Monday, December 24, 2007

On the trail of cosmic bullets



This diagram shows data recorded by Pierre Auger Observatory on March 5, 2005. A cosmic ray hit the atmosphere at close to the speed of light, creating billions of secondary particles that rained down over the pampa and triggered 14 of 1500 surface detectors (colored dots.) Meanwhile, telescopes around the edge of the array watched for the faint glow of particles hitting nitrogen molecules in the atmosphere. Together these techniques allow scientists to trace the origins of the most energetic particles in the universe.
Source: Pierre Auger Observatory


By Kurt Riesselmann


Do the most energetic particles in the universe come from supermassive black holes? New results from the Pierre Auger Observatory make that case.


Argentina’s Pampa Amarilla is a rather remote place, a dry plain stretching thousands of miles against the spectacular backdrop of the rugged, snowcapped peaks of the Andes.


Like every other place on Earth, the yellow pampa is bathed in a constant shower of cosmic rays—protons and atomic nuclei that fly through the universe at close to the speed of light. While some are known to come from the sun, most take a meandering path that gives no clue to where they came from.


Once in a while, an unusually powerful cosmic ray strikes the Earth’s atmosphere with almost as much energy as a bullet. Fortunately, such a projectile is no danger to human life. Entering the atmosphere, it loses energy and creates showers of lower-energy particles, which can spread across more than 15 square miles by the time they hit ground.


What cosmic gun could possibly fire such a thing?


Here, among the grazing cattle and gauchos on horseback, scientists of the Pierre Auger Observatory, the world’s largest cosmic-ray observatory, are closing in on the answer.


Catching rays


“The highest-energy cosmic rays must come from some of the most violent processes in the universe,” says the US Department of Energy’s Dennis Kovar, acting associate director of the Office of Science for High Energy Physics. “Up until now we have known very little about their source.”


Based in Argentina’s Mendoza Province, near the town of Malarg├╝e, the observatory is a model for international collaboration. Named after French physicist Pierre Auger, who discovered high-energy cosmic rays in 1938, the observatory involves 370 scientists and engineers from 17 countries. More than 40 funding agencies are sharing the US$54-million construction cost, with no country contributing more than a quarter of it.


Scattered across 1200 square miles of semi-arid land are what appear to be water tanks, spaced about a mile apart and painted beige to blend in with the landscape. Lined with photo sensors and sprouting solar panels and communications antennae, these Auger particle detectors have recorded about a million cosmic rays since January 2004, including about 100 ultrahigh-energy cosmic bullets—more than any other observatory has seen. The bullets are so rare that only one or two might hit each square mile per century.


“This result heralds a new window to the nearby universe and the beginning of cosmic-ray astronomy.” –Alan Watson

12 comments:

Carey said...

Merry, Merry, everyone.

Just an incredibly gorgeous evening and night here in San Diego for the Eve festivities. Mars glowed red appropriately.

It was one of those balmy postcard nights with everything sparkling.

Enjoy the spirit of the moment.

David B. Benson said...

Juan Cole writes:

Christmas in Iraq

There was no midnight mass among Christians in Iraq again this year. Too dangerous.

And of the estimated 800,000 Christians in the country in 2002, as few as half, 400,000, may be left. Many have fled to Syria, joining the 1.5 million Iraqi refugees there.

Even some Christians still in the country have been internally displaced.

None of the feel good human interest programs I saw on cable news this weekend focused on the displacement of indigenoous Christians.

If it is not on TV it doesn't exist.

David B. Benson said...

Christian Church in Hamdaniya, Iraq

The celibration appears to have been last Decemeber 12th...

Gerald said...

Bush's Real Record

A five page report but a good read!!!

Gerald said...

The Ten Commandments

Gerald said...

The Denial of the Incarnation

Gerald said...

"The logic of non-violence is the logic of crucifixion and leads the man of non-violence to the into the heart of the suffering Christ." - James W. Douglass. In this sense, the practice of non-violence is the antidote to war. Our churches practice politic silence regarding the dehumanization of Iraqis, loudly praying that our soldiers be divinely freed from suffering and death while they deliver unbelievable agony to the subject people. A non-violent anti-war movement must therefore begin by a re-humanization of the muted Iraqi voice. Every Iraqi killed by U.S. forces must receive a name and a home. Once the full humanity of the Iraqi victim is recognized, once we see the face of Christ in the broken Iraqi child, then the potency of our smart bombs will be bled into the sands of the forgiving desert. It is precisely through the power that is no power in this world that the powers of this world are brought to shame and are made to see their true weakness.

Gerald said...

Hitler Bush Is a War Criminal

Gerald said...

The Nightmare in Nazi America

Gerald said...

The absence of optimism is positively un-American.

Gerald said...

Let us never forget that Bush is seen by many Americans as a deity! He is the modern day savior to ease our problems.

capt said...

We actually had a little flurry of snow today. The local mountains are dusted white.

I hope everybody is safe and warm - that Santa was good to you all today.