MessageToEagle.com - “We found black holes grow enormously as a result of sucking in captured binary star
partners,” says physics and astronomy Professor Ben Bromley, lead author of the study, which is set for online
publication April 2 in Astrophysical Journal Letters.
A study led by a University of Utah astrophysicist found a new explanation for the growth of supermassive
black holes in the center of most galaxies: they repeatedly capture and swallow single stars from pairs of stars that wander too close.
“I believe this has got to be the dominant method for growing supermassive black holes,” he adds.
“There are two ways to grow a supermassive black hole: with gas clouds and with stars. Sometimes there’s gas and
sometimes there is not. We know that from observations of other galaxies. But there are always stars.”
“Our mechanism is an efficient way to bring a star to a black hole,” Bromley says. “It’s really hard to target a
single star at a black hole. It’s a lot easier to throw a binary at it,” just as it’s more difficult to hit a
target using a slingshot, which hurls a single stone, than with a bola, which hurls two weights connected by a cord.
A binary pair of stars orbiting each other “is essentially a single object much bigger than the size of the
individual stars, so it is going to interact with the black hole more efficiently,” he explains.
“The binary doesn’t have to get nearly as close for one of the stars to get ripped away and captured.”
But to prove the theory will require more powerful telescopes to find three key signs: large numbers of small
stars captured near supermassive black holes, more observations of stars being “shredded” by gravity from black
holes, and large numbers of “hypervelocity stars” that are flung from galaxies at more than 1 million mph when
their binary partners are captured.
Black holes get so big so fast that they are billions of times heavier than the Sun.Image Credits: NASA/CXC/M. Weiss
Bromley, a University of Utah astrophysicist, did the study with astronomers Scott Kenyon, Margaret Geller and
Warren Brown, all of the Smithsonian Astrophysical Observatory in Cambridge, Mass. The study was funded by
both institutions.
Black holes are objects in space so dense that not even light can escape their gravity, although powerful jets
of light and energy can be emitted from a black hole’s vicinity as gas and stars are sucked into it.
Small black holes result from the collapse of individual stars. But the centers of most galaxies, including
our own Milky Way, are occupied by what are popularly known as “supermassive” black holes that contain mass
ranging from 1 million to 10 billion stars the size of our sun.
Astrophysicists long have debated how supermassive black holes grew during the 14 billion years since the
universe began in a great expansion of matter and energy named the Big Bang. One side believes black holes
grow larger mainly by sucking in vast amounts of gas; the other side says they grow primarily by capturing
and sucking in stars.
Artist’s conception of a supermassive black hole (lower left) with its tremendous gravity capturing one star
(bluish, center) from a pair of binary stars, while hurling the second star (yellowish, upper right) away
at a hypervelocity of more than 1 million mph. The grayish blobs are other stars captured in a cluster
near the black hole. They appear distorted because the black hole’s gravity curves spacetime and thus
bends the starlight. Photo Credit: Ben Bromley, University of Utah.
Just last month, other researchers published a theory that a black hole sucks in “food” by tipping its “plates” – two
tilted gas disks colliding as they orbit the black hole – in a way that makes the speeding gas slow down so the
black hole can swallow it.
Bromley says that theory overcomes a key problem: gas flows into black holes inefficiently.
“But are misaligned gas disks common enough to be important for black hole growth?” he asks.
“It’s fair to say that gas contributes to the growth of black holes, but it is still uncertain how.”
The new theory about binary stars – a pair of stars that orbit each other – arose from Bromley’s earlier
research to explain hypervelocity stars, which have been observed leaving our Milky Way galaxy at speeds
ranging from 1.1 million to 1.8 million mph, compared with the roughly 350,000 mph speed of most stars.
“The hypervelocity stars we see come from binary stars that stray close to the galaxy’s massive black hole,” he says.
“The hole peels off one binary partner, while the other partner – the hypervelocity star – gets flung out in a gravitational slingshot.”
Artist’s conception of a supermassive black hole eating a star. Credits: NASA
“We put the numbers together for observed hypervelocity stars and other evidence, and found that the rate of binary
encounters [with our galaxy’s supermassive black hole] would mean most of the mass of the galaxy’s black hole came
from binary stars,” Bromley says. “We estimated these interactions for supermassive black holes in other galaxies and
found that they too can grow to billions of solar masses in this way.”
As many as half of all stars are in binary pairs, so they are plentiful in the Milky Way and other galaxies, he adds.
