidal disruptions is being able to measure the mass of the unlucky star, as we have done here.”

“Observing the destruction of a massive star by a supermassive black hole is spellbinding because more massive stars are expected to be significantly less common than lower-mass stars.”

What the ASASSN-14li result suggests for future research is another fascinating part of the result. In the star cluster that houses the supermassive black hole at the heart of our galaxy, astronomers have observed stars of a moderate mass similar to ASASSN-14li’s.

Astronomers may therefore be able to detect the presence of star clusters around supermassive black holes in farther away galaxies by being able to estimate the stellar masses of tidally shattered stars.

Scientists noted, “Until this study, there was a strong possibility that the elements observed in X-rays might have come from gas released in previous eruptions from the supermassive black hole. However, the pattern of elements analyzed here appears to have come from a single star.”

6th Edition of International Conference on Gravitational Waves

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Tuesday, August 22, 2023

Indian scientists detect gravitational waves that create humming in space

In a first, a team of scientists from India, Japan and Europe has found evidence of gravitational waves in the universe. The team included researchers from Indian Institute of Technology, Roorkee (IIT-R).


According to the results published in two seminal papers in the Astronomy and Astrophysics journal, the team monitored data from pulsars using six of the world's most sensitive radio telescopes, including India’s largest telescope, uGMRT.

The telescope, located in Pune, is operated by the National Centre for Radio Astrophysics (NCRA) and was instrumental in the discovery of ripples in the fabric of space-time, which are called nano-hertz gravitational waves. Such waves also originate from a dancing monster black hole pair believed to be crores of times heavier than our Sun.

The relentless cacophony of these gravitational waves from a large number of supermassive black hole pairs create the humming of our universe.

"These results have culminated due to years of efforts of many scientists, including early career researchers and undergraduate students. I am very grateful that IIT Roorkee has been able to constantly contribute in various ways in achieving these results," said professor Arumugam, Department of Physics, IIT Roorkee.

How pulsars helped detect waves

Pulsars are called cosmic clocks and they emit radio beams that are seen as flashes from the Earth regularly. Astronomers monitor these beams or signals using radio telescopes.

Albert Einstein said that gravitational waves change the arrival times of these radio waves and affect the measured ticks of our cosmic clocks. Due to irregular arrival times of radio waves from pulsars it was deduced that the universe is filled with gravitational waves.

Since these changes are extremely tiny, astronomers need sensitive telescopes and a collection of pulsars to separate these changes from other disturbances.

The team also consisted of members of the European Pulsar Timing Array (EPTA) and Indian Pulsar Timing Array (InPTA) consortia, as well as PhD student, Jaikhomba Singha.

6th Edition of International Conference on Gravitational Waves

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Sunday, August 20, 2023

Gravitational Waves Ripping Apart Whole Planets?


While most nerds are content to argue over whether Batman could take Wolverine in a fight, the ones at the Dead Planets Society are busy with bigger questions like, could a gravitational wave rip apart an entire planet? The latest episode of the New Scientist-owned podcast takes a godlike approach to the cosmos and tries to figure out if you could move celestial bodies around like chess on a chessboard, would it be possible to put two black holes near a planet in such a way that the resulting gravitational waves could pull it apart like a piece of monkey bread.



If the theoretical gravitational waves vibrated at the right frequency, they could potentially cause the Earth to stretch beyond its limit until it breaks into smaller chunks

Gravitational wave researcher Christopher Berry joined hosts Chelsea Whyte and Leah Crane on Dead Planet Society‘s most recent episode to discuss his area of expertise and whether or not gravitational waves could ever make an effective Death Star alternative.

What Causes Gravitational Waves?

Gravitational waves are usually caused by something extremely massive and dense, like a black hole, colliding with another black hole. the resulting cosmic ripples or “waves” radiate outward, disrupting space-time as they go. Because of how far away most of these space cataclysms are the waves that reach Earth are so miniscule they can only be detected with highly specialized instruments.The three podcasters started with the premise, “Is it possible to make a gravitational wave strong enough for humans to feel?” but the conversation quickly devolved into how to make waves big enough to destroy the Earth or, as Chelsea put it, “Yeah, or the solar system, or everything, everywhere.” According to Berry, the first problem would be distinguishing between gravitational waves and just plain gravity.

