Black Holes

Toroid

Founding Member
For the first time astronomers have observed the merging of the supermassive black holes from two galaxies.
Supermassive Black Holes Collide in First-Ever Views of Galactic Merger Final Stages
NGC 6240 - Wikipedia
For the first time, astronomers have observed the final stages of galactic mergers, peering through thick walls of gas and dust to see pairs of supermassive black holes drawing closer together and the black holes' rapid growth.

At the centers of most, if not all, galaxies are supermassive black holes with masses that are millions to billions of times that of Earth's sun. For instance, at the heart of our Milky Way galaxy lies Sagittarius A*, which is about 4.5 million solar masses in size.

Previous work found that mergers of galaxies might help fuel the growth of supermassive black holes. That research suggested that black holes at the cores of colliding galaxies may combine to become even larger black holes. [When Galaxies Collide: Photos of Great Galactic Crashes]

Galactic mergers likely give supermassive black holes ample opportunities to rip apart stars and devour matter. Such destruction releases extraordinary amounts of light and likely serves as the driving force behind quasars, which rank among the brightest objects in the universe.

However, support for the merger-based model of the growth of supermassive black holes has proven mixed, the new work's authors said. While some research has shown a link between quasars and merging galaxies, other studies have found no such association.

One possible explanation for the apparent lack of a link between quasars and merging galaxies is that gas and dust swirling around these galaxies is likely to heavily obscure the black holes. This would be true even during the early stages of mergers, when the galaxies are separated by more than 16,000 light-years of space. Computer simulations suggest that such concealment peaks during the final stages of mergers, when galactic cores are less than 10,000 light-years apart, the study authors said.

Now, the researchers have observed several pairs of galaxies in the late stages of merging, their core supermassive black holes pulling closer. The findings shed light on how even more-massive black holes might come about.

The scientists first searched for hidden black holes by sifting through 10 years' worth of X-ray data from NASA's Neil Gehrels Swift Observatory. When black holes devour matter, such "active" black holes can generate high-energy X-rays visible even through thick clouds of gas and dust.

Next, the researchers looked for galaxies matching these X-ray finds by combing through data from NASA's Hubble Space Telescope and the Keck Observatory in Hawaii. Deformable mirrors controlled by computer, a technology called adaptive optics at the Keck Observatory help sharpen images of stars, "leading to a huge increase in resolution," study lead author Michael Koss told Space.com. Koss is an astrophysicist at scientific research company Eureka Scientific in Oakland, California.

"It would be like going from 20/200 vision, where you are legally blind, to 20/20 vision, helping us see galaxies in incredible detail," he said.

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The messy cores of these colliding galaxies hide the final stage of two merging galactic nuclei. Top: NGC 6240, as imaged by Hubble's Wide Field Camera 3, paired with a close-up of the galactic cores in infrared light by the Keck Observatory in Hawaii. The other four galaxies are imaged by the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) as well as Keck.
Credit: M. Koss (Eureka Scientific, Inc.)/NASA/ESA;Keck images: M. Koss (Eureka Scientific, Inc.)/W.M. Keck Observatory; Pan-STARRS images: M. Koss (Eureka Scientific, Inc.)/Panoramic Survey Telescope and Rapid Response System
All in all, the scientists analyzed 96 galaxies observed with the Keck Observatory and 385 galaxies from the Hubble archive. All of those galaxies are located an average of 330 million light-years from Earth, relatively close by in cosmic terms, with many similar in size to the Milky Way.

The researchers found that more than 17 percent of these galaxies hosted a pair of black holes at their centers, signs of the late stages of a galactic merger. These findings matched the researchers' computer simulations, which suggested that highly active but heavily obscured black holes hidden within gas- and dust-rich galaxies are responsible for many mergers of supermassive black holes.

"Galactic mergers might be a key way of growing black holes," Koss said.

Our own Milky Way galaxy is currently undergoing a merger with the neighboring Andromeda galaxy, and the supermassive black holes at the two galactic cores will eventually smash together, Koss said.

"Right now, the galaxies are separated by millions of light-years, but we're moving toward Andromeda at 250,000 mph [400,000 km/h]," Koss said. "In 6 billion years, there will be no Milky Way galaxy or Andromeda galaxy — just one big galaxy."

