NASA sees 'watershed' cosmic blast in unique detail

Posted: Nov 21, 2013 by Francis Reddy

In the most common type of gamma-ray burst, illustrated here, a dying massive star forms a
black hole (left), which drives a particle jet into space.
Credit: NASA's Goddard Space Flight Center

(Phys.org) —On April 27, a blast of light from a dying star in a distant galaxy became the focus of astronomers around the world. The explosion, known as a gamma-ray burst and designated GRB 130427A, tops the charts as one of the brightest ever seen

A trio of NASA satellites, working in concert with ground-based robotic telescopes, captured never-before-seen details that challenge current theoretical understandings of how gamma-ray bursts work.

"We expect to see an event like this only once or twice a century, so we're fortunate it happened when we had the appropriate collection of sensitive space telescopes with complementary capabilities available to see it," said Paul Hertz, director of NASA's Astrophysics Division in Washington.

Gamma-ray bursts are the most luminous explosions in the cosmos, thought to be triggered when the core of a massive star runs out of nuclear fuel, collapses under its own weight, and forms a black hole. The black hole then drives jets of particles that drill all the way through the collapsing star and erupt into space at nearly the speed of light.

Gamma-rays are the most energetic form of light. Hot matter surrounding a new black hole and internal shock waves produced by collisions within the jet are thought to emit gamma-rays with energies in the million-electron-volt (MeV) range, or roughly 500,000 times the energy of visible light. The most energetic emission, with billion-electron-volt (GeV) gamma rays, is thought to arise when the jet slams into its surroundings, forming an external shock wave.

The Gamma-ray Burst Monitor (GBM) aboard NASA's Fermi Gamma-ray Space Telescope captured the initial wave of gamma rays from GRB 130427A shortly after 3:47 a.m. EDT April 27. In its first three seconds alone, the "monster burst" proved brighter than almost any burst previously observed.

Continue Learning: http://phys.org/news/2013-11-nasa-watershed-cosmic-blast-unique.html
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Dark Matter Reveals the Structure of the Universe

by BIG THINK EDITORS NOVEMBER 20, 2013, 12:00

Image via Bigthink.com

Physics is both deeply inspiring and deeply humbling, in a way that few other disciplines are today. On the one hand, physicists have found the elusive Higgs boson, the particle responsible for mass. On the other hand, physicists are comparatively clueless when it comes to dark matter, which makes up the vast majority of the Universe.

Comparatively clueless, that is to say, but not completely clueless.

In the video below, Joel Primack, an astrophysicist at the University of California-Santa Cruz, explains that we don’t yet know the real nature of the dark matter “beyond that it’s pretty cold.” Cold refers to the terminology that Primack coined in 1983. Dark matter is either hot, warm or cold “depending on how rapidly it’s moving in the early stages of the Big Bang,” Primack says.

Continue Learning: http://bigthink.com/big-think-tv/dark-matter-reveals-the-structure-of-the-universe?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+bigthink%2Fmain+(Big+Think+Main)

Through the Wormhole: The Riddle of Black Holes

Through the Wormhole: The Riddle of Black Holes

They are the most powerful objects in the universe. Nothing, not even light, can escape the gravitational pull of a black hole. Astronomers now believe there are billions of them out in the cosmos, swallowing up planets, even entire stars in violent feeding frenzies. New theoretical research into the twisted reality of black holes suggests that three-dimensional space could be an illusion. That reality actually takes place on a two-dimensional hologram at the edge of the universe.

http://science.discovery.com

Dartmouth researchers shed new light on dark energy, cosmic speed-up

The detailed, all-sky picture of the Cosmic Microwave
Background in the infant universe reveals 13.77 billion
year old temperature fluctuations (shown as color differences)
that correspond to the seeds that grew to become the galaxies.
Credit: NASA/WMAP Science Team.

In a new study, Dartmouth researchers rule out a controversial theory that the accelerating expansion of the universe is an illusion.

While the findings don't explain the cosmic speed-up, they eliminate one provocative possibility that our planet, solar system and galaxy are at the center of the universe and that there is no dark energy. The findings appear in the journal Physical Review D. A PDF of the study is available on request.

The 2011 Nobel Prize was awarded for the discovery that the expansion of the universe is accelerating. One leading idea to explain the acceleration is a new, mysterious substance called dark energy, which is thought to make up nearly three-fourths of the energy of the universe.

Continue Learning: http://www.spacedaily.com/reports/Dartmouth_researchers_shed_new_light_on_dark_energy_cosmic_speed_up_999.html