Using space telescopes to measure the black hole distortion

An innovative X-ray telescope operated by NASA, working in conjunction with a satellite of the European Space Agency, has been measured directly the rotation of a supermassive black hole lurking at the heart of a distant galaxy, researchers said on Wednesday .
The observation confirms the predictions of Albert Einstein’s theory of gravity capacity of general relativity with respect to twist and distort the structure of the cosmos and gives astronomers a powerful new tool to investigate the evolution of galaxies and black holes that now appear to be a common, if not necessary feature.

“The results we are announcing today is that, for the first time, we can definitely play features seen in the X-ray emission from a supermassive black hole and because the hole’s gravity is incredibly strong,” said Fiona Harrison, a researcher Main Nuclear Spectroscopic Telescope Array NASA or NuSTAR, X-ray telescope mission.
“The amazing thing about this observation is that we can see the curvature and torsion of space-time, the black hole distorts the very fabric of our universe. This distortion allows us to measure how fast the black hole is spinning.”
The galaxy in question, known as NGC 1365, is 56 million light years from Earth. The black hole in the center of the galaxy is 2 million times more massive than the sun.
By definition, black holes are not directly visible because their gravity is so intense that electromagnetic radiation can escape. But can be detected by illuminating radiation generated as gas particles and dust are sucked and heated to extreme temperatures.
The material falling into a black hole can form an accretion disk of debris spiral into the hole’s event horizon, the point defined by body mass and gravity beyond which nothing, not even light, can escape . Once an object crosses the event horizon, is lost forever in the known universe.
To measure the rotation of the black hole at the center of NGC 1365, the data was combined NuSTAR satellite observations with XMM-Newton of the European Space Agency, which is sensitive to low-energy X-rays.
The overlap allowed researchers rule out alternative explanations, resulting in a remarkable three days of observation that “solving a problem of two decades of life,” said Harrison. “Now we can say that the characteristics of the observed X-ray colors from black holes can definitely be used to measure the rotation of the black hole.”
In this case, the spacecraft studied X-rays reflected from the accretion disk around the black hole at the center of NGC 1365. Harrison said that the rotational energy was equivalent to the output of a billion stars over billions of years.
Asked if he could translate that into a more easily understandable speed, said “black holes are really weird …. It’s not like we can paint a small dot in the black hole, the event horizon, for example, and watch it rotate around a certain speed.’s probably more accurate to think of the amount of energy captured rotation, if that makes sense. ”
For at least one reporter, it was tough sledding. So Harrison offered an alternative explanation:
“We really spinning black holes twist and distort space-time,” she said. “If you were standing near the event horizon of the black hole in particular, you would have to turn around, because its twists spacetime, would be turning around once every four minutes just to stand still.”
Regardless of amazing physics involved, the ability to directly measure the rotation of the supermassive black holes gives astronomers a potentially powerful tool for the study of galaxy evolution.
“We know that today most, if not all, galaxies have a supermassive black hole at its center,” said Arvind Parmar, director of Astrophysics and Fundamental Physics at the European Space Agency. “The one in the center of our galaxy, the Milky Way, for example, weighs as much as four million suns.
“We believe that these black holes were born when the universe was only 10 percent of its current age. And when they were born, weighing only 20 to 30 times the mass of the sun. The real question is, how they grow from these small objects supermassive black holes we see today? ”
There are at least two possibilities. Black holes can grow by accumulation, ie, by sucking in surrounding material, or by collisions, when a black hole actually merges with another.
Accretion can cause rapid rotation while mergers of black holes can lead to different rates depending on the orientations of the holes colliding. The ability to measure the rotation could help astronomers determine which process is more common and the effect it has on the evolution of the galaxy.
“Even with these two wonderful missions, we can only measure the spins of these black holes in nearby galaxies bright,” said Parmar. “What I really like to do is to extend these studies to the more distant universe and see how the average rates of change in black hole spin with cosmic time.
“And this would allow us to investigate the importance of accumulation and the importance of the merger in the creation of the universe we see today,” he said. “It would help us understand why the universe looks as it does today.”

credit CNET


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