Infrared Sky Background

Review written by Csaba Kiss
Team: Cs. Kiss, P. Ábrahám, A. Pál, V. Asbóth


The night sky is nowhere empty. There is always some source of light even between the faintest stars or galaxies, and the origin of this glow cannot be easily determined. Astronomers usually refer to this phenomenon as the 'sky background': a (usually) faint glow between interesting objects. The definition of the background always depends on the actual measurement configuration, but there are two main classes. A background can be intrinsically diffuse (like e.g. the gas clouds of our Galaxy) or made of the accumulated light of unresolved sources (like the diffuse glow of the Milky Way for human's eye).In the latter case a better resolution decrease the number of sources in the background. A 'background' limits the detectability of faint sources in two ways. First, sources fainter than the background cannot be observed (photometric criterion) and second, the sources must be far enough from each other to see them separately (source density criterion). These limitations are commonly referred as the 'confusion noise'. (more)

Figure 3: Components of the far-infrared sky background and their distance scales.

We investigate two major aspects of the CFIRB:

    - Separation of the components of the Cosmic Far-Infrared Background:
    1. via differences in the spatial structure (Fourier spectra and confusion noise)
    2. absolute photometry using some specific observing modes The final aim is the determination of the absolute level of the cosmic far-infrared background
    - Detailed study of far-infrared confusion noise properties:
    1. dependence on wavelength, measurement configuration, etc.
    2. confusion noise limit prediction for current and future far-infrared space missions (Spitzer, ASTRO-F, Herschel)

Title Participants Project Page
Separating the extragalactic background from its foreground components at infrared wavelengths (M.S. Thesis of Viktória Asbóth) V. Asbóth, Kiss, Cs.
Far-infrared confusion noise as determined from Herschel measurements Kiss, Cs.

Previous projects

Title Participants ADS link Project Page
Small-scale structure of the galactic cirrus emission (2003) Kiss, Cs.; Ábrahám, P.; Klaas, U.; Lemke, D.; Héraudeau, Ph.; del Burgo, C.; Herbstmeier, U.
Mid-infrared spectrum of the zodiacal light observed with ISOPHOT (2002) Leinert, Ch.; Ábrahám, P.; Acosta-Pulido, J.; Lemke, D.; Siebenmorgen, R.
Sky confusion noise in the far-infrared: Cirrus, galaxies and the cosmic far-infrared background (2001) Kiss, Cs.; Ábrahám, P.; Klaas, U.; Juvela, M.; Lemke, D.
Zodiacal light observations with the Infrared Space Observatory (2000) Abraham, P.; Leinert, C.; Lemke, D.