“Why gamma-ray burst shocked scientists” – Prof of Physics Meg Urry

An X-ray telescope image of GRB130427A. Source: CNN.com
An X-ray telescope image of GRB130427A.
Source: CNN.com

Professor Meg Urry, Yale University Chairwoman of the Department of Physics has written an opinion piece, published on CNN, revealing why the April 27, 2013 gamma-ray burst took scientists by surprise.

Urry is also the director of the Yale Center for Astronomy and Astrophysics.  She writes:

On April 27, NASA’s Fermi and Swift satellites detected a strong signal from the brightest gamma-ray burst in decades. Because this was relatively close, it was thousands of times brighter than the typical gamma-ray bursts that are seen by Swift every few days. Scientists are now scrambling to learn more.

Some of the jets from this massive burst are headed Earth’s way, she reports.

This means GRB130427A’s jets must be aimed toward Earth — purely by chance, of course. For every jet pointed at us, there are hundreds of exploding stars across the universe whose jets point randomly in other directions. Telescopes on other planets in those directions could see those jets, and we might see the exploding stars as supernovae, but we don’t see the bright gamma-ray flashes from jets beamed away from us.

Urry believes that this may be the first time that scientists will be able to detect the elusive but theorized neutrino.

The proximity of GRB130427A means we can learn a great deal about it.

For example, most of the energy from supernovae is thought to be carried away by neutrinos — the lightweight, difficult-to-detect particles that are so important to understanding the fundamental laws of nature.

The world’s most powerful neutrino telescope, IceCube, uses Antarctic ice as the detector volume, with electronic equipment sunk throughout a cubic kilometer of ice — enough water to fill a million swimming pools — to detect signals from neutrinos interacting with the ice.

If there is a supernova associated with this gamma-ray burst, a big optical flash should be seen any day now by ground-based telescopes, preceded by a flood of neutrinos. (The neutrinos are emitted at the time of collapse, while the optical light is the consequence of explosive debris hitting material surrounding the star a bit later.)

Interestingly, an April 18 paper in the journal Nature reported that upper limits for neutrinos measured from IceCube are low enough that gamma-ray bursts are unlikely to be the sole source of ultra-high energy cosmic rays. Just nine days later, the bright nearby burst happened, leading to the Fermi detection of the highest energy gamma-ray ever.

Now there is a real chance IceCube will make the first detection of astrophysical neutrinos, from the supernova associated with GRB130427A.

Read the full article, click here.


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