An even better view of mergers in dusty, heavily obscured galaxies may come from NASA's highly anticipated James Webb Space Telescope, slated for launch in 2021. Improved images could also come from adaptive-optics systems in the next generation of very large ground-based telescopes, such as the Thirty Meter Telescope, the European Extremely Large Telescope and the Giant Magellan Telescope, Koss said. The James Webb Space Telescope should also be capable of measuring the masses, growth rates and other physical features for each member of nearby black hole pairs, according to the researchers.
 

Toroid

Founding Member
New observations of super massive black holes suggest they're more like three dimensional fountains rather than donuts.
What black holes REALLY look like: Astronomers say they act like 'fountains' | Daily Mail Online
Gas surrounding a supermassive black hole spews out from above and below the disk like a three-dimensional fountain, new simulations have revealed.

While it’s long been assumed that the rings of gas around active black holes took on the shape of a donut, researchers say the reality is far more complex.

Simulations and observations from the Atacama Large Millimeter/submillimetre Array (ALMA) suggest the ‘donut’ is actually a more dynamic structure made if three gaseous components that circulate constantly.
6852638-6447753-image-m-32_1543609580291.jpg
 

Toroid

Founding Member
Black hole ASASSN-14li is spinning at least half the speed of light completing one rotation in about two minutes. It's 290 million light years away and is roughly the same size as the supermassive black hole in the center of our galaxy Sagittarius A*.
This Huge Black Hole Is Spinning at Half the Speed of Light!
The crumbs left over from a supermassive black hole's recent meal have allowed scientists to calculate the monster's rotation rate, and the results are mind-boggling.

The huge black hole, known as ASASSN-14li, is spinning at least 50 percent the speed of light, research team members said.

"This black hole’s event horizon is about 300 times bigger than the Earth," study co-author Ron Remillard, of the Massachusetts Institute of Technology (MIT), said in a statement. (The event horizon is the limit beyond which nothing, not even light, can escape a black hole's gravitational clutches.) [Images: Black Holes of the Universe]

"Yet the black hole is spinning so fast it completes one rotation in about two minutes, compared to the 24 hours it takes our planet to rotate," Remillard added.

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This artist's illustration shows the region around a supermassive black hole after a star wandered too close and was ripped apart. Some of the remains of the star are pulled into an X-ray-bright disk where they circle the black hole before passing over the "event horizon," the boundary beyond which nothing, including light, can escape. The elongated spot depicts a bright region in the disk, which causes a regular variation in the X-ray brightness of the source, allowing the spin rate of the black hole to be estimated.
Credit: Illustration: NASA/CXC/M.Weiss; X-ray: NASA/CXC/MIT/D. Pasham et al: Optical: HST/STScI/I. Arcavi
ASASSN-14li lies at the heart of a galaxy 290 million light-years away from Earth and harbors between 1 million and 10 million times the mass of the sun. So, it's about as hefty as the black hole at the Milky Way's core, known as Sagittarius A*, which contains about 4 million solar masses. (Supermassive black holes can get much weightier; some tip the scales at tens of billions of solar masses.)

ASASSN-14li was discovered in November 2014, after it tore apart a star that strayed too close. This dramatic event caused a flash of bright light, which was spotted by a system of optical telescopes called the All-Sky Automated Survey for Supernovae (hence the black hole's name).

In the new study, a team led by Dheeraj Pasham, also of MIT, observed the X-ray light coming from the ASASSN-14li system. The researchers analyzed data gathered by a number of instruments, including NASA's Chandra X-ray Observatory and Neil Gehrels Swift space telescopes, as well as the European Space Agency's XMM-Newton spacecraft.

These datasets revealed a consistent flickering: ASASSN-14li's X-ray emissions rise and fall every 131 seconds. This clockwork signal is likely caused by a clump of the torn-apart star circling the black hole very close to the event horizon, study team members said.

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Scientists used NASA's Chandra and Hubble space telescopes, as well as other instruments, to study the supermassive black hole system ASASSN-14li and determine the spin rate of the black hole, a fundamental property that has been difficult for astronomers to measure.
Credit: X-ray: NASA/CXC/MIT/D. Pasham et al: Optical: HST/STScI/I. Arcavi
"The fact that we can track this region of bright X-ray emission as it circles the black hole lets us track just how quickly material in the disk is spinning," Pasham said in the same statement. "That gives us information about the spin rate of the supermassive black hole itself."

That spin speed is impressive but not unprecedented. The few supermassive black holes whose rotation rates have been clocked to date are in the same extreme neighborhood, generally whipping around between 33 percent and 84 percent the speed of light.

