Radio%20Astronomy

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Radio Astronomy

• A Story of Science, Technology and the Noisy
  World we Live in

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What is radio astronomy?
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The Visible Sky, Sagittarius Region
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The Radio Sky
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The EM Spectrum
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• Optical and Radio can be done from the ground!

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Telescopes for visible light
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Radio Telescope
receiver
parabolic reflector
control room
The 140 Foot Telescope Green Bank, WV
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What emits radio waves?
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• Recipe for Radio Waves

1. Hot Gases
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Electron accelerates as it passes near a proton.
EM waves are released
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Recipe for Radio Waves

• 2. Atomic and molecular transitions (spectral
  lines)

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434 nm
486 nm
656 nm
Hydrogen spectral lines in optical
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Electron accelerates to a lower energy state
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M33 Spiral Galaxy Optical Radio (HI) image
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Recipe for Radio Waves

• 3. Electrons and magnetic fields

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Electrons accelerate around magnetic field lines
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032954
Vela
053121
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Big Point

• Any accelerating charge emits radio waves!

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Big Point 2

• Celestial Objects at Enormous Distances Appear
  dim

• 0.00000000000000000000000001

watt/m2/Hz !!
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The Rest of the Story

• What else emits radio waves?

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Everything!!
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http//svs.gsfc.nasa.gov/index.html
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PCs
Unintentional Emitters
TV Cable
Power Line
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Intentional Emitters
Broadcast TV Cell Phone Service Radar
and
824-849 MHz
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Satellites!
GPS (and GLONASS) 1.22-1.25 GHz
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http//www.ntia.doc.gov/osmhome/allochrt.html
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What to do?

• Build the GBT!

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GBT Feed Arm
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Get away from civilization
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Get Some protection
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Black Holes Radio View of the Galactic Center
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Pulsars
55 discovered in globular clusters (Ransom et al).
Ter5ad

• Compact object orbiting the 23-millisecond
  pulsar PSR J0737-3039A, is not only, another
  neutron star, but is also a detectable pulsar.
• Powerful laboratory for GR!

Image Credit Michael Kramer (Jodrell Bank
Observatory, University of Manchester)
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Galactic Super Bubble
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Galactic Building Blocks
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Organic Molecules Seeds of Life
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www.gb.nrao.edu
National Radio Astronomy Observatory, Green Bank,
WV