- Attachment: Gamma Ray image
- What we “see” in our Universe is very limited, extremely limited. Our eyes can detect that part of the electromagnetic spectrum from about 400 to 700 nanometers wavelength. That is the wavelengths from blue light to red light and all the colors in between. We can use our radio receivers to detect the really long wavelengths. TV receivers, Microwave receivers detect other parts of the electromagnetic spectrum. Using only our eyes we are limited to the light form the Sun and the stars and the reflected light of the Moon and all that is around us in natural emitted and reflected light.
- Of course, technology has brought us many other man-made source of light. It all comes from electrons changing energy levels in atoms and emitting or absorbing electromagnetic radiation in return. The very shortest wavelengths are X-rays and Gamma Rays that are mostly emitted and absorbed by the nuclei of atoms rather than the electron shells of atoms. Technology has also brought us detectors that can “see” this part of the electromagnetic spectrum.
- Today we have a satellite in orbit that can detect Gamma Rays. It is the Fermi Gamma Ray Space Telescope. If we could “see” using these new detector’s eyes we would see flares spewing out from the surface of the Sun. We would see the accretion disks of high energy matter circling Blackholes. See Review #1321 to learn about the Gamma Ray Bubbles that came from the center of our galaxy.
- The telescope has identified 1,873 Gamma Ray emitting objects to date. Half of these are from active galaxies that have massive Blackholes at their centers. As these Blackholes swallow matter they emit massive amounts of high energy radiation. Many of these sources can not be seen with other parts of the electromagnetic spectrum. This is a mystery. Usually other parts of the spectrum are part of the emission, not just Gamma Rays. Other objects include Pulsars, Supernova remnants, Globular Star Clusters, and the center of our own Milky Way Galaxy. Still 1/3 of the catalog remains a mystery.
- Here are the top 5 sources that are found inside our Milky Way Galaxy.
-------------------- (1) The Crab Nebula in the Constellation Taurus the Bull. It is the remains of a supernova that exploded in 1054. It is 6,500 lightyears away. The original core of the star is now a super-dense neutron star called a Pulsar that spins and pulses 30 times per second. In the last 3 years the Gamma Ray emissions from the nebula has faded by 7%. Short lived Gamma Ray flares have been observed that are hundreds of times higher energies that the X-ray varieties. To account for this super-energy level the electrons near the Neutron Star must be accelerated to energies 10^15 times greater than visible light. That is 1,000 trillion times greater!
---------------------- (2) W44 is another supernova remnant thought to be 20,000 years old. It is located 9,800 lightyears away in the Constellation Aquila the Eagle. The Gamma Rays being detected are coming from the supernova shockwave that is colliding with surrounding gas clouds. Theory has it that high energy Cosmic Rays, which are accelerated protons, may be generated within the magnetic fields and then colliding with the shockwave. Because the protons are positive charges their paths get scrambled by these magnetic fields masking their origins. Astronomer are studying W44 to see it they can confirm this theory and the origins of the Cosmic Rays.
------------------ (3) V407 Cygni is a binary system with a White Dwarf star and a Red Giant star. The Red Giant is 500 times the size of our Sun. The binary is 9,000 lightyears away in the Constellation Cygnus the Swan. Gamma Ray flares are detected from the surface of the White Dwarf when gas from the Red Gant gets ripped away and explodes as it hit’s the super hot surface of the Neutron Star. The most recent explosion detected on March, 2010. This was totally unexpected as a Gamma Ray source by astronomers.
----------------- (4) Pulsar PSRJ0101-6422 in the Constellation Tucana the Toucan. This Pulsar is blinking in Gamma Rays at 400 times per second. Pulsars are Neutron Stars that are so dense that have the mass of the Sun in the size of Washington D.C. Lighthouse-like beams of radiation powered by the pulsar’s rapid rotation and strong magnetic field sweep across the sky with every spin. Astronomers have to be in the beam’s direction if it is to be detected. The pulses from this Pulsar are rotating at 400 times per second. This is as if Washington D.C. were spinning the fastest speed of a kitchen blender. Somehow it makes sense to visualize that.
------------------------ (5) 2FGL J0359.5+5410 is another Pulsar in the Constellation of Camelopardalis the Giraffe. These pulses have not been detected yet, probably because we are not in the beam path. Pulses at other wavelengths have not been detected either. However, the Gamma Ray spectrum resembles that of a Pulsar. We need more evidence so this source remains a mystery.
- Summarizing the Fermi Catalog to date, after 2 years of collecting Gamma Rays:
------------------------ 6% are Pulsars
------------------------ 4% are Supernova Remnants
----------------------- 1% are Non-Blazar Active Galaxies
----------------------- 1% are Globular Clusters, high mass binaries, and Normal Galaxies
------------------------ 31% are mysteries.
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707-536-3272, Monday, November 7, 2011
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