Black Hole
A black hole is a mathematically defined region of spacetime exhibiting such a strong gravitational pull that no particle or electromagnetic radiation can escape from it. The theory of general relativity predicts that a sufficiently compact mass can deform spacetime to form a black hole. The boundary of the region from which no escape is possible is called the event horizon. Although crossing the event horizon has enormous effect on the fate of the object crossing it, it appears to have no locally detectable features. In many ways a black hole acts like an ideal black body, as it reflects no light.
Objects whose gravitational fields are too strong for light to escape were first considered in the 18th century by John Michell and Pierre-Simon Laplace. The first modern solution of general relativity that would characterize a black hole was found by Karl Schwarzschild in 1916, although its interpretation as a region of space from which nothing can escape was first published by David Finkelstein in 1958. Long considered a mathematical curiosity, it was during the 1960s that theoretical work showed black holes were a generic prediction of general relativity. The discovery of neutron stars sparked interest in gravitationally collapsed compact objects as a possible astrophysical reality.
Black holes of stellar mass are expected to form when very massive stars collapse at the end of their life cycle. After a black hole has formed, it can continue to grow by absorbing mass from its surroundings. By absorbing other stars and merging with other black holes, supermassive black holes of millions of solar masses (M☉) may form. There is general consensus that supermassive black holes exist in the centers of most galaxies.
(Wikipedia)
A stellar-mass black hole
#1: A stellar-mass black hole
GRS 1915+105 : A stellar-mass black hole with about 14 times the Sun’s mass in the Milky Way.
Image credit: X-ray (NASA/CXC/Harvard/J.Neilsen); Optical & IR (Palomar DSS2)
Source and Reference: chandra.harvard.edu
Click here for Animations.
Click here for Animations.
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GRS 1915+105 Animations
GRS 1915+105 Animations
GRS 1915+105: Erratic Black Hole Regulates Itself
Spiral Galaxy M81 - A supermassive black hole
#2: Spiral Galaxy M81 - A supermassive black hole
M81 is a spiral galaxy about 12 million light years away that is both relatively large in the sky and bright, making it a frequent target for both amateur and professional astronomers.
Image credit: X-ray: NASA/CXC/SAO; Optical: Detlef Hartmann; Infrared: NASA/JPL-Caltech
Source and Reference: chandra.harvard.edu
M81 Animations chandra.harvard.edu
Simulation of gravitational lensing by a black hole, which distorts the image of a galaxy in the background
#5: Simulation of gravitational lensing by a black hole, which distorts the image of a galaxy in the background
Animated simulation of gravitational lensing caused by a black hole going past a background galaxy. A secondary image of the galaxy can be seen within the black hole Einstein ring on the opposite direction of that of the galaxy. The secondary image grows (remaining within the Einstein ring) as the primary image approaches the black hole. The surface brightness of the two images remains constant, but their angular size varies, hence producing an amplification of the galaxy luminosity as seen from a distant observer. The maximum amplification occurs when the background galaxy (or in the present case a bright part of it) is exactly behind the black hole.
Image source: commons.wikimedia.org
Simulated view of a black hole (center) in front of the Large Magellanic Cloud.
#6: Simulated view of a black hole (center) in front of the Large Magellanic Cloud.
Note the gravitational lensing effect, which produces two enlarged but highly distorted views of the Cloud. Across the top, the Milky Way disk appears distorted into an arc.
Simulated view of a black hole in front of the Large Magellanic Cloud. The ratio between the black hole Schwarzschild radius and the observer distance to it is 1:9. Of note is the gravitational lensing effect known as an Einstein ring, which produces a set of two fairly bright and large but highly distorted images of the Cloud as compared to its actual angular size.
Image source: commons.wikimedia.org
Black Holes: Monsters in Space (Artist's Concept)
#7: Black Holes: Monsters in Space (Artist's Concept)
This artist's concept illustrates a supermassive black hole with millions to billions times the mass of our sun. Supermassive black holes are enormously dense objects buried at the hearts of galaxies. (Smaller black holes also exist throughout galaxies.) In this illustration, the supermassive black hole at the center is surrounded by matter flowing onto the black hole in what is termed an accretion disk. This disk forms as the dust and gas in the galaxy falls onto the hole, attracted by its gravity.
