TheCOBEDiffuse Infrared Background Experiment Search for the Cosmic Infrared Background. I. Limits and Detections

Abstract

The Diffuse Infrared Background Experiment (DIRBE) on the Cosmic Background Explorer (COBE) spacecraft was designed primarily to conduct a systematic search for an isotropic cosmic infrared background (CIB) in ten photometric bands from 1.25 to 240 µm. The results of that search are presented here. Conservative limits on the CIB are obtained from the minimum observed brightness in all-sky maps at each wavelength, with the faintest limits in the DIRBE spectral range being at 3.5 µm (νI ν < 64 nW m −2 sr −1 , 95% CL) and at 240 µm (νI ν < 28 nW m −2 sr −1 , 95% CL). The bright foregrounds from interplanetary dust scattering and emission, stars, and interstellar dust emission are the principal impediments to the DIRBE measurements of the CIB. These foregrounds have been modeled and removed from the sky maps. Assessment of the random and systematic uncertainties in the residuals and tests for isotropy show that only the 140 and 240 µm data provide candidate detections of the CIB. The residuals and their uncertainties provide CIB upper limits more restrictive than the dark sky limits at wavelengths from 1.25 to 100 µm. No plausible solar system or Galactic source of the observed 140 and 240 µm residuals can be identified, leading to the conclusion that the CIB has been detected at levels of νI ν = 25 ± 7 and 14 ± 3 nW m −2 sr −1 at 140 and 240 µm respectively. The integrated energy from 140 to 240 µm, 10.3 nW m −2 sr −1 , is about twice the integrated optical light from the galaxies in the Hubble Deep Field, suggesting that star formation might have been heavily enshrouded by dust at high redshift. The detections and upper limits reported here provide new constraints on models of the history of energy-releasing processes and dust production since the decoupling of the cosmic microwave background from matter.

Submillimetre-wavelength detection of dusty star-forming galaxies at high redshift

“…Our value corresponds to a ν S ν , where S ν is the sky surface brightness, of 3.7 × 10 −8 ergs cm −2 s −1 ster −1 , which is a factor of a few less than current limits on the extragalactic background light. 13,14,15,16,17 Our strongest source in the two fields is the 4.6 mJy (∼ 6σ) source in the Lockman hole. In Figure 2 we show a deep K ′ image of the Lockman hole SCUBA field with a 3 mJy/beam contour superimposed on the bright source.…”

Dissecting the cosmic infra-red background withHerschel/PEP

“…After the discovery of the CIB (Puget et al 1996;Hauser et al 1998), numerous authors attempted to directly measure its surface brightness from COBE/DIRBE maps (e.g. Lagache et al 2000;Renault et al 2001;Wright 2004;Dole et al 2006 at 160 μm.…”

“…The cosmic IR background (CIB, Puget et al 1996;Hauser et al 1998) accounts for roughly half of the total extragalactic background light (EBL, Hauser & Dwek 2001;Lagache et al 2005), i.e., half of the energy radiated by all galaxies, at all cosmic epochs, at any wavelength (Dole et al 2006). It is therefore a crucial constraint on modes and times of galaxy formation.…”

X-ray Surveys of the Obscured Universe

“…The cosmic energy density spectrum from radio waves to high energy gamma rays in a νIν representation, where a horizontal line corresponds to equal radiation power per decade of energy. The FIR to UV data are from (left to right) [35,13,22,45,33,2]. The dotted line shows one of the models in [9] extrapolated from the visual to the EUV range.…”

“…the CMB, the interplanetary dust emission, the interstellar dust emission, scattering from the interplanetary dust (zodiacal light), galactic starlight and scattering by inter-stellar dust. In the far-infrared range different groups have recently detected the long-sought residual cosmic far-infrared background (CIB) signal [35,22,13] by carefully modelling the other components in the high-frequency tail of the Cosmic Microwave Background (see fig. 1).…”