Maps of Dust IR Emission for Use in Estimation of Reddening and CMBR Foregrounds

TL;DR: In this paper, the authors presented a reprocessed composite of the COBE/DIRBE and IRAS/ISSA maps, with the zodiacal foreground and confirmed point sources removed.

Abstract: We present a full sky 100 micron map that is a reprocessed composite of the COBE/DIRBE and IRAS/ISSA maps, with the zodiacal foreground and confirmed point sources removed. Before using the ISSA maps, we remove the remaining artifacts from the IRAS scan pattern. Using the DIRBE 100 micron and 240 micron data, we have constructed a map of the dust temperature, so that the 100 micron map can be converted to a map proportional to dust column density. The result of these manipulations is a map with DIRBE-quality calibration and IRAS resolution. To generate the full sky dust maps, we must first remove zodiacal light contamination as well as a possible cosmic infrared background (CIB). This is done via a regression analysis of the 100 micron DIRBE map against the Leiden- Dwingeloo map of H_I emission, with corrections for the zodiacal light via a suitable expansion of the DIRBE 25 micron flux. For the 100 micron map, no significant CIB is detected. In the 140 micron and 240 micron maps, where the zodiacal contamination is weaker, we detect the CIB at surprisingly high flux levels of 32 \pm 13 nW/m^2/sr at 140 micron, and 17 \pm 4 nW/m^2/sr at 240 micron (95% confidence). This integrated flux is ~2 times that extrapolated from optical galaxies in the Hubble Deep Field. The primary use of these maps is likely to be as a new estimator of Galactic extinction. We demonstrate that the new maps are twice as accurate as the older Burstein-Heiles estimates in regions of low and moderate reddening. These dust maps will also be useful for estimating millimeter emission that contaminates CMBR experiments and for estimating soft X-ray absorption.

Figures

FIG. 1.ÈThe 100 kmÈH I correlation with (a) no correction, (b) linear correction, and (c) quadratic correction for zodiacal contamination. The Ðts in the range [0, 200] K km s~1 are shown as solid lines.

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FIG. 13.ÈColor-color diagram for PSC sources. The diagonal line efficiently discriminates between galaxies (above the line) and stars (below the line). The square box is a strict color cut that retains 70% of stars. For clarity, only 1/10 of the stars are plotted.

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FIG. 7.ÈSlice of sky from (a) the BH map, (b) the Leiden-Dwingeloo H I map, (c) our dust map with DIRBE resolution, and (d) our dust map with IRAS resolution. The slice measures approximately 90¡ ] 30¡, centered at l \ 100¡, b \ ]35¡.

FIG. 2.ÈRatio of recovered vs. true column density of dust using a single-temperature Ðt to two components. A fraction of dust at tem-f Bperature is added to 18 K dust. The recovered column density is alwaysT Blower than the true column density, with contours spaced in units of 0.1.

FIG. 4.ÈFourier destriping of plate 379. (a) Raw ISSA HCON-0 image ; (b) FFT with wavenumber 0 in center ; (c) destriped image ; (d) FFT of destriped image. Note that one of the bins contains less power than the others. These are modes in which power from HCON-3 has replaced power in the otherkhHCONs; however HCON-3 covers only half the plate, resulting in less power.

FIG. 14.ÈContamination at 100 km from faint stars. The solid histogram represents the derived contamination at 100 km from stars with Ñuxes below our Ñux cut. The dotted histogram shows the Ñux from stars explicitly removed from the maps.

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FIG. 10.ÈH I correlation with (a) DIRBE 240 km (corrected for zodiacal contamination), (b) DIRBE 100 km (also corrected), and (c) our derived dust column density. This plot demonstrates that the gas to dust relationship deteriorates at high Ñux levels.

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FIG. 9.ÈPower spectrum of dust. The four solid curves represent four quadrants in the north Galactic sky at b [ 45¡, while the four dashed curves represent four quadrants of the south Galactic sky.

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FIG. 6.ÈResiduals from the B[V vs. regression, plotted againstMg2foreground reddening, for (a) the BH maps and (b) the DIRBE/IRAS maps. Pluses represent galaxies at southern declinations where the BH maps lack dust-to-gas ratio information, and asterisks are those lacking any BH values.

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