Measurement of the extragalactic background light at 8600Ã using dark cloud shadow and the CaII-triplet lines

Abstract

We present results of a measurement of the near infrared Extragalactic Background Light using the dark-cloud method. Long-slit spectra covering the opaque core of the intermediate--latitude globule DC303.8-14.2 and the almost unobscured off area were measured using nodding-along-the-slit measuring technique providing a differential spectrum free of most of the foreground components. A template for the only remaining major foreground component, the scattered integrated starlight dominated by the strong Ca II triplet lines at 8498, 8542, 8664$\tilde{A}$, from the dark core itself was constructed using the GAIA RVS spectral database. The derived EBL intensity is $1.62\pm 0.76(\ddot{I}{ƒ}_{stat})10^{-9}ergc{m}^{-2}{s}^{-1}{\tilde{A}}^{-1}s{r}^{-1}$ or $13.8\pm 6.5(\ddot{I}{ƒ}_{stat})$nW m${}^{-2}$sr${}^{-1}$; this represents a tentative detection at $2.1\ddot{I}ƒ$, level.

Accepted for publication in Astronomy and Astrophysics. 14 pages, 10 figures and 5 tables. Second submission after language-editing