The new results — which Pasham presented Wednesday (Jan. 9) at the 233rd meeting of the American Astronomical Society (AAS) in Seattle — could help astronomers better understand how supermassive black holes evolve.

These behemoths can grow in two main ways, Pasham said — by galaxy-scale mergers, and/or by steadily accreting smaller bits of surrounding material. A relatively low rotation rate would implicate mergers as the primary factor, because these random smashups likely wouldn't keep spinning the growing black hole up in the same direction.

However, "if you have a high-spin black hole, supermassive black hole, that's telling us that maybe steady accretion was dominant," Pasham said during a news conference at AAS Wednesday.

The new study was also published online Wednesday in the journal Science. You can read a preprint of it for free at arXiv.org.

Mike Wall's book about the search for alien life, "Out There" (Grand Central Publishing, 2018; illustrated by Karl Tate) is out now. Follow him on Twitter @michaeldwall. Follow us @Spacedotcom or Facebook. Originally published on Space.com.
 

Toroid

Founding Member
Next week during a press conference scientists will unveil the first ever image of a black hole.
The first image of a black hole to debut next week
Of all the phenomena that occur in the universe, one of the most perplexing for scientists is the black hole. These monsters consume everything near them with gravity so intense that even light can’t escape. While scientist knows a bit about black holes, and have known one exists at the center of our galaxy since the ’70s, there are no pictures of black holes to study.
Another oddity about black holes is that space-time around them is “weird” as one scientist describes. Next Wednesday, a press conference is set to be held, and at the conference, scientists will unveil the first ever photograph of a black hole.
The ESA notes that the image is of Sagittarius A, the supermassive black hole at the center of our galaxy – the Milky Way. Speculation suggests that the image will actually be of the “event horizon” which is the edge of the black hole where light can’t escape.
With the black hole surrounded by clouds of gas and dust obscuring the view. Some expect that the image will show a dark blob that is surrounded by a ring of bright light. The image marks the first time humans have ever seen a black hole.
Press briefings on the image will be held simultaneously in the US, Brussels, Santiago, Shanghai, Taipei, and Tokyo. To be clear, the image here isn’t the image that we will see next week.
 

nivek

As Above So Below
blackhole.jpg
 

Toroid

Founding Member

Toroid

Founding Member
The black hole M87* is larger than our entire solar system. It's in the supergiant galaxy Messier 87, Virgo A, NGC 4486 or M87.
Messier 87 - Wikipedia
Supermassive black hole[edit]

The supermassive black hole inside the core of Messier 87, as imaged by the Event Horizon Telescope in 2017. The central dark spot is the shadow of the black hole and is larger than the black hole itself.
The core contains a supermassive black hole, designated M87*,[66][30] whose mass is billions of times that of the Sun; estimates have ranged from (3.5 ± 0.8) × 109 M☉[67] to (6.6 ± 0.4) × 109 M☉,[67] with a measurement of 7009722000000000000♠7.22+0.34
−0.40×109 M☉ in 2016.[68] In April 2019, the Event Horizon Telescope released measurements of the black hole's mass as (6.5 ± 0.2stat ± 0.7sys ) × 109 M☉.[69] This is one of the highest known masses for such an object. A rotating disk of ionized gas surrounds the black hole, and is roughly perpendicular to the relativistic jet. The disk rotates at velocities of up to roughly 1,000 km/s,[70] and spans a maximum diameter of 0.12 parsecs (25,000 AU; 0.39 ly; 3,700×10^9 km).[71] By comparison, Pluto averages 39 astronomical units (0.00019 pc; 5.8×109 km) from the sun. Gas accretes onto the black hole at an estimated rate of one solar mass every ten years (about 90 Earth masses per day).[72] The Schwarzschild radius of the black hole is 5.9×10−4 parsecs (1.9×10−3 light-years), which is around 120 times the Earth–Sun distance.[73]

Observations suggest that the black hole may be displaced from the galactic center by about seven parsecs (23 light-years).[74] The displacement is in the opposite direction of the one-sided jet, which may indicate that the black hole was accelerated away by the jet. Another possibility is that the change in location occurred during the merger of two supermassive black holes.[74][75] A 2011 study did not find any statistically significant displacement.[76]

