2007-Dec-19, Wednesday

death in the night

2007-Dec-19, Wednesday 02:15 am
mellowtigger: (Default)
How's that for a sensational headline?

Story #1: sniper rifle

Gamma Ray Bursts (GRBs) are the brightest events in the whole universe. (Well, except for the creation of the universe itself in the Big Bang, as the theory goes.) If one of them happened in our part of the galaxy, the radiation from it could easily destroy Earth's biosphere. We would have to be in a path along the axis of rotation of the dieing star so that the "jet" of radiation is pointed our direction, but it's still a potent threat.  So you can understand why astronomers are keen on figuring out what causes them. Luckily, available theories indicate that they are usually rare events.
It isn't known if every hypernova is associated with a GRB. However, astronomers estimate only about one out of 100,000 supernovae produce a hypernova. This works out to about one gamma-ray burst per day, which is in fact what is observed.

What is almost certain is that the core of the star involved in a given hypernova is massive enough to collapse into a black hole (rather than a neutron star). So every GRB detected is also the "birth cry" of a new black hole.

- http://imagine.gsfc.nasa.gov/docs/science/know_l1/why_hyper.html
Astronomers expect GRBs to show up where there is lots of matter, lots of stars, like you'd expect to find in any galaxy. The current hubbub, though, is that a GRB was detected in the middle of nowhere. No galaxies, no stars.
Astronomers have amassed a great deal of evidence that GRBs are triggered by the explosive deaths of massive stars, which live very short lives. Because of their short lifespans, massive stars don’t have time to wander far from their birthplaces, usually dense clouds of gas and dust inside respectable-size galaxies. So GRB 070125 raises the perplexing question of how a massive star could be found so far away from any galaxy.
- http://www.nasa.gov/centers/goddard/news/topstory/2007/intergalatic_shot.html
They're going to use Hubble Space Telescope to take a long exposure image. They're hoping it will be able to discern faint light from a galaxy near that region of space.

Story #2: flamethrower

And if that's not enough to keep you whimpering at the immensity of the savage universe, consider this other black hole whose energy beam is striking another galaxy near to it, likely destroying life on countless planets whose only fault was to be in the wrong place at the wrong time.
This "death star galaxy" will produce large amounts of high-energy radiation, which may cause severe damage to the atmospheres of any planets in the companion galaxy that lie in the path of the jet. From the Earth we look down the barrel of jets from supermassive black holes, however these so-called "blazars" are at much safer distances of millions or billions of light years.
- http://chandra.harvard.edu/photo/2007/3c321/
"The right to live is tentative," indeed.  You see why I don't sleep well at night? ;)

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