Extragalactic Background Light Inferred from AEGIS Galaxy SED-type Fractions - Astrophysics > Cosmology and Nongalactic AstrophysicsReport as inadecuate

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Abstract: The extragalactic background light EBL is of fundamental importance bothfor understanding the entire process of galaxy evolution and for gamma-rayastronomy, but the overall spectrum of the EBL between 0.1-1000 microns hasnever been determined directly from galaxy spectral energy distribution SEDobservations over a wide redshift range. The evolving, overall spectrum of theEBL is derived here utilizing a novel method based on observations only. Thisis achieved from the observed evolution of the rest-frame K-band galaxyluminosity function up to redshift 4 Cirasuolo et al. 2010, combined with adetermination of galaxy SED-type fractions. These are based on fitting SWIREtemplates to a multiwavelength sample of about 6000 galaxies in the redshiftrange from 0.2 to 1 from the All-wavelength Extended Groth Strip InternationalSurvey AEGIS. The changing fractions of quiescent galaxies, star-forminggalaxies, starburst galaxies and AGN galaxies in that redshift range areestimated, and two alternative extrapolations of SED-types to higher redshiftsare considered. This allows calculation of the evolution of the luminositydensities from the UV to the IR, the evolving star formation rate density ofthe universe, the evolving contribution to the bolometric EBL from thedifferent galaxy populations including AGN galaxies and the buildup of the EBL.Our EBL calculations are compared with those from a semi-analytic model, fromanother observationally-based model and observational data. The EBLuncertainties in our modeling based directly on the data are quantified, andtheir consequences for attenuation of very high energy gamma-rays due to pairproduction on the EBL are discussed. It is concluded that the EBL is wellconstrained from the UV to the mid-IR, but independent efforts from infraredand gamma-ray astronomy are needed in order to reduce the uncertainties in thefar-IR.

Author: A. Dominguez Universidad de Sevilla-IAA-CSIC, J. R. Primack UCSC, D. J. Rosario UCSC, F. Prada IAA-CSIC, R. C. Gilmore SISSA, S.

Source: https://arxiv.org/

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