The extragalactic background light and the gamma-ray opacity of the universe

By E. Dwek, F. Krennrich. 2012

221 citations recorded by the source corpus.

Abstract The extragalactic background light (EBL) is one of the fundamental observational quantities in cosmology. All energy releases from resolved and unresolved extragalactic sources, and the light from any truly diffuse background, excluding the cosmic microwave background (CMB), contribute to its intensity and spectral energy distribution. It therefore plays a crucial role in cosmological tests for the formation and evolution of stellar objects and galaxies, and for setting limits on exotic energy releases in the universe. The EBL also plays an important role in the propagation of very high energy γ-rays which are attenuated en route to Earth by pair producing γ–γ interactions with the EBL and CMB. The EBL affects the spectrum of the sources, predominantly blazars, in the ∼10 GeV–10 TeV energy regime. Knowledge of the EBL intensity and spectrum will allow the determination of the intrinsic blazar spectrum in a crucial energy regime that can be used to test particle acceleration mechanisms and very high energy (VHE) γ-ray production models. Conversely, knowledge of the intrinsic γ-ray spectrum and the detection of blazars at increasingly higher redshifts will set strong limits on the EBL and its evolution. This paper reviews the latest developments in the determination of the EBL and its impact on the current understanding of the origin and production mechanisms of γ-rays in blazars, and on energy releases in the universe. The review concludes with a summary and future directions in Cherenkov Telescope Array techniques and in infrared ground-based and space observatories that will greatly improve our knowledge of the EBL and the origin and production of very high energy γ-rays.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/9aaec0cdf16c681104710313a9aa709c24771575

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Citations in the corpus

Cosmological Magnetic Fields: Their Generation, Evolution and Observation (2013, methodology): “9 contains two contributions: the intrinsic source spectrum in this band and the secondary cascade emission from e+e− pairs generated by interactions of TeV photons with the EBL.”
The extragalactic background light revisited and the cosmic photon–photon opacity (Corrigendum) (2017, methodology): “…published measurements of the total-light EBL in the near-IR based on COBE (Gorjian et al. 2000, Wright & Reese 2000, Cambresy et al. 2001, Hauser & Dwek 2001, Dwek & Krennrich 2005, 2013), and IRTS (Matsumoto et al. 2005; Kashlinsky 2006) observations, and rocket experiments (Zemkov et al. 2014).”
2FHL: THE SECOND CATALOG OF HARD FERMI-LAT SOURCES (2015, background): “The EBL contains all the photons, from the ultraviolet to the infrared, that have been emitted by star formation processes and supermassive black hole accretion throughout the history of the universe (e.g., Dwek & Krennrich 2013).”
The Search for Spatial Extension in High-latitude Sources Detected by the Fermi Large Area Telescope (2018, background): “The γ-rays interact with photons of the extragalactic background light (EBL, Hauser & Dwek 2001; Kashlinsky 2005) to form e+e−pairs (Nikishov 1962; Gould & Schréder 1967a, 1967b; Dwek & Krennrich 2013).”
THE EXTRAGALACTIC BACKGROUND LIGHT, THE HUBBLE CONSTANT, AND ANOMALIES: CONCLUSIONS FROM 20 YEARS OF TeV GAMMA-RAY OBSERVATIONS (2015, methodology): “In addition to constraints listed by Dwek & Krennrich (2013), we also include the lower limits at 3.6 and 4.5 mm from Ashby et al. (2013).”
Search for TeV Gamma-ray Emission from GRB 100621A, an extremely bright GRB in X-rays, with H.E.S.S (2014, background): “VHE gamma rays are absorbed by interactions with the extragalactic background light (EBL) and can thus only travel limited distances in the Universe (e.g. Dwek & Krennrich 2013).”