In the end the consensus seems to be that yes, you could use a gravitational wave to destroy a planet—or even a whole solar system if you so desired—but that the circumstances behind such a wave could never occur naturally.

“When you’re very close to a source of gravitational waves, at least the gravitational waves we’re talking about of, say, two black holes orbiting around each other, the space-time is really churned up, so it’s not so easy to distinguish a wave from the underlying gravity itself,” Berry explained.

Berry eventually settles on vibration as the key to making the Earth pull itself apart. If the theoretical gravitational waves vibrated at the right frequency, they could potentially cause the Earth to stretch beyond its limit until it breaks into smaller chunks. The conversation turns from there to a theoretical cosmic symphony of black holes placed in certain positions and at certain frequencies, generating waves at different notes.

Berry theorizes that you could send that signal in any direction in space and it would become a beautiful-sounding orchestra of pure destruction.

In the end the consensus seems to be that yes, you could use a gravitational wave to destroy a planet—or even a whole solar system if you so desired—but that the circumstances behind such a wave could never occur naturally.Only if one had the same control over the universe that a Minecraft player has over their own little world, could a scenerio be set up where planet-destroying gravitational waves could be generated.

In other words, don’t add”Pulled apart violently by a massive gravitational wave” to your 2023 bingo card just yet.

6th Edition of International Conference on Gravitational Waves

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Saturday, August 19, 2023

Could a gravitational wave rip apart an entire planet?


When we detect gravitational waves, it’s because they are warping space and time by a tiny amount – but this episode of Dead Planets Society is about making one that is far more powerful

You may not feel it, but at every single moment you are being ever-so-slightly stretched and squeezed by ripples in space-time. These ripples, called gravitational waves, are caused by the movements of massive objects like black holes, and researchers have detected them warping Earth by minuscule amounts. But what if they warped Earth by non-minuscule amounts?



In this episode of Dead Planets Society, our hosts Chelsea Whyte and Leah Crane get curious about whether we could make a gravitational wave that would be strong enough to feel – and what that might be like – or even strong enough to rip apart a planet. This means manipulating black holes because they are the densest objects in the universe, so they are the most efficient gravitational wave machines out there.

But it isn’t as easy as just putting a pair of black holes next to the planet and smashing them together, because the gravity from the black holes would destroy the planet regardless of any waves involved.

 Gravitational wave researcher Christopher Berry joins Leah and Chelsea this episode to talk about tuning the frequency of gravitational waves to vibrate the whole planet apart, whether it would be possible to disassemble the entire solar system with gravitational waves and how to create a deadly black hole symphony that could beam its cosmic music across the universe.

Dead Planets Society is a podcast that takes outlandish ideas about how to tinker with the cosmos – from punching a hole in a planet to unifying .

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Friday, August 18, 2023

WHEN BLACK HOLES COLLIDE: UNIVERSE-SHAKING EVIDENCE OF GRAVITATIONAL WAVE BACKGROUND SIGNAL FOUND


If you’ve ever watched a figure skater spinning on the ice, you might have noticed that they spin a lot faster when they tuck their arms and legs in and they slow down when they spread them out. That’s because rotational inertia is always conserved so objects with smaller diameters spin more quickly than larger objects with the same inertia. It’s a quirk of physics which allows skaters to spin until they puke and for the formation of pulsars. More on that in a minute.

Astronomers hit the ball out of the solar system when they named pulsars. They are as weird and as exotic as they sound, just as comfortable in a textbook as they are in actual space. In a Season 2 episode of Farscape (streaming now on Peacock!), the crew of Moya fly through a region of the uncharted territories known as The Five Pulsars. It is so named for the collection of pulsars it houses, which seem to affect some of the crew in unusual ways. As it turns out, there’s something stranger going on, just outside of their view.


