Radio and Multiwavelength Astronomy (2023)
Wednesdays, 7-9 PM online.
February 22; March 1, 8, 15, 22, 29; April 12 [skipping April 5]
Note: 7 classes for the standard 6-class $75 tuition.
This class focuses on two themes: (1) an introduction to multi-wavelength astronomy and (2) details of radio astronomy.
David Kiefer teaches astronomy at Brooklyn College. He is Chairman of the AAA Classes Committee and has taught a number of AAA classes. Jim Braatz is a radio astronomer working with NSF’s National Radio Astronomy Observatory (NRAO). He teaches graduate radio astronomy at the University of Virginia and leads student programs for the NRAO. His research is on radio waves from water molecules orbiting supermassive black holes, and the expansion of the universe.
Modern astronomy research and telescopes examine every portion of the electromagnetic family of waves: gamma, X-ray, ultraviolet, visible, infrared, microwave, radio. In Part I we’ll study the basics and the uniqueness of each type of wave; what they reveal; their specialized telescopes. In Part II we’ll focus on the seminal science of radio astronomy. Radio waves convey information on the vast, cold clouds of gas in space ; on objects obscured by interstellar dust; on conditions in hot, highly magnetized events in space, stars, black holes, and galaxies.
February 22 – WAVE ESSENTIALS AND IMAGES
Four representations of light- waves, ripples, rays, and particles.
General characteristics of all waves- medium, amplitude, frequency, wavelength, velocity
Specifics of light waves; colors, spectra
The electromagnetic (E/M) spectrum. Broad characteristics of each E/M family.
Satellites: sine qua non
False color images. Video and picture show. Mushroomed census of red & brown dwarfs from IR images.
March 1- PHYSICS OF E/M EMISSION
Thermal/non-thermal sources. Wien’s, Boltzmann’s, and Stephen’s Laws.
Light as photons/ Einstein: E = hf. Photon energy across the E/M spectrum.
Doppler shifts due to motion and cosmic expansion.
March 8- HISTORY OF RADIO ASTRONOMY AND A TOUR OF THE RADIO SKY.
Karl Jansky and the accidental discovery of radio astronomy
Grote Reber, the iconoclastic engineer who built the first “real” radio telescope
The discovery of significant sources of radio emission, including
* the cosmic microwave background (CMB)
* neutral hydrogen 21-cm line
The brightest radio sources in the sky
A tour of the radio sky
March 15- RADIO TELESCOPES AND INTERFEROMETRY
What is an antenna? Single-dish radio telescopes
Interferometry – the superpower of radio astronomy
A tour of famous and powerful telescopes around the world
March 22- LOWER ENERGY WAVES
Aspects of radio, microwave, IR, and visible waves.
Ray optics of mirrors, lenses, and waveguides. Telescope design and detectors. Typical sources.
Major telescopes employed. Discovery highlights and photos.
Newest designation: “submillimeter”.
–HIGHER ENERGY WAVES
Same survey for ultraviolet, X-ray, gamma waves.
March 29 – SOURCES OF RADIO WAVES AND HOW WE
USE THEM TO UNDERSTAND THE UNIVERSE
The CMB – the keystone for modern cosmology
Pulsars – revealing gravitational waves and fundamental physics
Masers – monochromatic tools to reveal cosmology, star formation, and more.
Radio jets from distant quasars
Radio emissions from star formation
April 12 – FOCUS ON SUPERMASSIVE BLACK HOLES AND COSMOLOGY. WRAP-UP
Using radio observations of water to weigh supermassive black holes
Measuring the expansion rate of the universe (Hubble Constant)
Wrap-up with Q&A