# AKARI observation of the fluctuation of the near-infrared background - Astrophysics > Cosmology and Nongalactic Astrophysics

AKARI observation of the fluctuation of the near-infrared background - Astrophysics > Cosmology and Nongalactic Astrophysics - Download this document for free, or read online. Document in PDF available to download.

Abstract: We report a search for fluctuations of the sky brightness toward the northecliptic pole NEP with the Japanese infrared astronomical satellite AKARI,at2.4, 3.2, and 4.1 \mum. We obtained circular maps with 100 diameter field ofview which clearly show a spatial structure on scale of a few hundred arcsec. Apower spectrum analysis shows that there is a significant excess fluctuation atangular scales larger than 10000 that can-t be explained by zodiacal light,diffuse Galactic light, shot noise of faint galaxies or clustering of lowredshift galaxies. These results are consistent with observations at 3.6 and4.5 \mum by NASA-s Spitzer Space Telescope. The fluctuating component observedat large angular scales has a blue stellar spectrum which is similar to that ofthe spectrum of the excess isotropic emission observed with IRTS. A significantspatial correlation between wavelength bands was found, and the slopes of thelinear correlations is consistent with the spectrum of the excess fluctuation.These findings indicate that the detected fluctuation could be attributed tothe first stars of the universe, i.e. pop. III stars. The observed fluctuationprovides an important constraints on the era of the first stars.

Author: T. Matsumoto, H. J. Seo, W. -S. Jeong, H. M. Lee, S. Matsuura, H. Matsuhara, S. Oyabu, J. Pyo, T. Wada

Source: https://arxiv.org/