The NANOGrav collaboration, an international team of scientists announced evidence of a gravitational wave background signal for the very first time. The news made headlines across all of the major science publications and has been the talk of science town since even before the announcement. So, what’s the big deal?

For most of humanity’s scientific career, we’ve been limited to the things we could actually see with our eyes. The invention of microscopes and telescopes expanded that view to the very small and the very far away, but even early astronomy was entirely optical. It wasn’t until later that we realized we could see more of the universe by looking for parts of the electromagnetic spectrum we can’t see.

Things like radio waves, X-rays, and infrared are all types of light, but their wavelengths are either too short or too long for our eyes to detect. We need machines to detect and translate that information for us. Over the last few decades, scientists have been working on new tools for detecting a totally different type of invisible signal, that of gravitational waves.

Most of the time astronomy is an activity which involves observing things in space, detecting gravitational waves is the practice of detecting movements in the fabric of spacetime itself. The existence of gravitational waves, the result of violent collisions of supermassive objects like black holes or neutron stars, was predicted decades ago but only confirmed in 2015. Researchers used LIGO, a pair of interferometers four kilometers on a side, made up of two perpendicular lasers to detect the merger of two black holes. Because we know the exact distance of the instrument and the precise speed of light, researchers know exactly how long it should take laser light to make the trip from one end of the instrument to the other. If the trip takes longer or shorter than it should, that’s a pretty good indication something is afoot.

When a gravitational wave passes through the instrument, the fabric of spacetime is stretched or compressed temporarily and the travel time of the laser light is altered. That’s how LIGO detects gravitational waves, but even it is limited in what it can see. Despite its huge length, LIGO can only detect short gravity waves with wavelengths measured in kilometers. Scientists suspected that much larger gravitational waves might be out there, but we didn’t have any good way to detect them. It would be like trying to see the curvature of the Earth from the ground. We needed a bigger instrument.


To pick up waves that large, astronomers needed an instrument larger than anything we could possibly construct. To detect low-frequency gravitational waves we would need an interferometer measured not in kilometers but in lightyears. Fortunately, scientists figured out a way to make the universe do the heavy lifting for us. And that’s where pulsars come back in.

When massive stars die, they sometimes explode in a violent supernova. The outer layers explode outward, spreading enriched chemicals across space, and they leave a solid core behind. That core is a neutron star with all of the rotational inertia of its former, larger self, but with a much tighter diameter. As a result, they spin wildly, sometimes hundreds of times a second.

These millisecond pulsars are scattered throughout the Milky Way and when their radio beams point toward Earth, we can detect their flickering light like distant cosmic lighthouses. Pulsars are useful because they pulse at such a consistent rate, allowing scientists to use them to measure the time between events against the background rate of pulses. Measuring the travel time of light across large distances is precisely how LIGO works, which got scientists thinking maybe they didn’t need to build a new instrument. They just needed to use the ones already there.

The NANOGrav team spent 15 years studiously measuring the distance to every pulsar they could find and documenting the time between pulses, looking for anomalies. In effect, they made an interferometer the size of the galaxy by stringing pulsars together and paying close attention to the travel time of their light.

Instead of measuring one event, like the black hole merger detected by LIGO in 2015, this new signal could represent the background gravitational waves of the universe. There are a couple of suspects for the source of the signal. It might be that we’re picking up the rumbles or black hole binaries spread out across the universe. As paired black holes orbit one another they drag nearby stars around with them. The drag slows them down and their orbits decay. As they get closer, gravitational perturbations ripple out through spacetime. Get enough black holes doing the tango and you might pick up a signal in the rumble of the cosmic dance floor.

Alternative explanations include interactions with dark matter or theoretical tangled cosmic strings. It might also be the quiet jostling left over from the early universe, potentially giving us a window into the bizarre physics of the Big Bang.

We’re in early days and we need more evidence before anyone will feel comfortable putting their chips down on one explanation or another. But we just figured out how to look at the universe a little more clearly, and whatever we end up seeing is sure to be exciting.

