Blazar Revisited

I've got one story online today about some sink holes that about to be repaired on SLAC grounds. The water drainage system is old and breaks down now and then, but SLAC is always quick to right the wrongs. It's not a terribly interesting topic, or story for that matter, and one of the hard parts of the job is making stories like these more readable. Because when you get down to it, the story could easily be told in one or two sentences.

But moving on.

A few days ago my blog featured information garnered from a SLAC scientist about recent studies of a "blazar." I tried to explain it informally here before writing the story as a writing exercise. I want to take the experiment one step further.

I'm posting below the rough draft of the article I wrote based on the information. Read through both, let me know which is clearer, which is better, what I could improve on the article below, and what is good about it. Then, after the story goes through the editing process and the scientist, I will post that as well. In this way, you can get a glimpse of a story before its written, as its written, and after its written.

And, if you feel like it, you can contribute to the editing process.

Enjoy.

When American astronomer H.D. Curtis spied a jet of light emanating from galaxy M87 in 1918, he ignited the study of a phenomenon that continues to this day. The jet consists of elementary particles—electrons, positrons, and protons—enclosed by a magnetic field, beaming from the galaxy's center at nearly the speed of light. Through a number of complex interactions, these particles create gamma rays. Recently, a team of SLAC scientists made a surprising discovery about the source of these gamma rays that raises as many questions as it answers.

M87 is the only galaxy of its kind close enough for detailed observation. Scientists believe that the two jets of particles—pointing in opposite directions from the disc-shaped galaxy—come from a Super Massive Black Hole at the center of the galaxy. Galaxies that actively produce these jets are called quasars. Because one jet points towards Earth, its properties appear more extreme, making M87 a type of quasar called a "blazar."

Scientists have studied the blazar for decades. One question involves the gamma rays it produces. How are they made? Where do they come from?

"We have ideas, but the details are not there," said SLAC physicist Teddy Cheung. "It's a mystery."

It's a mystery that scientists are now one step closer to solving. Cheung and his associates recently determined that the gamma rays are emanating from a disturbance, or "knot," traveling down the jet flow 100 parsecs—326,200 light-years—from its origin. This places gamma ray production 100 times further out than previously believed.

For several years, scientists have been observing this particular knot in several ways. The Hubble Space Telescope observed visible light, the Chandra X-ray Observatory focused on x-rays, and the Very Large Array received radio data. All three showed spikes in the knot's emissions early in 2005. Scientists then compared this spike to gamma ray observations of the entire jet stream made by the High Energy Stereoscopic System (HESS). Because HESS showed gamma rays spiked at the same time, scientists concluded that the gamma rays are produced in the knot.

Scientists have long believed the gamma rays come from an area closer to the origin, where the jet is more compact and processes that would create them are more easily theorized.

"The fact that the knot is producing gamma rays so far away from the jet's origin raises many questions about what exactly is going on in that knot," said Cheung. "Hopefully it's a question that will be solved by scientists in the future."