Radio and High Energy Telescopes Module 2

Module Two

Radio and High Energy Telescopes

Page 1: Introduction

• Introduction to radio and high energy telescopes.

Page 2: Radio Astronomy

• Properties of Radiation:

  • Both visible light and radio waves can penetrate Earth's atmosphere.

• Radio Telescopes:

  • Used to detect cosmic sources of radio waves.

  • Features a collecting area that focuses radiation onto a receiver.

  • Require a large collecting area due to faintness of cosmic radio waves.

  • Few sources emit radio waves; many are distant.

• Wave Characteristics:

  • Longer wavelengths result in increased diffraction.

Page 3: Large Radio Telescopes

• Arecibo Observatory:

  • Location: Puerto Rico.

  • Diameter: 305 meters.

  • Fixed position, can observe only objects within 20 degrees overhead.

  • Was the largest radio telescope until surpassed.

• FAST (Five-hundred-meter Aperture Spherical Telescope):

  • Location: China.

  • Diameter: 500 meters, currently the largest radio telescope.

Page 4: Advantages of Radio Astronomy

• Atmospheric Penetration:

  • Earth’s atmosphere does not reflect or scatter radio waves.

  • Radio waves can pass through clouds and rain.

  • Minimal interference from the Sun.

• Observational Benefits:

  • Radio waves allow discovery of weak light-emitting sources that may go unnoticed otherwise.

  • Cosmic dust does not obstruct radio waves, improving observation reliability.

Page 5: Characteristics of Radio Astronomy

• Centaurus Galaxy:

  • Comparisons of visible and radio images show significant differences.

  • Radio emissions displayed in false colors: red indicates higher emissions, blue indicates lower emissions.

• Galactic Structure:

  • Presence of radio lobes indicating large jets of gas from the galaxy's center.

  • Definition of a radio galaxy: emits more radio energy than visible light energy.

Page 6: Interferometry

• Interferometry Technique:

  • Analyzes the interference of radio signals to enhance detail in images.

  • This technique also applies to visible light telescopes.

  • Uses a series of interconnected smaller radio telescopes for improved imaging.

Page 7: Space-based Telescopes

• Atmospheric Limitations:

  • Earth's atmosphere only allows visible light, some infrared, and radio waves to pass; blocks other electromagnetic radiation.

• Infrared Study Applications:

  • Infrared light helps study space dust and cooler objects not emitting visible light.

• Deployment:

  • Infrared telescopes are used in balloons or spacecraft.

Page 8: Infrared Light

• Infrared Telescopes:

  • Designed as reflectors; James Webb (2020) launched for solar and dust observation.

• Visual Comparison:

  • Displays side-by-side images of visible light versus infrared light, highlighting better visibility in infrared due to the obstruction by cosmic dust.

Page 9: Spitzer Space Telescope

• Launch and Operation:

  • Launched in 2003, operates as an infrared space telescope.

  • Orbits the Sun, experiencing no interference from Earth.

Page 10: Ultraviolet Space Telescopes

• Properties of Ultraviolet Light:

  • Shorter wavelengths and higher frequencies than violet light.

  • Absorbed efficiently by the ozone layer in Earth’s atmosphere; requiring platforms above the atmosphere.

• Deployment Methods:

  • Ultraviolet telescopes are flown on balloons, rockets, or satellites.

• Observation Results:

  • Images showcase remnants of supernovae and star-forming regions in galaxies.

Page 11: High-Energy Astronomy

• Types of High Energy Radiation:

  • X-rays and gamma rays are characterized by short wavelengths and high frequencies.

  • Require space observation due to high opacity from Earth’s atmosphere.

• Objects of Interest:

  • Very high-temperature objects may emit high-energy radiation rather than visible light.

  • Comparison of appearances in different wavelengths (X-ray vs. visible light).

Page 12: High Energy Astronomy: X-Rays and Gamma Rays

• Observatory Requirements:

  • Specialized telescopes are needed as X-rays and gamma rays cannot be reflected like visible light.

  • Technique involves using nested mirrors for reflection to focus X-rays.

• Chandra X-ray Observatory:

  • Launched in 1999 for X-ray astronomy.

Page 13: High-Energy Astronomy - Supernova

• Observational Outcomes:

  • A false-color X-ray image displays remnants of the Cas-A supernova.

  • Characteristics: Gas at edges is at temperatures around 50 million degrees Kelvin.

  • Potential presence of a black hole indicated by bright central dot.

  • More than nine X-ray telescopes currently operational in orbit.

Page 14: Gamma Ray Observations

• Observational Limitations:

  • Gamma ray telescopes possess low resolution but are essential for high-energy astronomy.

• Prominent Observatories:

  • Examples include the Compton Gamma-Ray Observatory and Fermi Gamma-Ray Observatory.

• Interaction with Other Rays:

  • Gamma rays can be observed from Earth and have interactions with UV and IR light.

Page 15: Comparison of Images from Different Telescopes

• Various images from radio, infrared, visible, ultraviolet, X-ray, and gamma-ray observations are compared to illustrate differences in detail and resolution.

Page 16: Cosmic Ray Observations

• Definition:

  • Cosmic rays are high-energy particles traveling near the speed of light.

• Origin:

  • Created from interactions when supernova debris hits dust, resulting in acceleration.

• Protection:

  • Earth’s atmosphere serves as a shield against cosmic rays.

Page 17: Neutrino Observations

• Characteristics:

  • Neutrinos are low mass, high-speed particles with minimal interaction with matter.

  • Generated during thermonuclear fusion processes.

• Experimental Setup:

  • Detectors are located underground to minimize radiation interference, often using deuterium water.

• Potential Discoveries:

  • Detection of neutrons converting to protons could pave the way for telescope development.