An artist's conception of a supermassive black hole's jets. Credit: NASA / Dana Berry / SkyWorks Digital
The supermassive black holes in the cores of most massive galaxies wreak havoc on their immediate surroundings. During their most active phases — when they ignite as luminous quasars — they launch extremely powerful and high-velocity outflows of gas.
These outflows can sweep up and heat material, playing a pivotal role in the formation and evolution of massive galaxies. Not only have astronomers observed them across the visible Universe, they also play a key ingredient in theoretical models.
But the physical nature of the outflows themselves has been a longstanding mystery. What physical mechanism causes gas to reach such high speeds, and in some cases be expelled from the galaxy?
A new study provides the first direct evidence that these outflows are accelerated by energetic jets produced by the supermassive black hole.
Using the Very Large Telescope in Chile, a team of astronomers led by Clive Tadhunter from Sheffield University, observed the nearby active galaxy IC 5063. At locations in the galaxy where its jets are impacting regions of dense gas, the gas is moving at extraordinary speeds of over 600,000 miles per hour.
“Much of the gas in the outflows is in the form of molecular hydrogen, which is fragile in the sense that it is destroyed at relatively low energies,” said Tadhunter in a press release. “I find it extraordinary that the molecular gas can survive being accelerated by jets of highly energetic particles moving at close to the speed of light.
As the jets travel through the galactic matter, they disrupt the surrounding gas and generate shock waves. These shock waves not only accelerate the gas, but also heat it. The team estimates the shock waves heat the gas to temperatures high enough to ionize the gas and dissociate the molecules. Molecular hydrogen is only formed in the significantly cooler post-shock gas.
“We suspected that the molecules must have been able to reform after the gas had been completely upset by the interaction with a fast plasma jet,” said Raffaella Morganti from the Kapteyn Institute Groningen University. “Our direct observations of the phenomenon have confirmed that this extreme situation can indeed occur. Now we need to work at describing the exact physics of the interaction.”
In interstellar space, molecular hydrogen forms on the surface of dust grains. But in this scenario, the dust is likely to have been destroyed in the intense shock waves. While it is possible for molecular hydrogen to form without the aid of dust grains (as seen in the early Universe) the exact mechanism in this case is still unknown.
The research helps answer a longstanding question — providing the first direct evidence that jets accelerate the molecular outflows seen in active galaxies — and asks new ones.
This simulation shows the possible behavior of a gas cloud that has been observed approaching the black hole at the center of the Milky Way. Graphic by ESO/MPE/Marc Schartmann.
Wondering about the latest news on the intriguing object called ‘G2’ that is making its closest approach to the supermassive black hole at the center of our galaxy? You might be able to get the latest update on this object in real time during a rare live-streamed observing run from the W. M. Keck Observatory in Hawaii. Watch live above.
The two 10-meter Keck Observatory telescopes on the summit of Mauna Kea will be steered by astronomer Andrea Ghez and her team of observers from the UCLA Galactic Center Group for two nights to study our galaxy’s supermassive black hole, with an attempt to focus in on the enigmatic G2 to see if it is still intact. They’ll also be setting up a test for Einstein’s General Relativity and gathering more data on what they describe as The Paradox of Youth: young objects paradoxically developing around the black hole.
Here’s the time for the livestream in various timezones:
July 3, 2014 @ 9 pm – 10 pm Hawaii
July 4, 2014 @ Midnight – 1 am Pacific
July 4, 2014 @ 3 am – 4 am Eastern
The most previous observations by the Keck Observatory in Hawaii, according to an Astronomer’s Telegram from May 2, 2014 show that the gas cloud called ‘G2’ was surprisingly still intact, even during its closest approach to the supermassive black hole. This means G2 is not just a gas cloud, but likely has a star inside.
“We conclude that G2, which is currently experiencing its closest approach, is still intact, in contrast to predictions for a simple gas cloud hypothesis and therefore most likely hosts a central star,” said the May 2 Telegram. “Keck LGSAO observations of G2 will continue in the coming months to monitor how this unusual object evolves as it emerges from periapse passage.”
