New Observational Constraints and Modeling of the Infrared Background: Dust Obscured Star-Formation at z>1 and Dust in the Outer Solar System

TL;DR

This study measures the integrated galaxy light in the far-infrared, revealing that a significant portion remains unresolved and placing new limits on dust-obscured star formation at high redshifts, while also suggesting the presence of ice mantle dust in the solar system.

Contribution

It provides improved measurements of the far-infrared background, identifies biases in previous stacking analyses, and constrains the contribution of high-redshift galaxies to the infrared background.

Findings

Integrated galaxy light accounts for 55-95% of the infrared background at 70-500 microns.

Previous stacking estimates were biased high due to multiple counting from clustering.

Constraints suggest less dust-obscured star formation at z>1 than ultraviolet estimates indicate.

Abstract

We provide measurements of the integrated galaxy light at 70, 160, 250, 350 and 500 micron using deep far-infrared and submillimeter data from space (Spitzer) and balloon platform (BLAST) extragalactic surveys. We use the technique of stacking at the positions of 24 micron sources, to supplement the fraction of the integrated galaxy light that is directly resolved through direct detections. We demonstrate that the integrated galaxy light even through stacking, falls short by factors of 2-3 in resolving the extragalactic far-infrared background. We also show that previous estimates of the integrated galaxy light (IGL) through stacking, have been biased towards high values. This is primarily due to multiple counting of the far-infrared/submillimeter flux from 24 micron sources which are clustered within the large point spread function of a brighter far-infrared source. Using models for the evolution of the luminosity function at z<1.2 which are constrained by observations at 24 micron and 70 micron, and which are consistent with the results from the stacking analysis, we find that galaxies at z<1.2, account for ~95-55% of the extragalactic far-infrared background in the ~70-500 micron range respectively. This places strong upper limits on the fraction of dust obscured star-formation at z>1, which are remarkably, below the values derived from the extinction corrected ultraviolet luminosities of galaxies. We use the results to make predictions for the nature of galaxies that extragalactic surveys with Herschel Space Observatory will reveal. Finally, from our constraints on the far-infrared IGL, we provide evidence for the existence of ice mantle dust, orbiting the sun at a distance of ~40 AU, which is contributing intensity to both the near- and far-infrared background. [ABRIDGED]