 Supermassive black holes help to shape our universe, but their behavior is still poorly understood. (Source: PureInsight.org)
 A new NASA study examined the supermassive black hole at our galaxy's center and found that it sucks up less matter than previously thought, due to pressure from radiation. (Source: NASA/CXC/MIT/F.K. Baganoff et al.)
The Milky Way's black hole is causing a mess, but isn't gobbling matter as fast as was thought
One of the most complex and intriguing astrophysical phenomenon is the supermassive black hole. A superdense cluster of mass, the supermassive black hole gobbles up surrounding matter, sucking it into its gravity well. Despite the tremendous importance of these celestial bodies to the structure of our universe, scientists still remain confused about specifics of how they operate.
It is a well known fact that there is a supermassive black hole at the center of our galaxy, the Milky Way. Dubbed Sagittarius A* (Sgr A*), the black hole is rather weak, due to its inability to successfully capture significant mass. The black hole is bordered by dozens of young stars. It pulls gas off these stars, but is only able to suck in a small percentage of this high velocity stream.
Past estimates put its consumption rate at a mere 1 percent of the gas it pulls away from the stars. Now a new study, using data garnered from the NASA's Chandra X-ray Observatory, has determined that the black hole is likely eating far less than that figure even --- new models indicate it to be consuming a mere 0.01 percent of the gas it sucks off.
The observed data allowed the development of a theoretical model, which explains energetic behavior inside the region between the fuel source (young stars) and the event horizon (the central boundary of black hole, beyond which light can not escape).
The new model offers an explanation as to why even more gas was rushing away from the black hole than expected. Apparently, the black hole's accretion disk gets very hot due to the densely packed gas. Some of this gas escapes, colliding with neighboring gas particles in the "wind" in a phenomena commonly known as radiation. This radiation heats up the gas in the stream surrounding the black hole, and creates an outward pressure, driving gas away from the black hole. As a result the black hole is only able to eat a very small amount of gas.
That's good news for the Earth, as a hungry black hole could eventually suck in much of the Milky Way, including the Earth (of course, there's plenty of other cosmic disasters that could strike before then). With fears of the Milky Way's black hole allayed, the public can go back to worrying about their other phantom fears, like micro-black holes and the Large Hadron Collider.
The new study was among the best efforts to date showcasing the potential of NASA's Chandra X-ray Observatory. The observatory was able to record a wealth of data -- nearly one million seconds (two weeks) worth. Most of this data came from observations of gas traveling off of a supernova remnant.
Among the other fascinating phenomena observed was mysterious X-ray filaments. The filaments are thought to be the result of huge magnetic structures interacting with streams of energetic electrons produced by pulsars ( rapidly spinning neutron stars). This strange phenomena is known as a pulsar wind nebula.
The new view of Sgr A* and its smaller appetite were revealed at the 215th meeting of the American Astronomical Society in January 2009 by Roman Shcherbakov and Robert Penna of Harvard University and Frederick K. Baganoff of the Massachusetts Institute of Technology.
"Young lady, in this house we obey the laws of thermodynamics!" -- Homer Simpson
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