- 1703 - Milky Way Bubbles and Star Steamers? Our Galaxy has giant lobes of Gamma Ray bubbles exiting at the poles. It also has a halo of streams of stars from the cannibalization of Dwarf Galaxies. It also has a Dark Matter halo of unknown particles. Let’s review these mysteries.
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--------------------------- 1703 - Milky Way Bubbles and Star Steamers?
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- How things change when you look at the world, the Universe, through different eyes.
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- When Galileo first used the telescope he discovered that the Milky Way was not a glowing cloud but a countless number of individual stars.
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- Today, with Gamma Ray telescopes, orbiting in space, astronomers see “luminous” lobes , bubbles, extending above and below the galactic center extending thousands of lightyears. One lightyear is 5,880,000,000,000 miles.
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- We know the center of the Milky Way Galaxy is occupied by a super massive Blackhole. But, we can not explain how a Blackhole creates giant luminous lobes. Luminous in Gamma rays. We could not see these lobes before orbiting telescopes because our atmosphere blocks Gamma Rays from reaching the surface.
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- In 2003 astronomers were puzzled trying to study the Cosmic Microwave Background radiation. To get an accurate picture of the Universe outside they wanted to subtract microwave energy generated inside out Milky Way Galaxy.
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- A model was created for the galactic microwave emissions. It worked except for the inner part of the galaxy. At first astronomers believed this could be explained by hidden Dark Matter at the center of the galaxy. Could Dark Matter particles be colliding near the center creating this excess high energy?
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- The process of particle collision creating Gamma Ray emissions is called Synchrotron Radiation ,coming from electrons and protons. There is also Inverse Compton Scattering coming from photons. In 2009 the Fermi space satellite was designed to measure Gamma Rays and prove if this Dark Matter theory was right.
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- The hazy Gamma Rays detected exactly matched the microwave haze. What amazed astronomers was that the Gamma Ray emissions had clear, distinct edges. They showed up as gigantic bubbles, not a uniform radiation.
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- Making bubbles: Material falling into a Blackhole spins , like water draining out of the bathtub. The spinning hot gas and dust of charged particles creates an intense magnetic field, like a spinning electric motor. This magnetic field powers jets exiting out the poles of the spinning magnet. The shockwave from these jets create giant bubbles of Gamma Ray radiation. It is the edge of the shockwave that we are seeing.
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- Making bubbles: Another theory is that many giant supernovae near the center exploded driving a wind of hot gas out from the galactic center. Over 6 million years bubbles this size could be inflated.
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- The amazing aspect of the bubbles for astronomers is their intense luminosity in Gamma Rays, but, nearly invisible in light waves.
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- More intense studies are being made mapping microwave radiation and X-ray radiation on top of the Gamma Ray radiation.
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- Other Reviews about Gamma Rays: #1482, #1323, #1238, #1158, #26 available upon request.
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- Gamma Rays have billion of times more energy than visible light.
- Also See Fermi Gamma Ray Space Telescope
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- Synchrotron radiation = When a charged particle changes direction it emits radiation.
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- Inverse Compton radiation = When an electron smacks head-on with a photon the collision shoots off Gamma Ray radiation
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- Bremsstrahlung radiation = When an electron shoots past an ion ( a charged particle) the electrostatic attraction bends the path of the electron and it radiates Gamma Rays with its loss of energy.
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- Our Milky Way Galaxy is even more mysterious than we thought. Not only are there these Gamma Ray lobes outside the galaxy there is are halo of stars streaming around the galaxy.
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- Astronomers think this halo is the result of our Milky Way Galaxy gobbling up many tiny dwarf galaxies. In fact , the Milky Way is today not just one galaxy. At least 20 Dwarf Galaxies from 1/100th to 1/1,000,000th the size of the Milky Way are orbiting our big Galaxy. There are more dwarf galaxies that are likely still undiscovered.
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- Many of the Dwarf Galaxies swallowed up by the Milky Way left streams of stars that stretch across the sky. The process works like this:
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- The larger galaxy’s gravity creates tidal forces that pull more strongly on the near side than on the far side of the Dwarf Galaxy.
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- These tidal forces gradually stretch out the galaxy along the line between it and the large galaxy.
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- Individual stars get pulled off forming stellar streams.
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- The streams eventually spread and become more diffuse encircling the larger galaxy. The Milky Way was about one dozen of these star streams encircling it . Many more star streams likely exist but are too faint for astronomers to detect.
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- More mysterious still is in addition to these visible halo streams of stars, our galaxy has another halo of Dark Matter. Astronomers can not see it, don’t know what it is . They perceive it through its gravitational effects on Ordinary Matter.
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- The star streams are identified because regardless of the dispersion stars never forget where and when they were born. Their chemical compositions remain the same. Stars forming later in the galaxy will contain more of the heavier elements that were formed in supernovae explosions Every star has a fingerprint for when and where it was born.
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- Astronomers studying these streams hope to sketch out a sequence of cannibalizations and trace the accretion history of our galaxy. In the process maybe some of these galactic mysteries will be solved.
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RSVP, with comments, suggestions, corrections. Index of reviews available ---
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