Milky Way’s Giant Black Hole to Eat Space Cloud in 2013
by Clara Moskowitz
The colossal black hole at the center of our Milky Way galaxy will soon to get a big, tasty meal, astronomers say.
A humongous gas cloud is on a collision course for the Milky Way’s core — the home of Sagittarius A* (said: “Sagittarius A-star”), which scientists suspect is a supermassive black hole with the mass of 4 million suns. When the huge gas cloud arrives in the vicinity, which it will appear to us to do in mid-2013, it will surely be swallowed up by the hungry black hole, scientists say.
Astrophysicist Stefan Gillessen of the Max Planck Institute for Extraterrestrial Physics in Munich, Germany, has been observing the Milky Way’s center for about 20 years. So far, he’s seen only two stars come as close to Sagittarius A* as the cloud will. “They passed unharmed, but this time will be different: the gas cloud will be completely ripped apart by the tidal forces of the black hole,” Gillessen said in a statement…
(read more: Space.com) (image: Euro. Research Media Ctr.)
For the first time, scientists have peered to the edge of a colossal black hole and measured the point of no return for matter.
Image: This image from a simulation shows an energy jet launched from a spinning black hole surrounded by a disk of accreting material. The black hole is spinning at half the maximum rate, and its mass is that of the black hole at the center of the M87 elliptical galaxy. The central black hole ‘shadow’ due to extreme light bending is apparent in this simulation. Credit: Avery E. Broderick (University of Waterloo/Perimeter
A black hole has a boundary called an event horizon. Anything that falls within a black hole’s event horizon — be it stars, gas, or even light — can never escape.
“Once objects fall through the event horizon, they’re lost forever,” Shep Doeleman, assistant director of the MIT Haystack Observatory and research associate at the Smithsonian Astrophysical Observatory, said in a statement Thursday (Sept. 27). “It’s an exit door from our universe. You walk through that door, you’re not coming back.”
Although the event horizon is an imaginary line that’s impossible to observe, astronomers have imaged the region around a giant black hole at the center of a distant galaxy, and measured, for the first time, the closest stable orbit in which matter can circle the black hole. The findings were reported today in the journal Science.
The supermassive black hole in question lies at the center of the galaxy M87, which is about 50 million light-years from our own Milky Way. This behemoth black hole contains the mass of 6 billion suns.
Image: This views show the simulated event horizon-resolving images for the ultra-relativistic jet launched from the 7 billion solar-mass black hole at the center of the giant elliptical galaxy M87. Credit: Avery E. Broderick (University of Waterloo/Perimeter Institute)
By Ron Cowen of Nature magazine
A gas cloud that is careering towards the supermassive black hole at the centre of the Milky Way may be the visible trail of a planet-forming disk surrounding a young, low-mass star, astrophysicists propose.
Modeling work by Ruth Murray-Clay and Avi Loeb of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, suggests that planets can form within the powerful gravitational field of a giant black hole. And it heightens expectations about what astronomers might learn as the cloud nears the galaxy’s biggest black hole — an event expected to cause a spectacular light show that could begin as early as next year. The model is published today in Nature Communications.
Murray-Clay and Loeb began their study last autumn after hearing one of the first public talks about the gas cloud. The team that discovered it proposed that the cloud formed when gas flowing out from two stars collided. But Murray-Clay and Loeb immediately seized on the idea that the cloud’s mixture of gas and ionized dust might come from a planet-forming disk surrounding a single young star.
The idea isn’t as far-fetched as it might sound, because a ring of young stars is known to orbit at about 0.03 parsecs (one-tenth of a light year) from Sagittarius A*, the black hole of four million solar masses that lies at the Milky Way’s centre. In star-forming regions throughout the Galaxy, young stars often have planet-spawning disks, and Murray-Clay and Loeb reasoned that those in the region immediately surrounding a black hole might be no different.
According to their model, gravitational interactions dislodged a young, low-mass star orbiting near the ring’s inner edge. The ejected star, now heading towards Sagittarius A*, is too small and faint to be detected. However, material from the star’s disk — boiled off by ultraviolet radiation from other young stars and then stretched out by the black hole’s tidal gravitational forces to form an elongated cloud — can be observed.
Largest water reservoir discovered in black hole.
The reservoir holds as much as 140 trillion oceans, or more than 4,000 times more than exists in the entire Milky Way. It exists as vapour spread across hundreds of light years.
While water has been found across much of the universe previously, this is interesting because of the fact this reservoir is 12 billion light years away, meaning that this water existed when the universe was only 1.6 billion years old.
NGC 4151 is a spiral galaxy with an actively growing supermassive black hole at its center.
This composite image of NGC 4151 contains X-rays from Chandra (blue), optical data (yellow), and radio emission (red). The structure has been dubbed “The Eye of Sauron” by astronomers due to its resemblance to the character in “The Lord of the Rings” movies.
A recent study has shown that the X-ray emission was likely caused by an outburst powered by the supermassive black hole located in the white region in the center of the galaxy.
We could be living inside a black hole. This head-spinning idea is one cosmologist’s conclusion based on a modification of Einstein’s equations of general relativity that changes our picture of what happens at the core of a black hole.
In an analysis of the motion of particles entering a black hole, published in March, Nikodem Poplawski of Indiana University in Bloomington showed that inside each black hole there could exist another universe (Physics Letters B, DOI: 10.1016/j.physletb.2010.03.029). “Maybe the huge black holes at the centre of the Milky Way and other galaxies are bridges to different universes,” Poplawski says. If that is correct - and it’s a big “if” - there is nothing to rule out our universe itself being inside a black hole.
In Einstein’s general relativity (GR), the insides of black holes are “singularities” - regions where the density of matter reaches infinity. Whether the singularity is an actual point of infinite density or just a mathematical inadequacy of GR is unclear, as the equations of GR break down inside black holes. Either way, the modified version of Einstein’s equations used by Poplawski does away with the singularity altogether.