IC hard gamma-rays

[neufer]

NASA's Fermi Space Telescope Explores New Energy Extremes
Orbiter CH Space News, Jan. 10, 2012

[size=150][color=#FF0000]Above 100 GeV,[/color][/size] [url=http://asterisk.apod.com/viewtopic.php?f=31&t=23648&p=148274&hilit=ngc+1275#p148274][size=150]NGC 1275[/size][/url] [size=150][color=#FF0000]becomes undetectable, while the radio galaxy IC 310 shines brightly.[/color][/size] Credit: NASA / DOE / Fermi LAT Collaboration & A. Neronov et al.

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[b][color=#0000FF]Fermi sources with energies greater than 10 GeV. From some of these sources, Fermi's LAT detects only one gamma-ray photon every four months. Credit: NASA / DOE / Fermi LAT Collaboration.[/color][/b]

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Fermi's view of the gamma-ray sky continually improves. This image of the entire sky includes three years of observations by Fermi's Large Area Telescope (LAT). It shows how the sky appears at energies greater than 1 billion electron volts (1 GeV). Brighter colors indicate brighter gamma-ray sources. A diffuse glow fills the sky and is brightest along the plane of our galaxy (middle). Discrete gamma-ray sources include pulsars and supernova remnants within our galaxy as well as distant galaxies powered by supermassive black holes. Credit: NASA / DOE / Fermi LAT Collaboration.

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<<After more than three years in space, NASA's Fermi Gamma-ray Space Telescope is extending its view of the high-energy sky into a largely unexplored electromagnetic range. Today, the Fermi team announced its first census of energy sources in this new realm.

Fermi's Large Area Telescope (LAT) scans the entire sky every three hours, continually deepening its portrait of the sky in gamma rays, the most energetic form of light. While the energy of visible light falls between about 2 and 3 electron volts, the LAT detects gamma rays with energies ranging from 20 million to more than 300 billion electron volts (GeV).

At higher energies, gamma rays are rare. Above 10 GeV, even Fermi's LAT detects only one gamma ray every four months.

"Before Fermi, we knew of only four discrete sources above 10 GeV, all of them pulsars," said David Thompson, an astrophysicist at NASA's Goddard Space Flight Center in Greenbelt, Md. "With the LAT, we've found hundreds, and we're showing for the first time just how diverse the sky is at these high energies."

Any object producing gamma rays at these energies is undergoing extraordinary astrophysical processes. More than half of the 496 sources in the new census are active galaxies, where matter falling into a supermassive black hole powers jets that spray out particles at nearly the speed of light.

Only about 10 percent of the known sources lie within our own galaxy. They include rapidly rotating neutron stars called pulsars, the expanding debris from supernova explosions, and in a few cases, binary systems containing massive stars.

More than a third of the sources are completely unknown, having no identified counterpart detected in other parts of the spectrum. With the new catalog, astronomers will be able to compare the behavior of different sources across a wider span of gamma-ray energies for the first time.

Just as bright infrared sources may fade to invisibility in the ultraviolet, some of the gamma-ray sources above 1 GeV vanish completely when viewed at higher, or "harder," energies. One example is the well-known radio galaxy NGC 1275, which is a bright, isolated source below 10 GeV. At higher energies it fades appreciably and another nearby source begins to appear. Above 100 GeV, NGC 1275 becomes undetectable by Fermi, while the new source, the radio galaxy IC 310, shines brightly.

The Fermi hard-source list is the product of an international team led by Pascal Fortin at the Ecole Polytechnique's Laboratoire Leprince-Ringuet in Palaiseau, France, and David Paneque at the Max Planck Institute for Physics in Munich. The catalog serves as an important roadmap for ground-based facilities called Atmospheric Cherenkov Telescopes, which have amassed about 130 gamma-ray sources with energies above 100 GeV. They include the Major Atmospheric Gamma Imaging Cherenkov telescope (MAGIC) on La Palma in the Canary Islands, the Very Energetic Radiation Imaging Telescope Array System (VERITAS) in Arizona, and the High Energy Stereoscopic System (H.E.S.S.) in Namibia. "Our catalog will have a significant impact on ground-based facilities' work by pointing them to the most likely places to find gamma-ray sources emitting above 100 GeV," Paneque said. Compared to Fermi's LAT, these ground-based observatories have much smaller fields of view. They also make fewer observations because they cannot operate during daytime, bad weather or a full moon.>>

[bystander]

NASA's Fermi Space Telescope Explores New Energy Extremes
NASA | Fermi | 2012 Jan 10

To The Extreme… NASA’s Fermi Gamma-Ray Telescope Gathers In High Energy
Universe Today | Tammy Plotner | 2012 Jan 17

[brightside]

Great article

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[size=200][color=#FF0000]Fermi all sky: 1 to 30 GeV[/color][/size]

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[size=200][color=#0000FF]Planck all sky: 0.125 to 3.56 meV[/color][/size]

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[Ann]

C'mon, Art, you're not asking me to understand what 0.125 to 3.56 meV means, are you? Is it infrared? Don't you know that that kind of concept is too red for my little blue-wired brain to wrap itself around?

Ann

[bystander]

[url=http://en.wikipedia.org/wiki/Electromagnetic_spectrum][size=120][b]Wikipedia: Electromagnetic spectrum[/b][/size][/url]

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[neufer]

C'mon, Art, you're not asking me to understand what 0.125 to 3.56 meV means, are you? Is it infrared? Don't you know that that kind of concept is too red for my little blue-wired brain to wrap itself around?

• 0.125 to 3.56 meV = 30 GHz to 857 GHz

To put it in a context that you might better understand, Ann:

When you are up at all hours of the night posting to the Asterisk*
your little blue-wired brainwaves are probably continuous, high-voltage (> 0.150 mV) delta waves.

Therefore, from space, your thoughts might be detectable by Planck but (probably) not by Fermi.

(I'm somewhat less sure about the situation with beyond.)

<<Parasomnias are a category of sleep disorders that involve abnormal and unnatural movements, behaviors, emotions, perceptions, and dreams that occur while falling asleep, sleeping, between sleep stages, or during arousal from sleep. Some NREM parasomnias (sleep-walking, night-terrors, and confusional arousal) are common during childhood but decrease in frequency with increasing age. Parasomnias are often associated with disruptions in slow wave sleep. Sleep walking and sleep talking most often occur during periods of high-delta wave activity. Sleep walkers have also been shown to have more Hypersynchronous Delta Activity (HSD): continuous, high-voltage (> 0.150 mV) delta waves seen in sleep EEGs.>>

[Beyond]

Only 'somewhat' less sure I thought you'd be at least one hell-of-a-lot-less-sure, just like me YEE-HAA!!