For additional info, see our two previous articles about G2:
"Helical jets from one supermassive black hole caused by a very closely orbiting companion (see blue dots). The third black hole is part of the system, but farther away and therefore emits relatively straight jets."
Credit: Roger Deane (large image); NASA Goddard (inset bottom left; modified from original)
In a galaxy four billion light-years away, three supermassive black holes are locked in a whirling embrace. It’s the tightest trio of black holes known to date and even suggests that these closely packed systems are more common than previously thought.
“What remains extraordinary to me is that these black holes, which are at the very extreme of Einstein’s Theory of General Relativity, are orbiting one another at 300 times the speed of sound on Earth,” said lead author Roger Deane from the University of Cape Town in a press release.
“Not only that, but using the combined signals from radio telescopes on four continents we are able to observe this exotic system one third of the way across the Universe. It gives me great excitement as this is just scratching the surface of a long list of discoveries that will be made possible with the Square Kilometer Array.”
The system, dubbed SDSS J150243.091111557.3, was first identified as a quasar — a supermassive black hole at the center of a galaxy, which is rapidly accreting material and shining brightly — four years ago. But its spectrum was slightly wacky with its doubly ionized oxygen emission line [OIII] split into two peaks instead of one.
A favorable explanation suggested there were two active supermassive black holes hiding in the galaxy’s core.
An active galaxy typically shows single-peaked narrow emission lines, which stem from a surrounding region of ionized gas, Deane told Universe Today. The fact that this active galaxy shows double-peaked emission lines, suggests there are two surrounding regions of ionized gas and therefore two active supermassive black holes.
But one of the supermassive black holes was enshrouded in dust. So Deane and colleagues dug a little further. They used a technique called Very Long Baseline Interferometry (VLBI), which is a means of linking telescopes together, combining signals separated by up to 10,000 km to see detail 50 times greater than the Hubble Space Telescope.
Observations from the European VLBI network — an array of European, Chinese, Russian, and South American antennas — revealed that the dust-covered supermassive black hole was once again two instead of one, making the system three supermassive black holes in total.
The VLBI network. Image Credit: Roger Deane
“This is what was so surprising,” Deane told Universe Today. “Our aim was to confirm the two suspected black holes. We did not expect one of these was in fact two, which could only be revealed by the European VLBI Network due [to the] very fine detail it is able to discern.”
Deane and colleagues looked through six similar galaxies before finding their first trio. The fact that they found one so quickly suggests that they’re more common than previously thought.
The inner pair of black holes of the triple system as seen by the European VLBI Network (EVN). Image Credit: R.P. Deane et al.
Before today, only four triple black hole systems were known, with the closest pair being 2.4 kiloparsecs apart — roughly 2,000 times the distance from Earth to the nearest star, Proxima Centauri. But the closest pair in this trio is separated by only 140 parsecs — roughly 10 times that same distance.
Although Deane and colleagues relied on the phenomenal resolution of the VLBI technique in order to spatially separate the two close-in black holes, they also showed that their presence could be inferred from larger-scale features. The orbital motion of the black hole, for instance, is imprinted on its large jets, twisting them into a helical-like shape. This may provide smaller telescopes with a tool to find them with much greater efficiency.
“If the result holds up, it’ll be very cool,” binary supermassive black hole expert Jessie Runnoe from Pennsylvania State University told Universe Today. This research has multiple implications for understanding further phenomena.
The first sheds light on galaxy evolution. Two or three supermassive black holes are the smoking gun that the galaxy has merged with another. So by looking at these galaxies in detail, astronomers can understand how galaxies have evolved into their present-day shapes and sizes.
The second sheds light on a phenomenon known as gravitational radiation. Einstein’s General Theory of Relativity predicts that when one of the two or three supermassive black holes spirals inward, gravitational waves — ripples in the fabric of space-time itself — propagate out into space.
