Astrophysics (Index)About

gamma rays

(GR)
(electromagnetic radiation, wavelength 10 picometers and less)

Gamma rays (GRs) are generally described as electromagnetic radiation (EMR) with wavelengths in the range of 0-10 pm. In the EMR spectrum, they include everything beyond X-rays in frequency and photon energy. They are generally the result of nuclear reactions, and are present in cosmic rays. They are often specified by their photon energy in electron volts (eV), as opposed to using their frequency or wavelength. Equivalent to the above-cited wavelength-range "everything beyond 124 keV", but astronomers often cite the line between X-rays and gamma rays as 100 keV (i.e., a round number of eV): this discrepancy is largely moot because discussions of EMR in the 100-124 keV photon-energy range, the energy of interest is likely to be stated.

There is no consensus across all scientists/technologists on the boundary between EMR termed X-rays and gamma rays: the distinction originally arose from the manner in which they are produced: X-rays were from high-voltage vacuum tubes producing cathode rays, and gamma rays are one type of emission occurring during radioactive decay, of radioactive substances such as radium. However, both these types of sources produce EMR, and the wavelength ranges overlap. Mechanisms that produce this short-wavelength EMR don't completely adhere to any particular absolute limits, making any such limits somewhat arbitrary, and in astronomical observation, there will be some particular instrument or source that spans any chosen boundary.

The targets of gamma-ray astronomy include gamma-ray transients (gamma-ray bursts, GRBs) and a gamma-ray background (cosmic gamma ray background as well as a galactic gamma ray background due to the interaction of cosmic rays with the interstellar medium) as well as gamma-ray sources, such as the Crab Nebula. Among the space telescopes/observatories:

Among ground Cherenkov detectors:


(EMR,spectrum,band)
Further reading:
https://en.wikipedia.org/wiki/Gamma_ray
https://en.wikipedia.org/wiki/Gamma-ray_astronomy
WaveLFreqPhoton
Energy
  
0pminfinfbegingamma rays
10pm30EHz124keVendgamma rays

Referenced by pages:
active galaxy
AGILE
active galactic nucleus (AGN)
air shower
ARGO-YBJ Experiment
ASTRO-H
black-body radiation
cosmic gamma ray background (CGB)
Compton Gamma Ray Observatory (CGRO)
Cherenkov detector
Cherenkov radiation
CNO cycle
Compton scattering
Compton telescope
COSI
Cherenkov Telescope Array (CTA)
curvature radiation
Dawn
Dragonfly
electromagnetic spectrum
electromagnetic radiation (EMR)
electron volt (eV)
Fermi (FGST)
Fred Lawrence Whipple Observatory (FLWO)
frequency
GRANAT
gamma-ray burst (GRB)
hardness
High-altitude Water Cherenkov Observatory (HAWC)
high-energy astrophysics (HEA)
HEAO-1
HEASARC
High Energy Stereoscopic System (HESS)
INTEGRAL
ionizing radiation
potassium/thorium ratio (K/Th ratio)
LHAASO
magnetar
Mars Observer (MO)
Milagro
MMX
millisecond pulsar (MSP)
NEAR Shoemaker (NEAR)
neon burning
neutron spectrometer
nuclear statistical equilibrium (NSE)
nucleosynthesis
observational astronomy
OSO 7
pair production
pair telescope
Penrose Compton scattering (PCS)
photodisintegration
photodissociation
photon energy
Psyche
radioactive heating
rare designator prefixes
radio source (RS)
scintillator
soft gamma repeater (SGR)
Solar Maximum Mission (SMM)
source
spark chamber
Swift
Tunka experiment
TD-1A
tidal disruption event (TDE)
telescope type
3C 279
ultra-high-energy gamma rays (UHEGR)
VERITAS
VHE
very-high-energy gamma rays (VHEGR)
wavelength
X-ray

Index