Implications of cosmological gamma-ray absorption

Kneiske, T.; Mannheim, K.; Hartmann, D. H.

doi:10.1051/0004-6361:20020211

Cited by 157 publications

(230 citation statements)

References 63 publications

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“…1. Energy dependent attenuation resulting from the interaction of HE/VHE γ-rays with the low energy photons from the EBL for different redshifts z (EBL model: KN low from Kneiske et al 2002). The grey shaded area gives the energy range of the highest energy bin in the 1FGL catalog which will be investigate for attenuation features.…”

Section: Methods and Data Samplementioning

confidence: 99%

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Searching for an extragalactic background light attenuation signature in the Fermi/LAT 1st year catalog data

Raue

2010

A&A

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Observations of distant sources of high-energy (HE) γ-rays are affected by attenuation resulting from the interaction of the γ-rays with low energy photons from the diffuse meta-galactic radiation fields at ultraviolet (UV) to infrared (IR) wavelengths (extragalactic background light; EBL). Recently, a large data-set of HE observations from the 1st year survey of the Large Area Telescope (LAT) instrument on-board of the Fermi satellite became available, covering an energy range from 100 MeV up to 100 GeV. In this paper, the potential of such large HE data-sets to probe the density of the EBL -especially in the UV to optical -is explored. The data from the catalog is investigated for an attenuation signature in the energy range 10-100 GeV and the results are compared with the predictions from EBL model calculations. No clear signature is found. The statistics are still limited by (1) the sensitivity of Fermi/LAT to detect sources above 10 GeV, (2) the number of firmly identified sources with known redshift, both which will improve over the coming years.

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Section: Methods and Data Samplementioning

confidence: 99%

“…Fig. 1 displays the EBL attenuation for the low EBL model from Kneiske et al (2002) for the energy range 1 GeV to 200 GeV for several redshifts. It can be seen that significant EBL attenuation is only expected for the flux in highest energy bin.…”

Section: Methods and Data Samplementioning

confidence: 99%

Searching for an extragalactic background light attenuation signature in the Fermi/LAT 1st year catalog data

Raue

2010

A&A

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“…The method of galaxy counts is used to estimate the EBL, but it only provides a lower limit owing to the unknown of unresolved sources. Various models for the EBL have been published: Salamon & Stecker (1998), Malkan & Stecker (1998, , Kneiske et al (2002Kneiske et al ( , 2004, Primack et al (2005Primack et al ( , 2008, Gilmore et al (2008Gilmore et al ( , 2009, Franceschini et al (2008), Razzaque et al (2009), Finke et al (2010). These models include different degrees of complexity, observational constraints, and data inputs.…”

Section: Introductionmentioning

confidence: 99%

Constraining extragalactic background light from TeV blazars

Yang

Wang

2010

A&A

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Aims. Our goal is to research the upper limits to the extragalactic background light (EBL). Methods. The upper limits to the extragalactic background light (EBL) are presented, using the Fermi and very high energy (VHE) spectra recently observed in TeV blazars. We use an assumption that the VHE intrinsic photon index cannot be harder than the Fermi index measured by the Fermi-LAT. Results. These upper limits are compatible with ones given by most EBL models; however, the models of high EBL density are contradicted by TeV blazars.

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“…We follow the equations presented in Kneiske et al (2002) to calculate the EBL. The two basic ingredients for the calculation are (i) the cosmic star formation rate ρ * and (ii) the luminosity L ν (τ) of a specific stellar population of age τ as e.g.…”

Section: Ebl Modelmentioning

confidence: 99%

“…Further details on the calculation can be found in Kneiske et al (2002). Photons from the star ionize the dense gas cloud surrounding the formation site.…”

Section: Ebl Modelmentioning

confidence: 99%

First stars and the extragalactic background light: how recentγ-ray observations constrain the early universe

Kneiske

Mazin

2009

A&A

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Context. The formation of the first stars (Population III; PopIII) marks the end of the dark ages of the universe, a subject of lively scientific debate. Not (yet) accessible to direct observations, this early stage of the universe is mostly studied via theoretical calculations and numerical simulations. An indirect window is provided by integrated present day observables such as the metal abundance or the diffuse extragalactic photon fields. Aims. We aim to derive constraints on the properties of the PopIII and low metallicity Population II (LM PopII) stars utilizing limits on the density of the extragalactic background light (EBL), recently derived from very-high-energy (E > 100 GeV; VHE) observations. Methods. A model calculation for the evolving EBL density produced by PopIII/LM PopII stars is presented. The model utilizes stellar population spectra (SPS) for zero and low metallicity stars and accounts for the changing emission of an aging stellar population. Emission from the dense HII regions surrounding the stars (nebula) is included. The resulting EBL density for different scenarios (metallicity, star formation rate, initial mass function) is compared to the limit on the EBL density. The potential for detecting a cut-off in HE/VHE spectra is discussed. Results. Assuming a maximum contribution from PopIII/LM PopII stars to the EBL density of 5 nW m −2 s −1 at 2 μm, a limit on the star formation rate (SFR) of the first stars of 0.3 to 3 M Mpc −3 yr −1 in the redshift range 7−14 is derived. The limit depends on the assumed shape of the SFR and metallicity. Conclusions. The EBL can be used as a probe to investigate the properties of PopIII/LM PopII stars. Limits on the EBL density derived from VHE observations can provide constraints on the parameters of the these stars, in particular the star formation rate.

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Implications of cosmological gamma-ray absorption

Cited by 157 publications

References 63 publications

Searching for an extragalactic background light attenuation signature in the Fermi/LAT 1st year catalog data

Searching for an extragalactic background light attenuation signature in the Fermi/LAT 1st year catalog data

Constraining extragalactic background light from TeV blazars

First stars and the extragalactic background light: how recentγ-ray observations constrain the early universe

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