Supermassive black hole

Listen to this eerie echo coming from Milky Way’s supermassive black hole

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 Scientists have detected a mysterious “echo” originating from the supermassive black hole at the center of the Milky Way. A team in France estimates that this eerie sound was made approximately 200 years ago, when the black hole stirred from a state of dormancy.

According to researchers with the National Center for Scientific Research (CNRS), this acoustic phenomenon signifies an intense period of activity in which our galaxy’s black hole consumed vast amounts of gas and dust. Particles were drawn towards the black hole’s event horizon, a point of no return from which even light cannot escape. As the massive black hole ingested this material, brilliant X-ray light bursts occurred, producing echoes that can be translated into sound waves here on Earth.

Dr. Frederic Marin, the corresponding author from Strasbourg University, explains that this discovery provides evidence of a past awakening of this gigantic entity – an object four million times more massive than the Sun. It sheds new light on the enigmatic and dynamic environment of supermassive black holes, which are incredibly dense regions at the centers of galaxies. These black holes exert a powerful gravitational pull, drawing in any surrounding gas and dust.

Sagittarius A* (Sgr A*), the supermassive black hole at the center of our own galaxy, is only 26,000 light-years away. Dr. Marin explains that their research reveals the missing evidence that X-rays from giant molecular clouds originate from the reflection of an intense but short-lived flare produced at or near Sgr A*. This discovery helps us understand the historical activity of our galaxy’s center.

Scroll down to hear what our galaxy’s black hole sounds like

image of a much wider view of the center of the Milky Way obtained by Chandra.
New data from NASA’s Imaging X-ray Polarimetry Explorer (IXPE) has provided evidence that the supermassive black hole at the center of the Milky Way Galaxy- known as Sagittarius A* (Sgr A*) – went through a very intense period of activity some 200 years ago after gobbling up gas and dust that came within its range. The IXPE data, which shows the echo of this past activity, can be seen in orange in the bottom image. It was combined with data from Chandra, another NASA X-ray observatory, seen in blue, which shows only direct light from the Galactic center. The top image is a much wider view of the center of the Milky Way obtained by Chandra. CREDIT © NASA/CXC/SAO/IXPE

One of the few black holes where matter flow can be observed, Sgr A* is challenging to study due to its absorption of all surrounding light. Scientists have spent decades looking for signs of black hole activity. To illustrate the black hole’s emergence from its dormant state, Dr. Marin likens it to a single glow-worm in a forest suddenly becoming as bright as the Sun.

The research also offers an explanation for the unusually bright galactic molecular clouds near Sgr A*, which are reflecting the X-rays emitted by the black hole two centuries ago. The international team integrated data from the IXPE (Imaging X-ray Polarimetry Explorer) space telescope and the Chandra X-ray Observatory to conduct their study.

Their findings suggest that the primary source of the emission is Sgr A*, as the polarization angle is consistent with this. The degree of polarization indicates that about 200 years ago, the X-ray luminosity of Sgr A* momentarily matched that of a Seyfert galaxy – a type of galaxy with an extremely active center producing strong radiation bursts.

Just as a compass points to its source, the polarized X-ray light emanates directly from Sgr A*. The scientists are now focusing on determining the physical mechanisms that enable a black hole to transition from a quiescent to an active state.

Black holes are formed when a dying star collapses under its own gravitational force, leading to a supernova, an extraordinarily powerful stellar explosion. These astronomical entities have such immense gravitational pull that even light cannot escape, rendering them invisible. Supermassive black holes, which can be billions of times larger than the Sun, are believed to be present at the center of all large galaxies.

Interstellar was right. Falling into a black hole is not the end, says Stephen Hawking.

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“If you feel you are in a black hole, don’t give up, there’s a way out,” Stephen Hawking told the Royal Institute of Technology in Stockholm

An artist's impression of a supermassive black hole at the centre of a distant quasar

An artist’s impression of a supermassive black hole at the centre of a distant quasar

Interstellar was right. Falling into a black hole is not the end, professor Stephen Hawking has claimed.

Although physicists had assumed that all matter must be destroyed by the huge gravitational forces of a black hole, Hawking told delegates in Sweden that it could escape and even pop into another dimension.

The theory solves the ‘information paradox’ which has puzzled scientists for decades. While quantum mechanics says that nothing can ever be destroyed, general relativity says it must be.

However under Hawking’s new theory, anything that is sucked into a black hole is effectively trapped at the event horizon – the sphere surrounding the hole from which it was thought that nothing can escape.

