Low-resolution spectrum of the extragalactic background light with the AKARI InfraRed camera

The Extragalactic Background Light (EBL) as integrated light from outside of our Galaxy includes information about the early universe and the Dark Ages. We analyzed spectral data of the astrophysical diffuse emission obtained with the low-resolution spectroscopy mode on the AKARI Infra-Red Camera (IRC) in the 1.8-5.3μm wavelength region. Although previous EBL observations in this wavelength region were restricted to observations by DIRBE and IRTS, this study adds a new independent result with negligible contamination of Galactic stars owing to higher sensitivity for point sources. Two other major foreground components, zodiacal light (ZL) and diffuse Galactic light (DGL), were subtracted by taking correlations with ZL brightness estimated by the DIRBE ZL model and with the 100μm dust thermal emission, respectively. The isotropic emission was obtained as EBL, which shows significant excess over integrated light of galaxies at <4μm. The obtained EBL is consistent with the previous measurements by IRTS and DIRBE.