[Paleopsych] Space.com: Creation of Black Hole Detected

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Thu May 12 19:21:14 UTC 2005

Creation of Black Hole Detected 

    By [13]Robert Roy Britt
    Senior Science Writer

    Astronomers photographed a cosmic event this morning which they
    believe is the birth of a black hole, SPACE.com has learned.

    A faint visible-light flash moments after a high-energy gamma-ray
    burst likely heralds the [14]merger of two dense neutron stars to
    create a relatively low-mass black hole, said Neil Gehrels of NASA's
    Goddard Space Flight Center. It is the first time an optical
    counterpart to a very short-duration gamma-ray burst has ever been

    Gamma rays are the most energetic form of radiation on the
    electromagnetic spectrum, which also includes X-rays, light and radio

    The merger occurred 2.2 billion light-years away, so it actually took
    place 2.2 billion years ago and the light just reached Earth this

    Quick global effort

    Gehrels said the burst occurred just after midnight East Coast time.
    It was detected by NASA's orbiting Swift telescope. Swift
    automatically repositioned itself within 50 seconds to image the same
    patch of sky in X-rays. It just barely caught an X-ray afterglow,
    Gehrels said in a telephone interview.

    The X-ray counterpart was barely detectable and only observed for a
    few minutes.

    An email was sent out to astronomers worldwide, and large
    observatories then tracked to the location and spotted a faint
    visible-light afterglow.

    Gamma ray bursts are [15]mysterious beasts. They come from all over
    the universe. Long-duration bursts, lasting a few seconds, are thought
    to be associated with the formation of black holes when massive stars
    explode and collapse. In recent years, scientists have detected X-ray
    and optical afterglows of these long bursts.

    Very short-duration bursts, like the one this morning, last only a
    tiny fraction a second. Until now, no optical afterglows from these
    bursts have been detected. Theorists think a burst like this
    represents the formation of a black hole a few times the mass of the
    Sun, but if so, then there should be flashes of X-rays and visible
    light, too.

    The burst has been named GRB050509b.

    What happened

    Steinn Sigurdsson, a Penn State University researcher who is excited
    about the observations but was not involved in them, explained what
    theorists think happened:

    Over a long time period, at least a hundred million years and perhaps
    billions of years, the two neutron stars spiraled toward each other.
    Neutron stars themselves are [16]very dense objects, collapsed stellar

    "A fraction of a second before contact, the lower mass neutron star is
    disrupted and forms a neutrino driven accretion disk around the higher
    mass neutron star," Sigurdsson told SPACE.com. "It implodes under the
    weight and forms a maximally spinning low-mass black hole."

    Astronomers can't see black holes, because light and everything else
    that enters them is lost to observation. But just before material
    falls in, some high-energy process -- likely involving magnetism and
    speeds approach that of light -- vents some of the material back into

    The gamma ray burst signals the formation of a superheated jet of gas
    being shot out from the chaotic region around the newly formed black
    hole at a significant fraction of light-speed, Sigurdsson said.

    "This really does look like a merger scenario," said Gehrels, who
    heads up the scientific operations for the Swift satellite.

    The first gamma-ray burst was detected by accident in 1967. It was
    found by U.S. satellites deployed to monitor possible violations of
    the nuclear test ban treaty. Researchers now know that one erupts
    roughly every day somewhere in the cosmos. Most originate many
    billions of light years away.

    Each burst can briefly outshine an entire galaxy. Gamma-ray bursts in
    our own galaxy are [17]very rare. Some scientists speculate that such
    bursts in the Milky Way's past might have [18]caused mass extinctions
    on Earth.


   14. http://www.space.com/scienceastronomy/neutron_stars_031203.html
   15. http://www.space.com/scienceastronomy/burst_blackholes_030305.html
   16. http://www.space.com/scienceastronomy/neutron_stars_031203.html
   17. http://www.space.com/scienceastronomy/bright_flash_050218.html

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