Future radio telescopes should be able to measure gravitational waves from such systems as their orbits decay.
“Further in the future, the Square Kilometer Array will allow us to find and study these systems in exquisite detail, and really allow us [to] gain a much better understanding of how black holes shape galaxies over the history of the Universe,” said coauthor Matt Jarvis from the Universities of Oxford and Western Cape.
The research was published today in the journal Nature.
The blazar 3C 454.3 photographed by the Sloan Digital Sky Survey. It's currently in bright outburst and nearly as bright as the star next to it. Both are about magnitude +13.6. Credit: SDSS
Have an 8-inch or larger telescope? Don’t mind staying up late? Excellent. Here’s a chance to stare deeper into the known fabric of the universe than perhaps you’ve ever done before. The violent blazer 3C 454.3 is throwing a fit again, undergoing its most intense outburst seen since 2010. Normally it sleeps away the months around 17th magnitude but every few years, it can brighten up to 5 magnitudes and show in amateur telescopes. While magnitude +13 doesn’t sound impressive at first blush, consider that 3C 454.3 lies 7 billion light years from Earth. When light left the quasar, the sun and planets wouldn’t have skin in the game for another two billion years.
If we could see the blazar 3C 354.3 up close it would look something like this. A bright accretion disk surrounds a black hole. Twin jets of radiation beam from the center. Credit: Cosmovision
Blazars form in the the cores of active galaxies where supermassive black holes reside. Matter falling into the black hole spreads into a spinning accretion disk before spiraling down the hole like water down a bathtub drain.
Superheated to millions of degrees by gravitational compression the disk glows brilliantly across the electromagnetic spectrum. Powerful spun-up magnetic fields focus twin beams of light and energetic particles called jets that blast into space perpendicular to the disk.
Blazars and quasars are thought to be one and the same, differing only by the angle at which we see them. Quasars – far more common – are actively- munching supermassive black holes seen from the side, while in blazars – far more rare – we stare directly or nearly so into the jet like looking into the beam of a flashlight.
An all-sky view in gamma ray light made with the Fermi Gamma-ray Space Telescope shows bright gamma-ray emission in the plane of the Milky Way (center), bright pulsars and super-massive black holes including the active blazar 3C 454.3 at lower left. Credit: NASA/DOE/International LAT Team
3C 454.3 is one of the top ten brightest gamma ray sources in the sky seen by the Fermi Gamma-ray Space Telescope. During its last major flare in 2005, the blazar blazed with the light of 550 billion suns. That’s more stars than the entire Milky Way galaxy! It’s still not known exactly what sets off these periodic outbursts but possible causes include radiation bursts from shocked particles within the jet or precession (twisting) of the jet bringing it close to our line of sight.
3c 454.3 is near the star Alpha Pegasi just to the west of the Great Square. Use this chart to star hop from Alpha to IM Peg (mag. ~ 5.7). Once there, the detailed map below will guide you to the blazar. Stellarium
The current outburst began in late May when the Italian Space Agency’s AGILE satellite detected an increase in gamma rays from the blazar. Now it’s bright visually at around magnitude +13.6 and fortunately not difficult to find, located in the constellation Pegasus near the bright star Alpha Pegasi (Markab) in the lower right corner of the Great Square asterism.
Using the wide view map, find your way to IM Peg via Markab and then make a copy of the detailed map below to use at the telescope to star hop to 3C 454.3. The blazar lies immediately south of a star of similar magnitude. If you see what looks like a ‘double star’ at the location, you’ve nailed it. Incredible isn’t it to look so far into space back to when the universe was just a teenager? Blows my mind every time.