And he claims that anything which fell in could re-emerge back into our universe, or a parallel one, through Hawking radiation – protons which manage to escape from the black hole because of quantum fluctuations.

“If you feel you are in a black hole, don’t give up, there’s a way out,” Hawking told an audience held at the KTH Royal Institute of Technology in Stockholm

In the film Interstellar, Cooper, played by Matthew McConaughey, plunges into the black hole Gargantura. As Cooper’s ship breaks apart in the force, he evacuates and ends up in a Tesseract – a four dimensional cube. He eventually makes it out of the black hole.

The blac hole Gargantua from the film Interstellar

The black hole Gargantua from the film Interstellar

Black holes are stars that have collapsed under their own gravity, producing such extreme forces that even light can’t escape.

But Hawking claims that information never makes it inside the black hole in the first place and instead is ‘translated’ into a kind of hologram which sits in the event horizon.

“I propose that the information is stored not in the interior of the black hole as one might expect, but on its boundary, the event horizon,” said Prof Hawking

“The idea is the super translations are a hologram of the ingoing particles,” he said. “Thus they contain all the information that would otherwise be lost.”

Hawking also believes that radiation leaving the black hole can pick up some of the information stored at the event horizon and carry it back out. However it is unlikely to be in the same state in which it entered.

“The information about ingoing particles is returned, but in a chaotic and useless form,” he said. “This information paradox. For all practical purposes, the information is lost.

“The message of this lecture is that black holes ain’t as black as they are painted. They are not the eternal prisons they were once thought. Things can get out of a black hole both on the outside and possibly come out in another universe.”

Hawking and colleagues are expected to publish a paper on the work next month.

“He is saying that the information is there twice already from the very beginning, so it’s never destroyed in the black hole to begin with,” Sabine Hossenfelder of the Nordic Institute for Theoretical Physics in Stockholm told New Scientist. “At least that’s what I understood.”

MILKY WAY CORE DRIVES WIND AT 2 MILLION MILES PER HOUR

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At a time when our earliest human ancestors had recently mastered walking upright, the heart of our Milky Way galaxy underwent a titanic eruption, driving gases and other material outward at 2 million miles per hour.

Now, at least 2 million years later, astronomers are witnessing the aftermath of the explosion: billowing clouds of gas towering about 30,000 light-years above and below the plane of our galaxy.

The enormous structure was discovered five years ago as a gamma-ray glow on the sky in the direction of the galactic center. The balloon-like features have since been observed in X-rays and radio waves. But astronomers needed NASA’s Hubble Space Telescope to measure for the first time the velocity and composition of the mystery lobes. They now seek to calculate the mass of the material being blown out of our galaxy, which could lead them to determine the outburst’s cause from several competing scenarios.

Astronomers have proposed two possible origins for the bipolar lobes: a firestorm of star birth at the Milky Way’s center or the eruption of its supermassive black hole. Although astronomers have seen gaseous winds, composed of streams of charged particles, emanating from the cores of other galaxies, they are getting a unique, close-up view of our galaxy’s own fireworks.

“When you look at the centers of other galaxies, the outflows appear much smaller because the galaxies are farther away,” said Andrew Fox of the Space Telescope Science Institute in Baltimore, Maryland, lead researcher of the study. “But the outflowing clouds we’re seeing are only 25,000 light-years away in our galaxy. We have a front-row seat. We can study the details of these structures. We can look at how big the bubbles are and can measure how much of the sky they are covering.”

Fox’s results will be published in The Astrophysical Journal Letters and will be presented at the American Astronomical Society meeting in Seattle, Washington.

The giant lobes, dubbed Fermi Bubbles, initially were spotted using NASA’s Fermi Gamma-ray Space Telescope. The detection of high-energy gamma rays suggested that a violent event in the galaxy’s core aggressively launched energized gas into space. To provide more information about the outflows, Fox used Hubble’s Cosmic Origins Spectrograph (COS) to probe the ultraviolet light from a distant quasar that lies behind the base of the northern bubble. Imprinted on that light as it travels through the lobe is information about the velocity, composition, and temperature of the expanding gas inside the bubble, which only COS can provide.

Fox’s team was able to measure that the gas on the near side of the bubble is moving toward Earth and the gas on the far side is travelling away. COS spectra show that the gas is rushing from the galactic center at roughly 2 million miles an hour (3 million kilometers an hour).

“This is exactly the signature we knew we would get if this was a bipolar outflow,” explained Rongmon Bordoloi of the Space Telescope Science Institute, a co-author on the science paper. “This is the closest sightline we have to the galaxy’s center where we can see the bubble being blown outward and energized.”

