Fermi sees brightest-ever blazar flare

Dec 09, 2009 Francis Reddy
Unprecedented flares from the blazar 3C 454.3 in the constellation Pegasus now make it the brightest persistent gamma-ray source in the sky. That title usually goes to the Vela pulsar in our galaxy, which is millions of times closer. These all-sky images, which show the numbers of high-energy gamma-rays captured by Fermi's Large Area Telescope on Dec. 3 and Nov. 18, clearly show the change. Credit: NASA/DOE/Fermi LAT

(PhysOrg.com) -- A galaxy located billions of light-years away is commanding the attention of NASA's Fermi Gamma-ray Space Telescope and astronomers around the globe. Thanks to a series of flares that began September 15, the galaxy is now the brightest source in the gamma-ray sky -- more than ten times brighter than it was in the summer.

Astronomers identify the object as 3C 454.3, an active galaxy located 7.2 billion light-years away in the constellation Pegasus. But even among active galaxies, it's exceptional.

"We're looking right down the barrel of a particle jet powered by the galaxy's ," said Gino Tosti at the National Institute of Nuclear Physics in Perugia, Italy. "Some change within that jet -- we don't know what -- is likely responsible for these flares."

Blazars, like many active galaxies, emit oppositely directed jets of particles traveling near the speed of light when matter falls toward their central supermassive black holes. What makes a blazar so bright in is its orientation: One of the jets happens to be aimed straight at us.

Most of the time, the brightest persistent source in the gamma-ray sky is the Vela pulsar, which at a distance of about 1,000 light-years lies practically next door.

"3C 454.3 is millions of times farther away, yet the current flare makes it twice as bright as Vela," said Lise Escande at the Center for Nuclear Studies in Gradignan, near Bordeaux, France. "That represents an incredible energy release, and one the source can't sustain for very long."

According to Massimo Villata at Italy's Torino Observatory, 3C 454.3 also is flaring at radio and visible wavelengths, if less dramatically. "In red light, the blazar brightened by more than two and a half times to magnitude 13.7, and it is also very bright at high radio frequencies."

The Fermi team is alerting astronomers to monitor the event over as broad a range of wavelengths as possible. "That's our best bet for understanding what's going on inside that jet," Tosti said.

Source: NASA's Goddard Space Flight Center (news : web)

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User comments : 3

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omatumr
2.3 / 5 (3) Dec 09, 2009
Mysterious

Now what could be the energy source that shoots a particle jet down the gamma-ray barrel?

Perhaps data in the chart of the nuclides contains the answer.

With kind regards,
Oliver K. Manuel
abhishekbt
5 / 5 (2) Dec 10, 2009
Sounds like the begining of an Action packed thriller!
With a little luck we could be able to decipher one such 'mystery' in our life time.
Parsec
5 / 5 (4) Dec 10, 2009
The energy source for most particle jets has been pretty well nailed down from the hundreds of symmetric jets we can observe around the universe. Black hole accretion disks convert up to 15% of the matter in them to energy from simple friction and emit a great deal of that in the form of narrowly focused jets located at the rotation poles.

For a supposedly educated person Oliver K. Manuel, you make an awful lot of really uneducated posts. I don't mind that, but you seem quite proud of your titles.

So where is the mystery here?