Derivation of a large isotopic diffuse sky emission component at 1.25 and 2.2 μm from the COBE/DIRBE data

Journal Article · Thu Oct 01 04:00:00 EDT 2015 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/811/2/77· OSTI ID:22882545

Sano, K.; Kataza, H. ^[1]; Kawara, K. ^[2]; Matsuura, S. ^[3]; Arai, T. ^[4]

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1. Department of Astronomy, Graduate School of Science, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033 (Japan)
2. Institute of Astronomy, University of Tokyo, 2-21-1, Osawa, Mitaka, Tokyo 181-0015 (Japan)
3. Department of Physics, School of Science and Engineering, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337 (Japan)
4. Frontier Research Institute for Interdisciplinary Science, Tohoku University, Sendai 980-8578 (Japan)

Using all-sky maps obtained with COBE/DIRBE, we reanalyzed the diffuse sky brightness at 1.25 and 2.2 μm, which consists of zodiacal light, diffuse Galactic light (DGL), integrated starlight (ISL), and isotropic emission including the extragalactic background light. Our new analysis including an improved estimate of the DGL and the ISL with the 2MASS data showed that deviations of the isotropic emission from isotropy were less than 10% in the entire sky at high Galactic latitude (|b|>35{sup ∘}). We derived the DGL to 100 μm brightness ratios of ∼4.79 and ∼1.49 n W m{sup −2} MJy{sup −1} at 1.25 and 2.2 μm, respectively. The result of our analysis revealed a significantly large isotropic component at 1.25 and 2.2 μm with intensities of 60.15 ± 16.14 and 27.68±6.21 n W m{sup −2} sr{sup −1}, respectively. This intensity is larger than the integrated galaxy light, upper limits from γ-ray observation, and potential contribution from exotic sources (i.e., Population III stars, intrahalo light, direct collapse black holes, and dark stars). We therefore conclude that the excess light may originate from the local universe: the Milky Way and/or the solar system.

• OSTI ID: 22882545
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 811; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United Kingdom
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
BLACK HOLES
BRIGHTNESS
COSMIC DUST
EMISSION
ISOTROPY
MILKY WAY
SCATTERING
SOLAR SYSTEM
STARS
UNIVERSE
ZODIACAL LIGHT