New Theory On Size Of Black Holes.
Black holes are slowly giving up their dark secrets
Astronomers have put forward a brand new theory about why black holes become so hugely massive – claiming some of them have no ‘table manners’, and tip their ‘food’ directly into their mouths, eating more than one course simultaneously. Researchers from the UK and Australia investigated how some black holes grow so fast that they are billions of times heavier than the sun.
The team from the University of Leicester (UK) and Monash University in Australia sought to establish how black holes got so big so fast. Their research is due to be published in the Monthly Notices of the Royal Astronomical Society. The research was funded by the UK Science and Technology Facilities Council.
Professor Andrew King from the Department of Physics and Astronomy, University of Leicester, said: “Almost every galaxy has an enormously massive black hole in its centre. Our own galaxy, the Milky Way, has one about four million times heavier than the sun. But some galaxies have black holes a thousand times heavier still. We know they grew very quickly after the Big Bang.”
“These hugely massive black holes were already full—grown when the universe was very young, less than a tenth of its present age.” Black holes grow by sucking in gas. This forms a disc around the hole and spirals in, but usually so slowly that the holes could not have grown to these huge masses in the entire age of the universe. `We needed a faster mechanism,’ says Chris Nixon, also at Leicester, “so we wondered what would happen if gas came in from different directions.”
Nixon, King and their colleague Daniel Price in Australia made a computer simulation of two gas discs orbiting a black hole at different angles. After a short time the discs spread and collide, and large amounts of gas fall into the hole. According to their calculations black holes can grow 1,000 times faster when this happens.
“If two guys ride motorbikes on a Wall of Death and they collide, they lose the centrifugal force holding them to the walls and fall,” says King. The same thing happens to the gas in these discs, and it falls in towards the hole.
This may explain how these black holes got so big so fast. “We don’t know exactly how gas flows inside galaxies in the early universe,” said King, “but I think it is very promising that if the flows are chaotic it is very easy for the black hole to feed.” The two biggest black holes ever discovered are each about ten billion times bigger than the Sun. Source: R&D
Black Hole Punch Can Launch a Planet
Every galaxy appears to harbour a Black Hole
Punched by the gravitational fist of Sagittarius A* (Sgr A*), the location of the supermassive black hole that lives at the center of our galaxy, a planet could be hurled through space at speeds of up to 30 million miles per hour (48 million kilometers per hour), the Harvard-Smithsonian Center for Astrophysics and Dartmouth College report this week.
“These warp-speed planets would be some of the fastest objects in our galaxy. If you lived on one of them, you’d be in for a wild ride,” Harvard-Smithsonian’s Avi Loeb said in a press release about the research.
The only known objects that move faster than these planets are subatomic particles, added Dartmouth’s Idan Ginsburg. Scientists got to thinking about runaway planets after colleagues discovered a star launching out of the Milky Way at 1.5 million miles per hour (2.4 million kilometers per hour).
Simulations showed the star — known as a hypervelocity star — must have been part of a double-star system that ended up in the wrong part of the Milky Way.
“A double-star system wanders too close to the supermassive black hole at the galactic center. Strong gravitational forces rip the stars from each other, sending one away at high speed while the other is captured into orbit around the black hole,” writes Christine Pulliam, spokeswoman for the Harvard-Smithsonian Center for Astrophysics.
So, what exactly IS a Black Hole? Join us as we explore one of the most exotic objects in the whole universe. Why can’t anything escape a black hole? What’s at the bottom of a black hole? Watch and find out!
Turns out the same thing can happen to planets. Ginsburg, Loeb and Darthmouth’s Gary Wegner created computer models showing what would happen if each star had a planet or two orbiting nearby.
“They found that the star ejected outward could carry its planets along for the ride. The second star, as it’s captured by the black hole, could have its planets torn away and flung into the icy blackness of interstellar space at tremendous speeds,” Pulliam wrote.
A typical hypervelocity planet would slingshot outward at 7 to 10 million miles per hour, she added, noting that “a small fraction of them could gain much higher speeds under ideal conditions.”
Because any tag-along planets would have to be in tight orbits around their parent stars, astronomers may be able to detect them by looking for a hypervelocity star that dims slightly as its planet passes across its face, relative to the view from Earth. Source: Discovery News
Related articles
- Our Galaxy’s Giant Black Hole May Munch on Asteroids (topalternativenews.com)
- Hungry black holes eat two courses at once (newscientist.com)
