Tag: black hole

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Most Intense Gamma-Ray Burst Ever Shocks Scientists

On October 9, 2022, an intense pulse of gamma-ray radiation swept through our solar system, overwhelming gamma-ray detectors on numerous orbiting satellites, and sending astronomers on a chase to study the event using the most powerful telescopes in the world.

The new source, dubbed GRB 221009A for its discovery date, turned out to be the brightest gamma-ray burst (GRB) ever recorded.

In a new study that appeared in March, in The Astrophysical Journal Letters, has shed new light on the decades-long quest to understand the origin of these extreme cosmic explosions.

The gamma-ray emission from GRB 221009A lasted over 300 seconds. Astronomers think that such “long-duration” GRBs are the birth cry of a black hole, formed as the core of a massive and rapidly spinning star collapses under its own weight. The newborn black hole launches powerful jets of plasma at near the speed of light, which pierce through the collapsing star and shine in gamma-rays.

With GRB 221009A being the brightest burst ever recorded, a real mystery lay in what would come after the initial burst of gamma-rays. “As the jets slam into gas surrounding the dying star, they produce a bright ‘afterglow’ of light across the entire spectrum,” says Tanmoy Laskar, assistant professor of physics and astronomy at the University of Utah, and lead author of the study. “The afterglow fades quite rapidly, which means we have to be quick and nimble in capturing the light before it disappears, taking its secrets with it.”

As part of a campaign to use the world’s best radio and millimeter telescopes to study the afterglow of GRB 221009A, astronomers Edo Berger and Yvette Cendes of the Center for Astrophysics (CfA) rapidly gathered data with the SMA.
After analyzing and combining the data from the SMA and other telescopes all over the world, the astronomers were flummoxed: the millimeter and radio wave measurements were much brighter than expected based on the visible and X-ray light.

“This is one of the most detailed datasets we have ever collected, and it is clear that the millimeter and radio data just don’t behave as expected,” says CfA research associate Yvette Cendes. “A few GRBs in the past have shown a brief excess of millimeter and radio emission that is thought to be the signature of a shockwave in the jet itself, but in GRB 221009A the excess emission behaves quite differently than in these past cases.”
She adds, “It is likely that we have discovered a completely new mechanism to produce excess millimeter and radio waves.”

In 2005 an explosion 50,000 light years away, on the other side of the galaxy, was characterized at the time as the largest of it kind ever seen on Earth. If it had been just 10 light years away it could have caused mass extinctions and severely damaged our atmosphere. As it was, the blast was more than 100 times more powerful than any previous explosion ever recorded. The exploding neutron star is called a magnestar for its intense magnetic fields. No bigger than a large Earth city, the explosion was said to produce more energy in a tenth of a second than our own sun turns out in 100,000 years.

Fortunately, scientists say, there are no such magnestars within 4,000 light years of Earth. Some scientists, like astrophysicist Paul LaViolette (whose work has been outlined in Atlantis Rising Magazine) have argued that catastrophic events in Earth’s history may have been the result of of just such stellar explosions (https://www.cambridge.org/core/journals/radiocarbon/article/evidence-for-a-solar-flare-cause-of-the-pleistocene-mass-extinction/799A4720B75245B4627AFE412661B3B6).

AR #114

Is Anybody Home

by Martin Ruggles

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Flash in Supermassive Black Hole Aimed at Us

Astronomers have determined the source of an incredibly bright X-ray, optical and radio signal appearing from halfway across the Universe. The signal, named AT 2022cmc, was discovered earlier this year by the Zwicky Transient Facility in California. Findings published in Nature Astronomy, suggest that it is likely from a jet of matter, streaking out from a supermassive black hole at close to the speed of light.

The team, including researchers from MIT and the University of Birmingham, believe the jet is the product of a black hole that suddenly began devouring a nearby star, releasing a huge amount of energy in the process. Their findings could shed new light on how supermassive black holes feed and grow.


Astronomers have observed other such “tidal disruption events,” or TDEs, in which a passing star is torn apart by a black hole’s tidal forces. However AT 2022cmc is brighter than any TDE discovered to date, and is also the farthest TDE ever detected, at some 8.5 billion light years away.


The team measured the distance to the AT 2022cmc using the European Southern Observatory’s Very Large Telescope, in Chile.


Dr Matt Nicholl, associate professor at the University of Birmingham, said: “Our spectrum told us that the source was hot: around 30,000 degrees, which is typical for a TDE. But we also saw some absorption of light by the galaxy where this event occurred. These absorption lines were highly shifted towards redder wavelengths, telling us that this galaxy was much further away than we expected!”


