HEAPOW: Unseen is Important (2010 Dec 13)

[bystander]

HEAPOW: Unseen is Important (2010 Dec 13)

Often the story's told by what's there, though sometimes what's missing is most important. This has turned out to be the case in the explanation of Hanny's Voorwerp, a mysterious green glow found by Hanny van Arkel, a Dutch school teacher and avid participant in the Galaxy Zoo project. Galaxy Zoo lets volunteers scan online images of galaxies to categorize them and to search for peculiar and mysterious cosmic objects. Such as the Voorwerp (Dutch for "object") shown in the image above, just below the large spiral galaxy IC 2497. The Voorwerp is really a huge patch of ionized gas and an intense puzzle to astronomers. Illumination by radiation produced by a supermassive blackhole in the center of IC 2497 was presumed a likely culprit, but optical images of IC 2497 showed no sign of the tell-tale activity expected near the nucleus of the galaxy. Maybe the active supermassive black hole is really hidden by thick clouds of gas and dust in the galaxy's nucleus. Astronomers tried to detect infrared radiation from these clouds, to no avail. Then, using the Suzaku X-ray satellite, astronomers tried to directly detect evidence of a hidden active black hole in IC 2497 using the penetrating power of its hard X-ray emission. But Suzaku showed no signs of any such X-ray emission. Strangely, this means that the black hole near the center of IC 2497 shut off in the recent past, and the Voorwerp is only a faint echo of this once-mighty beast. A case of sudden death on a cosmic scale.

The Sudden Death of the Nearest Quasar - Hanny's Voorwerp Explained
http://asterisk.apod.com/vie ... 82#p136082

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HEAPOW: Unseen is Important (2010 Dec 13)

Huge Gamma Ray Bubbles Found Around Milky Way

Explanation: Did you know that our Milky Way Galaxy has huge bubbles emitting gamma rays from the direction of the galactic center? Neither did anybody. As the data from the Earth-orbiting Fermi satellite began acuminating over the past two years, however, a large and unusual feature toward our Galaxy's center became increasingly evident. The two bubbles are visible together as the red and white spotted oval surrounding the center of the above all sky image, released yesterday. The plane of our Galaxy runs horizontally across the image center. Assuming the bubbles emanate from our Galaxy's center, the scale of the bubbles is huge, rivaling the entire Galaxy in size, and spanning about 50,000 light years from top to bottom. Earlier indications of the bubbles has been found on existing all sky maps in the radio, microwave, and X-ray. The cause of the bubbles is presently unknown, but will likely be researched for years to come.