Astronomy Picture of the Day

NASA ^ | 3/18/10 | NASA, DOE, International Fermi LAT

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Fermi Catalogs the Gamma-ray Sky
Credit: NASA, DOE, International Fermi LAT Collaboration

Explanation: What shines in the gamma-ray sky? The most complete answer yet to that question is offered by the Fermi Gamma-ray Space Telescope's first all-sky catalog. Fermi's sources of cosmic gamma-rays feature nature's most energetic particle accelerators, ultimately producing 100 MeV to 100 GeV photons, photons with more than 50 million to 50 billion times the energy of visible light. Distilled from 11 months of sky survey data using Fermi's Large Area Telescope (LAT), the 1,451 cataloged sources include energetic star burst galaxies and active galactic nuclei (AGN) far beyond the Milky Way. But within our own galaxy are many pulsars (PSR) and pulsar wind nebulae (PWN), supernova remnants (SNR), x-ray binary stars (HXB) and micro-quasars (MQO). Fermi's all sky map is shown centered on the Milky Way with the diffuse gamma-ray emission from the Galactic plane running horizontally through the frame. To locate the cataloged gamma-ray sources, just slide your cursor over the map. For now, 630 of the sources cataloged at gamma-ray energies remain otherwise unidentified, not associated with sources detected at lower energies.

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[thefactor]

Well there’s one picture I will never understand. Especially the day after St. Pat’s.

[rarestia]

Think of it as an abstract. Check out the larger pic on the APOD site. It’s pretty cool that we’ve identified and classified cosmic objects in this way, and the tools we have to do the identification are only getting better as we get older.

[Condor51]

Fermi Catalogs the Gamma-ray Sky

Gamma Rays and Gamma Ray Bursts are super cool, as in neat.

If I was 30 years younger. Okay 40 ;-), but as wise as I am today, I'd make them my life's study.

Not to long ago Gamma Ray Bursts were 'thought' to come from only our Milky Way Galaxy. Then they did a study to 'confirm' this - which was what they expected to find, only 'bursting' along our galactic plane. But that's not what they found.

They found that these Gamma Ray Bursts were coming from the farthest reaches of the *known* Universe, 14.5 Billion LYr's away. These were 'Super Gamma Ray Bursts' caused by a HUGH Star, and I mean HUGH, going Suer Nova. But that was not good. Thanks to good ole Einstein their results meant that with the Energy released, it would take MORE MASS than our entire Universe contains! It looked like E=mc² was out the window. Could Einstein have been wrong?

They pondered this major problem and concluded that Super Gamma Rays Bursts are like Pulsars from a Black Hole, rays shooting out both ends of its axis, not exploding in all directions. With that being the case E=mc² worked again and all was right in the world of physics.

But here's the bad news -- 'Super Gamma Rays Bursts' are kind of like the 'Death Star' in the 1st Star Wars movie. If one 'bursts' and its axis was aimed at the Earth we'd all be cooked in a nanosecond as soon as it reached us. So for all we know there could be one coming at us now and it could hit any time. So when I think of this, I say the hell with Global Warming.

But there's something else with this conclusion. If one Gamma Ray Beam is coming towards us from 14.5 Billion LYr's away, that means the beam from the other end is going the same distance the other way.

Ergo, our Universe has to be 'older' and 'bigger' than 14.5 LYr's, MORE LIKE 29! We just can't see it. Or, it could be 'infinite' and that's a bad word in physics. ;-)

[sig226]

It’s 96 billion light years across; 13 or so billion light years old.

[null and void]

Pulsar Wind Nebulae.

Gama rays are PWNed!