6th Edition of International Conference on Gravitational Waves

visit:gravity.sfconferences.com

Nomination link: https://x-i.me/granom

#BlackHoleCollisions #GravitationalWaveBackground #UniverseShakingEvidence #CosmicCollisions #AstrophysicsDiscovery #WaveofGravity #SpaceRipples


Wednesday, August 16, 2023

Physicists Create New Model of Ringing Black Holes

 

A new analysis has revealed the presence of “nonlinear” effects contained in gravitational waves.


When two black holes merge to form a larger black hole, they create violent disturbances in the fabric of spacetime, generating gravitational waves that propagate outwards. Previous research on black hole mergers relied on linear mathematics to model the behavior of these waves, assuming that they did not interact with each other. However, a recent analysis has delved deeper into these collisions, uncovering nonlinear effects in the behavior of gravitational waves.

“Nonlinear effects are what happens when waves on the beach crest and crash” says Keefe Mitman, a Caltech graduate student who works with Saul Teukolsky (PhD ’74), the Robinson Professor of Theoretical Astrophysics at Caltech with a joint appointment at Cornell University. “The waves interact and influence each other rather than ride along by themselves. With something as violent as a black hole merger, we expected these effects but had not seen them in our models until now. New methods for extracting the waveforms from our simulations have made it possible to see the nonlinearities.”

                     

In the future, the new model can be used to learn more about the actual black hole collisions that have been routinely observed by LIGO (Laser Interferometer Gravitational-wave Observatory) ever since it made history in 2015 with the first direct detection of gravitational waves from space. LIGO will turn back on later this year after getting a set of upgrades that will make the detectors even more sensitive to gravitational waves than before.

Mitman and his colleagues are part of a team called the Simulating eXtreme Spacetimes collaboration, or SXS. Founded by Teukolsky in collaboration with Nobel Laureate Kip Thorne (BS ’62), Richard P. Feynman Professor of Theoretical Physics, Emeritus, at Caltech, the SXS project uses supercomputers to simulate black hole mergers. The supercomputers model how the black holes evolve as they spiral together and merge using the equations of Albert Einstein’s general theory of relativity. In fact, Teukolsky was the first to understand how to use these relativity equations to model the “ringdown” phase of the black hole collision, which occurs right after the two massive bodies have merged.

“Supercomputers are needed to carry out an accurate calculation of the entire signal: the inspiral of the two orbiting black holes, their merger, and the settling down to a single quiescent remnant black hole,” Teukolsky says. “The linear treatment of the settling down phase was the subject of my PhD thesis under Kip quite a while ago. The new nonlinear treatment of this phase will allow more accurate modeling of the waves and eventually new tests of whether general relativity is, in fact, the correct theory of gravity for black holes.”

The SXS simulations have proved instrumental in identifying and characterizing the nearly 100 black hole smashups detected by LIGO so far. This new study represents the first time that the team has identified nonlinear effects in simulations of the ringdown phase.

The SXS simulations have proved instrumental in identifying and characterizing the nearly 100 black hole smashups detected by LIGO so far. This new study represents the first time that the team has identified nonlinear effects in simulations of the ringdown phase.

In gravitational terms, this means that the simulations produce new types of waves. “If you dig deeper under the large waves, you will find an additional new wave with a unique frequency,” Mitman says.

In the big picture, these new simulations will help researchers to better characterize future black hole collisions observed by LIGO and to better test Einstein’s general theory of relativity.

Says co-author Macarena Lagos of Columbia University, “This is a big step in preparing us for the next phase of gravitational-wave detection, which will deepen our understanding of gravity in these incredible phenomena taking place in the far reaches of the cosmos.”

6th Edition of International Conference on Gravitational Waves

visit:gravity.sfconferences.com

Nomination link: https://x-i.me/granom

#RingingBlackHoles #NewPhysicsModel #BlackHoleRipples #CosmicVibrations #GravityWaves #AstroResearch #QuantumGravity #GravitationalWaves #BlackHoleDynamics #AstroModeling #TheoreticalPhysics #NewScientificDiscovery

Sunday, August 13, 2023

Gravitational Waves: New Portal to Explore the Universe



Gravitational waves, invisible ripples in the fabric of spacetime, have become a groundbreaking tool in astrophysics, opening new avenues for understanding the cosmos. The existence of these waves was first predicted by Albert Einstein's General Theory of Relativity in 1915, yet it took a century of technological advancements before scientists could confirm their existence in 2016.