Also shown is an outflowing jet of energetic particles, believed to be powered by the black hole's spin. The regions near black holes contain compact sources of high energy X-ray radiation thought, in some scenarios, to originate from the base of these jets. This high energy X-radiation lights up the disk, which reflects it, making the disk a source of X-rays. The reflected light enables astronomers to see how fast matter is swirling in the inner region of the disk, and ultimately to measure the black hole's spin rate.
Image source: commons.wikimedia.org
Supermassive black hole at the center of the Milky Way galaxy
Supermassive black hole at the center of the Milky Way galaxy
Astronomers have observed the largest X-ray flare ever detected from the supermassive black hole at the center of the Milky Way galaxy. This event, detected by NASA’s Chandra X-ray Observatory, raises questions about the behavior of this giant black hole and its surrounding environment.
The supermassive black hole at the center of our galaxy, called Sagittarius A*, or Sgr A*, is estimated to contain about 4.5 million times the mass of our sun.
A supermassive black hole - A composite image
Spiral Galaxy M81 - A supermassive black hole
#2: Spiral Galaxy M81 - A supermassive black hole
M81 is a spiral galaxy about 12 million light years away that is both relatively large in the sky and bright, making it a frequent target for both amateur and professional astronomers.
Image credit: X-ray: NASA/CXC/SAO; Optical: Detlef Hartmann; Infrared: NASA/JPL-Caltech
Source and Reference: chandra.harvard.edu
M81 Animations chandra.harvard.edu
A composite NASA image of the spiral galaxy M81
#2: A composite NASA image of the spiral galaxy M81, located about 12 million light years away. This composite NASA image of the spiral galaxy M81, located about 12 million light years away, includes X-ray data from the Chandra X-ray Observatory (blue), optical data from the Hubble Space Telescope (green), infrared data from the Spitzer Space Telescope (pink) and ultraviolet data from GALEX (purple). The inset shows a close-up of the Chandra image. At the center of M81 is a supermassive black hole that is about 70 million times more massive than the Sun.
Image credit: X-ray: NASA/CXC/Wisconsin/D.Pooley & CfA/A.Zezas; Optical: NASA/ESA/CfA/A.Zezas; UV: NASA/JPL-Caltech/CfA/J.Huchra et al.; IR: NASA/JPL-Caltech/CfA
Source and Reference: chandra.harvard.edu
More images of M81
Chandra X-ray Image of M81
Chandra X-ray Image of M81
The biggest black holes may feed just like the smallest ones, according to data from NASA's Chandra X-ray Observatory and ground-based telescopes. This discovery supports the implication of Einstein's relativity theory that black holes of all sizes have similar properties,
Image source: chandra.harvard.edu
Optical Image of M81
Optical Image of M81
show optical data from the Hubble Space Telescope (green).
Image source: chandra.harvard.edu
Infra-red Image of M81
Infra-red Image of M81
show infrared data from the Spitzer Space Telescope (pink).
Image source: chandra.harvard.edu
UV Image of M81
UV Image of M81
show ultraviolet data from GALEX (purple).
Image source: chandra.harvard.edu
Gravitational Waves Detected
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Gravitational Waves Detected (Video)
Where does Physics go from here now that we’ve found gravitational waves?
Einstein's gravitational waves 'seen' from black holes
Scientists have observed the warping of space-time generated by the collision of two black holes more than a billion light-years from Earth.
Scientists are claiming a stunning discovery in their quest to fully understand gravity. For the first time, scientists detect tiny, rhythmic distortions in space and time - gravitational waves - predicted by Einstein 100 years ago..
Scientists record a fourth set of gravitational waves (September 28, 2017)
Looking for gravitational waves.
Last year, researchers confirmed the existence of gravitational waves with two Laser Interferometer Gravitational-wave Observatory (LIGO) detectors. Shortly thereafter, they detected twoadditional gravitational wave-causing events that sent ripples through the universe. Well, we can now add a fourth to that list, as astronomers announced another set of waves.
2017 Nobel Prize in Physics Awarded to LIGO Black Hole Researchers
From left: Rainer Weiss, Barry Barish and Kip Thorne, the architects and leaders of LIGO, the Laser Interferometer Gravitational-wave Observatory.
Rainer Weiss, a professor at the Massachusetts Institute of Technology, and Kip Thorne and Barry Barish, both of the California Institute of Technology, were awarded the Nobel Prize in Physics on Tuesday for the discovery of ripples in space-time known as gravitational waves, which were predicted by Albert Einstein a century ago but had never been directly seen.
In announcing the award, the Royal Swedish Academy called it “a discovery that shook the world.”