Detailed map showing the location of the blazar 3C 454.3. I’ve drawn a small asterism using a group of brighter stars with their magnitudes marked. A scale showing 30 arc minutes (1/2 degree) is at right. Click to enlarge. Created with Chris Marriott’s SkyMap software
To further explore 3C 454.3 and blazars vs. quasars I encourage you to visit check out Stefan Karge’s excellent Frankfurt Quasar Monitoring site. It’s packed with great information and maps for finding the best and brightest of this rarified group of observing targets. Karge suggests that flickering of the blazar may cause it to appear somewhat brighter or fainter than the current magnitude. You’re watching a violent event subject to rapid and erratic changes. For an in-depth study of 3C 454.3, check out the scientific paper that appeared in the 2010 Astrophysical Journal.
Learn more about quasars and blazers with a bit of great humor
Finally, I came across a wonderful video while doing research for this article I thought you’d enjoy as well.
A Hubble Space Telescope image of NGC 5548. Credit: ESA/Hubble and NASA. Acknowledgement: Davide de Martin
Sometimes it takes a second look — or even more — at an astronomical object to understand what’s going on. This is what happened after astronomers obtained this image of NGC 5548 using the Hubble Space Telescope in 2013. While crunching the data, they saw some gas moving around the galaxy in a way that they did not understand.
From the supermassive black hole embedded in the galaxy’s heart, the researchers detected gas moving outward quite quickly — blocking about 90% of the X-rays being emitted from the black hole, a common feature of objects of this type. So, astronomers marshalled a bunch of telescopes to figure out the answer.
Here’s what they knew before: black holes force matter into a spiral that surround the object, creating a flat plane of material known as an accretion disc. Heating in this disc sends out the aforementioned X-rays as well as some ultraviolet radiation. But NGC 5548 is doing something different.
The gas stream, researchers stated, “absorbs most of the X-ray radiation before it reaches the original cloud, shielding it from X-rays and leaving only the ultraviolet radiation. The same stream shields gas closer to the accretion disc. This makes the strong winds possible, and it appears that the shielding has been going on for at least three years.”
Artist’s conception of the environment around NGC 5548. This shows a dark swarm of material above the supermassive black hole, as well as the view that the Hubble Space Telescope had of the scene. Credit: NASA, ESA, and A. Feild (STScI)
Quite the suite of telescopes did follow-up observations: NASA’s Swift spacecraft, Nuclear Spectroscopic Telescope Array (NuSTAR) and Chandra X-ray Observatory, and ESA’s X-ray Multi-Mirror Mission (XMM-Newton) and Integral gamma-ray observatory (INTEGRAL).
“This is a milestone in understanding how supermassive black holes interact with their host galaxies,” stated lead researcher Jelle Kaastra of the SRON Netherlands Institute for Space Research.
“We were very lucky. You don’t normally see this kind of event with objects like this. It tells us more about the powerful ionised winds that allow supermassive black holes in the nuclei of active galaxies to expel large amounts of matter. In larger quasars than NGC 5548, these winds can regulate the growth of both the black hole and its host galaxy.”
Artist rendering of a supermassive black hole. Credit: NASA / JPL-Caltech.
It’s oft-repeated that black holes are powerful gravity wells, because they represent a dense concentration of matter in one location. But what about their magnetic fields? A new study suggests that this force could be at least as strong as gravity in supermassive black holes, the singularities that lurk in the center of many galaxies.
Simulations of magnetic fields of gas falling into these beasts suggest that this action — if the gas carries a magnetic field — makes the field stronger until it equals gravity.
Magnetic fields can affect properties such as how luminous black holes appear (in radio) and how powerful the jets emanating from the singularity are. The scientists speculate that when you see bright jets from a black hole, this could imply a strong magnetic field indeed.
A computer simulation of gas (yellow) falling into a black hole, and jets emanating from the singularity. Credit: Alexander Tchekhovskoy (LBNL)
“Surprisingly, the magnetic field strength around these exotic objects is comparable to the magnetic field produced in something more familiar: a magnetic resonance imaging (MRI) machine that you can find in your local hospital,” the Max Planck Institute for Radio Astronomy stated.
“Both supermassive black holes and MRI machines produce magnetic fields that are roughly 10,000 times stronger than the Earth’s surface magnetic field, which is what guides an ordinary compass.”
