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Gamma Signature, Astronomer's Telegram Cast Light on Dazzling Blazar
Public Lecture May 12: Angels & Demons—The┬áScience Revealed
Making (Your) Photographs into Something More

SLAC Today

Thursday - April 30, 2009

Gamma Signature, Astronomer's Telegram Cast Light on Dazzling Blazar

(Image - FGST sky map)
Fermi Gamma-Ray Space Telescope's all-sky gamma map, with Blazar 3C 454.3 labeled in the lower left corner. (Image courtesy of NASA.)

When it comes to watching the skies, two sets of eyes are always better than one, especially if one pair can see, say, radio waves, while the other has X-ray or even gamma-ray vision. The Fermi Gamma-Ray Space Telescope's Large Area Telescope collaboration has recently released a paper giving the gamma-ray perspective on an astronomical object that flared last summer, an active galactic nucleus—or quasar—known as 3C 454.3. The paper, accepted by the Astrophysical Journal and posted yesterday on the ArXiv preprint archive, reveals that the structure of these distant, energetic monsters is more complex than scientists had previously guessed. The paper also hints at a more comprehensive picture to come, next time unfolding in full color, using data from radio, infrared, optical, X-ray and gamma bands.

A quasar is thought to be fueled by an enormous swirl of gas, or accretion disk, that has gathered around a massive black hole at the center of a distant galaxy. As gas particles stream into the black hole's maw, protons and electrons near the black hole are propelled outward at close to light speeds in a jet perpendicular to the disk. When this jet outshines the surrounding galaxy, it's often called a blazar—perhaps one of nature's most powerful particle accelerators. In a process that's poorly understood, the jets quake and shudder, shaking the high-energy beams and causing them to radiate.

"We don't see the particles unless they produce some signature of their presence," said SLAC astrophysicist Greg Madejski, who with Benoit Lott of France's National Institue of Nuclear and Particle Physics at Bordeaux, coordinated the work on the paper. "It's like peeling an onion—we look at the radiation and look at what produces the radiation, then that tells us about the content and structure of the jet."  Read more...

For additional recent results from the Fermi Gamma-ray Space Telescope, see "Gamma Plus Radio Equals New View of Cosmic Jets" in Symmetry Breaking.

Public Lecture May 12: Angels & Demons—The Science behind the Scenes


Does antimatter really exist? How and why do scientists produce and use it? Is there an underground complex deep beneath the Swiss/French border, creating antimatter? Come find out whether the truth is stranger than fiction.

On Tuesday, May 12, SLAC physicist Norman Graf will discuss the real science behind Angels & Demons, Dan Brown's blockbuster novel and the basis of an upcoming Tom Hanks movie. Graf's talk is one in a series of public lectures across the U.S., Canada and Puerto Rico to share the science of antimatter and the Large Hadron Collider, and the excitement of particle physics research.

Graf's lecture will take place May 12, 7:30—8:30 p.m. in Panofsky Auditorium. The event is free and open to all. For details and directions, see the SLAC Public Lecture Web site.

Making (Your) Photographs into Something More

If you would like to to see how the pros might transform your photo into a work of art, you are invited to submit up to five digital photos for the May 14 presentation, "Making Photographs." Bay Area photographers Robert Kato, Oliver Klink and Larry Stueck will present selected photographs submitted by SLAC staff, post-processed to show the hidden information and impact within the images.

Submissions of candidate photos are needed by May 6. The presentation will take place on Thursday, May 14, from noon to 1:00 p.m. in Kavli Auditorium. For submission guidelines and further details, see the event announcement.

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