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Related Concept Videos

The Electromagnetic Spectrum02:37

The Electromagnetic Spectrum

The electromagnetic spectrum consists of all the types of electromagnetic radiation arranged according to their frequency and wavelength. Each of the various colors of visible light has specific frequencies and wavelengths associated with them, and you can see that visible light makes up only a small portion of the electromagnetic spectrum. Because the technologies developed to work in various parts of the electromagnetic spectrum are different, for reasons of convenience and historical...
The Electromagnetic Spectrum01:24

The Electromagnetic Spectrum

Electromagnetic waves are categorized according to their wavelengths and frequencies, giving the electromagnetic spectrum. These waves are classified as radio, infrared, ultraviolet, etc. Radio waves refer to electromagnetic radiation with wavelengths ranging from millimeters to kilometers. Radio waves are commonly used for audio communications (i.e., radios) and typically result from an alternating current in the wires of a broadcast antenna. They cover a broad wavelength range and are used...
Detection of Black Holes01:10

Detection of Black Holes

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Types of Radioactivity03:23

Types of Radioactivity

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Emission Spectra02:39

Emission Spectra

When solids, liquids, or condensed gases are heated sufficiently, they radiate some of the excess energy as light. Photons produced in this manner have a range of energies, and thereby produce a continuous spectrum in which an unbroken series of wavelengths is present.
Schwarzschild Radius and Event Horizon01:21

Schwarzschild Radius and Event Horizon

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Related Experiment Video

Updated: Jul 11, 2026

Characterizing Far-infrared Laser Emissions and the Measurement of Their Frequencies
09:38

Characterizing Far-infrared Laser Emissions and the Measurement of Their Frequencies

Published on: December 18, 2015

Quasars, blazars, and gamma rays.

C D Dermer, R Schlickeiser

    Science (New York, N.Y.)
    |September 18, 1992
    PubMed
    Summary

    The Compton Gamma Ray Observatory (CGRO) discovered 13 new extragalactic gamma-ray sources, mostly blazars, expanding our understanding of active galactic nuclei. These findings reveal energetic processes in the universe, originating from supermassive black holes.

    Area of Science:

    • High-energy astrophysics
    • Extragalactic astronomy
    • Cosmic ray physics

    Background:

    • Previously, only quasar 3C 273 was known as an extragalactic source of >100 MeV gamma radiation.
    • The Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory (CGRO) was launched to survey the gamma-ray sky.

    Purpose of the Study:

    • To identify and characterize extragalactic sources of high-energy gamma radiation.
    • To investigate the properties of these sources and their relationship to active galactic nuclei (AGN).

    Main Methods:

    • Utilizing data from the Energetic Gamma Ray Experiment Telescope (EGRET) aboard the Compton Gamma Ray Observatory (CGRO).
    • Analyzing gamma-ray emissions from extragalactic sources.
    • Correlating gamma-ray findings with multi-wavelength observations (radio, optical) to identify blazar properties.

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    Femtosecond Laser Filaments for Use in Sub-Diffraction-Limited Imaging and Remote Sensing
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    Visualization of Low-Level Gamma Radiation Sources Using a Low-Cost, High-Sensitivity, Omnidirectional Compton Camera
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    Main Results:

    • Discovery of 13 new extragalactic gamma-ray sources in less than a year of CGRO observations, bringing the total to 14.
    • All identified sources exhibit blazar characteristics, including high optical polarization, variability, and flat-spectrum radio emission.
    • These sources are likely rare, favorably aligned radio galaxies and quasars with relativistic jets.

    Conclusions:

    • The CGRO's EGRET instrument has significantly increased the number of known extragalactic gamma-ray sources.
    • Blazars are dominant sources of high-energy gamma rays beyond our galaxy.
    • Gamma-ray observations provide crucial insights into the central engines of AGN and extreme astrophysical processes.