A black hole is a region in space where the gravitational pull is so strong that nothing, not even light, can escape from it.

The Chandra X-Ray Observatory is a space telescope launched by NASA in 1999 to observe X-rays from high-energy sources in the universe.

The electromagnetic spectrum is the range of frequencies of electromagnetic radiation and their corresponding wavelengths and energies.

The European Organisation for Astronomical Research in the Southern Hemisphere, commonly referred to as the European Southern Observatory (ESO), is an intergovernmental research organisation made up of 16 member states for ground-based astronomy.

The Fermi Gamma-ray Space Telescope (FGST, also FGRST), formerly called the Gamma-ray Large Area Space Telescope (GLAST), is a space observatory being used to perform gamma-ray astronomy observations from low Earth orbit.

Gamma Ray is a German power metal band formed in 1989 by Kai Hansen.

General relativity, also known as the general theory of relativity, is a theory of gravitation that was developed by Albert Einstein in the early 20th century.

Gravitational-wave astronomy is a subfield of astronomy concerned with the detection and study of gravitational waves emitted by astrophysical sources.