But the study assumed conservatively that only 10 percent of stars exist in binary pairs.
The new study looked at each step in the process of a supermassive black hole eating binary stars, and calculated
what would be required for the process to work in terms of the rates at which hypervelocity stars are produced,
binary partners are captured, the captured stars are bound to the black hole in elongated orbits and then sucked into it.
The scientists then compared the results with actual observations of supermassive black holes, stars clustering
near them and “tidal disruption events” in which black holes in other galaxies are seen to shred stars while
pulling them into the hole.
“It fits together, and it works,” Bromley says. “When we look at observations of how stars are accumulating in
our galactic center, it’s clear that much of the mass of the black hole likely came from binary stars that were torn apart.”
” Once the tub – the area near the black hole – is occupied by a cluster of captured stars, they go “down the drain”
into the black hole over millions of years. His study shows the “tub” fills at about the same rate it drains, meaning
stars captured by a supermassive black hole eventually are swallowed.
The study’s key conclusions:
The theory accurately predicts the rate (one every 1,000 to 100,000 years) at which hypervelocity stars are
observed leaving our galaxy and at which stars are captured into the star cluster seen near our galaxy’s
supermassive black hole.
The rate of “tidal disruption events,” which are stars being shredded and pulled into supermassive black holes
in other galaxies, also matches what the theory predicts, based on the limited number seen since they first were
observed in the early 2000s. That rate also is one every 1,000 to 100,000 years.
The calculations show how the theory’s rate of binary capture and consumption can explain how the Milky Way’s
supermassive black hole has at least doubled to quadrupled in mass during the past 5 billion to 10 billion years.
When the researchers considered the number of stars near the Milky Way’s center, their speed and the odds they
will encounter the supermassive black hole, they estimated that one binary star will be torn apart every 1,000
years by the hole’s gravity.
During the last 10 billion years, that would mean the Milky Way’s supermassive black hole ate 10 million solar
masses – more than enough to account for the hole’s actual size of 4 million solar masses.
“We found a wide range of black hole masses can be explained by this process,” Bromley says.
"The Most Profound Mystery In All Of Science" -
Dark Energy
Little is known about this force and its its repulsive gravity, which is causing the expansion of the universe to accelerate.
The riddles of dark matter and cosmic inflation, along with dark energy, these are the three pillars of modern cosmological theory,"
and none of them can be explained with physics that we know," Michael Turner, director of the Kavli Institute for Cosmological Physics says.
Powerful Jet Pointing Directly At Earth
They are among the most fascinating cosmic phenomena. Astronomers know them as blazars and each of them harbors a supermassive black hole and jets emanating
in opposite directions from near its poles. These sources are unique evidence of the most extreme speeds and energies known in the extreme Universe...
Mercury Surprises Scientists
On March 17, MESSENGER (MErcury Surface, Space Environment, GEochemistry, and Ranging) completed its one-year primary mission, orbiting Mercury, capturing nearly 100,000 images, and recording data
that reveals new information about the planet's core, topography, and the mysterious radar bright material in the permanently shadowed areas near the poles.
Living Earth Simulator - Supercomputer Predicting The Future
In Douglas Adams book the Hitchhikers Guide to the Galaxy we encounter a machine called Deep Thought. It is the most powerful computer ever built. Deep Thought is capable of answering questions
concerning life, the Universe, and simply everything. Now scientists are planning to create a similar machine. It is called the Living Earth Simulator (LES).
Warp-Speed Planets Are Some Of The Fastest Objects In The Milky Way
Warped planets are some of the fastest objects in the Milky Way and they zoom through space near the speed of light.
Some years ago astronomers were astonished when they they found the first runaway star flying out of our Galaxy at a speed of 1.5 million miles per hour.
The discovery intrigued theorists, who wondered: If a star can get tossed outward at such an extreme velocity, could the same thing happen to planets?
Though the universe is filled with billions upon billions of stars, the discovery of a single variable star in 1923 altered the
course of modern astronomy. And, at least one famous astronomer of the time lamented that the discovery had shattered his world view.
Bright Star In The Constellation Lyra Is Cooler Than The Human Body
The coldest class of stars have temperatures as cool as the human body.
Astronomers hunted these dark orbs, termed Y dwarfs, for more than a decade without success.
When viewed with a visible-light telescope, they are nearly impossible to see.
Thermonuclear Burning In A Neutron Star Detected For The First Time!
It's a very important discovery!