Because AT 2022cmc was so bright and lasted so long, we knew that something truly gargantuan must be powering it – a supermassive black hole, claimed Dr Benjamin Gompertz, School of Physics and Astronomy, University of Birmingham.


How could such a distant event appear so bright in our sky? The team says the black hole’s jet may be pointing directly toward Earth, making the signal appear brighter than if the jet were pointing in any other direction. The effect is “Doppler boosting,” and is similar to the amped-up sound of a passing siren.


AT 2022cmc is the fourth Doppler-boosted TDE ever detected and the first such event that has been observed since 2011. It is also the first boosted TDE discovered using an optical sky survey. As more powerful telescopes start up in the coming years, they will reveal more TDEs, which can shed light on how supermassive black holes grow and shape the galaxies around them.

https://www.birmingham.ac.uk/news/2022/mysteriously-bright-flash-is-a-black-hole-jet-pointing-straight-toward-earth-astronomers-say


AR #71

The Super Collision Threat

by Nancy L. Williams

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Quantum Wormhole in Action

Scientists have, for the first time, developed a quantum experiment that allows them to study the dynamics, or behavior, of a special kind of theoretical wormhole. The experiment has not created an actual wormhole (a rupture in space and time), rather it allows researchers to probe connections between theoretical wormholes and quantum physics, a prediction of so-called quantum gravity. Quantum gravity refers to a set of theories that seek to connect gravity with quantum physics, two fundamental and well-studied descriptions of nature that appear inherently incompatible with each other.

“We found a quantum system that exhibits key properties of a gravitational wormhole yet is sufficiently small to implement on today’s quantum hardware,” says Maria Spiropulu, the principal investigator of the U.S. Department of Energy Office of Science research program Quantum Communication Channels for Fundamental Physics (QCCFP) and the Shang-Yi Ch’en Professor of Physics at Caltech. “This work constitutes a step toward a larger program of testing quantum gravity physics using a quantum computer. It does not substitute for direct probes of quantum gravity in the same way as other planned experiments that might probe quantum gravity effects in the future using quantum sensing, but it does offer a powerful testbed to exercise ideas of quantum gravity.”


The research is published in the journal Nature (https://www.nature.com/articles/s41586-022-05424-3).
Wormholes are bridges between two remote regions in spacetime. They have not been observed experimentally, but scientists have theorized about their existence and properties for close to 100 years. In 1935, Albert Einstein and Nathan Rosen described wormholes as tunnels through the fabric of spacetime in accordance with Einstein’s general theory of relativity, which describes gravity as a curvature of spacetime. Researchers call wormholes Einstein–Rosen bridges after the two physicists who invoked them, while the term “wormhole” itself was coined by physicist John Wheeler in the 1950s.


In the new study, the team of physicists performed this type of experiment for the first time. They used a “baby” SYK-like model prepared to preserve gravitational properties, and they observed the wormhole dynamics on a quantum device at Google, namely the Sycamore quantum processor. To accomplish this, the team had to first reduce the SYK model to a simplified form, a feat they achieved using machine learning tools on conventional computers.


“We employed learning techniques to find and prepare a simple SYK-like quantum system that could be encoded in the current quantum architectures and that would preserve the gravitational properties,” says Spiropulu. “In other words, we simplified the microscopic description of the SYK quantum system and studied the resulting effective model that we found on the quantum processor. It is curious and surprising how the optimization on one characteristic of the model preserved the other metrics! We have plans for more tests to get better insights on the model itself.”


https://www.caltech.edu/about/news/physicists-observe-wormhole-dynamics-using-a-quantum-computer

AR #48

The Wormhole Dance”

by William Henry

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The Missing Dark Matter Halos

Could newly discovered signs of disturbance in the dwarf galaxies of one of Earth’s nearest galaxy clusters mean we need an alternative gravity theory?

According to the standard model of cosmology, the vast majority of galaxies are surrounded by a halo of dark matter particles. This halo is invisible, but its mass exerts a strong gravitational pull on galaxies in the vicinity. A new study led by the University of Bonn and the University of Saint Andrews (Scotland) challenges this view of the Universe. The results suggest that the dwarf galaxies of Earth’s second closest galaxy cluster – known as the Fornax Cluster – are free of such dark matter halos. The study appeared in the journal Monthly Notices of the Royal Astronomical Society.
Dwarf galaxies are small, faint galaxies that can usually be found in galaxy clusters or near larger galaxies. Because of this, they might be affected by the gravitational effects of their larger companions. “We introduce an innovative way of testing the standard model based on how much dwarf galaxies are disturbed by gravitational ,tides’ from nearby larger galaxies”, said Elena Asencio, a PhD student at the University of Bonn and the lead author of the story. Tides arise when gravity from one body pulls differently on different parts of another body. These are similar to tides on Earth, which arise because the moon pulls more strongly on the side of Earth which faces the moon.