That shaking happened in February 2016, when an international collaboration of physicists and astronomers announced that they had recorded gravitational waves emanating from the collision of a pair of massive black holes a billion light years away, it mesmerized the world. The work validated Einstein’s longstanding prediction that space-time can shake like a bowlful of jelly when massive objects swing their weight around, and it has put astronomers on intimate terms with the deepest levels of physical reality, of a void booming and rocking with invisible cataclysms.
Astrophysical Jets (Black Hole Beams, Black Hole Death Rays, 'Relativistic Jets')
Scientists penetrate mystery of raging black hole beams
Astrophysical jets (black hole beams)
Artist's impression of astrophysical jets emitting from the binary system V404 Cygni. Credit: G Pérez Díaz (IAC)
They are nature's very own Death Star beams - ultra-powerful jets of energy that shoot out from the vicinity of black holes like deadly rays from the Star Wars super-weapon.
Now a team of scientists led by the University of Southampton has moved a step closer to understanding these mysterious cosmic phenomena - known as relativistic jets - by measuring how quickly they 'switch on' and start shining brightly once they are launched.
Read more at: https://phys.org/news/2017-10-scientists-penetrate-mystery-raging-black.html#jCp
Nature’s ‘Death Stars’ revealed
Nature’s ‘Death Stars’ revealed
Scientists discover powerful beams of energy that fire from black holes are created by matter squeezed so tight they erupt as streams of plasma
'Relativistic jets' are powerful beams of energy that fire from black holes
Scientists have long puzzled how the jets, which flash visible light, are created
Research found the jets form when gravity squeezes matter until it fires outward
The stream accelerates across a distance of 19,000 miles (30,000 km) before it gives off a series of typical visible light flashes
Read more: http://www.dailymail.co.uk/sciencetech/article-5031749/Researchers-confirm-black-hole-relativistic-jets-form.html#ixzz4xCFlZQjq
How a Distant Black Hole Devoured a Star
How a Distant Black Hole Devoured a Star
This illustration steps through the events that scientists think likely resulted in Swift J1644+57.
On March 28, 2011, NASA's Swift detected intense X-ray flares thought to be caused by a black hole devouring a star. In one model, illustrated here, a sun-like star on an eccentric orbit plunges too close to its galaxy's central black hole. About half of the star's mass feeds an accretion disk around the black hole, which in turn powers a particle jet that beams radiation toward Earth.
Credits: NASA/Goddard Space Flight Center/Swift
Two studies appearing in the Aug. 25 issue of the journal Nature provide new insights into a cosmic accident that has been streaming X-rays toward Earth since late March. NASA's Swift satellite first alerted astronomers to intense and unusual high-energy flares from the new source in the constellation Draco.
Swift continues to record high-energy flares from J1644+57 more than three months after the source's first appearance.
Swift's X-Ray Telescope continues to record high-energy flares from Swift J1644+57 more than three months after the source's first appearance. Astronomers believe that this behavior represents the slow depletion of gas in an accretion disk around a supermassive black hole. The first flares from the source likely coincided with the disk's creation, thought to have occurred when a star wandering too close to the black hole was torn apart.
This source is still producing X-rays and may remain bright enough for Swift to observe into next year.
Astronomers soon realized the source, known as Swift J1644+57, was the result of a truly extraordinary event -- the awakening of a distant galaxy's dormant black hole as it shredded and consumed a star. The galaxy is so far away, it took the light from the event approximately 3.9 billion years to reach Earth.
Why every picture of a black hole is an illustration
Read the article at www.vox.com Most images of black holes are illustrations. Here’s what our telescopes actually capture. Copy
What Hawking meant when he said ‘there are no black holes’
Illustration of the supermassive black holes.
This artist’s concept shows a supermassive black hole with millions to billions times the mass of our sun. Supermassive black holes are enormously dense objects buried at the hearts of galaxies, and fundamental aspects of their behavior have baffled scientists. Image by NASA/JPL-Caltech (www.pbs.org/)
In this illustration, the supermassive black hole at the center is surrounded by matter flowing onto the black hole in what is termed an accretion disk. This disk forms as the dust and gas in the galaxy falls onto the hole, attracted by its gravity. Also shown is an outflowing jet of energetic particles, believed to be powered by the black hole's spin. NASA/JPL-Caltech (www.vox.com)
Read the article at www.pbs.org What Hawking meant when he said ‘there are no black holes’ Copy