Extragalactic background light

<p>The diffuse extragalactic background light (EBL) is all the accumulated radiation in the <a href="/facts/Universe/XbfpnDmM">universe</a> due to <a href="/facts/Star_formation/SMyfVDY6">star formation</a> processes, plus a contribution from <a href="/facts/Active_galactic_nuclei/qT1owvXz">active galactic nuclei</a> (AGNs). This radiation covers almost all wavelengths of the <a href="/facts/Electromagnetic_spectrum/24LARvFY">electromagnetic spectrum</a>, except the microwave, which is dominated by the primordial <a href="/facts/Cosmic_microwave_background/ThB2HkLS">cosmic microwave background</a>. The EBL is part of the <a href="/facts/Diffuse_extragalactic_background_radiation/jwE5U2dV">diffuse extragalactic background radiation</a> (DEBRA), which by definition covers the entire electromagnetic spectrum. After the <a href="/facts/Cosmic_microwave_background/ThB2HkLS">cosmic microwave background</a>, the EBL produces the second-most energetic diffuse background, thus being essential for understanding the full energy balance of the universe.
</p><p>The understanding of the EBL is also fundamental for extragalactic very-high-energy (VHE, 30 GeV-30 TeV) astronomy. VHE <a href="/facts/Photon/mFNhAEzA">photons</a> coming from cosmological distances are attenuated by <a href="/facts/Pair_production/MmN9EUG0">pair production</a> with EBL photons. This interaction is dependent on the <a href="/facts/Spectral_energy_distribution/6vC1Pnl6">spectral energy distribution</a> (SED) of the EBL. Therefore, it is necessary to know the SED of the EBL in order to study intrinsic properties of the emission in the VHE sources.
</p>

Extragalactic background light open-in-new

Extragalactic background light