The Fornax Cluster has a rich population of dwarf galaxies. Recent observations show that some of these dwarfs appear distorted, as if they have been perturbed by the cluster environment. “Such perturbations in the Fornax dwarfs are not expected according to the Standard Model,” said Pavel Kroupa, Professor at the University of Bonn and Charles University in Prague. “This is because, according to the standard model, the dark matter halos of these dwarfs should partly shield them from tides raised by the cluster.”


The authors analyzed the expected level of disturbance of the dwarfs, which depends on their internal properties and their distance to the gravitationally powerful cluster center. Galaxies with large sizes but low stellar masses and galaxies close to the cluster centre are more easily disturbed or destroyed. They compared the results with their observed level of disturbance evident from photographs taken by the VLT Survey Telescope of the European Southern Observatory.


“The comparison showed that, if one wants to explain the observations in the standard model” – said Elena Asencio – “the Fornax dwarfs should already be destroyed by gravity from the cluster center even when the tides it raises on a dwarf are sixty-four times weaker than the dwarf’s own self-gravity.” Not only is this counter-intuitive, she said, it also contradicts previous studies, which found that the external force needed to disturb a dwarf galaxy is about the same as the dwarf’s selfgravity.


The authors conclude that, in the standard model, it is not possible to explain the observed morphologies of the Fornax dwarfs in a self-consistent way. They repeated the analysis using Milgromian dynamics (MOND). Instead of assuming dark matter halos surrounding galaxies, the MOND theory proposes a correction to Newtonian dynamics by which gravity experiences a boost in the regime of low accelerations.

(https://doi.org/10.1093/mnras/stac1765 / https://arxiv.org/abs/2208.02265)

AR #70

Why Can’t Science See the Light?

by Michael Tymn

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Fusion Energy: New Approach Opens the Door?

Scientists at the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL) have uncovered critical new details about fusion facilities that use lasers to compress the fuel that produces fusion energy. The new data could help lead to the improved design of future laser facilities that harness the fusion process that drives the sun and stars.

Fusion combines light elements in the form of plasma — the hot, charged state of matter composed of free electrons and atomic nuclei — that generates massive amounts of energy. Scientists are seeking to replicate fusion on Earth for a virtually inexhaustible supply of power to generate electricity.

Major experimental facilities include tokamaks, the magnetic fusion devices that PPPL studies; stellarators, the magnetic fusion machines that PPPL also studies and have recently become more widespread around the world; and laser devices used in what are called inertial confinement experiments.

The researchers explored the impact of adding tungsten metal, which is used to make cutting tools and lamp filaments, to the outer layer of plasma fuel pellets in inertial confinement research. They found that tungsten boosts the performance of the implosions that cause fusion reactions in the pellets. The tungsten helps block heat that would prematurely raise the temperature at the center of the pellet.

The research team confirmed the findings by making measurements using krypton gas, sometimes used in fluorescent lamps. Once added to the fuel, the gas emitted high-energy light known as X-rays that was captured by an instrument called a high-resolution X-ray spectrometer. The X-rays conveyed clues about what was happening inside the capsule.  
“I was excited to see that we could make these unprecedented measurements using the technique we have been developing these past few years. This information helps us evaluate the pellet’s implosion and helps researchers calibrate their computer simulations,” said PPPL physicist Lan Gao, lead author of the paper reporting the results in Physical Review Letters. “Better simulations and theoretical understanding in general can help researchers design better future experiments.”

The scientists performed the experiments at the National Ignition Facility (NIF), a DOE user facility at Lawrence Livermore National Laboratory. The facility shines 192 lasers onto a gold cylinder, or hohlraum, that is one centimeter tall and encases the fuel. The laser beams heat the hohlraum, which radiates X-rays evenly onto the fuel pellet within.

https://www.pppl.gov/news/2022/uncovering-novel-way-bring-earth-energy-powers-sun-and-stars

 

AR #82

New Energy Scientists Get New Respect

by Jeanne Manning

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Colossal Black Holes Dance at Heart of Galaxy

Astronomers find evidence for the tightest-knit supermassive black hole duo observed to date

By Whitney Clavin

Locked in an epic cosmic waltz 9 billion light years away, two supermassive black holes appear to be orbiting around each other every two years. The two giant bodies each have masses that are hundreds of millions of times larger than that of our sun, and the objects are separated by a distance roughly 50 times that which separates our sun and Pluto. When the pair merge in roughly 10,000 years, the titanic collision is expected to shake space and time itself, sending gravitational waves across the universe.

