DIRBE Minus 2MASS: Confirming the CIRB in 40 New Regions at 2.2 and 3.5 μm

Abstract

With the release of the 2MASS All-Sky Point Source Catalog, stellar fluxes from 2MASS are used to remove the contribution due to Galactic stars from the intensity measured by DIRBE in 40 new regions in the North and South Galactic polar caps. After subtracting the interplanetary and Galactic foregrounds, a consistent residual intensity of 14.69 ± 4.49 kJy sr-1 at 2.2 μm is found. Allowing for a constant calibration factor between the DIRBE 3.5 μm and the 2MASS 2.2 μm fluxes, a similar analysis leaves a residual intensity of 15.62 ± 3.34 kJy sr-1 at 3.5 μm. The intercepts of the DIRBE minus 2MASS correlation at 1.25 μm show more scatter and are a smaller fraction of the foreground, leading to a still weak limit on the CIRB of 8.88 ± 6.26 kJy sr-1 (1 σ).