New information on how strong the magnetic fields was based on recent work with the Very Long Baseline Array, a networked group of radio telescopes in the United States. Specifically, the information came from a program named MOJAVE (Monitoring Of Jets in Active galactic nuclei with VLBA Experiments) that looks at jets around several hundred supermassive black holes.
The researchers emphasized that more observational research will be needed to supplement the simulations. The work will be published today in Nature. Leading the research was Mohammad Zamaninasab, a past researcher at Max Planck.
The Whirlpool galaxy seen in both optical and X-ray light. Image Credit: X-ray: NASA/CXC/Wesleyan Univ./R.Kilgard, et al; Optical: NASA/STScI
In any galaxy there are hundreds of X-ray binaries: systems consisting of a black hole capturing and heating material from a relatively low-mass orbiting companion star. But high-mass X-ray binaries — systems consisting of a black hole and an extremely high-mass companion star — are hard to come by. In the Milky Way there’s only one: Cygnus X-1. But 30 million light-years away in the Whirlpool galaxy, M51, there are a full 10 high-mass X-ray binaries.
Nearly a million seconds of observing time with NASA’s Chandra X-ray Observatory has revealed these specks. “This is the deepest, high-resolution exposure of the full disk of any spiral galaxy that’s ever been taken in the X-ray,” said Roy Kilgard, from Wesleyan University, at a talk presented at the American Astronomical Society meeting today in Boston. “It’s a remarkably rich data set.”
Within the image there are 450 X-ray points of light, 10 of which are likely X-ray binaries.
The Whilpool galaxy is thought to have so many X-ray binaries because it’s in the process of colliding with a smaller companion galaxy. This interaction triggers waves of star formation, creating new stars at a rate seven times faster than the Milky Way and supernova deaths at a rate 10-100 times faster. The more-massive stars simply race through their evolution in a few million years and collapse to form neutron stars or black holes quickly.
“In this image, there’s a very strong correlation between the fuzzy purple stuff, which is hot gas in the X-ray, and the fuzzy red stuff, which is hydrogen gas in the optical,” said Kilgard. “Both of these are tracing the star formation very actively. You can see it really enhanced in the northern arm that approaches the companion galaxy.”
Eight of the 10 X-ray binaries are located close to star forming regions.
Chandra is providing astronomers with an in depth look at a class of objects that has only one example in the Milky Way.
“We’re catching them at a short window in their evolutionary cycle,” said Kilgard. “The massive star that formed the black hole has died, and the massive star that is accreting material onto the black hole has not yet died. The window at which these objects are X-ray bright is really short. It’s maybe only tens of thousands of years.”
This simulation shows the G2 gas cloud/star during its close approach to the black hole at the center of the Milky Way. Image by ESO/MPE/Marc Schartmann.
Observatories around the world and in space have been honed-in on the center of our galaxy, looking for possible fireworks to erupt as a mystery object heads towards our galaxy’s supermassive black hole. The object – called G2 – is being watched in an intense observing campaign across all wavelengths with multiple observatories. This is the first time astronomers have been able to watch an encounter with a black hole like this in real time, and the hope is that watching G2’s demise will reveal not only what this object actually is, but also provide more information on how matter behaves near black holes and how supermassive black holes “eat” and evolve.
“We’re indeed working on new observation of G2 right now,” astronomer Leo Meyer from UCLA told Universe Today, “and we’re in a position to make a significant new statement about it very soon.”
G2 was first spotted in 2011 and was quickly deemed to be heading towards our galaxy’s supermassive black hole, called Sgr A*. Astronomers estimate G2 has a mass roughly three times that of Earth (versus the black hole, which is 4 million times the mass of our Sun). G2 is not falling directly into the black hole, but it will pass Sgr A* at about 100 times the distance between Earth and the Sun. But that’s close enough to predict that G2 is doomed for destruction.