A Caltech-led team of astronomers has discovered evidence for this scenario taking place within a fiercely energetic object known as a quasar. Quasars are active cores of galaxies in which a supermassive black hole is siphoning material from a disk encircling it. In some quasars, the supermassive black hole creates a jet that shoots out at near the speed of light. The quasar observed in the new study, PKS 2131-021, belongs to a subclass of quasars called blazars in which the jet is pointing toward the Earth. Astronomers already knew quasars could possess two orbiting supermassive black holes, but finding direct evidence for this has proved difficult.


Reporting in The Astrophysical Journal Letters, the researchers argue that PKS 2131-021 is a very rare candidate for a pair of supermassive black holes caught in the act of merging. The first candidate pair, within a quasar called OJ 287, orbit each other at greater distances, circling every nine years versus the two years it takes for the PKS 2131-021 pair to complete an orbit.


The telltale evidence came from radio observations of PKS 2131-021 that span 45 years. According to the study, a powerful jet emanating from one of the two black holes within PKS 2131-021 is shifting back and forth due to the pair’s orbital motion. This causes periodic changes in the quasar’s radio-light brightness. Five different observatories registered these oscillations, including Caltech’s Owens Valley Radio Observatory (OVRO), the University of Michigan Radio Astronomy Observatory (UMRAO), MIT’s Haystack Observatory, the National Radio Astronomy Observatory (NRAO), Metsähovi Radio Observatory in Finland, and NASA’s Wide-field Infrared Survey Explorer (WISE) space satellite.


The combination of the radio data yields a nearly perfect sinusoidal light curve unlike anything observed from quasars before.


“When we realized that the peaks and troughs of the light curve detected from recent times matched the peaks and troughs observed between 1975 and 1983, we knew something very special was going on,” says Sandra O’Neill, lead author of the new study and an undergraduate student at Caltech who is mentored by Tony Readhead, Robinson Professor of Astronomy, Emeritus.


Most, if not all, galaxies possess monstrous black holes at their cores, including our own Milky Way galaxy. When galaxies merge, their black holes “sink” to the middle of the newly formed galaxy and eventually join together to form an even more massive black hole. As the black holes spiral toward each other, they increasingly disturb the fabric of space and time, sending out gravitational waves, which were first predicted by Albert Einstein more than 100 years ago.

 

AR #114

Gravity’s Riddle

by Susan Martiinez, Ph.D.

 

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‘Dark’ Free-Floating Black Hole Detected

By Robert Sanders

Astronomers may have discovered the first free-floating black hole in the Milky Way galaxy, thanks to a technique called gravitational microlensing. With new observations, they hope to find many more such ghost stars.

If, as astronomers believe, the death of large stars leave behind black holes, there should be hundreds of millions of them scattered throughout the Milky Way galaxy. The problem is, isolated black holes are invisible.
Now, a team led by University of California, Berkeley, astronomers has for the first time discovered what may be a free-floating black hole by observing the brightening of a more distant star as its light was distorted by the object’s strong gravitational field — so-called gravitational microlensing.


The team, led by graduate student Casey Lam and Jessica Lu, a UC Berkeley associate professor of astronomy, estimates that the mass of the invisible compact object is between 1.6 and 4.4 times that of the sun. Because astronomers think that the leftover remnant of a dead star must be heavier than 2.2 solar masses in order to collapse to a black hole, the UC Berkeley researchers caution that the object could be a neutron star instead of a black hole. Neutron stars are also dense, highly compact objects, but their gravity is balanced by internal neutron pressure, which prevents further collapse to a black hole.


Whether a black hole or a neutron star, the object is the first dark stellar remnant — a stellar “ghost” — discovered wandering through the galaxy unpaired with another star.


“This is the first free-floating black hole or neutron star discovered with gravitational microlensing,” Lu said. “With microlensing, we’re able to probe these lonely, compact objects and weigh them. I think we have opened a new window onto these dark objects, which can’t be seen any other way.”


Determining how many of these compact objects populate the Milky Way galaxy will help astronomers understand the evolution of stars — in particular, how they die — and of our galaxy, and perhaps reveal whether any of the unseen black holes are primordial black holes, which some cosmologists think were produced in large quantities during the Big Bang.


The analysis by Lam, Lu and their international team has been accepted for publication in The Astrophysical Journal Letters. Notably, a competing team from the Space Telescope Science Institute (STScI) in Baltimore analyzed the same microlensing event and claims that the mass of the compact object is closer to 7.1 solar masses and indisputably a black hole. A paper describing the analysis by the STScI team, led by Kailash Sahu, has been accepted for publication in The Astrophysical Journal.

 

AR #64

Human Evolution and the Cygnus Connection By Greg Little