Astrophysics (Index)About

X-ray

(electromagnetic radiation, wavelength 0.01 to 10 nanometers)

The term X-ray generally refers to electromagnetic radiation (EMR) with a wavelength within the range of 0.01-10 nm, lying between ultraviolet and gamma rays. Lower energy/frequency X-rays, toward the ultraviolet end, are termed soft and higher energy/frequency, toward the gamma rays end are termed hard. The intervening line between soft and hard is in the general region of 0.1-0.2 nm or 5-10 keV. The phrase cosmic X-ray survey has been used for surveys of X-ray sources at cosmological distances, e.g., distant active galactic nuclei. Rather than by frequency or wavelength, X-rays are often cited by photon energy, in electron volts (eV). The equivalent to the above-cited range for X-rays is 124 eV to 124 keV, but astronomers do cite the line between X-rays and gamma rays as 100 keV: this is largely moot as in discussions of EMR in the 100-124 keV photon-energy range, the energy of interest is likely to be stated.

There is not a consensus across all scientists/technologists on the boundary between EMR termed X-rays, especially between X-rays and gamma rays: the distinction originally arose from the type of device that could produce them: 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. In astronomical observation, every boundary possibility would still be spanned by some instruments and sources.


(EMR,spectrum,band)
Further reading:
http://en.wikipedia.org/wiki/Xray
WaveLFreqPhoton
Energy
  
0.01nm30EHz124keVbeginX-ray
10nm30PHz124eVendX-ray

Referenced by pages:
ACIS
active galaxy
AGILE
active galactic nucleus (AGN)
ALEXIS
Ariel 5
ASCA
ASTRO-H
Athena
atmospheric escape
anomalous X-ray pulsar (AXP)
BeppoSAX
binary star
black-body radiation
Chandra Deep Field North (CDFN)
Chandra Deep Field South (CDFS)
Chandra X-ray Observatory (CXO)
color-magnitude diagram (CMD)
Compton reflection
Compton scattering
cooling flow
Cosmic Evolution Survey (COSMOS)
cosmic X-ray background (CXB)
diffuse emission
DQ Tau
Extended Chandra Deep Field-South Survey (ECDFS)
electromagnetic spectrum
electromagnetic radiation (EMR)
eROSITA
extreme ultraviolet (EUV)
electron volt (eV)
EXOSAT
filter
frequency
galaxy cluster (CL)
gamma rays (GR)
Ginga
grazing incidence optics (GIO)
GRANAT
grating
hardness
high-B radio pulsar (HBRP)
high-energy astrophysics (HEA)
HEAO-1
HEAO-2
HEASARC
High Energy Transient Explorer (HETE)
International Cometary Explorer (ICE)
intracluster medium (ICM)
intergalactic medium (IGM)
INTEGRAL
ionizing radiation
ionosphere
Japan Aerospace Exploration Agency (JAXA)
KID
K-line
Kramers opacity law
Lynx
M82
Massive Cluster Survey (MACS)
magnetar
Mars 2020
MAXI
Mars Exploration Rover (MER)
Mars Pathfinder (MPF)
Mars Science Laboratory (MSL)
millisecond pulsar (MSP)
MIT X-ray Burst Source Catalog (MXB)
NEAR Shoemaker (NEAR)
neutron star (NS)
NICER
nova (N)
NuSTAR
Orbiting Astronomical Observatory (OAO)
obscured fraction-luminosity relation
OSO 7
photodissociation
pre-main-sequence star (PMS)
planetary nebula (PN)
pulsar (PSR)
pulsar wind nebula (PWN)
quasi-periodic oscillation (QPO)
Rosat Bright Survey (RBS)
Rho Ophiuchi Cloud Complex
Rosat Hard Survey (RHS)
Rosalind Franklin
ROSAT
Rosetta
rp-process
radio source (RS)
RXTE
scintillator
Spitzer Extragalactic Representative Volume Survey (SERVS)
soft gamma repeater (SGR)
slew survey
SMART-1
Solar Maximum Mission (SMM)
Solar Orbiter (SolO)
spectrograph
spectrometer
spectroscope
Spektr-RG (SRG)
SS 433
STAR-X
stellar-mass black hole
superconducting tunnel junction (STJ)
Sun
Sun surface features
Suzaku
Swift
Subaru XMM-Newton Deep Survey (SXDS)
Taurus-Auriga Complex
tidal disruption event (TDE)
Thermal Bremsstrahlung
Thomson optical depth (τT)
3C 295
3C 9
transient
Uhuru
ultraviolet (UV)
ultraluminous X-ray source (ULX)
Ulysses
ultraviolet astronomy
wavelength
Wien's displacement law
Wolf-Rayet star
Wolter telescope
XBONG
XEUV
X-ray luminosity function (XLF)
X-ray luminous galaxy cluster
XMM-Newton
X-ray burster (XRB)
X-ray source
Yohkoh

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