The black hole is the first, and, to date, the only one to be imaged. An image taken by the Event Horizon Telescope in 2017 was published on 10 April 2019. [32][77][78] The image shows the shadow of the black hole, which is about 2.6 times larger than its Schwarzschild radius, surrounded by an asymmetric emission ring with a diameter of 3.36×10−3 parsecs (0.0110 light-years).[79] The telescope's astronomers proposed to name the black hole Pōwehi, which some people believe to mean "embellished dark source of unending creation" but actually just means "dim" or "dark" in the Hawaiian language.[80] The name, taken from the Kumulipo chant, reflects the role of the Mauna Kea Observatories in creating the image.[81]
Here's how big the M87 black hole is compared to Earth
m87_black_hole_size_comparison.png
 

nivek

As Above So Below
Of course that did not stop trolls from claiming that a "straight white male" was responsible, although (for what it matters) the person named is gay and asked that people stop.

The first picture of a black hole made Katie Bouman an overnight celebrity. Then internet trolls descended.

Well it seems it was one youtube video which claimed that, I did not even know of it until you posted it, but still I am so sick and tired of people making an issue of everything as being either racial or political...

...
 

Toroid

Founding Member
Alternate theory on how black holes may form.
https://phys.org/news/2019-06-decipher-history-supermassive-black-holes.html
Astrophysicists at Western University have found evidence for the direct formation of black holes that do not need to emerge from a star remnant. The production of black holes in the early universe, formed in this manner, may provide scientists with an explanation for the presence of extremely massive black holes at a very early stage in the history of our universe.

Shantanu Basu and Arpan Das from Western's Department of Physics & Astronomy have developed an explanation for the observed distribution of supermassive black hole masses and luminosities, for which there was previously no scientific explanation. The findings were published today by Astrophysical Journal Letters.

The model is based on a very simple assumption: supermassive black holes form very, very quickly over very, very short periods of time and then suddenly, they stop. This explanation contrasts with the current understanding of how stellar-mass black holes are formed, which is they emerge when the centre of a very massive star collapses in upon itself.

"This is indirect observational evidence that black holes originate from direct-collapses and not from stellar remnants," says Basu, an astronomy professor at Western who is internationally recognized as an expert in the early stages of star formation and protoplanetary disk evolution.

Basu and Das developed the new mathematical model by calculating the mass function of supermassive black holes that form over a limited time period and undergo a rapid exponential growth of mass. The mass growth can be regulated by the Eddington limit that is set by a balance of radiation and gravitation forces or can even exceed it by a modest factor.

"Supermassive black holes only had a short time period where they were able to grow fast and then at some point, because of all the radiation in the universe created by other black holes and stars, their production came to a halt," explains Basu. "That's the direct-collapse scenario."

During the last decade, many supermassive black holes that are a billion times more massive than the Sun have been discovered at high 'redshifts,' meaning they were in place in our universe within 800 million years after the Big Bang. The presence of these young and very massive black holes question our understanding of black hole formation and growth. The direct-collapse scenario allows for initial masses that are much greater than implied by the standard stellar remnant scenario, and can go a long way to explaining the observations. This new result provides evidence that such direct-collapse black holes were indeed produced in the early universe.

Basu believes that these new results can be used with future observations to infer the formation history of the extremely massive black holes that exist at very early times in our universe.
 

Toroid

Founding Member
Two supermassive black holes on collision course 2.5 billion light years away.
https://phys.org/news/2019-07-pair-supermassive-black-holes-collision.html
Astronomers have spotted a distant pair of titanic black holes headed for a collision.

Each black hole's mass is more than 800 million times that of our sun. As the two gradually draw closer together in a death spiral, they will begin sending gravitational waves rippling through space-time. Those cosmic ripples will join the as-yet-undetected background noise of gravitational waves from other supermassive black holes.

Even before the destined collision, the gravitational waves emanating from the supermassive black hole pair will dwarf those previously detected from the mergers of much smaller black holes and neutron stars.

"Supermassive black hole binaries produce the loudest gravitational waves in the universe," says co-discoverer Chiara Mingarelli, an associate research scientist at the Flatiron Institute's Center for Computational Astrophysics in New York City. Gravitational waves from supermassive black hole pairs "are a million times louder than those detected by LIGO."

The study was led by Andy Goulding, an associate research scholar at Princeton University. Goulding, Mingarelli and collaborators from Princeton and the U.S. Naval Research Laboratory in Washington, D.C., report the discovery July 10 in The Astrophysical Journal Letters.