Shown here are VLT observations from 2006, 2010 and 2013, colored blue, green and red respectively showing a gas cloud being ripped apart by the supermassive black hole at the center of the galaxy. Credit: ESO/S. Gillessen.
By last July, observations from the Very Large Telescope showed the object being stretched over more than 160 billion kilometers by the black hole’s extreme gravitational field.
Closest approach was expected to have happened by now (April 2014), but nobody’s talking publicly yet about what has been observed, although Meyer hinted news would be coming soon.
The last notification on the G2 Gas Cloud Wiki page (put together by Stefan Gillessen of the Max Planck Institute in Germany, who has lead several observing runs) was posted on April 21, 2014. This notification reported no strong flare of Sgr A* although it was around the expected time peri-center passing for G2, but there has been a rather constant radio detection of 22 GHz at that location with Japanese VLBI Network.
Northwestern University’s Daryl Haggard said in an early April 2014 press release that recent Chandra observations do not show any enhanced emissions in X-rays, adding “from the X-ray perspective, the gas cloud is late to the party, but it remains to be seen whether G2 is fashionably late or a no show.”
And that points to one question about G2: what is it exactly? Haggard called it a gas cloud, but UCLA astronomer Andrea Ghez said there’s actually a debate about what it is.
“There are two camps on that,” she told Universe Today. “Some people have suggested this is a gas cloud. But I think it’s a star. Its orbit looks so much like the orbits of other stars. There’s clearly some phenomenon that is happening, and there is some layer of gas that’s interacting because you see the tidal stretching, but that doesn’t prevent a star being in the center.”
Some astronomers argue that they aren’t seeing the amount of stretching or “spaghettification” that would be expected if this was just a cloud of gas.
Montage of simulation images showing G2 during its close approach to the black hole at the center of the Milky Way. Images by ESO/MPE/Marc Schartmann
Meyer said the stretching from the object tidally reacting to the back hole clearly points to gas, but that doesn’t tell you if something is hidden inside it or not.
“While it is getting stretched, the luminosity is staying surprisingly constant, and that is puzzling the theorists,” Meyer said.
Another puzzle is the timing of when G2’s closest approach would take place. When news of G2 first broke, it was thought that the time of closest approach to the black hole would be in mid-2013. But further observations determined that that estimate was not accurate and Spring 2014 was actually when closest approach would occur.
“This makes this year’s observations so relevant and our upcoming report significant — especially regarding the issue whether there is a star inside the cloud or not,” Meyer told Universe Today via email.
But, Ghez said, we’ll soon know the answer of what this object is.
“This is just the process of science and it’s interesting – because we’ll have a limited set of observations to find out what this is,” she said. “And it may be a gas cloud or it may be a star, but it’s pretty exciting in astronomy to have an event that everybody gets to line up and buy tickets for.”
Another question is if there actually will be any “fireworks” – as Meyer called it – when G2 meets its ultimate doom as it gets shredded and possibly eaten by the black hole. As the object approaches the black hole and gets disrupted, the gas will rain down onto the back hole, increasing the black hole’s mass, possibly making it brighter. Will this create a “flash” or possibly even a jet from the black hole?
“We don’t know, and there are a lot of uncertainties,” Meyer said at the American Astronomical Society meeting in January 2014. “This is something we haven’t seen before, and even if we don’t know if something will happen or not, it still is worth looking. It’s a unique opportunity to learn about fundamental astrophysics. Even if it’s not super-spectacular, we can still learn things.”
Meyer hinted in January that astronomers might not see much at all.
“Whatever gas might end up in the black hole might get smeared out so much that the amount of mass that gets dumped into the back might be very little,” he said. “This dietary supplement might be very little, like a pea or something!”
Our galaxy’s supermassive black hole has long been fairly inactive, but in 2013, NASA’s Swift Gamma-Ray Burst mission detected the brightest flare ever observed from Sgr A*. However, it’s not certain if this burst was related to G2 or not.
