ISOPHOT Surveys and the Extragalactic Background

Abstract

The higher spatial resolution and sensitivity of ISO allowed several extragalactic surveys to be extended to greater depth than obtained with IRAS. With the extended wavelength range deep surveys were performed for the first time at wavelengths up to ~ 200 μm. They favour galaxy models with strong evolution. With ISO's new capabilities the spectral energy distributions of larger samples of ULIRGs in the local universe and those of quasars and radio galaxies were determined. These data are applicable as templates to the more distant universe. Foreground components from zodiacal light and cirrus to the intracluster dust emission were studied in connection with their separation from the extragalactic background radiation.

Sky confusion noise in the far-infrared: Cirrus, galaxies and the cosmic far-infrared background

“…The 170 µm confusion noise C 0 = 15 ± 4 mJy is in good agreement with the 13 mJy obtained by Juvela et al (see the overview of Lemke et al 2000), and somewhat lower than the values of 18 mJy determined by Lagache & Puget (2000) from the analysis of the Marano 1 field and the 22 mJy derived by Matsuhara et al (2000) from the investigation of the Lockman Hole region. Our derived CFIRB value of 14 ± 3 nW m −2 sr −1 is the same as predicted from models by Pei et al (1999).…”

“…Ackermann et al (1992) investigated the sensitivity limits, including the effect of the CFIRB, for ISOPHOT and predicted that the long wavelength observations would be limited by galaxy confusion in the regions of faintest cirrus. Recently Lagache & Puget (2000), Matsuhara et al (2000) and Juvela et al (for an overview see Lemke et al (2000)) analysed ISOPHOT maps and separated the cirrus and extragalactic components. They announced the detection of the CFIRB with a fluctuation power in the range of 5 − 12×10 3 Jy 2 sr −1 at 170 and 180 µm, close to the predictions of Guiderdoni et al (1997).…”