The COS observations also measure, for the first time, the composition of the material being swept up in the gaseous cloud. COS detected silicon, carbon, and aluminum, indicating that the gas is enriched in the heavy elements produced inside stars and represents the fossil remnants of star formation.

COS measured the temperature of the gas at approximately 17,500 degrees Fahrenheit, which is much cooler than most of the super-hot gas in the outflow, thought to be at about 18 million degrees Fahrenheit. “We are seeing cooler gas, perhaps interstellar gas in our galaxy’s disk, being swept up into that hot outflow,” Fox explained.

This is the first result in a survey of 20 faraway quasars whose light passes through gas inside or just outside the Fermi Bubbles — like a needle piercing a balloon. An analysis of the full sample will yield the amount of mass being ejected. The astronomers can then compare the outflow mass with the velocities at various locations in the bubbles to determine the amount of energy needed to drive the outburst and possibly the origin of the explosive event.

One possible cause for the outflows is a star-making frenzy near the galactic center that produces supernovas, which blow out gas. Another scenario is a star or a group of stars falling onto the Milky Way’s supermassive black hole. When that happens, gas superheated by the black hole blasts deep into space. Because the bubbles are short-lived compared to the age of our galaxy, it suggests this may be a repeating phenomenon in the Milky Way’s history. Whatever the trigger is, it likely occurs episodically, perhaps only when the black hole gobbles up a concentration of material.

“It looks like the outflows are a hiccup,” Fox said. “There may have been repeated ejections of material that have blown up, and we’re catching the latest one. By studying the light from the other quasars in our program, we may be able to detect the fossils of previous outflows.”

Galactic winds are common in star-forming galaxies, such as M82, which is furiously making stars in its core. “It looks like there’s a link between the amount of star formation and whether or not these outflows happen,” Fox said. “Although the Milky Way overall currently produces a moderate one to two stars a year, there is a high concentration of star formation close to the core of the galaxy.”

At a time when our earliest human ancestors had recently mastered walking upright, the heart of our Milky Way galaxy underwent a titanic eruption, driving gases and other material outward at 2 million miles per hour.

Now, at least 2 million years later, astronomers are witnessing the aftermath of the explosion: billowing clouds of gas towering about 30,000 light-years above and below the plane of our galaxy.

The enormous structure was discovered five years ago as a gamma-ray glow on the sky in the direction of the galactic center. The balloon-like features have since been observed in X-rays and radio waves. But astronomers needed NASA’s Hubble Space Telescope to measure for the first time the velocity and composition of the mystery lobes. They now seek to calculate the mass of the material being blown out of our galaxy, which could lead them to determine the outburst’s cause from several competing scenarios.

Astronomers have proposed two possible origins for the bipolar lobes: a firestorm of star birth at the Milky Way’s center or the eruption of its supermassive black hole. Although astronomers have seen gaseous winds, composed of streams of charged particles, emanating from the cores of other galaxies, they are getting a unique, close-up view of our galaxy’s own fireworks.

“When you look at the centers of other galaxies, the outflows appear much smaller because the galaxies are farther away,” said Andrew Fox of the Space Telescope Science Institute in Baltimore, Maryland, lead researcher of the study. “But the outflowing clouds we’re seeing are only 25,000 light-years away in our galaxy. We have a front-row seat. We can study the details of these structures. We can look at how big the bubbles are and can measure how much of the sky they are covering.”

Fox’s results will be published in The Astrophysical Journal Letters and will be presented at the American Astronomical Society meeting in Seattle, Washington.

The giant lobes, dubbed Fermi Bubbles, initially were spotted using NASA’s Fermi Gamma-ray Space Telescope. The detection of high-energy gamma rays suggested that a violent event in the galaxy’s core aggressively launched energized gas into space. To provide more information about the outflows, Fox used Hubble’s Cosmic Origins Spectrograph (COS) to probe the ultraviolet light from a distant quasar that lies behind the base of the northern bubble. Imprinted on that light as it travels through the lobe is information about the velocity, composition, and temperature of the expanding gas inside the bubble, which only COS can provide.

Fox’s team was able to measure that the gas on the near side of the bubble is moving toward Earth and the gas on the far side is travelling away. COS spectra show that the gas is rushing from the galactic center at roughly 2 million miles an hour (3 million kilometers an hour).

“This is exactly the signature we knew we would get if this was a bipolar outflow,” explained Rongmon Bordoloi of the Space Telescope Science Institute, a co-author on the science paper. “This is the closest sightline we have to the galaxy’s center where we can see the bubble being blown outward and energized.”