For the first time, an international team of scientists have detected all phases of thermonuclear burning in a
neutron star, located close to the center of the galaxy in the globular cluster Terzan 5.
First Evidence - Bizarre Superfluid Matter Found At Neutron Star Core
Many mysteries regarding neutron stars have to be solved and one of such mysteries has just been revealed, the first direct evidence for
this bizarre state of matter in the core of a neutron star.
Neutron stars contain the densest known matter that is directly observable. One teaspoon of neutron star material weighs six billion tons.
Fermi Detects Unknown Objects Producing Gamma Rays
Fermi Gamma-Ray Telescope has just crossed a new electromagnetic frontier and detected unknown objects producing gamma rays.
According to new reports from astronomers, about a third of the new sources remain unidentified
for the moment and they are not associated with any know objects producing so much gamma ray
Puzzling Phenomenon: "Planet Pile-Ups" And "Planet Deserts"
An interesting phenomenon has puzzled astronomers for long time.
In young solar systems emerging around baby stars, some orbits are more popular than others, resulting in “planet pile-ups” and “planet deserts."
Elusive Planet Still Hiding In The System
Direct imaging of exoplanets has been a field in rapid development over the past few years, with detections of several planets and low-mass brown-dwarfs.
Among these discoveries, one claimed planet detection that stands out as peculiar in many ways is that of Fomalhaut b.
MessageToEagle.com - “We found black holes grow enormously as a result of sucking in captured binary star
partners,” says physics and astronomy Professor Ben Bromley, lead author of the study, which is set for online
publication April 2 in Astrophysical Journal Letters.
Little is known about this force and its its repulsive gravity, which is causing the expansion of the universe to accelerate.
The riddles of dark matter and cosmic inflation, along with dark energy, these are the three pillars of modern cosmological theory,"
and none of them can be explained with physics that we know," Michael Turner, director of the Kavli Institute for Cosmological Physics says.
They are among the most fascinating cosmic phenomena. Astronomers know them as blazars and each of them harbors a supermassive black hole and jets emanating
in opposite directions from near its poles. These sources are unique evidence of the most extreme speeds and energies known in the extreme Universe...
On March 17, MESSENGER (MErcury Surface, Space Environment, GEochemistry, and Ranging) completed its one-year primary mission, orbiting Mercury, capturing nearly 100,000 images, and recording data
that reveals new information about the planet's core, topography, and the mysterious radar bright material in the permanently shadowed areas near the poles.
In Douglas Adams book the Hitchhikers Guide to the Galaxy we encounter a machine called Deep Thought. It is the most powerful computer ever built. Deep Thought is capable of answering questions
concerning life, the Universe, and simply everything. Now scientists are planning to create a similar machine. It is called the Living Earth Simulator (LES).
Warped planets are some of the fastest objects in the Milky Way and they zoom through space near the speed of light.
Some years ago astronomers were astonished when they they found the first runaway star flying out of our Galaxy at a speed of 1.5 million miles per hour.
The discovery intrigued theorists, who wondered: If a star can get tossed outward at such an extreme velocity, could the same thing happen to planets?
Though the universe is filled with billions upon billions of stars, the discovery of a single variable star in 1923 altered the
course of modern astronomy. And, at least one famous astronomer of the time lamented that the discovery had shattered his world view.
The coldest class of stars have temperatures as cool as the human body.
Astronomers hunted these dark orbs, termed Y dwarfs, for more than a decade without success.
When viewed with a visible-light telescope, they are nearly impossible to see.
It's a very important discovery!
For the first time, an international team of scientists have detected all phases of thermonuclear burning in a
neutron star, located close to the center of the galaxy in the globular cluster Terzan 5.
Many mysteries regarding neutron stars have to be solved and one of such mysteries has just been revealed, the first direct evidence for
this bizarre state of matter in the core of a neutron star.
Neutron stars contain the densest known matter that is directly observable. One teaspoon of neutron star material weighs six billion tons.
Fermi Gamma-Ray Telescope has just crossed a new electromagnetic frontier and detected unknown objects producing gamma rays.
An interesting phenomenon has puzzled astronomers for long time.
In young solar systems emerging around baby stars, some orbits are more popular than others, resulting in “planet pile-ups” and “planet deserts."
Direct imaging of exoplanets has been a field in rapid development over the past few years, with detections of several planets and low-mass brown-dwarfs.
Among these discoveries, one claimed planet detection that stands out as peculiar in many ways is that of Fomalhaut b.