- 3562 - GAMMA RAYS - light for different eyes. Astronomers need more Infrared telescopes in order to see these most distant Gamma Ray Bursts. Analyzing these Gamma Ray Bursts is like culling a line of sight through the Universe that could map out evolution in 3 dimensions. With many lines of sight recorded a detailed picture begins to form.
--------------------- 3562 - GAMMA RAYS - light for different eyes.
- Where Do Gamma Rays Come From?
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- Gamma Rays are light of the maximum possible energy. With wavelengths shorter than 10^-11 meters, each Gamma Ray photon has an energy of at least 100,000 electron volts. That is 100,000 times more energy than visible light. Some Gamma Rays have even shorter wavelengths and even more energy. The most energetic Gamma Ray recorded was 100,000,000,000 electron volts.
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- See Review 3560 to learn about “cosmic rays” which are not rays at all. They are particles. High speed particles.
- Sunlight at the core of the Sun starts out as Gamma Rays and loses energy as it passes through layers and layers of gas. It leaves the surface as ultraviolet and visible light.
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- To create Gamma Rays you need a lot of energy. Energy that comes from colliding particles at near the speed of light. Or, from the annihilation of matter and anti-matter, accretion disks and jets around Blackholes, or radioactive decay in fusion reactors.
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- When a massive star blows up as a supernova it emits Gamma Rays. Some Gamma Ray bursts are so intense they can outshine 100,000,000 galaxies. If astronomers want to see a distant galaxy that is far, far away, a Gamma Ray Burster is the one to catch.
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- Astronomers want the farthest distances to go back farther in time. They are looking for a redshift of 10 which corresponds to the age of the Universe at 500,000,000 years, 3.6% its current age. After catching some 60 long bursts they have recorded only one with a redshift greater than 6.
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- Short duration Gamma-Ray Bursts are believed to be the result of 2 colliding neutron stars. The bursts last only a fraction of a second in these collisions.
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- Long duration bursts last tens of seconds. These typically lie at a much greater distance when the age of the Universe was only a few billion years old. Long duration bursts are believed to be massive supernova that become rapidly spinning Blackholes. These events can become intensely magnetized neutron stars called “Magnetars“.
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- The bursts are short lived but the afterglows can last for days. Powerful jets pour out of the supernova heating the gas that surrounds the star. This creates the optical and radio waves that continue to radiate energy.
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- A Gamma Ray Burst was detected with a redshift of 6.295 when the age of the Universe was 900,000,000 years old. The expansion of the Universe over time makes the Burst appear to last longer because the radiation is stretch out and also stretched to longer wavelengths. High energy X-rays can become stretched into the infrared wavelengths. The optical wavelengths are missing because the intergalactic clouds of neutral hydrogen have absorbed all the visible light along the way.
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- The afterglow of the Gamma Ray Burst starts out about one lightyear distant from the supernova. It passes through the host galaxy and then through billions of lightyears of interstellar medium to reach the Earth.
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- The light we observe can contain fingerprints of the interstellar gas and dust it has encountered. The spectroscopy data on this light shows absorption lines for the atoms and elements the light passed through. One conclusion reached is that these distant galaxies contain less than 10% of the heavy elements that we find today in the Milky Way.
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April 30, 2022 GAMMA RAYS - light for different eyes. 1158 3562
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