The COS observations also measure, for the first time, the composition of the material being swept up in the gaseous cloud. COS detected silicon, carbon, and aluminum, indicating that the gas is enriched in the heavy elements produced inside stars and represents the fossil remnants of star formation.

COS measured the temperature of the gas at approximately 17,500 degrees Fahrenheit, which is much cooler than most of the super-hot gas in the outflow, thought to be at about 18 million degrees Fahrenheit. “We are seeing cooler gas, perhaps interstellar gas in our galaxy’s disk, being swept up into that hot outflow,” Fox explained.

This is the first result in a survey of 20 faraway quasars whose light passes through gas inside or just outside the Fermi Bubbles — like a needle piercing a balloon. An analysis of the full sample will yield the amount of mass being ejected. The astronomers can then compare the outflow mass with the velocities at various locations in the bubbles to determine the amount of energy needed to drive the outburst and possibly the origin of the explosive event.

One possible cause for the outflows is a star-making frenzy near the galactic center that produces supernovas, which blow out gas. Another scenario is a star or a group of stars falling onto the Milky Way’s supermassive black hole. When that happens, gas superheated by the black hole blasts deep into space. Because the bubbles are short-lived compared to the age of our galaxy, it suggests this may be a repeating phenomenon in the Milky Way’s history. Whatever the trigger is, it likely occurs episodically, perhaps only when the black hole gobbles up a concentration of material.

Weird Ancient Black Hole Has Extra Suck.

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Astronomers observing distant quasars have discovered something puzzling about a very rare class of these enigmatic objects — some appear to be sucking material inwards at relativistic speeds, whereas the vast majority of quasars do exactly the opposite.

Quasars dominated the early Cosmos, generating vast quantities of radiation that can be observed today right at the edge of our observable Universe. Consisting of an active supermassive black hole and a searing disk of plasma in the cores of young galaxies, the vast majority of quasars eject material from their energetic environments at high speed.

This may sound counter-intuitive; black holes consume matter after all, they don’t eject it. But in a quasar’s hot accretion disk — composed of a superheated soup of blended stars, gas and dust that strayed too close to the supermassive black hole’s gravitational wrath — the intense radiation blasts the surrounding material away from the black hole. Although some material inevitably gets fed from the accretion disk into the black hole, vast quantities are ejected at up to a significant fraction of the speed of light.

However, by taking a Doppler speed check of the motion of gas around known quasars, a team of researchers analyzing data from the Sloan Digital Sky Survey (SDSS-III) have discovered a very rare subset of quasars that don’t fit the norm.

“The gas in this new type of quasar is moving in two directions: some is moving toward Earth but most of it is moving at high velocities away from us, possibly toward the quasar’s black hole,” said Niel Brandt, study co-author and Distinguished Professor of Astronomy and Astrophysics at Penn State University. “Just as you can use the Doppler shift for sound to tell if an airplane is moving away from you or toward you, we used the Doppler shift for light to tell whether the gas in these quasars is moving away from Earth or toward these distant black holes, which have a mass from millions to billions of times that of the sun.”

“Matter falling into black holes may not sound surprising,” added team leader Patrick Hall of York University in Toronto, “but what we found is, in fact, quite mysterious and was not predicted by current theories.

“The gas in the disc must eventually fall into the black hole to power the quasar, but what is often seen instead is gas blown away from the black hole by the heat and light of the quasar, heading toward us at velocities up to 20 percent of the speed of light,” he said. “If the gas is falling into the black hole, then we don’t understand why it’s so rare to see infalling gas. There’s nothing else unusual about these quasars. If gas can be seen falling into them, why not in other quasars?”

So how rare are these objects? 1-in-10,000 rare. Of the tens of thousands of quasars known, only 17 such objects have been discovered so far.

For now, the researchers are baffled as to why these few distant supermassive black holes, which have masses millions to billions of times of the mass of our sun, appear to have more suck than the rest of their quasar cousins. Their work has been published in the journal Monthly Notices of the Royal Astronomical Society (doi: 10.1093/mnras/stt1012).

One explanation, says Hall, is that in actuality, the majority of gas is being ejected from the quasar, but it is moving in a peculiar fashion. Perhaps gas is rapidly orbiting around the black hole’s superheated accretion disk, sometimes traveling toward, sometimes away from us, but the Doppler measurements appear to show a bias toward the gas that is moving away. This may give the impression that the gas is being sucked into the black hole, when, in fact, it’s being ejected.

Regardless, these are strange objects that don’t appear to fit with current quasar theory, something astrophysicists will have to work on for a while yet.

Source: Physorg.com