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RXTE Homes in on a Black Hole's Jets

For decades, X-ray astronomers have studied the complex behaviour of binary systems pairing a normal star with a black hole. In these systems, gas from the normal star streams toward the black hole and forms a disk around it. Friction within the disk heats the gas to millions of degrees -- hot enough to produce X-rays. At the disk's inner edge, near the black hole, strong magnetic fields eject some of the gas into dual, oppositely directed jets that blast outward at about half the speed of light.
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Backwards Black Holes Might Make Bigger Jets

Black holes are immense distortions of space and time with gravity that is so great, even light itself cannot escape. Astronomers have known for more than a decade that all galaxies, including our own Milky Way, are anchored by tremendous, so-called supermassive black holes, containing billions of suns' worth of mass. The black holes are surrounded and nourished by disks of gas and dust, called accretion disks. Powerful jets stream out from below and above the disks like lasers, and fierce winds blow off from the disks themselves.
The black holes can spin either in the same direction as the disks, called prograde black holes, or against the flow -- the retrograde black holes. For decades, astronomers thought that the faster the spin of the black hole, the more powerful the jet. But there were problems with this "spin paradigm" model. For example, some prograde black holes had been found with no jets.

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Supermassive Black Holes
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When black holes go rogue, they kill galaxies

It was already known that "supermassive" black holes at the centre of most galaxies sometimes emit vast amounts of radiation. But nobody had a good idea how common such violence is. A snapshot of the universe doesn't give enough information to judge this because the activity of the black holes is thought to be intermittent, depending on how much nearby matter they have to feed on.
Now a team of astronomers have compiled a chronicle of activity going back deep into cosmic history, using the orbiting Chandra telescope to spot X-rays emitted by the black holes together with images from Hubble  to look at their host galaxies. Previous surveys with less sensitive instruments were unable to spot the distant faint sources picked up by Chandra and Hubble. The team now have a set of galaxies reaching 13 billion light years.

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Black holes
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Black holes and galaxy death

Black holes are thought to reside at the centre of almost every galaxy, with some growing to more than a billion times the mass of the Sun. Now a team of UK astronomers believe that these supermassive black holes are commonplace, release more than enough energy to strip their host galaxies apart and in the process shut down these galaxies' star formation for good. On Friday 16th April, team member Asa Bluck of the University of Nottingham, who led this research, will explain the dramatic impact of these monster black holes in his talk at the RAS National Astronomy Meeting (NAM 2010) in Glasgow.
For many years black holes have fascinated scientists and the public alike, with their peculiar ability to warp space and time and their almost sinister tendency to devour everything they encounter. Before it falls in, as matter swirls around the black hole it forms an "accretion disk", where it heats up and radiates energy. The supermassive black holes have such a strong gravitational field that the infalling matter releases a vast amount of energy, making each accretion disk far brighter than the combined output of the hundreds of billions of stars in the galaxy around it.

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Title: A General Formula for Black Hole Gravitational Wave Kicks
Authors: James R. van Meter, M. Coleman Miller, John G. Baker, William D. Boggs, Bernard J. Kelly

Although the gravitational wave kick velocity in the orbital plane of coalescing black holes has been understood for some time, apparently conflicting formulae have been proposed for the dominant out-of-plane kick, each a good fit to different data sets. This is important to resolve because it is only the out-of-plane kicks that can reach more than 500 km/s and can thus eject merged remnants from galaxies. Using a different ansatz for the out-of-plane kick, we show that we can fit almost all existing data to better than 5 %. This is good enough for any astrophysical calculation, and shows that the previous apparent conflict was only because the two data sets explored different aspects of the kick parameter space.

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Retrograde spin of supermassive black holes may create jets that control galaxy evolution

Scattered throughout every galaxy are black holes, regions that gobble up matter and energy. Although we can't see black holes, scientists can infer their size, location and other properties by using sensitive telescopes to detect the heat they generate. This heat, which we see as X-rays, is produced as material spirals around a black hole faster and faster until it reaches a point of no return - the "event horizon" - from which nothing, not even light, can escape.
In addition to a galaxy's collection of black holes, which includes black holes up to 10 times the sun's mass, there is a supermassive black hole embedded in the heart of each galaxy that is roughly one million to one billion times the mass of the sun. About 10 percent of these giant black holes feature jets of plasma, or highly ionised gas, that extend perpendicularly from each side of the event horizon. By spewing huge amounts of mostly kinetic energy, or energy created by motion, from the black holes into the universe, the jets affect how stars and other bodies form, and play a crucial role in the evolution of clusters of galaxies, the largest structures in the universe.

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New black hole simulator uses real star data

A new interactive program that uses data from more than 100,000 stars reveals the spectacular light show you'd see if you dared to wander close to a black hole. It demonstrates how the extreme gravity of a black hole could appear to shred background constellations of stars, spinning them around as though in a giant black washing machine.
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-- Edited by Blobrana on Tuesday 9th of February 2010 08:44:09 PM

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A team of astronomers recently discovered 33 sets of double black holes in distant galaxies. Though these black hole pairs had been predicted theoretically, only a handful had been observed so far.

"[The findings] show that dual supermassive black hole systems are much more common than previously known from observations" - researcher Julia Comerford, an astrophysicist at the University of California, Berkeley.

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UC Irvine professor talks about his outer space research.
UC Irvine physics and astronomy professor Aaron Barth spoke at the university Tuesday morning about his teams research on black holes.
His team has been responsible for the discovery of eight of what are believed to be some of the smallest known black holes in the universe.

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First Black Holes May Have Incubated in Giant, Starlike Cocoons
The first large black holes in the universe likely formed and grew deep inside gigantic, starlike cocoons that smothered their powerful x-ray radiation and prevented surrounding gases from being blown away, says a new study led by the University of Colorado at Boulder.
The formation process involved two stages, said Mitchell Begelman, a professor and the chair of CU-Boulder's astrophysical and planetary sciences department. The predecessors to black hole formation, objects called supermassive stars, probably started forming within the first few hundred million years after the Big Bang some 14 billion years ago. A supermassive star eventually would have grown to a huge size -- as much as tens of millions of times the mass of our sun -- and would have been short-lived, with its core collapsing in just in few million years, he said.
In the new study to be published in Monthly Notices of the Royal Astronomical Society in London, Begelman calculated how supermassive stars might have formed, as well as the masses of their cores. These calculations allowed him to estimate their subsequent size and evolution, including how they ultimately left behind "seed" black holes.

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