Radio Astronomy Listening to the Sky

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And…

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The (Re)birth of radio astronomy

Grote Reber, W9GFZ

Built a 9m parabolic dish in his backyard in 1937

Conducted first all-sky radio survey, 1941

After his work came a post- war boom!

Grote Reber (1911-2002)

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Later advances

Increased wavelength range

& integration with studies at other wavelengths: visible, IR, x-ray, gamma

Larger dishes = more sensitivity

Interferometry = better angular resolution

Dual nature of radio waves: they probe both sedate, slow processes, and some of the most energetic phenomena in the universe!

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Radio Astronomy Today

Many observatories spanning the globe

Large-area dishes for high sensitivity

Extremely high resolution via interferometry

Coordination between observatories for continuous observations

Coordination of observatories at different wavelengths!

Tracing of solar activity crucial to “space weather” forecasting for the health of satellites & electronic equipment!

Arecibo,

Puerto

Rico

Very Large Array (VLA), New Mexico

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Mapping Planets with RADAR

Venus: surface obscured by permanent clouds

Radar map by Magellan satellite

Visible light image

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Mapping Cold Gas in Galaxies

Trace out star formation in galaxy

Trace out dynamics of gas clouds

M31 visible light image M31 in radio at CO resonance

115 GHz

Doppler map

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Mapping the Stellar Lifecycle

Slide 16

Pulsars: Timekeepers of the Universe

Neutron star: theoretical idea from Zwicky (1930’s)

Observation: Jocelyn Bell Burnell & Antony Hewish, 1967 Nobel Prize (Hewish), 1974

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Supernova Remnants

Radio emission from shock front: expanding material striking interstellar medium

Radio is the best tool for detecting new SNRs!

Casseiopeia A Supernova Remnant Tycho’s Supernova Remnant

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The Galactic Center

At visible wavelengths this region is obscured by dust!

Sgr A = galactic center (supermassive black hole)

Combined VLA / Green Bank Telescope image

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