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Very high energy (VHE $>$100 GeV) gamma rays coming from blazars can produce pairs when interacting with the Extragalactic Background Light (EBL) and the Cosmic Microwave Background, generating an electromagnetic cascade. Depending on the…

High Energy Astrophysical Phenomena · Physics 2015-09-07 M. Fernandez Alonso , A. D. Supanitsky , A. C. Rovero

We present a two-parameter model of the extragalactic gamma-ray background (EGB) in the 0.1-100 GeV range as measured by the Large Area Telescope (LAT) onboard the Fermi satellite. The EGB can be fully explained as the sum of three distinct…

Cosmology and Nongalactic Astrophysics · Physics 2011-05-25 Massimo Cavadini , Ruben Salvaterra , Francesco Haardt

I discuss how measurements of the absorption of $\gamma$-rays from GeV to TeV energies via pair production on the extragalactic background light (EBL) can probe important issues in galaxy formation. We use semi-analytic models (SAMs) of…

Astrophysics · Physics 2007-05-23 Joel R. Primack

We present a revised measurement of the optical extragalactic background light (EBL), based on the contribution of resolved galaxies to the integrated galaxy light (IGL). The cosmic optical background radiation (COB), encodes the light…

The absorption of gamma-rays in the intergalactic medium due to the EBL (Extragalactic Background Light) causes the observed blazar spectrum to be fainter and softer than their intrinsic state. It could thus be expected to see an effective…

High Energy Astrophysical Phenomena · Physics 2009-01-22 B. Behera , S. J. Wagner

Extragalactic background light (EBL) anisotropy traces variations in the total production of photons over cosmic history, and may contain faint, extended components missed in galaxy point source surveys. Infrared EBL fluctuations have been…

Very high energy (VHE; $E \geq$ 100GeV) $\gamma-$ray from cosmological distances are attenuated by the extragalactic background light (EBL) in the IR to UV band. By contrasting measured versus intrinsic emission, the EBL photon density can…

High Energy Astrophysical Phenomena · Physics 2020-09-01 Longhua Qin , Jiancheng Wang , Quangui Gao , Weiwei Na , Huaizhen Li , Ju Ma , Jianping Yang

We calculate the absorption of 10-500 GeV gamma-rays at high redshifts. This calculation requires the determination of the high-redshift evolution of the intergalactic starlight photon field, including its IR-UV spectral energy…

Astrophysics · Physics 2008-11-26 M. H. Salamon , F. W. Stecker

(Abridged) We have used HST WFPC2 and ground-based spectroscopy to measure the integrated extragalactic background light (EBL) at optical wavelengths. We have also computed the integrated light from individual galaxy counts in the images…

Astrophysics · Physics 2009-11-07 R. A. Bernstein , W. L. Freedman , B. F. Madore

Axion-like particles (ALPs) provide a feasible explanation for the observed lower TeV opacity of the Universe. If the anomaly TeV transparency is caused by ALPs, then the fluxes of distant extragalactic sources will be enhanced at photon…

High Energy Astrophysical Phenomena · Physics 2021-11-17 Yun-Feng Liang , Xing-Fu Zhang , Ji-Gui Cheng , Hou-Dun Zeng , Yi-Zhong Fan , En-Wei Liang

Here is reviewed our current understanding of Galactic and extragalactic diffuse gamma-ray emission. The spectrum of the extragalactic gamma-ray background above 30 MeV can be well described by a power law with photon index s=2.1. In the…

Astrophysics · Physics 2007-05-23 Martin Pohl

Observations of distant sources of high-energy (HE) gamma-rays are affected by attenuation resulting from the interaction of the gamma-rays with low energy photons from the diffuse meta-galactic radiation fields at ultraviolet (UV) to…

Cosmology and Nongalactic Astrophysics · Physics 2011-08-12 Martin Raue

The extragalactic background light (EBL) consists of integrated light from all sources of emission throughout the history of the universe. At near-infrared wavelengths, the EBL is dominated by stellar emission across cosmic time; however,…

Cosmology and Nongalactic Astrophysics · Physics 2022-02-09 Yun-Ting Cheng , Tzu-Ching Chang

The study of the extragalactic background light (EBL) in the optical and near infrared has received a lot of attention in the last decade, especially near a wavelength of $\lambda\approx 3.4\operatorname{\mu m}$, with remaining tension…

The diffuse extragalactic background light consists of the sum of the starlight emitted by galaxies through the history of the Universe, and it could also have an important contribution from the first stars, which may have formed before…

Astrophysics · Physics 2012-08-27 H. E. S. S. Collaboration , : , F. Aharonian

Several recent papers claim the detection of a near infrared Extragalactic Background Light (EBL) intensity at 1.25 - 4 um that exceeds the integrated light of galaxies by factors of >3. When combined with a claimed optical detection of the…

Astrophysics · Physics 2009-11-11 K. Mattila

(Abridged) Statistical analysis of the unresolved light in the Hubble Deep Field (HDF) strongly constrains possible sources of the optical Extragalactic Background Light (EBL). To test for the statistical signature of previously undetected…

Astrophysics · Physics 2007-05-23 Michael S. Vogeley

We discuss how measurements of the absorption of gamma-rays from GeV to TeV energies via pair production on the extragalactic background light (EBL) can probe important issues in galaxy formation. Semi-analytic models (SAMs) of galaxy…

Astrophysics · Physics 2009-11-10 Joel R. Primack , James S. Bullock , Rachel S. Somerville

The Extragalactic Background Light (EBL) carries a huge astrophysical and cosmological content: its frequency spectrum and redshift evolution are determined by the integrated emission of unresolved sources, these being galaxies, active…

Cosmology and Nongalactic Astrophysics · Physics 2024-07-03 Sarah Libanore , Ely D. Kovetz