Ghez has said these observations of G2 are similar to the search for extraterrestrial life: the odds to see something are against you, but you still have to look, because if you find something, it will be spectacular.
This is exciting for astronomers, since they usually don’t get to see events like this take place “in real time.” In astrophysics, timescales of events taking place are usually very long — not over the course of several months. But it’s important to note that G2 actually met its demise around 25,000 years ago. Because of the amount of time it takes light to travel, we can only now observe this event which happened long ago.
Unfortunately, this event is beyond what amateur astronomers can observe.
“We really need to use the worlds’ most advanced observatories to observe this,” Meyer said in January, “as we have to go to multiple wavelengths and use adaptive optics since the galactic center is not visible to light in seen by our eyes, and you need a high angular resolution to see it.”
Multi-wavelength view of the elliptical galaxy NGC 5044. Credit: Digitised Sky Survey/NASA Chandra/Southern Observatory for Astrophysical Research/Very Large Array (Robert Dunn et al. 2010)
Contradicting past theories, cold gas has been found in abundance in some elliptical galaxies — showing that there must be some other explanation why these types of galaxies don’t form new stars. Astronomers believe that the jets from supermassive black holes in these galaxies’ center must push around the gas and prevent stars from forming.
Researchers spotted the gas for the first time using old data from the recently retired Herschel space observatory, which was able to peer well into the infrared — where it spotted carbon ions and oxygen atoms. This find stands against the previous belief that these galaxies were “red and dead”, referring to their physical appearance and the fact that they form no new stars.
“We looked at eight giant elliptical galaxies that nobody had looked at with Herschel before and we were delighted to find that, contrary to previous belief, six out of eight abound with cold gas”, stated Norbert Werner, a researcher at Stanford University in California who led the study.
“These galaxies are red, but with the giant black holes pumping in their hearts, they are definitely not dead,” added Werner.
NGC 1399, an elliptical galaxy about 65 million light years from Earth. Credit: NASA, Chandra
Previously, scientists thought that the galaxies got rid of their cold gas or had used it all up during a burst of earlier star formation. With cold gas found in the majority of the sample, researchers then used other observatories to try to find warmer gas up to tens of millions of Kelvin (or Fahrenheit or Celsius).
X-ray information from NASA’s Chandra X-ray Observatory revealed that there is hot gas cooling in six of the eight galaxies, but not in the remaining two of the sample.
“This is consistent with theoretical expectations: once cooled, the hot gas would become the warm and cold gas that are observed at longer wavelengths. However, in these galaxies the cooling process somehow stopped, and the cold gas failed to condense and form stars,” the European Space Agency stated.
“While the six galaxies with plenty of cold gas harbour moderately active black holes at their centres,” ESA added, “the other two show a marked difference. In the two galaxies without cold gas, the central black holes are accreting matter at frenzied pace, as confirmed by radio observations showing powerful jets of highly energetic particles that stem from their cores.”
A team of astronomers from South Africa have noticed a series of supermassive black holes in distant galaxies that are all spinning in the same direction. Credit: NASA/JPL-Caltech
Gas around supermassive black holes tends to clump into immense clouds, periodically blocking the view of these huge X-ray sources from Earth, new research reveals.
Observations of 55 of these “galactic nuclei” revealed at least a dozen times when an X-ray source dimmed for a time as short as a few hours or as long as years, which likely happened when a gas cloud blotted out the signal seen from Earth. This is different than some previous models suggesting the gas was more uniform.
“Evidence for the clouds comes from records collected over 16 years by NASA’s Rossi X-ray Timing Explorer, a satellite in low-earth orbit equipped with instruments that measured variations in X-ray sources,” stated the Royal Astronomical Society.
“Those sources include active galactic nuclei, brilliantly luminous objects powered by supermassive black holes as they gather and condense huge quantities of dust and gas.”
The research was led by Alex Markowitz, an astrophysicist at the University of California, San Diego and the Karl Remeis Observatory in Bamberg, Germany.
