extragalactic background light


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extragalactic background light

[¦ek·strə·gə¦lak·tik ′bak‚grau̇nd ‚līt]
(astronomy)
The contribution to the brightness of the sky from light coming from outside the Galaxy, chiefly distant galaxies, excluding resolved galaxies.
References in periodicals archive ?
Though some challenges remain, further data from LORRI could provide a definitive measurement of the extragalactic background light at optical wavelengths, and may be instrumental in completing our understanding of the history of stars and galaxies in the universe," the researchers wrote in the study.
They were trying to decipher the extragalactic background light, or EBL, a diffuse glow that fills the universe (SN:9/7/13, p.
Washington, May 25 ( ANI ): The evolution of the extragalactic background light (EBL) over the past 5 billion years has been measured for the first time.
That bath of ancient and young photons suffusing the Universe today is called the extragalactic background light (EBL).
cole Polytechnique) have carried out the first measurement of the intensity of the diffuse extragalactic background light in the nearby Universe, a fog of photons that has filled the Universe ever since its formation.
By using HESS to measure the gamma-ray spectra emitted by relatively close blazars, they evaluated the effect of the interaction of highly energetic gamma rays with the diffuse extragalactic background light within a sphere of a three billion light year radius.
The combination of its superior location and experimental capabilities led to a long list of exciting discoveries of several very high energy (VHE) gamma ray sources over the past few years, including supernova remnants, the source at the Galactic Centre, compact binary systems, microquasars, pulsar wind nebulae, gamma rays from cosmic-ray interactions with dense molecular clouds, a starburst galaxy, stellar and galaxy clusters, active galactic nuclei, and "dark sources" with no obvious counterparts, in addition to conducting the first VHE survey of the sky, measuring the local cosmic-ray electron and iron nuclei spectra, constraining the level of extragalactic background light, and providing upper limits to dark mater annihilation.
But the vast majority of stellar photons continue traversing the cosmos, creating a ubiquitous if faint glow that scientists call extragalactic background light, or EBL.
But measuring the extragalactic background light is a challenge researchers are eager to take on.
Over such a great distance, a substantial proportion of the gamma rays should be absorbed by the extragalactic background light, but calculations that account for the expected absorption yield an unexpected emission spectrum for the blazar.
Coauthor David Williams, adjunct professor of physics at UC Santa Cruz, said the findings may indicate something new about the emission mechanisms of blazars, the extragalactic background light, or the propagation of gamma-ray photons over long distances.
The total sum of starlight in the cosmos is known to astronomers as the extragalactic background light (EBL).