Far-infrared detection limits – I. Sky confusion due to Galactic cirrus |
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Authors: | Woong-Seob Jeong Hyung Mok Lee Soojong Pak Takao Nakagawa Suk Minn Kwon Chris P. Pearson Glenn J. White |
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Affiliation: | Astronomy Program in Graduate School of Earth and Environmental Sciences, Seoul National University, Shillim-Dong Kwanak-Gu, Seoul 151-742, South Korea;Korea Astronomy Observatory, Whaam-Dong, Youseong-Gu, Taejeon 305-348, South Korea;Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Yoshinodai 3-1-1, Sagamihara, Kanagawa 229-8510, Japan;Department of Science Education, Kangwon National University, Hyoja-Dong, Chunchon-Si, Kangwon-Do 200-701, South Korea;Centre for Astrophysics and Planetary Science, University of Kent, Canterbury, Kent CT2 7NR |
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Abstract: | Fluctuations in the brightness of the background radiation can lead to confusion with real point sources. This type of confusion with background emission is relevant when making infrared (IR) observations with relatively large beam sizes, since the amount of fluctuation tends to increase with the angular scale. To quantitively assess the effect of the background emission on the detection of point sources for current and future far-IR observations by space-borne missions such as Spitzer , ASTRO-F , Herschel and Space Infrared Telescope for Cosmology and Astrophysics ( SPICA ), we have extended the Galactic emission map to a higher level of angular resolution than that of the currently available data. Using this high-resolution map, we estimate the sky confusion noise owing to the emission from interstellar dust clouds or cirrus, based on fluctuation analysis and detailed photometry over realistically simulated images. We find that the confusion noise derived by simple fluctuation analysis agrees well with the results from realistic simulations. Although sky confusion noise becomes dominant in long wavelength bands (>100 μm) with 60–90 cm aperture missions, it is expected to be two orders of magnitude lower for the next generation of space missions (with larger aperture sizes) such as Herschel and SPICA . |
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Keywords: | methods: data analysis techniques: image processing ISM: structure galaxies: photometry infrared: ISM |
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