Black Hole Shadow: Very Large Telescope Zaps the Sky

Image of the Day: Laser Strikes at Supermassive Black Hole at Core of the Milky Way Galaxy

It's not the sequel to War of the Worlds! Astronomers at the Very Large Telescope (VLT) site in Chile are trying to measure the distortions of Earth's ever changing atmosphere. Constant imaging of high-altitude atoms excited by the laser -- which appear like an artificial star -- allow astronomers to instantly measure atmospheric blurring. In this case, the VLT was observing our Galaxy's center, and so Earth's atmospheric blurring in that direction was needed.

At the center of the Milky Way is Sagittarius A -believed to be a supermassive black hole, which lurk at the center of all spiral galaxies. If we can observe Sagittarius A*'s surroundings we can confirm once and for all whether it's a black hole - and prove Einstein right (or wrong!) . Relativity theory predicts the existence of black holes. If relativity breaks down, we might not see a black hole at all, but something totally weird.

Relativity describes how large masses can bend space, and a black hole is where the mass is so large that space gives up altogether and becomes a singularity. Black holes are already well understood, we think, but we've only ever observed them at second hand - the behavior of orbiting objects or bent light rays. To actually view the shadow of a black hole, the cut-off point where light is swallowed and cannot escape, would be a massive advance - and only the beginning.

Technorati Tags: Very Large Telescope, Chile, relativity, black hole

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"Naked Singularities" Could Negate All Laws of Physics

Fast-spinning black holes might reveal all - physics-math - 08 August 2009 - New Scientist

IT IS the ultimate cosmic villain: space and time come to an abrupt end in its presence and the laws of physics break down. Now it seems a "naked" black hole may yet emerge in our universe, after spinning away its event horizon.

In 1969, physicist Roger Penrose postulated that every singularity, or black hole, must be shrouded by an event horizon from which nothing, including light, can escape. His Cosmic Censorship Conjecture has it that singularities are always hidden.

If the conjecture doesn't hold, it would be bad news for cosmologists. If even one location in the universe cannot be described by the laws of physics, the future of the universe - as predicted by those laws - is cast into doubt. Our description of photons, for instance, may be undermined because those photons may have interacted with a naked singularity while zipping across the universe.

In theory, adding matter to a black hole could make it spin fast enough to shed its event horizon, but previously, physicists have calculated that the spin of black holes has an inherent speed limit that prevents such shedding. This limit is partly determined by the swirling tornado of space-time that surrounds a spinning black hole. Past simulations showed that if material was added that made space-time swirl faster, adding yet more material would be increasingly difficult because the increased centrifugal force might fling it outwards before it could reach the black hole's event horizon, spin it up and disrupt it.
Infalling matter can disrupt a black hole's event horizon, exposing a 'naked' singularity

However, these simulations began by adding matter to a black hole spinning at its maximum possible rate, say Ted Jacobson and Thomas Sotiriou at the University of Maryland at College Park. They simulated adding matter orbiting in the same direction to a black hole spinning just below its maximum rate. Their work suggests that the event horizon could then be disrupted and shed (www.arxiv.org/abs/0907.4146).

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Spitzer Space Telescope Discovers Galaxy, "Wild Creature of the Dark"

NASA - Coiled Creature of the Night

NASA's Spitzer Space Telescope has imaged a wild creature of the dark -- a coiled galaxy with an eye-like object at its center.

The galaxy, called NGC 1097, is located 50 million light-years away. It is spiral-shaped like our Milky Way, with long, spindly arms of stars. The "eye" at the center of the galaxy is actually a monstrous black hole surrounded by a ring of stars. In this color-coded infrared view from Spitzer, the area around the invisible black hole is blue and the ring of stars, white.

The black hole is huge, about 100 million times the mass of our sun, and is feeding off gas and dust along with the occasional unlucky star. Our Milky Way's central black hole is tame in comparison, with a mass of a few million suns.

The ring around the black hole is bursting with new star formation. An inflow of material toward the central bar of the galaxy is causing the ring to light up with new stars.

The galaxy's red spiral arms and the swirling spokes seen between the arms show dust heated by newborn stars. Older populations of stars scattered through the galaxy are blue. The fuzzy blue dot to the left, which appears to fit snuggly between the arms, is a companion galaxy. Astronomers say it is unclear whether this companion poked a hole in the larger galaxy, or just happens to be aligned in a gap in the arms.

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