This article delves into the intricacies of gravitational waves and their profound implications for cosmic exploration.

The Science Behind Gravitational Waves

According to Einstein's General Theory of Relativity, spacetime is a four-dimensional fabric that embeds the universe. When massive objects accelerate or decelerate, they create distortions in this fabric - similar to how a spinning bowling ball would distort a rubber sheet. These distortions are gravitational waves. They propagate at the speed of light, compressing and stretching spacetime as they travel.

Detecting the Undetectable

Gravitational waves are extraordinarily weak, making their detection a challenge of astronomical proportions. The first direct detection was achieved by the Laser Interferometer Gravitational-Wave Observatory (LIGO) in 2016. The detected waves originated from the collision of two black holes about 1.3 billion light years away.

LIGO employs two massive interferometers situated thousands of kilometers apart in the United States. Each interferometer uses laser beams bouncing between mirrors at the ends of two four-kilometer-long arms arranged in an "L" shape. As a gravitational wave passes through, it minutely distorts the space between the mirrors, causing the laser beam paths to fluctuate. These fluctuations, albeit minuscule, can be detected and analyzed to confirm the presence of a gravitational wave.

Gravitational Wave Astronomy

The detection of gravitational waves marked the dawn of a new era in astronomy. Traditional astronomy relies on electromagnetic waves (like visible light, X-rays, and radio waves) to observe cosmic objects. Gravitational waves offer a unique and complementary perspective.

Black Holes and Neutron Stars: The study of gravitational waves can provide insights into some of the most enigmatic celestial objects, such as black holes and neutron stars, that are often challenging to study through traditional methods. By observing the gravitational waves produced by their mergers, we can learn about their properties, such as mass, spin, and size.

Cosmology and The Early Universe: Gravitational waves could also revolutionize our understanding of the early universe. The Cosmic Microwave Background (CMB) radiation, electromagnetic radiation that has provided much of our current understanding of the early universe, was emitted 380,000 years after the Big Bang. Gravitational waves, on the other hand, could offer insights from the very first moments after the Big Bang, providing a window into an era that is currently unobservable.

The Future of Gravitational Wave Astronomy

The future of gravitational wave astronomy is bright with plans for new and more sensitive detectors. The European Space Agency is planning a space-based observatory, the Laser Interferometer Space Antenna (LISA), which is expected to be operational in the 2030s. This ambitious project will detect low-frequency gravitational waves from supermassive black hole mergers and other cosmic events that are undetectable by earth-based observatories.

Moreover, collaborations like the Nanohertz Observatory for Gravitational Waves (NANOGrav) use pulsars - highly magnetized, rotating neutron stars that emit beams of electromagnetic radiation - to detect gravitational waves. They provide a unique way to probe the universe at frequencies much lower than LIGO and future space-based observatories can reach.

A New Era of Exploration

Gravitational waves are a transformative addition to our astronomical toolkit, offering a novel way to observe and understand the universe. They open up exciting possibilities for studying the most mysterious and powerful events in the cosmos and shine a light on the parts of the universe that have remained shrouded in darkness. As we continue to refine our detection techniques and broaden our explorations, we step further into a new era of cosmic discovery and understanding.

6th Edition of International Conference on Gravitational Waves

visit:gravity.sfconferences.com

Nomination link: https://x-i.me/granom

#UniverseExploration#CosmicDiscoveries#NewFrontiers#AstroExploration#GravitationalWaveObservations#CosmicJourney#SpaceExploration#WaveofDiscovery#UnveilingCosmos#AstronomyAdvances#GravityWaves

JWST reveals surprising scarcity of supermassive black holes

A team of astronomers used the James Webb Space Telescope (JWST) to discover that the early universe was between 4 and 6 billion years old...