The two supermassive black holes are especially interesting because they are around 2.5 billion light-years away from Earth. Since looking at distant objects in astronomy is like looking back in time, the pair belong to a universe 2.5 billion years younger than our own. Coincidentally, that's roughly the same amount of time the astronomers estimate the black holes will take to begin producing powerful gravitational waves.

In the present-day universe, the black holes are already emitting these gravitational waves, but even at light speed the waves won't reach us for billions of years. The duo is still useful, though. Their discovery can help scientists estimate how many nearby supermassive black holes are emitting gravitational waves that we could detect right now.

Detecting the gravitational wave background will help resolve some of the biggest unknowns in astronomy, such as how often galaxies merge and whether supermassive black hole pairs merge at all or become stuck in a near-endless waltz around each other.

"It's a major embarrassment for astronomy that we don't know if supermassive black holes merge," says study co-author Jenny Greene, a professor of astrophysical sciences at Princeton. "For everyone in black hole physics, observationally this is a long-standing puzzle that we need to solve."

Supermassive black holes contain millions or even billions of suns' worth of mass. Nearly all galaxies, including the Milky Way, contain at least one of the behemoths at their core. When galaxies merge, their supermassive black holes meet up and begin orbiting one another. Over time, this orbit tightens as gas and stars pass between the black holes and steal energy.

Once the supermassive black holes get close enough, though, this energy theft all but stops. Some theoretical studies suggest that black holes then stall at around 1 parsec (roughly 3.2 light-years) apart. This slowdown lasts nearly indefinitely and is known as the final parsec problem. In this scenario, only very rare groups of three or more supermassive black holes result in mergers.

Astronomers can't just look for stalled pairs because long before the black holes are 1 parsec apart, they're too close to distinguish as two separate objects. Moreover, they don't produce strong gravitational waves until they overcome the final-parsec hurdle and get closer together. (Observed as they were 2.5 billion years ago, the newfound supermassive black holes appear about 430 parsecs apart.)

If the final parsec problem doesn't exist, then astronomers expect that the universe is filled with the clamor of gravitational waves from supermassive black hole pairs. "This noise is called the gravitational wave background, and it's a bit like a chaotic chorus of crickets chirping in the night," says Goulding. "You can't discern one cricket from another, but the volume of the noise helps you estimate how many crickets are out there." (When two supermassive black holes finally collide and combine, they send out a thundering chirp that dwarfs all others. Such an event is brief and extraordinarily rare, though, so scientists don't expect to detect one any time soon.)

The gravitational waves generated by supermassive black hole pairs are outside the frequencies currently observable by experiments such as LIGO and Virgo. Instead, gravitational wave hunters rely on arrays of special stars called pulsars that act like metronomes. The rapidly spinning stars send out radio waves in a steady rhythm. If a passing gravitational wave stretches or compresses the space between Earth and the pulsar, the rhythm is slightly thrown off.

Detecting the gravitational wave background using one of these pulsar timing arrays takes patience and plenty of monitored stars. A single pulsar's rhythm might be disrupted by only a few hundred nanoseconds over a decade. The louder the background noise, the bigger the timing disruption and the sooner the first detection will be made.

Goulding, Greene and the other observational astronomers on the team detected the two titans with the Hubble Space Telescope. Although supermassive black holes aren't directly visible through an optical telescope, they are surrounded by bright clumps of luminous stars and warm gas drawn in by the powerful gravitational tug. For its time in history, the galaxy harboring the newfound supermassive black hole pair "is basically the most luminous galaxy in the universe," Goulding says. What's more, the galaxy's core is shooting out two unusually colossal plumes of gas. After the researchers pointed the Hubble Space Telescope at the galaxy to uncover the origins of its spectacular gas clouds, they discovered that the system contained not one but two massive black holes.

The observationalists then teamed up with gravitational wave physicists Mingarelli and Princeton graduate student Kris Pardo to interpret the finding in the context of the gravitational wave background. The discovery provides an anchor point for estimating how many supermassive black hole pairs are within detection distance of Earth. Previous estimates relied on computer models of how often galaxies merge, rather than actual observations of supermassive black hole pairs.

Based on the findings, Pardo and Mingarelli predict that in an optimistic scenario there are about 112 nearby supermassive black holes emitting gravitational waves. The first detection of the gravitational wave background from supermassive black holes should therefore come within the next five years or so. If such a detection isn't made, that would be evidence that the final parsec problem may be insurmountable. The team is currently looking at other galaxies similar to the one harboring the newfound supermassive black hole pair. Finding additional pairs will help them further hone their predictions.
 
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